[Illustration: ORVILLE WRIGHT IN THE 80-MILE-AN-HOUR “BABY WRIGHT”
RACER.]
How It Flies
or,
THE CONQUEST OF THE AIR
The Story of Man’s Endeavors to Fly and of the
Inventions by which He Has Succeeded
By
RICHARD FERRIS, B.S., C.E.
Illustrated by Over One Hundred and Fifty Half-tones and Line
Drawings, Showing the Stages of Development from the
Earliest Balloon to the Latest Monoplane and Biplane
New York
THOMAS NELSON AND SONS
381-385 Fourth Avenue
Copyright, 1910, by
THOMAS NELSON & SONS
THE TROW PRESS, NEW YORK
PREFACE
In these pages, by means of simple language and suitable pictures, the
author has told the story of the Ships of the Air. He has explained
the laws of their flight; sketched their development to the present
day; shown how to build the flying machine and the balloon, and how
to operate them; recounted what man has done, and what he hopes to do
with their aid. In a word, all the essential facts that enter into the
Conquest of the Air have been gathered into orderly form, and are here
presented to the public.
We who live to-day have witnessed man’s great achievement; we have seen
his dream of ages come true. Man has learned to _fly_!
The air which surrounds us, so intangible and so commonplace that
it seldom arrests our attention, is in reality a vast, unexplored
ocean, fraught with future possibilities. Even now, the pioneers of
a countless fleet are hovering above us in the sky, while steadily,
surely these wonderful possibilities are unfolded.
The Publishers take pleasure in acknowledging their indebtedness to the
_Scientific American_ for their courtesy in permitting the use of many
of the illustrations appearing in this book.
NEW YORK, October 20, 1910.
CONTENTS
CHAPTER PAGE
PREFACE 7
I. INTRODUCTORY 11
II. THE AIR 20
III. LAWS OF FLIGHT 37
IV. FLYING MACHINES 55
V. FLYING MACHINES: THE BIPLANE 78
VI. FLYING MACHINES: THE MONOPLANE 112
VII. FLYING MACHINES: OTHER FORMS 141
VIII. FLYING MACHINES: HOW TO OPERATE 151
IX. FLYING MACHINES: HOW TO BUILD 174
X. FLYING MACHINES: MOTORS 193
XI. MODEL FLYING MACHINES 215
XII. THE GLIDER 241
XIII. BALLOONS 257
XIV. BALLOONS: THE DIRIGIBLE 296
XV. BALLOONS: HOW TO OPERATE 340
XVI. BALLOONS: HOW TO MAKE 351
XVII. MILITARY AERONAUTICS 363
XVIII. BIOGRAPHIES OF PROMINENT AERONAUTS 379
XIX. CHRONICLE OF AVIATION ACHIEVEMENTS 407
XX. EXPLANATION OF AERONAUTICAL
TERMS 452
HOW IT FLIES
Chapter I.
INTRODUCTORY.
The sudden awakening--Early successes--Influence of the gasoline
engine on aeroplanes--On dirigible balloons--Interested
inquiry--Some general terms defined.
In the year 1908 the world awakened suddenly to the realization that at
last the centuries of man’s endeavor to fly mechanically had come to
successful fruition.
There had been a little warning. In the late autumn of 1906,
Santos-Dumont made a flight of 720 feet in a power-driven machine.
There was an exclamation of wonder, a burst of applause--then a relapse
into unconcern.
In August, 1907, Louis Bleriot sped free of the ground for 470 feet;
and in November, Santos-Dumont made two flying leaps of barely 500
feet. That was the year’s record, and it excited little comment. It is
true that the Wright brothers had been making long flights, but they
were in secret. There was no public knowledge of them.
In 1908 came the revelation. In March, Delagrange flew in a Voisin
biplane 453 feet, carrying Farman with him as a passenger. Two weeks
later he flew alone nearly 2½ miles. In May he flew nearly 8 miles. In
June his best flight was 10½ miles. Bleriot came on the scene again
in July with a monoplane, in which he flew 3¾ miles. In September,
Delagrange flew 15 miles--in less than 30 minutes. In the same month
the Wrights began their wonderful public flights. Wilbur, in France,
made records of 41, 46, 62, and 77 miles, while Orville flew from 40 to
50 miles at Fort Myer, Va. Wilbur Wright’s longest flight kept him in
the air 2 hours and 20 minutes.
The goal had been reached--men had achieved the apparently impossible.
The whole world was roused to enthusiasm.
Since then, progress has been phenomenally rapid, urged on by the
striving of the inventors, the competition of the aircraft builders,
and the contests for records among the pilots.
By far the largest factor in the triumph of the aeroplane is the
improved gasoline engine, designed originally for automobiles. Without
this wonderful type of motor, delivering a maximum of power with a
minimum of weight, from concentrated fuel, the flying machine would
still be resting on the earth.
[Illustration: The Renard and Krebs airship _La France_, at
Chalais-Meudon.]
Nor has the influence of the gasoline motor been much less upon that
other great class of aircraft, the dirigible balloon. After 1885, when
Renard and Krebs’ airship _La France_ made its two historic voyages
from Chalais-Meudon to Paris, returning safely to its shed, under the
propulsion of an electric motor, the problem of the great airship lay
dormant, waiting for the discovery of adequate motive power. If the
development of the dirigible balloon seems less spectacular than that
of the aeroplane, it is because the latter had to be created; the
dirigible, already in existence, had only to be revivified.
Confronted with these new and strange shapes in the sky, some making
stately journeys of hundreds of miles, others whirring hither and
thither with the speed of the whirlwind, wonder quickly gives way to
the all-absorbing question: _How do they fly?_ To answer fully and
satisfactorily, it seems wise, for many readers, to recall in the
succeeding chapters some principles doubtless long since forgotten.
* * * * *
As with every great advance in civilization, this expansion of the
science of aeronautics has had its effect upon the language of the day.
Terms formerly in use have become restricted in application, and other
terms have been coined to convey ideas so entirely new as to find no
suitable word existent in our language. It seems requisite, therefore,
first to acquaint the reader with clear definitions of the more common
terms that are used throughout this book.
_Aeronautics_ is the word employed to designate the entire subject of
aerial navigation. An _aeronaut_ is a person who sails, or commands,
any form of aircraft, as distinguished from a passenger.
_Aviation_ is limited to the subject of flying by machines which are
not floated in the air by gas. An _aviator_ is an operator of such
machine.
[Illustration: A free balloon, with parachute.]
Both aviators and aeronauts are often called _pilots_.
A _balloon_ is essentially an envelope or bag filled with some gaseous
substance which is lighter, bulk for bulk, than the air at the surface
of the earth, and which serves to float the apparatus in the air. In
its usual form it is spherical, with a car or basket suspended below
it. It is a _captive balloon_ if it is attached to the ground by a
cable, so that it may not rise above a certain level, nor float away in
the wind. It is a _free balloon_ if not so attached or anchored, but is
allowed to drift where the wind may carry it, rising and falling at the
will of the pilot.
[Illustration: A dirigible balloon.]
A _dirigible balloon_, sometimes termed simply a dirigible, usually has
its gas envelope elongated in form. It is fitted with motive power to
propel it, and steering mechanism to guide it. It is distinctively the
_airship_.
_Aeroplanes_ are those forms of flying machines which depend for their
support in the air upon the spread of surfaces which are variously
called wings, sails, or planes. They are commonly driven by propellers
actuated by motors. When not driven by power they are called _gliders_.
[Illustration: A biplane glider.]
Aeroplanes exist in several types: the _monoplane_, with one spread
of surface; the _biplane_, with two spreads, one above the other; the
_triplane_, with three spreads, or decks; the _multiplane_, with more
than three.
The _tetrahedral plane_ is a structure of many small cells set one upon
another.
_Ornithopter_ is the name given to a flying machine which is operated
by flapping wings.
[Illustration: A parachute descending.]
_Helicopter_ is used to designate machines which are lifted vertically
and sustained in the air by propellers revolving in a horizontal plane,
as distinguished from the propellers of the aeroplane, which revolve in
vertical planes.
A _parachute_ is an umbrella-like contrivance by which an aeronaut may
descend gently from a balloon in mid-air, buoyed up by the compression
of the air under the umbrella.
For the definition of other and more technical terms the reader is
referred to the carefully prepared Glossary toward the end of the book.
Chapter II.
THE AIR.
Intangibility of air--Its
substance--Weight--Extent--Density--Expansion
by heat--Alcohol fire--Turbulence of the
air--Inertia--Elasticity--Viscosity--Velocity of
winds--Aircurrents--Cloud levels--Aerological stations--High
altitudes--Practical suggestions--The ideal highway.
The air about us seems the nearest approach to nothingness that we know
of. A pail is commonly said to be empty--to have nothing in it--when it
is filled only with air. This is because our senses do not give us any
information about air. We cannot see it, hear it, touch it.
When air is in motion (wind) we hear the noises it makes as it passes
among other objects more substantial; and we feel it as it blows by us,
or when we move rapidly through it.
We get some idea that it exists as a substance when we see dead leaves
caught up in it and whirled about; and, more impressively, when in the
violence of the hurricane it seizes upon a body of great size and
weight, like the roof of a house, and whisks it away as though it were
a feather, at a speed exceeding that of the fastest railroad train.
In a milder form, this invisible and intangible air does some of our
work for us in at least two ways that are conspicuous: it moves ships
upon the ocean, and it turns a multitude of windmills, supplying the
cheapest power known.
That this atmosphere is really a fluid ocean, having a definite
substance, and in some respects resembling the liquid ocean upon which
our ships sail, and that we are only crawling around on the bottom
of it, as it were, is a conception we do not readily grasp. Yet this
conception must be the foundation of every effort to sail, to fly, in
this aerial ocean, if such efforts are to be crowned with success.
As a material substance the air has certain physical properties, and
it is the part of wisdom for the man who would fly to acquaint himself
with these properties. If they are helpful to his flight, he wants to
use them; if they hinder, he must contrive to overcome them.
In general, it may be said that the air, being in a gaseous form,
partakes of the properties of all gases--and these may be studied
in any text-book on physics, Here we are concerned only with those
qualities which affect conditions under which we strive to fly.
Of first importance is the fact that air has _weight_. That is, in
common with all other substances, it is attracted by the mass of the
earth exerted through the force we call gravity. At the level of the
sea, this attraction causes the air to press upon the earth with a
weight of nearly fifteen pounds (accurately, 14.7 lbs.) to the square
inch, when the temperature is at 32° F. That pressure is the weight of
a column of air one inch square at the base, extending upward to the
outer limit of the atmosphere--estimated to be about 38 miles (some say
100 miles) above sea-level. The practical fact is that normal human
life cannot exist above the level of 15,000 feet, or a little less than
three miles; and navigation of the air will doubtless be carried on at
a much lower altitude, for reasons which will appear as we continue.
The actual weight of a definite quantity of dry air--for instance,
a cubic foot--is found by weighing a vessel first when full of air,
and again after the air has been exhausted from it with an air-pump.
In this way it has been determined that a cubic foot of dry air,
at the level of the sea, and at a temperature of 32° F., weighs 565
grains--about 0.0807 lb. At a height above the level of the sea, a
cubic foot of air will weigh less than the figure quoted, for its
density decreases as we go upward, the pressure being less owing to
the diminished attraction of the earth at the greater distance. For
instance, at the height of a mile above sea-level a cubic foot of air
will weigh about 433 grains, or 0.0619 lb. At the height of five miles
it will weigh about 216 grains, or 0.0309 lb. At thirty-eight miles
it will have no weight at all, its density being so rare as just to
balance the earth’s attraction. It has been calculated that the whole
body of air above the earth, if it were all of the uniform density of
that at sea-level, would extend only to the height of 26,166 feet.
Perhaps a clearer comprehension of the weight and pressure of the ocean
of air upon the earth may be gained by recalling that the pressure of
the 38 miles of atmosphere is just equal to balancing a column of water
33 feet high. The pressure of the air, therefore, is equivalent to the
pressure of a flood of water 33 feet deep.
[Illustration: Comparative Elevations of Earth and Air.]
But air is seldom dry. It is almost always mingled with the vapor
of water, and this vapor weighs only 352 grains per cubic foot at
sea-level. Consequently the mixture--damp air--is lighter than dry air,
in proportion to the moisture it contains.
[Illustration: Apparatus to show effects of heat on air currents. _a_,
alcohol lamp; _b_, ice. The arrows show direction of currents.]
Another fact very important to the aeronaut is that the air is in
_constant motion_. Owing to its ready expansion by heat, a body of
air occupying one cubic foot when at a temperature of 32° F. will
occupy more space at a higher temperature, and less space at a lower
temperature. Hence, heated air will flow upward until it reaches a
point where the natural density of the atmosphere is the same as its
expanded density due to the heating. Here another complication comes
into play, for ascending air is cooled at the rate of one degree for
every 183 feet it rises; and as it cools it grows denser, and the speed
of its ascension is thus gradually checked. After passing an altitude
of 1,000 feet the decrease in temperature is one degree for each 320
feet of ascent. In general, it may be stated that air is expanded
one-tenth of its volume for each 50° F. that its temperature is raised.
This highly unstable condition under ordinary changes of temperature
causes continual movements in the air, as different portions of it are
constantly seeking that position in the atmosphere where their density
at that moment balances the earth’s attraction.
Sir Hiram Maxim relates an incident which aptly illustrates the effect
of change of temperature upon the air. He says: “On one occasion,
many years ago, I was present when a bonded warehouse in New York
containing 10,000 barrels of alcohol was burned.... I walked completely
around the fire, and found things just as I expected. The wind was
blowing a perfect hurricane through every street in the direction of
the fire, although it was a dead calm everywhere else; the flames
mounted straight in the air to an enormous height, and took with them a
large amount of burning wood. When I was fully 500 feet from the fire,
a piece of partly burned one-inch board, about 8 inches wide and 4 feet
long, fell through the air and landed near me. This board had evidently
been taken up to a great height by the tremendous uprush of air caused
by the burning alcohol.”
That which happened on a small scale, with a violent change of
temperature, in the case of the alcohol fire, is taking place on a
larger scale, with milder changes in temperature, all over the world.
The heating by the sun in one locality causes an expansion of air
at that place, and cooler, denser air rushes in to fill the partial
vacuum. In this way winds are produced.
So the air in which we are to fly is in a state of constant motion,
which may be likened to the rush and swirl of water in the rapids of a
mountain torrent. The tremendous difference is that the perils of the
water are in plain sight of the navigator, and may be guarded against,
while those of the air are wholly invisible, and must be met as they
occur, without a moment’s warning.
[Illustration:
The solid arrows show the directions of a cyclonic wind on
the earth’s surface. At the centre the currents go directly
upward. In the upper air above the cyclone the currents have the
directions of the dotted arrows.]
Next in importance, to the aerial navigator, is the air’s _resistance_.
This is due in part to its density at the elevation at which he is
flying, and in part to the direction and intensity of its motion, or
the wind. While this resistance is far less than that of water to the
passage of a ship, it is of serious moment to the aeronaut, who must
force his fragile machine through it at great speed, and be on the
alert every instant to combat the possibility of a fall as he passes
into a rarer and less buoyant stratum.
[Illustration:
Diagram showing disturbance of wind currents by inequalities of
the ground, and the smoother currents of the upper air. Note the
increase of density at A and B, caused by compression against the
upper strata.]
Three properties of the air enter into the sum total of its
resistance--inertia, elasticity, and viscosity. Inertia is its tendency
to remain in the condition in which it may be: at rest, if it is still;
in motion, if it is moving. Some force must be applied to disturb this
inertia, and in consequence when the inertia is overcome a certain
amount of force is used up in the operation. Elasticity is that
property by virtue of which air tends to reoccupy its normal amount
of space after disturbance. An illustration of this tendency is the
springing back of the handle of a bicycle pump if the valve at the
bottom is not open, and the air in the pump is simply compressed, not
forced into the tire. Viscosity may be described as “stickiness”--the
tendency of the particles of air to cling together, to resist
separation. To illustrate: molasses, particularly in cold weather,
has greater viscosity than water; varnish has greater viscosity than
turpentine. Air exhibits some viscosity, though vastly less than that
of cold molasses. However, though relatively slight, this viscosity has
a part in the resistance which opposes the rapid flight of the airship
and aeroplane; and the higher the speed, the greater the retarding
effect of viscosity.
The inertia of the air, while in some degree it blocks the progress
of his machine, is a benefit to the aeronaut, for it is inertia which
gives the blades of his propeller “hold” upon the air. The elasticity
of the air, compressed under the curved surfaces of the aeroplane, is
believed to be helpful in maintaining the lift. The effect of viscosity
may be greatly reduced by using surfaces finished with polished
varnish--just as greasing a knife will permit it to be passed with
less friction through thick molasses.
In the case of winds, the inertia of the moving mass becomes what is
commonly termed “wind pressure” against any object not moving with it
at an equal speed. The following table gives the measurements of wind
pressure, as recorded at the station on the Eiffel Tower, for differing
velocities of wind:
+----------+------------+---------------+
| Velocity | Velocity | Pressure |
| in Miles | in Feet | in Pounds on |
| per Hour | per Second | a Square Foot |
+----------+------------+---------------+
| 2 | 2.9 | 0.012 |
| 4 | 5.9 | 0.048 |
| 6 | 8.8 | 0.108 |
| 8 | 11.7 | 0.192 |
| 10 | 14.7 | 0.300 |
| 15 | 22.0 | 0.675 |
| 20 | 29.4 | 1.200 |
| 25 | 36.7 | 1.875 |
| 30 | 44.0 | 2.700 |
| 35 | 51.3 | 3.675 |
| 40 | 58.7 | 4.800 |
| 45 | 66.0 | 6.075 |
| 50 | 73.4 | 7.500 |
| 60 | 88.0 | 10.800 |
| 70 | 102.7 | 14.700 |
| 80 | 117.2 | 19.200 |
| 90 | 132.0 | 24.300 |
| 100 | 146.7 | 30.000 |
+----------+------------+---------------+
In applying this table, the velocity to be considered is the net
velocity of the movements of the airship and of the wind. If the ship
is moving 20 miles an hour _against_ a head wind blowing 20 miles an
hour, the net velocity of the wind will be 40 miles an hour, and the
pressure 4.8 lbs. a square foot of surface presented. Therefore the
airship will be standing still, so far as objects on the ground are
concerned. If the ship is sailing 20 miles an hour _with_ the wind,
which is blowing 20 miles an hour, the pressure per square foot will be
only 1.2 lbs.; while as regards objects on the ground, the ship will be
travelling 40 miles an hour.
[Illustration:
Apparatus for the study of the action of air in motion; a blower
at the farther end of the great tube sends a “wind” of any
desired velocity through it. Planes and propellers of various
forms are thus tested.]
Systematic study of the movements of the air currents has not been
widespread, and has not progressed much beyond the gathering of
statistics which may serve as useful data in testing existing theories
or formulating new ones.
It is already recognized that there are certain “tides” in the
atmosphere, recurring twice daily in six-hour periods, as in the case
of the ocean tides, and perhaps from the same causes. Other currents
are produced by the earth’s rotation. Then there are the five-day
oscillations noted by Eliot in India, and daily movements, more or less
regular, due to the sun’s heat by day and the lack of it by night.
The complexity of these motions makes scientific research extremely
difficult.
Something definite has been accomplished in the determination of wind
velocities, though this varies largely with the locality. In the United
States the average speed of the winds is 9½ miles per hour; in Europe,
10⅓ miles; in Southern Asia, 6½ miles; in the West Indies, 6⅕ miles; in
England, 12 miles; over the North Atlantic Ocean, 29 miles per hour.
Each of these average velocities varies with the time of year and time
of day, and with the distance from the sea. The wind moves faster over
water and flat, bare land than over hilly or forest-covered areas.
Velocities increase as we go upward in the air, being at 1,600 feet
twice what they are at 100 feet. Observations of the movements of cloud
forms at the Blue Hill Observatory, near Boston, give the following
results:
+---------------+---------+---------------+
| Cloud Form | Height | Average Speed |
| | in Feet | per Hour |
+---------------+---------+---------------+
| Stratus | 1,676 | 19 miles. |
| Cumulus | 5,326 | 24 miles. |
| Alto-cumulus | 12,724 | 34 miles. |
| Cirro-cumulus | 21,888 | 71 miles. |
| Cirrus | 29,317 | 78 miles. |
+---------------+---------+---------------+
In winter the speed of cirrus clouds may reach 96 miles per hour.
There are forty-nine stations scattered over Germany where statistics
concerning winds are gathered expressly for the use of aeronauts. At
many of these stations records have been kept for twenty years. Dr.
Richard Assman, director of the aerological observatory at Lindenburg,
has prepared a comprehensive treatise of the statistics in possession
of these stations, under the title of _Die Winde in Deutschland_. It
shows for each station, and for each season of the year, how often the
wind blows from each point of the compass; the average frequency of
the several degrees of wind; when and where aerial voyages may safely
be made; the probable drift of dirigibles, etc. It is interesting to
note that Friedrichshafen, where Count Zeppelin’s great airship sheds
are located, is not a favorable place for such vessels, having a yearly
record of twenty-four stormy days, as compared with but two stormy days
at Celle, four at Berlin, four at Cassel, and low records at several
other points.
In practical aviation, a controlling factor is the density of the air.
We have seen that at an altitude of five miles the density is about
three-eighths the density at sea-level. This means that the supporting
power of the air at a five-mile elevation is so small that the area of
the planes must be increased to more than 2½ times the area suited to
flying near the ground, or that the speed must be largely increased.
Therefore the adjustments necessary for rising at the lower level and
journeying in the higher level are too large and complex to make flying
at high altitudes practicable--leaving out of consideration the bitter
cold of the upper regions.
Mr. A. Lawrence Rotch, director of the Blue Hill Observatory, in his
valuable book, _The Conquest of the Air_, gives this practical summary
of a long series of studious observations: “At night, however, because
there are no ascending currents, the wind is much steadier than in the
daytime, making night the most favorable time for aerial navigation
of all kinds.... A suitable height in the daytime, unless a strong
westerly wind is sought, lies above the cumulus clouds, at the height
of about a mile; but at night it is not necessary to rise so high; and
in summer a region of relatively little wind is found at a height of
about three-fourths of a mile, where it is also warmer and drier than
in the daytime or at the ground.”
Notwithstanding all difficulties, the fact remains that, once they are
overcome, the air is the ideal highway for travel and transportation.
On the sea, a ship may sail to right or left on one plane only. In
the air, we may steer not only to right or left, but above and below,
and obliquely in innumerable planes. We shall not need to traverse
long distances in a wrong direction to find a bridge by which we may
cross a river, nor zigzag for toilsome miles up the steep slopes of a
mountain-side to the pass where we may cross the divide. The course of
the airship is the proverbial bee-line--the most economical in time as
well as in distance.
Chapter III.
LAWS OF FLIGHT.
The bird--Nature’s models--Man’s methods--Gravity--The
balloon--The airship--Resistance of the air--Winds--The
kite--Laws of motion and force--Application to
kite-flying--Aeroplanes.
If we were asked to explain the word “flying” to some foreigner who did
not know what it meant, we should probably give as an illustration the
bird. This would be because the bird is so closely associated in our
thoughts with flying that we can hardly think of the one without the
other.
It is natural, therefore, that since men first had the desire to fly
they should study the form and motions of the birds in the air, and
try to copy them. Our ancestors built immense flopping wings, into
the frames of which they fastened themselves, and with great muscular
exertion of arms and legs strove to attain the results that the bird
gets by apparently similar motions.
However, this mental coupling of the bird with the laws of flight has
been unfortunate for the achievement of flight by man. And this is
true even to the present day, with its hundreds of successful flying
machines that are not in the least like a bird. This wrongly coupled
idea is so strong that scientific publications print pages of research
by eminent contributors into the flight of birds, with the attempt
to deduce lessons therefrom for the instruction of the builders and
navigators of flying machines.
These arguments are based on the belief that Nature never makes a
mistake; that she made the bird to fly, and therefore the bird must be
the most perfect model for the successful flying machine. But the truth
is, the bird was not made primarily to fly, any more than man was made
to walk. Flying is an incident in the life of a bird, just as walking
is an incident in the life of a man. Flying is simply a bird’s way of
getting about from place to place, on business or on pleasure, as the
case may be.
Santos-Dumont, in his fascinating book, _My Air-Ships_, points out
the folly of blindly following Nature by showing that logically such
a procedure would compel us to build our locomotives on the plan of
gigantic horses, with huge iron legs which would go galloping about
the country in a ridiculously terrible fashion; and to construct our
steamships on the plan of giant whales, with monstrous flapping fins
and wildly lashing tails.
Sir Hiram Maxim says something akin to this in his work, _Artificial
and Natural Flight_: “It appears to me that there is nothing in Nature
which is more efficient, or gets a better grip on the water, than a
well-made screw propeller; and no doubt there would have been fish with
screw propellers, providing Dame Nature could have made an animal in
two pieces. It is very evident that no living creature could be made in
two pieces, and two pieces are necessary if one part is stationary and
the other revolves; however, the tails and fins very often approximate
to the action of propeller blades; they turn first to the right and
then to the left, producing a sculling effect which is practically the
same. This argument might also be used against locomotives. In all
Nature we do not find an animal travelling on wheels, but it is quite
possible that a locomotive might be made that would walk on legs at
the rate of two or three miles an hour. But locomotives with wheels
are able to travel at least three times as fast as the fleetest animal
with legs, and to continue doing so for many hours at a time, even when
attached to a very heavy load. In order to build a flying machine with
flapping wings, to exactly imitate birds, a very complicated system of
levers, cams, cranks, etc., would have to be employed, and these of
themselves would weigh more than the wings would be able to lift.”
As with the man-contrived locomotive, so the perfected airship will be
evolved from man’s understanding of the obstacles to his navigation
of the air, and his overcoming of them by his inventive genius. This
will not be in Nature’s way, but in man’s own way, and with cleverly
designed machinery such as he has used to accomplish other seeming
impossibilities. With the clearing up of wrong conceptions, the path
will be open to more rapid and more enduring progress.
When we consider the problem of flying, the first obstacle we encounter
is the attraction which the earth has for us and for all other objects
on its surface. This we call weight, and we are accustomed to measure
it in pounds.
Let us take, for example, a man whose body is attracted by the earth
with a force, or weight, of 150 pounds. To enable him to rise into the
air, means must be contrived not only to counteract his weight, but to
lift him--a force a little greater than 150 pounds must be exerted. We
may attach to him a bag filled with some gas (as hydrogen) for which
the earth has less attraction than it has for air, and which the air
will push out of the way and upward until a place above the earth is
reached where the attraction of air and gas is equal. A bag of this
gas large enough to be pushed upward with a force equal to the weight
of the man, plus the weight of the bag, and a little more for lifting
power, will carry the man up. This is the principle of the ordinary
balloon.
Rising in the air is not flying. It is a necessary step, but real
flying is to travel from place to place through the air. To accomplish
this, some mechanism, or machinery, is needed to propel the man after
he has been lifted into the air. Such machinery will have weight,
and the bag of gas must be enlarged to counterbalance it. When this
is done, the man and the bag of gas may move through the air, and
with suitable rudders he may direct his course. This combination of
the lifting bag of gas and the propelling machinery constitutes the
dirigible balloon, or airship.
[Illustration: Degen’s apparatus to lift the man and his flying
mechanism with the aid of a gas-balloon. See Chapter IV.]
The airship is affected equally with the balloon by prevailing winds.
A breeze blowing 10 miles an hour will carry a balloon at nearly that
speed in the direction in which it is blowing. Suppose the aeronaut
wishes to sail in the opposite direction? If the machinery will propel
his airship only 10 miles an hour in a calm, it will virtually stand
still in the 10-mile breeze. If the machinery will propel his airship
20 miles an hour in a calm, the ship will travel 10 miles an hour--as
related to places on the earth’s surface--against the wind. But so far
as the air is concerned, his speed through it is 20 miles an hour,
and each increase of speed meets increased resistance from the air,
and requires a greater expenditure of power to overcome. To reduce
this resistance to the least possible amount, the globular form of the
early balloon has been variously modified. Most modern airships have a
“cigar-shaped” gas bag, so called because the ends look like the tip
of a cigar. As far as is known, this is the balloon that offers less
resistance to the air than any other.
Another mechanical means of getting up into the air was suggested
by the flying of kites, a pastime dating back at least 2,000 years,
perhaps longer. Ordinarily, a kite will not fly in a calm, but with
even a little breeze it will mount into the air by the upward thrust
of the rushing breeze against its inclined surface, being prevented
from blowing away (drifting) by the pull of the kite-string. The same
effect will be produced in a dead calm if the operator, holding
the string, runs at a speed equal to that of the breeze--with this
important difference: not only will the kite rise in the air, but it
will travel in the direction in which the operator is running, a part
of the energy of the runner’s pull upon the string producing a forward
motion, provided he holds the string taut. If we suppose the pull on
the string to be replaced by an engine and revolving propeller in the
kite, exerting the same force, we have exactly the principle of the
aeroplane.
As it is of the greatest importance to possess a clear understanding of
the natural processes we propose to use, let us refer to any text-book
on physics, and review briefly some of the natural laws relating to
motion and force which apply to the problem of flight:
(_a_) Force is that power which changes or tends to change the
position of a body, whether it is in motion or at rest.
(_b_) A given force will produce the same effect, whether the
body on which it acts is acted upon by that force alone, or by
other forces at the same time.
(_c_) A force may be represented graphically by a straight
line--the point at which the force is applied being the beginning
of the line; the direction of the force being expressed by the
direction of the line; and the magnitude of the force being
expressed by the length of the line.
(_d_) Two or more forces acting upon a body are called component
forces, and the single force which would produce the same effect
is called the resultant.
(_e_) When two component forces act in different directions
the resultant may be found by applying the principle of the
parallelogram of forces--the lines (_c_) representing the
components being made adjacent sides of a parallelogram, and the
diagonal drawn from the included angle representing the resultant
in direction and magnitude.
(_f_) Conversely, a resultant motion may be resolved into its
components by constructing a parallelogram upon it as the
diagonal, either one of the components being known.
[Illustration: The Deutsch de la Muerthe dirigible balloon
_Ville-de-Paris_; an example of the “cigar-shaped” gas envelope.]
Taking up again the illustration of the kite flying in a calm, let us
construct a few diagrams to show graphically the forces at work upon
the kite. Let the heavy line AB represent the centre line of the kite
from top to bottom, and C the point where the string is attached, at
which point we may suppose all the forces concentrate their action
upon the plane of the kite. Obviously, as the flyer of the kite is
running in a horizontal direction, the line indicating the pull of
the string is to be drawn horizontal. Let it be expressed by CD. The
action of the air pressure being at right angles to the plane of the
kite, we draw the line CE representing that force. But as this is a
_pressing_ force at the point C, we may express it as a _pulling_ force
on the other side of the kite by the line CF, equal to CE and in the
opposite direction. Another force acting on the kite is its weight--the
attraction of gravity acting directly downward, shown by CG. We have
given, therefore, the three forces, CD, CF, and CG. We now wish to find
the value of the pull on the kite-string, CD, in two other forces, one
of which shall be a lifting force, acting directly upward, and the
other a propelling force, acting in the direction in which we desire
the kite to travel--supposing it to represent an aeroplane for the
moment.
We first construct a parallelogram on CF and CG, and draw the diagonal
CH, which represents the resultant of those two forces. We have then
the two forces CD and CH acting on the point C. To avoid obscuring the
diagram with too many lines, we draw a second figure, showing just
these two forces acting on the point C. Upon these we construct a new
parallelogram, and draw the diagonal CI, expressing their resultant.
Again drawing a new diagram, showing this single force CI acting upon
the point C, we resolve that force into two components--one, CJ,
vertically upward, representing the lift; the other, CK, horizontal,
representing the travelling power. If the lines expressing these forces
in the diagrams had been accurately drawn to scale, the measurement of
the two components last found would give definite results in pounds;
but the weight of a kite is too small to be thus diagrammed, and only
the principle was to be illustrated, to be used later in the discussion
of the aeroplane.
[Illustration]
Nor is the problem as simple as the illustration of the kite suggests,
for the air is compressible, and is moreover set in motion in the form
of a current by a body passing through it at anything like the ordinary
speed of an aeroplane. This has caused the curving of the planes (from
front to rear) of the flying machine, in contrast with the flat plane
of the kite. The reasoning is along this line: Suppose the main plane
of an aeroplane six feet in depth (from front to rear) to be passing
rapidly through the air, inclined upward at a slight angle. By the
time two feet of this depth has passed a certain point, the air at
that point will have received a downward impulse or compression which
will tend to make it flow in the direction of the angle of the plane.
The second and third divisions in the depth, each of two feet, will
therefore be moving with a partial vacuum beneath, the air having been
drawn away by the first segment. At the same time, the pressure of the
air from above remains the same, and the result is that only the front
edge of the plane is supported, while two-thirds of its depth is pushed
down. This condition not only reduces the supporting surface to that of
a plane two feet in depth, but, what is much worse, releases a tipping
force which tends to throw the plane over backward.
In order that the second section of the plane may bear upon the air
beneath it with a pressure equal to that of the first, it must be
inclined downward at double the angle (with the horizon) of the first
section; this will in turn give to the air beneath it a new direction.
The third section of the plane must then be set at a still deeper
angle to give it support. Connecting these several directions with a
smoothly flowing line without angles, we get the curved line of section
to which the main planes of aeroplanes are bent.
With these principles in mind, it is in order to apply them to the
understanding of how an aeroplane flies. Wilbur Wright, when asked
what kept his machine up in the air--why it did not fall to the
ground--replied: “It stays up because it doesn’t have time to fall.”
Just what he meant by this may be illustrated by referring to the
common sport of “skipping stones” upon the surface of still water. A
flat stone is selected, and it is thrown at a high speed so that the
flat surface touches the water. It continues “skipping,” again and
again, until its speed is so reduced that the water where it touches
last has time to get out of the way, and the weight of the stone
carries it to the bottom. On the same principle, a person skating
swiftly across very thin ice will pass safely over if he goes so fast
that the ice hasn’t time to break and give way beneath his weight. This
explains why an aeroplane must move swiftly to stay up in the air,
which has much less density than either water or ice. The minimum
speed at which an aeroplane can remain in the air depends largely upon
its weight. The heavier it is, the faster it must go--just as a large
man must move faster over thin ice than a small boy. At some aviation
contests, prizes have been awarded for the slowest speed made by an
aeroplane. So far, the slowest on record is that of 21.29 miles an
hour, made by Captain Dickson at the Lanark meet, Scotland, in August,
1910. As the usual rate of speed is about 46 miles an hour, that is
slow for an aeroplane; and as Dickson’s machine is much heavier than
some others--the Curtiss machine, for instance--it is remarkably slow
for that type of aeroplane.
Just what is to be gained by offering a prize for slowest speed is
difficult to conjecture. It is like offering a prize to a crowd of boys
for the one who can skate slowest over thin ice. The minimum speed is
the most dangerous with the aeroplane as with the skater. Other things
being equal, the highest speed is the safest for an aeroplane. Even
when his engine stops in mid-air, the aviator is compelled to keep up
speed sufficient to prevent a fall by gliding swiftly downward until
the very moment of landing.
The air surface necessary to float a plane is spread out in one area in
the monoplane, and divided into two areas, one above the other and 6
to 9 feet apart, in the biplane; if closer than this, the disturbance
of the air by the passage of one plane affects the supporting power
of the other. It has been suggested that better results in the line
of carrying power would be secured by so placing the upper plane that
its front edge is a little back of the rear edge of the lower plane,
in order that it may enter air that is wholly free from any currents
produced by the rushing of the lower plane.
As yet, there is a difference of opinion among the principal aeroplane
builders as to where the propeller should be placed. All of the
monoplanes have it in front of the main plane. Most of the biplanes
have it behind the main plane; some have it between the two planes. If
it is in front, it works in undisturbed air, but throws its wake upon
the plane. If it is in the rear, the air is full of currents caused
by the passage of the planes, but the planes have smooth air to glide
into. As both types of machine are eminently successful, the question
may not be so important as it seems to the disputants.
The exact form of curve for the planes has not been decided upon.
Experience has proven that of two aeroplanes having the same surface
and run at the same speed, one may be able to lift twice as much as
the other because of the better curvature of its planes. The action of
the air when surfaces are driven through it is not fully understood.
Indeed, the form of plane shown in the accompanying figure is called
the aeroplane paradox. If driven in either direction it leaves the air
with a _downward_ trend, and therefore exerts a proportional lifting
power. If half of the plane is taken away, the other half is pressed
downward. All of the lifting effect is in the curving of the top side.
It seems desirable, therefore, that such essential factors should be
thoroughly worked out, understood, and applied.
[Illustration: Section of the “paradox” aeroplane.]
Chapter IV.
FLYING MACHINES.
Mythological--Leonardo da Vinci--Veranzio--John
Wilkins--Besnier--Marquis de
Bacqueville--Paucton--Desforges--Meerwein--Stentzel--Henson--Von
Drieberg--Wenham--Horatio Phillips--Sir Hiram
Maxim--Lilienthal--Langley--Ader--Pilcher--Octave
Chanute--Herring--Hargrave--The Wright
brothers--Archdeacon--Santos-Dumont--Voisin--Bleriot.
The term Flying Machines is applied to all forms of aircraft which are
heavier than air, and which lift and sustain themselves in the air by
mechanical means. In this respect they are distinguished from balloons,
which are lifted and sustained in the air by the lighter-than-air gas
which they contain.
From the earliest times the desire to fly in the air has been one of
the strong ambitions of the human race. Even the prehistoric mythology
of the ancient Greeks reflected the idea in the story of Icarus, who
flew so near to the sun that the heat melted the wax which fastened his
wings to his body, and he fell into the sea.
Perhaps the first historical record in the line of mechanical flight
worthy of attention exists in the remarkable sketches and plans for a
flying mechanism left by Leonardo da Vinci at his death in 1519. He had
followed the model of the flying bird as closely as possible, although
when the wings were outspread they had an outline more like those of
the bat. While extremely ingenious in the arrangement of the levers,
the power necessary to move them fast enough to lift the weight of a
man was far beyond the muscular strength of any human being.
It was a century later, in 1617, that Veranzio, a Venetian, proved his
faith in his inventive ability by leaping from a tower in Venice with
a crude, parachute-like contrivance. He alighted without injury.
In 1684, an Englishman, John Wilkins, then bishop of Chester, built
a machine for flying in which he installed a steam-engine. No record
exists of its performance.
In 1678, a French locksmith by the name of Besnier devised what
seems now a very crude apparatus for making descending flights, or
glides, from elevated points. It was, however, at that date considered
important enough to be described in the _Journal of the Savants_. It
was a wholly unscientific combination of the “dog-paddle” motion in
swimming, with wing areas which collapsed on the upward motion and
spread out on the downward thrust. If it was ever put to a test it must
have failed completely.
In 1742, the Marquis de Bacqueville constructed an apparatus which
some consider to have been based on Besnier’s idea--which seems rather
doubtful. He fastened the surfaces of his aeroplane directly to his
arms and legs, and succeeded in making a long glide from the window
of his mansion across the garden of the Tuileries, alighting upon a
washerwoman’s bench in the Seine without injury.
Paucton, the mathematician, is credited with the suggestion of a flying
machine with two screw propellers, which he called “pterophores”--a
horizontal one to raise the machine into the air, and an upright one
to propel it. These were to be driven by hand. With such hopelessly
inadequate power it is not surprising that nothing came of it, yet
the plan was a foreshadowing of the machine which has in these days
achieved success.
The Abbé Desforges gained a place in the annals of aeronautics by
inventing a flying machine of which only the name “Orthoptere” remains.
[Illustration: Meerwein’s Flying Machine. _A_, shows the position of
the man in the wings, their comparative size, and the operating levers;
_B_, position when in flight.]
About 1780, Karl Friedrich Meerwein, an architect, and the Inspector of
Public Buildings for Baden, Germany, made many scientific calculations
and experiments on the size of wing surface needed to support a man
in the air. He used the wild duck as a standard, and figured that a
surface of 126 square feet would sustain a man in the air. This agrees
with the later calculations of such experimenters as Lilienthal and
Langley. Other of Meerwein’s conclusions are decidedly ludicrous. He
held that the build of a man favors a horizontal position in flying, as
his nostrils open in a direction which would be away from the wind, and
so respiration would not be interfered with! Some of his reasoning is
unaccountably astray; as, for instance, his argument that because the
man hangs in the wings the weight of the latter need not be considered.
It is almost needless to say that his practical trials were a total
failure.
[Illustration: Plan of Degen’s apparatus.]
The next prominent step forward toward mechanical flight was made by
the Australian watchmaker Degen, who balanced his wing surfaces with a
small gas balloon. His first efforts to fly not being successful, he
abandoned his invention and took to ballooning.
Stentzel, an engineer of Hamburg, came next with a machine in the form
of a gigantic butterfly. From tip to tip of its wings it measured 20
feet, and their depth fore and aft was 5½ feet. The ribs of the wings
were of steel and the web of silk, and they were slightly concave on
the lower side. The rudder-tail was of two intersecting planes, one
vertical and the other horizontal. It was operated by a carbonic-acid
motor, and made 84 flaps of the wings per minute. The rush of air it
produced was so great that any one standing near it would be almost
swept off his feet. It did not reach a stage beyond the model, for it
was able to lift only 75 lbs.
[Illustration: Stentzel’s machine.]
In 1843, the English inventor Henson built what is admitted to be the
first aeroplane driven by motive power. It was 100 feet in breadth
(spread) and 30 feet long, and covered with silk. The front edge was
turned slightly upward. It had a rudder shaped like the tail of a
bird. It was driven by two propellers run by a 20-horse-power engine.
Henson succeeded only in flying on a down grade, doubtless because of
the upward bend of the front of his plane. Later investigations have
proven that the upper surface of the aeroplane must be convex to gain
the lifting effect. This is one of the paradoxes of flying planes which
no one has been able to explain.
In 1845, Von Drieberg, in Germany, revived the sixteenth-century ideas
of flying, with the quite original argument that since the legs of
man were better developed muscularly than his arms, flying should be
done with the legs. He built a machine on this plan, but no successful
flights are recorded.
In 1868, an experimenter by the name of Wenham added to the increasing
sum of aeronautical knowledge by discovering that the lifting power of
a large supporting surface may be as well secured by a number of small
surfaces placed one above another. Following up these experiments, he
built a flying machine with a series of six supporting planes made
of linen fabric. As he depended upon muscular effort to work his
propellers, he did not succeed in flying, but he gained information
which has been valuable to later inventors.
[Illustration: Von Drieberg’s machine; view from above.]
[Illustration:
Wenham’s arrangement of many narrow surfaces in six tiers, or
decks. _a_, _a_, rigid framework; _b_, _b_, levers working
flapping wings; _e_, _e_, braces. The operator is lying prone.]
The history of flying machines cannot be written without deferential
mention of Horatio Phillips of England. The machine that he made in
1862 resembled a large Venetian blind, 9 feet high and over 21 feet
long. It was mounted on a carriage which travelled on a circular track
600 feet long, and it was driven by a small steam engine turning a
propeller. It lifted unusually heavy loads, although not large enough
to carry a man. It seems to open the way for experiments with an
entirely new arrangement of sustaining surfaces--one that has never
since been investigated. Phillips’s records cover a series of most
valuable experiments. Perhaps his most important work was in the
determination of the most advantageous form for the surfaces of
aeroplanes, and his researches into the correct proportion of motive
power to the area of such surfaces. Much of his results have not yet
been put to practical use by designers of flying machines.
[Illustration: Phillips’s Flying Machine--built of narrow slats like a
Venetian blind.]
The year 1888 was marked by the construction by Sir Hiram Maxim of his
great aeroplane which weighed three and one-half tons, and is said
to have cost over $100,000. The area of the planes was 3,875 square
feet, and it was propelled by a steam engine in which the fuel used
was vaporized naphtha in a burner having 7,500 jets, under a boiler of
small copper water tubes. With a steam pressure of 320 lbs. per square
inch, the two compound engines each developed 180 horse-power, and each
turned a two-bladed propeller 17½ feet in diameter. The machine was
used only in making tests, being prevented from rising in the air by a
restraining track. The thrust developed on trial was 2,164 lbs., and
the lifting power was shown to have been in excess of 10,000 lbs. The
restraining track was torn to pieces, and the machine injured by the
fragments. The dynamometer record proved that a dead weight of 4½ tons,
in addition to the weight of the machine and the crew of 4 men, could
have been lifted. The stability, speed, and steering control were
not tested. Sir Hiram Maxim made unnumbered experiments with models,
gaining information which has been invaluable in the development of the
aeroplane.
[Illustration: View of a part of Maxim’s aeroplane, showing one of the
immense propellers. At the top is a part of the upper plane.]
The experiments of Otto Lilienthal in gliding with a winged structure
were being conducted at this period. He held that success in flying
must be founded upon proficiency in the art of balancing the
apparatus in the air. He made innumerable glides from heights which
he continually increased until he was travelling distances of nearly
one-fourth of a mile from an elevation of 100 feet. He had reached the
point where he was ready to install motive power to drive his glider
when he met with a fatal accident. Besides the inspiration of his
daring personal experiments in the air, he left a most valuable series
of records and calculations, which have been of the greatest aid to
other inventors in the line of artificial flight.
[Illustration: Lilienthal in his biplane glider.]
In 1896, Professor Langley, director of the Smithsonian Institution
at Washington, made a test of a model flying machine which was the
result of years of experimenting. It had a span of 15 feet, and a
length of 8½ feet without the extended rudder. There were 4 sails or
planes, 2 on each side, 30 inches in width (fore-and-aft measurement).
Two propellers revolving in opposite directions were driven by a
steam engine. The diameter of the propellers was 3 feet, and the
steam pressure 150 lbs. per square inch. The weight of the machine
was 28 lbs. It is said to have made a distance of 1 mile in 1 minute
45 seconds. As Professor Langley’s experiments were conducted in
strict secrecy, no authoritative figures are in existence. Later a
larger machine was built, which was intended to carry a man. It had
a spread of 46 feet, and was 35 feet in length. It was four years in
building, and cost about $50,000. In the first attempt to launch it,
from the roof of a house-boat, it plunged into the Potomac River. The
explanation given was that the launching apparatus was defective. This
was remedied, and a second trial made, but the same result followed.
It was never tried again. This machine was really a double, or tandem,
monoplane. The framework was built of steel tubing almost as thin
as writing paper. Every rib and pulley was hollowed out to reduce
the weight. The total weight of the engine and machine was 800 lbs.,
and the supporting surface of the wings was 1,040 square feet. The
aeroplanes now in use average from 2 to 4 lbs. weight to the square
foot of sustaining surface.
About the same time the French electrician Ader, after years of
experimenting, with the financial aid of the French Government, made
some secret trials of his machine, which had taken five years to build.
It had two bat-like wings spreading 54 feet, and was propelled by two
screws driven by a 4-cylinder steam engine which has been described as
a marvel of lightness. The inventor claimed that he was able to rise
to a height of 60 feet, and that he made flights of several hundred
yards. The official tests, however, were unsatisfactory, and nothing
further was done by either the inventor or the government to continue
the experiments. The report was that in every trial the machines had
been wrecked.
The experiments of Lilienthal had excited an interest in his ideas
which his untimely death did not abate. Among others, a young English
marine engineer, Percy S. Pilcher, took up the problem of gliding
flight, and by the device of using the power exerted by running boys
(with a five-fold multiplying gear) he secured speed enough to float
his glider horizontally in the air for some distance. He then built an
engine which he purposed to install as motive power, but before this
was done he was killed by a fall from his machine while in the air.
[Illustration: Plan of Chanute’s movable-wing glider.]
Before the death of Lilienthal his efforts had attracted the attention
of Octave Chanute, a distinguished civil engineer of Chicago, who,
believing that the real problem of the glider was the maintenance of
equilibrium in the air, instituted a series of experiments along that
line. Lilienthal had preserved his equilibrium by moving his body about
as he hung suspended under the wings of his machine. Chanute proposed
to accomplish the same end by moving the wings automatically. His
attempts were partially successful. He constructed several types of
gliders, one of these with two decks exactly in the form of the present
biplane. Others had three or more decks. Upward of seven hundred glides
were made with Chanute’s machines by himself and assistants, without
a single accident. It is of interest to note that a month before the
fatal accident to Lilienthal, Chanute had condemned that form of
glider as unsafe.
[Illustration: Chanute’s two-deck glider.]
In 1897, A. M. Herring, who had been one of the foremost assistants of
Octave Chanute, built a double-deck (biplane) machine and equipped it
with a gasoline motor between the planes. The engine failed to produce
sufficient power, and an engine operated by compressed air was tried,
but without the desired success.
In 1898, Lawrence Hargrave of Sydney, New South Wales, came into
prominence as the inventor of the cellular or box kite. Following the
researches of Chanute, he made a series of experiments upon the path
of air currents under variously curved surfaces, and constructed some
kites which, under certain conditions, would advance against a wind
believed to be absolutely horizontal. From these results Hargrave was
led to assert that “soaring sails” might be used to furnish propulsion,
not only for flying machines, but also for ships on the ocean sailing
against the wind. The principles involved remain in obscurity.
During the years 1900 to 1903, the brothers Wright, of Dayton, Ohio,
had been experimenting with gliders among the sand dunes of Kitty
Hawk, North Carolina, a small hamlet on the Atlantic Coast. They
had gone there because the Government meteorological department had
informed them that at Kitty Hawk the winds blew more steadily than at
any other locality in the United States. Toward the end of the summer
of 1903, they decided that the time was ripe for the installation of
motive power, and on December 17, 1903, they made their first four
flights under power, the longest being 853 feet in 59 seconds--against
a wind blowing nearly 20 miles an hour, and from a starting point on
level ground.
[Illustration: Wilbur Wright gliding at Kitty Hawk, N. C., in 1903.]
During 1904 over one hundred flights were made, and changes in
construction necessary to sail in circles were devised. In 1905, the
Wrights kept on secretly with their practice and development of their
machine, first one and then the other making the flights until both
were equally proficient. In the latter part of September and early
part of October, 1905, occurred a series of flights which the Wrights
allowed to become known to the public. At a meeting of the Aeronautical
Society of Great Britain, held in London on December 15, 1905, a letter
from Orville Wright to one of the members was read. It was dated
November 17, 1905, and an excerpt from it is as follows:
“During the month of September we gradually improved in our practice,
and on the 26th made a flight of a little over 11 miles. On the 30th we
increased this to 12⅕th miles; on October 3, to 15⅓ miles; on October
4, to 20¾ miles, and on October 5, to 24¼ miles. All these flights
were made at about 38 miles an hour, the flight of October 5 occupying
30 minutes 3 seconds. Landings were caused by the exhaustion of the
supply of fuel in the flights of September 26 and 30, and October 8,
and in those of October 3 and 4 by the heating of the bearings in the
transmission, of which the oil cups had been omitted. But before the
flight on October 5, oil cups had been fitted to all the bearings, and
the small gasoline can had been replaced with one that carried enough
fuel for an hour’s flight. Unfortunately, we neglected to refill the
reservoir just before starting, and as a result the flight was limited
to 38 minutes....
[Illustration: A Wright machine in flight.]
“The machine passed through all of these flights without the slightest
damage. In each of these flights we returned frequently to the
starting point, passing high over the heads of the spectators.”
These statements were received with incredulity in many parts of
Europe, the more so as the Wrights refused to permit an examination of
their machine, fearing that the details of construction might become
known before their patents were secured.
[Illustration: The Archdeacon machine on the Seine.]
During the summer of 1905, Captain Ferber and Ernest Archdeacon of
Paris had made experiments with gliders. One of the Archdeacon machines
was towed by an automobile, having a bag of sand to occupy the place
of the pilot. It rose satisfactorily in the air, but the tail became
disarranged, and it fell and was damaged. It was rebuilt and tried
upon the waters of the Seine, being towed by a fast motor-boat at a
speed of 25 miles an hour. The machine rose about 50 feet into the air
and sailed for about 500 feet.
Archdeacon gathered a company of young men about him who speedily
became imbued with his enthusiasm. Among them were Gabriel Voisin,
Louis Bleriot, and Leon Delagrange. The two former, working together,
built and flew several gliders, and when Santos-Dumont made his
historic flight of 720 feet with his multiple-cell machine on November
13, 1906 (the first flight made in Europe), they were spurred to new
endeavors.
Within a few months Voisin had finished his first biplane, and
Delagrange made his initial flight with it--a mere hop of 30 feet--on
March 16, 1907.
Bleriot, however, had his own ideas, and on August 6, 1907, he flew
for 470 feet in a monoplane machine of the tandem type. He succeeded
in steering his machine in a curved course, a feat which had not
previously been accomplished in Europe.
In October of the same year, Henri Farman, then a well-known automobile
driver, flew the second Voisin biplane in a half circle of 253 feet--a
notable achievement at that date.
But Santos-Dumont had been pushing forward several different types of
machines, and in November he flew first a biplane 500 feet, and a few
days later a monoplane 400 feet.
At this point in our story the past seems to give place to the
present. The period of early development was over, and the year 1908
saw the first of those remarkable exploits which are recorded in the
chapter near the end of this work entitled, “Chronicle of Aviation
Achievements.”
It is interesting to note that the machines then brought out are those
of to-day. Practically, it may be said that there has been no material
change from the original types. More powerful engines have been put
in them, and the frames strengthened in proportion, but the Voisin,
the Bleriot, and the Wright types remain as they were at first. Other
and later forms are largely modifications and combinations of their
peculiar features.
Chapter V.
FLYING MACHINES: THE BIPLANE.
Successful types of aeroplanes--Distinguishing features--The
Wright biplane--Construction--New type--Five-passenger
machine--The Voisin biplane--New racing type--The Curtiss
biplane--The Cody biplane--The Sommer biplane--The
Baldwin biplane--New stabilizing plane--The Baddeck No.
2--Self-sustaining radiator--The Herring biplane--Stabilizing
fins.
In the many contests for prizes and records, two types of flying
machines have won distinctive places for themselves--the biplane and
the monoplane. The appearance of other forms has been sporadic, and
they have speedily disappeared without accomplishing anything which had
not been better done by the two classes named.
This fact, however, should not be construed as proving the futility of
all other forms, nor that the ideal flying machine must be of one of
these two prominent types. It is to be remembered that record-making
and record-breaking is the most serious business in which any machines
have so far been engaged; and this, surely, is not the field of
usefulness to humanity which the ships of the air may be expected
ultimately to occupy. It may yet be proved that, successful as these
machines have been in what they have attempted, they are but transition
forms leading up to the perfect airship of the future.
[Illustration: The Wright biplane in flight.]
The distinguishing feature of the biplane is not alone that it has two
main planes, but that they are placed one above the other. The double
(or tandem) monoplane also has two main planes, but they are on the
same level, one in the rear of the other.
A review of the notable biplanes of the day must begin with the Wright
machine, which was not only the first with which flights were made, but
also the inspiration and perhaps the pattern of the whole succeeding
fleet.
THE WRIGHT BIPLANE.
The Wright biplane is a structure composed of two main surfaces,
each 40 feet long and 6 feet 6 inches wide, set one above the other,
parallel, and 6 feet apart. The planes are held rigidly at this
distance by struts of wood, and the whole structure is trussed with
diagonal wire ties. It is claimed by the Wrights that these dimensions
have been proven by their experiments to give the maximum lift with
the minimum weight.
[Illustration:
Diagram showing the construction of the Wright biplane. The lever
_R_ is connected by the bar _A_ with the rudder gearing _C_, and
is pivoted at the bottom on a rolling shaft _B_, through which
the warping wires _W_^1, _W_^2 are operated. The semicircular
planes _F_ aid in stabilizing the elevator system.]
The combination of planes is mounted on two rigid skids, or runners
(similar to the runners of a sleigh), which are extended forward and
upward to form a support for a pair of smaller planes in parallel,
used as the elevator (for directing the course of the aeroplane upward
or downward). It has been claimed by the Wrights that a rigid skid
under-structure takes up the shock of landing, and checks the momentum
at that moment, better than any other device. But it necessitated
a separate starting apparatus, and while the starting impulse thus
received enabled the Wrights to use an engine of less power (to keep
the machine going when once started), and therefore of less dead
weight, it proved a handicap to their machines in contests where they
were met by competing machines which started directly with their own
power. A later model of the Wright biplane is provided with a wheeled
running gear, and an engine of sufficient power to raise it in the air
after a short run on the wheels.
Two propellers are used, run by one motor. They are built of wood, are
of the two-bladed type, and are of comparatively large diameter--8
feet. They revolve in opposite directions at a speed of 450
revolutions per minute, being geared down by chain drive from the
engine speed of 1,500 revolutions per minute.
The large elevator planes in front have been a distinctive feature of
the Wright machine. They have a combined area of 80 square feet, adding
that much more lifting surface to the planes in ascending, for then
the under side of their surfaces is exposed to the wind. If the same
surfaces were in the rear of the main planes their top sides would have
to be turned to the wind when ascending, and a depressing instead of a
lifting effect would result.
To the rear of the main planes is a rudder composed of two parallel
vertical surfaces for steering to right or left.
The feature essential to the Wright biplane, upon which the letters
patent were granted, is the flexible construction of the tips of the
main planes, in virtue of which they may be warped up or down to
restore disturbed equilibrium, or when a turn is to be made. This
warping of the planes changes the angle of incidence for the part of
the plane which is bent. (The angle of incidence is that which the
plane makes with the line in which it is moving. The bending downward
of the rear edge would enlarge the angle of incidence, in that way
increasing the compression of the air beneath, and lifting that end
of the plane.) The wing-warping controls are actuated by the lever
at the right hand of the pilot, which also turns the rudder at the
rear--that which steers the machine to right or to left. The lever at
the left hand of the pilot moves the elevating planes at the front of
the machine.
[Illustration: Sketch showing relative positions of planes and of the
operator in the Wright machine: _A_, _A_, the main planes; _B_, _B_,
the elevator planes. The motor is placed beside the operator.]
The motor has 4 cylinders, and develops 25 to 30 horse-power, giving
the machine a speed of 39 miles per hour.
A newer model of the Wright machine is built without the large
elevating planes in front, a single elevating plane being placed just
back of the rear rudder. This arrangement cuts out the former lifting
effect described above, and substitutes the depressing effect due to
exposing the top of a surface to the wind.
[Illustration: _Courtesy of N. Y. Times._
The new model Wright biplane--without forward elevator.]
The smallest of the Wright machines, popularly called the “Baby
Wright,” is built upon this plan, and has proven to be the fastest of
all the Wright series.
THE VOISIN BIPLANE.
While the Wrights were busily engaged in developing their biplane in
America, a group of enthusiasts in France were experimenting with
gliders of various types, towing them with high speed automobiles along
the roads, or with swift motor-boats upon the Seine. As an outcome
of these experiments, in which they bore an active part, the Voisin
brothers began building the biplanes which have made them famous.
As compared with the Wright machine, the Voisin aeroplane is of much
heavier construction. It weighs 1,100 pounds. The main planes have a
lateral spread of 37 feet 9 inches, and a breadth of 7 feet, giving
a combined area of 540 square feet, the same as that of the Wright
machine. The lower main plane is divided at the centre to allow the
introduction of a trussed girder framework which carries the motor and
propeller, the pilot’s seat, the controlling mechanism, and the running
gear below; and it is extended forward to support the elevator. This
is much lower than in the Wright machine, being nearly on the level of
the lower plane. It is a single surface, divided at the centre, half
being placed on each side of the girder. It has a combined area of 42
square feet, about half of that of the Wright elevator, and it is only
4 feet from the front edge of the main planes, instead of 10 feet as in
the Wright machine. A framework nearly square in section, and about 25
feet long, extends to the rear, and supports a cellular, or box-like,
tail, which forms a case in which is the rudder surface for steering
to right or to left.
[Illustration: Diagram showing details of construction of the Voisin
biplane. _C_, _C_, the curtains forming the stabilizing cells.]
A distinctive feature of the Voisin biplane is the use of four vertical
planes, or curtains, between the two main planes, forming two nearly
square “cells” at the ends of the planes.
At the rear of the main planes, in the centre, is the single propeller.
It is made of steel, two-bladed, and is 8 feet 6 inches in diameter.
It is coupled directly to the shaft of the motor, making with it 1,200
revolutions per minute. The motor is of the V type, developing 50
horse-power, and giving a speed of 37 miles per hour.
[Illustration: Diagram showing the simplicity of control of the Voisin
machine, all operations being performed by the wheel and its sliding
axis.]
The controls are all actuated by a rod sliding back and forth
horizontally in front of the pilot’s seat, having a wheel at the end.
The elevator is fastened to the rod by a crank lever, and is tilted
up or down as the rod is pushed forward or pulled back. Turning
the wheel from side to side moves the rudder in the rear. There are
no devices for controlling the equilibrium. This is supposed to be
maintained automatically by the fixed vertical curtains.
[Illustration:
Voisin biplanes at the starting line at Rheims in August, 1909.
They were flown by Louis Paulhan, who won third prize for
distance, and Henri Rougier, who won fourth prize for altitude.
In the elimination races to determine the contestants for the
Bennett Cup, Paulhan won second place with the Voisin machine,
being defeated only by Tissandier with a Wright machine. Other
noted aviators who fly the Voisin machine are M. Bunau-Varilla
and the Baroness de la Roche.]
The machine is mounted on two wheels forward, and two smaller wheels
under the tail.
This description applies to the standard Voisin biplane, which has
been in much favor with many of the best known aviators. Recently
the Voisins have brought out a new type in which the propeller has
been placed in front of the planes, exerting a pulling force upon the
machine, instead of pushing it as in the earlier type. The elevating
plane has been removed to the rear, and combined with the rudder.
A racing type also has been produced, in which the vertical curtains
have been removed and a parallel pair of long, narrow ailerons
introduced between the main planes on both sides of the centre. This
machine, it is claimed, has made better than 60 miles per hour.
The first Voisin biplane was built for Delagrange, and was flown by him
with success.
THE FARMAN BIPLANE.
The second biplane built by the Voisins went into the hands of Henri
Farman, who made many flights with it. Not being quite satisfied with
the machine, and having an inventive mind, he was soon building a
biplane after his own designs, and the Farman biplane is now one of the
foremost in favor among both professional and amateur aviators.
It is decidedly smaller in area of surface than the Wright and Voisin
machines, having but 430 square feet in the two supporting planes. It
has a spread of 33 feet, and the planes are 7 feet wide, and set 6 feet
apart. In the Farman machine the vertical curtains of the Voisin have
been dispensed with. The forward elevator is there, but raised nearly
to the level of the upper plane, and placed 9 feet from the front edge
of the main planes. To control the equilibrium, the two back corners
of each plane are cut and hinged so that they hang vertically when not
in flight. When in motion these flaps or ailerons stream out freely
in the wind, assuming such position as the speed of the passing air
gives them. They are pulled down by the pilot at one end or the other,
as may be necessary to restore equilibrium, acting in very much the
same manner as the warping tips of the Wright machine. A pair of tail
planes are set in parallel on a framework about 20 feet in the rear of
the main planes, and a double rudder surface behind them. Another model
has hinged ailerons on these tail planes, and a single rudder surface
set upright between them. These tail ailerons are moved in conjunction
with those of the main planes.
[Illustration: The Farman biplane, showing the position of the hinged
ailerons when at rest. At full speed these surfaces stream out in the
wind in line with the planes to which they are attached.]
[Illustration: Diagram of the Farman biplane. A later type has the
hinged ailerons also on the tail planes.]
The motor has 4 cylinders, and turns a propeller made of wood, 8 feet 6
inches in diameter, at a speed of 1,300 revolutions per minute--nearly
three times as fast as the speed of the Wright propellers, which are
about the same size. The propeller is placed just under the rear edge
of the upper main plane, the lower one being cut away to make room
for the revolving blades. The motor develops 45 to 50 horse-power, and
drives the machine at a speed of 41 miles per hour.
The “racing Farman” is slightly different, having the hinged ailerons
only on one of the main planes. The reason for this is obvious. Every
depression of the ailerons acts as a drag on the air flowing under the
planes, increasing the lift at the expense of the speed.
[Illustration: Sketch of Farman machine, showing position of operator.
_A_, _A_, main planes; _B_, elevator; _C_, motor; _P_, tail planes.]
The whole structure is mounted upon skids with wheels attached by a
flexible connection. In case of a severe jar, the wheels are pushed up
against the springs until the skids come into play.
The elevator and the wing naps are controlled by a lever at the
right hand of the pilot. This lever moves on a universal joint, the
side-to-side movement working the flaps, and the forward-and-back
motion the elevator. Steering to right or left is done with a bar
operated by the feet.
[Illustration: Henri Farman carrying a passenger across country.]
Farman has himself made many records with his machine, and so have
others. With a slightly larger and heavier machine than the one
described, Farman carried two passengers a distance of 35 miles in one
hour.
THE CURTISS BIPLANE.
This American rival of the Wright biplane is the lightest machine
of this type so far constructed. The main planes are but 29 feet in
spread, and 4 feet 6 inches in width, and are set not quite 5 feet
apart. The combined area of the two planes is 250 square feet. The main
planes are placed midway of the length of the fore-and-aft structure,
which is nearly 30 feet. At the forward end is placed the elevator, and
at the rear end is the tail--one small plane surface--and the vertical
rudder surface in two parts, one above and the other below the tail
plane. Equilibrium is controlled by changing the slant of two small
balancing planes which are placed midway between the main planes at the
outer ends, and in line with the front edges. These balancing planes
are moved by a lever standing upright behind the pilot, having two arms
at its upper end which turn forward so as to embrace his shoulders. The
lever is moved to right or to left by the swaying of the pilot’s body.
[Illustration: Glenn H. Curtiss in his machine ready to start. The fork
of the balancing lever is plainly seen at his shoulders. Behind him is
the radiator, with the engine still further back.]
The motor is raised to a position where the shaft of the propeller is
midway between the levels of the main planes, and within the line of
the rear edges, so that they have to be cut away to allow the passing
of the blades. The motor is of the V type, with 8 cylinders. It is 30
horse-power and makes 1,200 revolutions per minute. The propeller is of
steel, two-bladed, 6 feet in diameter, and revolves at the same speed
as the shaft on which it is mounted. The high position of the engine
permits a low running gear. There are two wheels under the rear edges
of the main planes, and another is placed half-way between the main
planes and the forward rudder, or elevator. A brake, operated by the
pilot’s foot, acts upon this forward wheel to check the speed at the
moment of landing.
Another type of Curtiss machine has the ailerons set in the rear of the
main planes, instead of between them.
The Curtiss is the fastest of the biplanes, being excelled in speed
only by some of the monoplanes. It has a record of 51 miles per hour.
THE CODY BIPLANE.
The Cody biplane has the distinction of being the first successful
British aeroplane. It was designed and flown by Captain S. F. Cody, at
one time an American, but for some years an officer in the British army.
It is the largest and heaviest of all the biplanes, weighing about
1,800 lbs., more than three times the weight of the Curtiss machine.
Its main planes are 52 feet in lateral spread, and 7 feet 6 inches in
width, and are set 9 feet apart. The combined area of these sustaining
surfaces is 770 square feet. The upper plane is arched, so that the
ends of the main planes are slightly closer together than at the centre.
The elevator is in two parts placed end to end, about 12 feet in front
of the main planes. They have a combined area of 150 square feet.
Between them and above them is a small rudder for steering to right or
left in conjunction with the large rudder at the rear of the machine.
The latter has an area of 40 square feet.
There are two small balancing planes, set one at each end of the main
planes, their centres on the rear corner struts, so that they project
beyond the tips of the planes and behind their rear lines.
[Illustration: The Cody biplane in flight. Captain Cody has both hands
raised above his head, showing the automatic stability of his machine.]
The biplane is controlled by a lever rod having a wheel at the end.
Turning the wheel moves the rudders; pushing or pulling the wheel works
the elevator; moving the wheel from side to side moves the balancing
planes.
There are two propellers, set one on each side of the engine, and well
forward between the main planes. They are of wood, of the two-bladed
type, 7 feet in diameter. They are geared down to make 600 revolutions
per minute. The motor has 8 cylinders and develops 80 horse-power at
1,200 revolutions per minute.
The machine is mounted on a wheeled running gear, two wheels under the
front edge of the main planes and one a short distance forward in the
centre. There is also a small wheel at each extreme end of the lower
main plane.
The Cody biplane has frequently carried a passenger, besides the pilot,
and is credited with a speed of 38 miles per hour.
The first aeroplane flights ever made in England were by Captain Cody
on this biplane, January 2, 1909.
THE SOMMER BIPLANE.
The Sommer biplane is closely similar to the Farman machine, but has
the hinged ailerons only on the upper plane. Another difference is that
the tail has but one surface, and the rudder is hung beneath it. Its
dimensions are:--Spread of main planes, 34 feet; depth (fore-and-aft),
6 feet 8 inches; they are set 6 feet apart. The area of the main planes
is 456 square feet; area of tail, 67 square feet; area of rudder, 9
square feet. It is driven by a 50-horsepower Gnome motor, turning an
8-foot, two-bladed propeller.
M. Sommer has flown with three passengers, a total weight of 536 lbs.,
besides the weight of the machine.
THE BALDWIN BIPLANE.
The Baldwin biplane, designed by Captain Thomas S. Baldwin, the
distinguished balloonist, resembles the Farman type in some features,
and the Curtiss in others. It has the Curtiss type of ailerons, set
between the wings, but extending beyond them laterally. The elevator is
a single surface placed in front of the machine, and the tail is of the
biplane type with the rudder between. The spread of the main planes is
31 feet 3 inches, and their depth 4 feet 6 inches. A balancing plane of
9 square feet is set upright (like a fin) above the upper main plane,
on a swivel. This is worked by a fork fitting on the shoulders of the
pilot, and is designed to restore equilibrium by its swinging into
head-resistance on one side or the other as may be necessary.
[Illustration: The Baldwin biplane, showing balancing plane above upper
main plane.]
The motive power is a 4-cylinder Curtiss motor, which turns a propeller
7 feet 6 inches in diameter, set just within the rear line of the main
planes, which are cut away to clear the propeller blades.
THE BADDECK BIPLANE.
The newest biplane of the Aerial Experiment Association follows in
general contour its successful precursor, the “Silver Dart,” with
which J. A. D. McCurdy made many records. The “Baddeck No. 2” is of
the biplane type, and both the planes are arched toward each other.
They have a spread of 40 feet, and are 7 feet in depth at the centre,
rounding to 5 feet at the ends, where the wing tips, 5 feet by 5 feet,
are hinged. The elevator is also of the biplane type, two surfaces each
12 feet long and 28 inches wide, set 30 inches apart. This is mounted
15 feet in front of the main planes. The tail is mounted 11 feet in the
rear of the main planes, and is the same size and of the same form as
the elevator.
The controls are operated by the same devices as in the Curtiss
machine. The propeller is 7 feet 8 inches in diameter, and is turned
by a six-cylinder automobile engine of 40 horse-power running at 1,400
revolutions per minute. The propeller is geared down to run at 850
revolutions per minute. The motor is placed low down on the lower
plane, but the propeller shaft is raised to a position as nearly as
possible that of the centre of resistance of the machine. The speed
attained is 40 miles per hour.
[Illustration: The McCurdy biplane, “Baddeck No. 2.”]
A unique feature of the mechanism is the radiator, which is built of
30 flattened tubes 7 feet 6 inches long, and 3 inches wide, and very
thin. They are curved from front to rear like the main planes, and give
sufficient lift to sustain their own weight and that of the water
carried for cooling the cylinders. The running gear is of three wheels
placed as in the Curtiss machine. The “Baddeck No. 2” has made many
satisfactory flights with one passenger besides the pilot.
THE HERRING BIPLANE.
At the Boston Aircraft Exhibition in February, 1910, the Herring
biplane attracted much attention, not only because of its superiority
of mechanical finish, but also on account of its six triangular
stabilizing fins set upright on the upper plane. Subsequent trials
proved that this machine was quite out of the ordinary in action. It
rose into the air after a run of but 85 feet, and at a speed of only
22 miles per hour, and made a 40-degree turn at a tipping angle of 20
degrees. As measured by the inventor, the machine rose in the air with
the pilot (weighing 190 lbs.), with a thrust of 140 lbs., and required
only a thrust of from 80 to 85 lbs. to keep it flying.
The spread of the planes is 28 feet, and they are 4 feet in depth,
with a total supporting surface of 220 feet. A 25 horse-power Curtiss
motor turns a 4-bladed propeller of 6 feet diameter and 5-foot pitch
(designed by Mr. Herring) at the rate of 1,200 revolutions per minute.
[Illustration: The L. A. W. (League of American Wheelmen) biplane at
the Boston Aircraft Exhibition, February, 1910. Note the peculiar
curve of the divided planes. The motor is of the rotating type, of 50
horse-power.]
The elevator consists of a pair of parallel surfaces set upon hollow
poles 12 feet in front of the main planes. The tail is a single surface.
The stabilizing fins act in this manner: when the machine tips to one
side, it has a tendency to slide down an incline of air toward the
ground. The fins offer resistance to this sliding, retarding the upper
plane, while the lower plane slides on and swings as a pendulum into
equilibrium again.
THE BREGUET BIPLANE.
The Breguet biplane is conspicuous in having a biplane tail of so
large an area as to merit for the machine the title “tandem biplane.”
The main planes have a spread of 41 feet 8 inches, and an area of 500
square feet. The tail spreads 24 feet, and its area is about 280 square
feet. The propeller is three-bladed, 8 feet in diameter, and revolves
at a speed of 1,200 revolutions per minute. It is placed in front of
the main plane, after the fashion of the monoplanes. The motive power
is an 8-cylinder R-E-P engine, developing 55 horse-power.
[Illustration: _Courtesy of N. Y. Sun._
The Seddon tandem biplane, constructed by Lieutenant Seddon of the
British Navy. The area of its planes is 2,000 square feet. Compare its
size with that of the monoplane in the background. It is intended to
carry ten persons.]
[Illustration:
Wright biplane. Curtiss biplane.
Comparative build and area of prominent American biplanes.]
[Illustration:
Voisin biplane. Breguet biplane.
Comparative build and area of prominent European biplanes.]
Chapter VI.
FLYING MACHINES: THE MONOPLANE.
The common goal--Interchanging features--The Bleriot
machine--First independent flyer--Construction and controls--The
“Antoinette”--Large area--Great stability--Santos-Dumont’s
monoplane--Diminutive size--R-E-P monoplane--encased
structure--Hanriot machine--Boat body--Sturdy build--Pfitzner
machine--Lateral type--Thrusting propeller--Fairchild,
Burlingame, Cromley, Chauviere, Vendome, and Moisant monoplanes.
In all the ardent striving of the aviators to beat each other’s
records, a surprisingly small amount of personal rivalry has been
developed. Doubtless this is partly because their efforts to perform
definite feats have been absorbing; but it must also be that these men,
who know that they face a possible fall in every flight they make,
realize that their competitors are as brave as themselves in the face
of the same danger; and that they are actually accomplishing marvellous
wonders even if they do no more than just escape disastrous failure.
Certain it is that each, realizing the tremendous difficulties all must
overcome, respects the others’ ability and attainments.
Consequently we do not find among them two distinctly divergent
schools of adherents, one composed of the biplanists, the other of the
monoplanists. Nor are the two types of machines separated in this book
for any other purpose than to secure a clearer understanding of what
is being achieved by all types in the progress toward the one common
goal--the flight of man.
The distinctive feature of the monoplane is that it has but one main
plane, or spread of surface, as contrasted with the two planes, one
above the other, of the biplane. Besides the main plane, it has a
secondary plane in the rear, called the tail. The office of this tail
is primarily to secure longitudinal, or fore-and-aft, balance; but
the secondary plane has been so constructed that it is movable on a
horizontal axis, and is used to steer the machine upward or downward.
While most of the biplanes now have a horizontal tail-plane, they were
not at first so provided, but carried the secondary plane (or planes)
in front of the main planes. Even in the latest type brought out by the
conservative Wright brothers, the former large-surfaced elevator in
front has been removed, and a much smaller tail-plane has been added in
the rear, performing the same function of steering the machine up or
down, but also providing the fore-and-aft stabilizing feature formerly
peculiar to the monoplane. Another feature heretofore distinctively
belonging to the monoplane has been adopted by some of the newer
biplanes, that of the traction propeller--pulling the machine behind it
through the air, instead of pushing it along by a thrusting propeller
placed behind the main planes.
The continual multiplication of new forms of the monoplane makes it
possible to notice only those which exhibit the wider differences.
THE BLERIOT MONOPLANE.
The Bleriot monoplane has the distinction of being the first wholly
successful flying machine. Although the Wright machine was making
flights years before the Bleriot had been built, it was still dependent
upon a starting device to enable it to leave the ground. That is, the
Wright machine was not complete in itself, and was entirely helpless
at even a short distance from its starting tower, rail, and car, which
it was unable to carry along. Because of its completeness, M. Bleriot
was able to drive his machine from Toury to Artenay, France (a distance
of 8¾ miles) on October 31, 1908, make a landing, start on the return
trip, make a second landing, and again continue his journey back to
Toury, all under his own unassisted power. This feat was impossible to
the Wright machine as it was then constructed, thus leaving the Bleriot
monoplane in undisputed pre-eminence in the history of aviation.
[Illustration: A Bleriot monoplane, “No. XI,” in flight.]
At a little distance, where the details of construction are not
visible, the Bleriot machine has the appearance of a gigantic bird. The
sustaining surface, consisting of a single plane, is divided into two
wings made of a stiff parchment-like material, mounted one on each side
of a framework of the body, which is built of mahogany and whitewood
trussed with diagonal ties of steel wire.
The main plane has a lateral spread of 28 feet and a depth of 6 feet,
and is rounded at the ends. It has an area of about 150 square feet,
and is slightly concave on the under side. The tail-plane is 6 feet
long and 2 feet 8 inches in depth; at its ends are the elevators,
consisting of pivoted wing tips each about 2 feet 6 inches square
with rounded extremities. The rudder for steering to left or right
is mounted at the extreme rear end of the body, and has an area of 9
square feet.
[Illustration: The Bleriot “No. XII.,” showing new form of tail, and
the complete encasing with fabric.]
The body is framed nearly square in front and tapers to a wedge-like
edge at the rear. It extends far enough in front of the main plane to
give room for the motor and propeller. The seat for the pilot is on a
line with the rear edge of the main plane, and above it. The forward
part of the body is enclosed with fabric.
[Illustration: Forward chassis of Bleriot monoplane, showing caster
mounting of wheels. The framing of the body is shown by the dotted
lines.]
The machine is mounted on three wheels attached to the body: two at
the front, with a powerful spring suspension and pivoted like a caster,
and the other rigidly at a point just forward of the rudders.
The lateral balance is restored by warping the tips of the main plane;
if necessary, the elevator tips at the rear may be operated to assist
in this. All the controls are actuated by a single lever and a drum to
which the several wires are attached.
[Illustration:
Diagram of Bleriot “No. XI.,” from the rear. _A_, _A_, main
plane; _B_, tail; _C_, body; _D_, _D_, wing tips of tail; _E_,
rudder; _H_, propeller; _M_, motor; _O_, axis of wing tips; _R_,
radiator; _a_, _a_, _b_, _b_, spars of wings; _h_, _h_, guy
wires; _p_, _k_, truss.]
The motors used on the Bleriot machines have varied in type and power.
In the “No. XI.,” with which M. Bleriot crossed the English Channel,
the motor was a 3-cylinder Anzani engine, developing 24 horse-power at
1,200 revolutions per minute. The propeller was of wood, 2-bladed, and
6 feet 9 inches in diameter. It was mounted directly on the shaft, and
revolved at the same speed, giving the machine a velocity of 37 miles
per hour. This model has also been fitted with a 30 horse-power R-E-P
(R. Esnault-Pelterie) motor, having 7 cylinders. The heavier type “No.
XII.” has been fitted with the 50 horse-power Antoinette 8-cylinder
engine, or the 7-cylinder rotating Gnome engine, also of 50 horse-power.
[Illustration: Sketches showing relative size, construction, and
position of pilot in the Bleriot machines; “No. XI.” (the upper), and
“No. XII.” (the lower).]
The total weight of the “No. XI.” monoplane is 462 pounds, without the
pilot.
THE ANTOINETTE MONOPLANE.
The Antoinette is the largest and heaviest of the monoplanes. It
was designed by M. Levavasseur, and has proved to be one of the
most remarkable of the aeroplanes by its performances under adverse
conditions; notably, the flight of Hubert Latham in a gale of 40 miles
per hour at Blackpool in October, 1909.
The Antoinette has a spread of 46 feet, the surface being disposed
in two wings set at a dihedral angle; that is, the outer ends of the
wings incline upward from their level at the body, so that at the front
they present the appearance of a very wide open “V.” These wings are
trapezoidal in form, with the wider base attached to the body, where
they are 10 feet in depth (fore and aft). They are 7 feet in depth at
the tips, and have a total combined area of 377 square feet. The great
depth of the wings requires that they be made proportionally thick to
be strong enough to hold their form. Two trussed spars are used in each
wing, with a short mast on each, half-way to the tip, reaching below
the wing as well as above it. To these are fastened guy wires, making
each wing an independent truss. A mast on the body gives attachment
for guys which bind the whole into a light and rigid construction. The
framework of the wings is covered on both sides with varnished fabric.
[Illustration: The Antoinette monoplane in flight.]
The body is of triangular section. It is a long girder; at the front,
in the form of a pyramid, expanding to a prism at the wings, and
tapering toward the tail. It is completely covered with the fabric,
which is given several coats of varnish to secure the minimum of skin
friction.
[Illustration: Diagram showing construction of the Antoinette
monoplane.]
The tail is 13 feet long and 9 feet wide, in the form of a
diamond-shaped kite. The rear part of it is hinged to be operated as
the elevator. There is a vertical stabilizing fin set at right angles
to the rigid part of the tail. The rudder for steering to right or
left is in two triangular sections, one above and the other below the
tail-plane. The entire length of the machine is 40 feet, and its weight
is 1,045 pounds.
It is fitted with a motor of the “V” type, having 8 cylinders, and
turning a 2-bladed steel propeller 1,100 revolutions per minute,
developing from 50 to 55 horse-power.
The control of the lateral balance is by ailerons attached to the rear
edges of the wings at their outer ends. These are hinged, and may be
raised as well as lowered as occasion demands, working in opposite
directions, and thus doubling the effect of similar ailerons on the
Farman machine, which can only be pulled downward.
The machine is mounted on two wheels under the centre of the main
plane, with a flexible wood skid projecting forward. Another skid is
set under the tail.
It is claimed for the Antoinette machine that its inherent stability
makes it one of the easiest of all for the beginner in aviation. With
as few as five lessons many pupils have become qualified pilots, even
winning prizes against competitors of much wider experience.
[Illustration: Diagrams showing comparative size and position of
surfaces and structure of the Bleriot (left) and Antoinette (right)
monoplanes.]
THE SANTOS-DUMONT MONOPLANE.
This little machine may be called the “runabout” of the aeroplanes. It
has a spread of only 18 feet, and is but 20 feet in total length. Its
weight is about 245 pounds.
The main plane is divided into two wings, which are set at the body
at a dihedral angle, but curve downward toward the tips, forming an
arch. The depth of the wings at the tips is 6 feet. For a space on each
side of the centre they are cut away to 5 feet in depth, to allow the
propeller to be set within their forward edge. The total area of the
main plane is 110 square feet.
The tail-plane is composed of a vertical surface and a horizontal
surface intersecting. It is arranged so that it may be tilted up or
down to serve as an elevator, or from side to side as a rudder. Its
horizontal surface has an area of about 12 square feet.
The engine is placed above the main plane and the pilot’s seat below
it. The body is triangular in section, with the apex uppermost,
composed of three strong bamboo poles with cross-pieces held in place
by aluminum sockets, and cross braced with piano wire.
[Illustration: Santos-Dumont’s _La Demoiselle_ in flight.]
The motor is of the opposed type, made by Darracq, weighing only 66
pounds, and developing 30 horse-power at 1,500 revolutions per minute.
The propeller is of wood, 2-bladed, and being mounted directly on the
shaft of the motor, revolves at the same velocity. The speed of the
Santos-Dumont machine is 37 miles per hour.
[Illustration: The Darracq motor and propeller of the Santos-Dumont
machine. The conical tank in the rear of the pilot’s seat holds the
gasoline.]
The lateral balance is preserved by a lever which extends upward and
enters a long pocket sewed on the back of the pilot’s coat. His leaning
from side to side warps the rear edges of the wings at their tips. The
elevator is moved by a lever, and the rudder by turning a wheel.
While this machine has not made any extended flights, Santos-Dumont has
travelled in the aggregate upward of 2,000 miles in one or another of
this type.
The plans, with full permission to any one to build from them, he gave
to the public as his contribution to the advancement of aviation.
Several manufacturers are supplying them at a cost much below that of
an automobile.
[Illustration: Sketch showing position of pilot in Santos-Dumont
machine. _A_, main plane; _B_, tail plane; _C_, motor.]
THE R-E-P MONOPLANE.
The Robert Esnault-Pelterie (abbreviated by its inventor to R-E-P)
monoplane, viewed from above, bears a striking resemblance to a bird
with a fan-shaped tail. It is much shorter in proportion to its spread
than any other monoplane, and the body being entirely covered with
fabric, it has quite a distinct appearance.
The plane is divided into two wings, in form very much like the wings
of the Antoinette machine. Their spread, however, is but 35 feet. Their
depth at the body is 8 feet 6 inches, and at the tips, 5 feet. Their
total combined area is 226 square feet.
The body of the R-E-P machine has much the appearance of a boat, being
wide at the top and coming to a sharp keel below. The boat-like prow in
front adds to this resemblance. As the body is encased in fabric, these
surfaces aid in maintaining vertical stability.
A large stabilizing fin extends from the pilot’s seat to the tail. The
tail is comparatively large, having an area of 64 square feet. Its rear
edge may be raised or lowered to serve as an elevator. The rudder for
steering to right or left is set below in the line of the body, as in a
boat. It is peculiar in that it is of the “compensated” type; that is,
pivoted near the middle of its length, instead of at the forward end.
The control of the lateral balance is through warping the wings. This
is by means of a lever at the left hand of the pilot, with a motion
from side to side. The same lever moved forward or backward controls
the elevator. The steering lever is in front of the pilot’s seat, and
moves to right or to left.
[Illustration: Elevation, showing large stabilizing fin; boat-like body
encased in fabric; and compensated rudder, pivoted at the rear end of
the fin.]
[Illustration: Plan, showing comparative spread of surfaces, and the
attachment of wheels at the wing tips.
Graphic sketch showing elevation and plan of the R-E-P monoplane.]
The motor is an invention of M. Esnault-Pelterie, and may be of 5, 7,
or 10 cylinders, according to the power desired. The cylinders are
arranged in two ranks, one in the rear of the other, radiating outward
from the shaft like spokes in a wheel. The propeller is of steel,
4-bladed, and revolves at 1,400 revolutions per minute, developing 35
horse-power, and drawing the machine through the air at a speed of 47
miles per hour.
THE HANRIOT MONOPLANE.
Among the more familiar machines which have been contesting for records
at the various European meets during the season of 1910, the Hanriot
monoplane earned notice for itself and its two pilots, one of them the
fifteen-year-old son of the inventor. At Budapest the Hanriot machine
carried off the honors of the occasion with a total of 106 points for
“best performances,” as against 84 points for the Antoinette, and 77
points for the Farman biplane. A description of its unusual features
will be of interest by way of comparison.
In general appearance it is a cross between the Bleriot and the
Antoinette, the wings being shaped more like the latter, but rounded
at the rear of the tips like the Bleriot. Its chief peculiarity is in
the body of the machine, which is in form very similar to a racing
shell--of course with alterations to suit the requirements of the
aeroplane. Its forward part is of thin mahogany, fastened upon ash
ribs, with a steel plate covering the prow. The rear part of the
machine is covered simply with fabric.
The spread of the plane is 24 feet 7 inches, and it has an area of 170
square feet. The length of the machine, fore-and-aft, is 23 feet. Its
weight is 463 pounds. It is mounted on a chassis having both wheels
and skids, somewhat like that of the Farman running gear, but with two
wheels instead of four.
The Hanriot machine is sturdily built all the way through, and has
endured without damage some serious falls and collisions which would
have wrecked another machine.
It is fitted either with a Darracq or a Clerget motor, and speeds at
about 44 miles per hour.
THE PFITZNER MONOPLANE.
The Pfitzner monoplane has the distinction of being the first American
machine of the single-plane type. It was designed and flown by the
late Lieut. A. L. Pfitzner, and, though meeting with many mishaps, has
proved itself worthy of notice by its performances, through making use
of an entirely new device for lateral stability. This is the sliding
wing tip, by which the wing that tends to fall from its proper level
may be lengthened by 15 inches, the other wing being shortened as much
at the same time.
There is no longitudinal structure, as in the other monoplanes, the
construction being transverse and built upon four masts set in the
form of a square, 6 feet apart, about the centre. These are braced by
diagonal struts, and tied with wires on the edges of the squares. They
also support the guys reaching out to the tips of the wings.
[Illustration: The Pfitzner monoplane from the rear, showing the
sliding wing tips; dihedral angle of the wings; square body; and
transverse trussed construction.]
The plane proper is 31 feet in spread, to which the wing tips add 2½
feet, and is 6 feet deep, giving a total area of 200 square feet. A
light framework extending 10 feet in the rear carries a tail-plane 6
feet in spread and 2 feet in depth. Both the elevator and the rudder
planes are carried on a similar framework, 14 feet in front of the main
plane.
[Illustration: The Pfitzner monoplane, showing the structure of the
body; the two conical gasoline tanks above; the propeller in the rear.
Lieutenant Pfitzner at the wheel.]
The wings of the main plane incline upward from the centre toward the
tips, and are trussed by vertical struts and diagonal ties.
The motor is placed in the rear of the plane, instead of in front, as
in all other monoplanes. It is a 4-cylinder Curtiss motor, turning a
6-foot propeller at 1,200 revolutions per minute, and developing 25
horse-power.
The Pfitzner machine has proved very speedy, and has made some
remarkably sharp turns on an even keel.
OTHER MONOPLANES.
Several machines of the monoplane type have been produced, having some
feature distinct from existing forms. While all of these have flown
successfully, few of them have made any effort to be classed among the
contestants for honors at the various meets.
One of these, the Fairchild monoplane, shows resemblances to the R-E-P,
the Antoinette, and the Bleriot machines, but differs from them all
in having two propellers instead of one; and these revolve in the
same direction, instead of in contrary directions, as do those of all
other aeroplanes so equipped. The inventor claims that there is little
perceptible gyroscopic effect with a single propeller, and even less
with two. The propeller shafts are on the level of the plane, but the
motor is set about 5 feet below, connections being made by a chain
drive.
[Illustration: The Beach type of the Antoinette, an American
modification of the French machine, at the Boston Exhibition, 1910.]
The Burlingame monoplane has several peculiarities. Its main plane is
divided into two wings, each 10 feet in spread and 5 feet in depth,
and set 18 inches apart at the body. They are perfectly rigid. The
tail is in two sections, each 4 feet by 5 feet, and set with a gap of
6 feet between the sections, in which the rudder is placed. Thus the
spread of the tail from tip to tip is 16 feet, as compared with the 21½
foot spread of the main plane. The sections of the tail are operated
independently, and are made to serve as ailerons to control the lateral
balance, and also as the elevator.
The Cromley monoplane, another American machine, is modelled after the
Santos-Dumont _Demoiselle_. It has a main plane divided into two wings,
each 9 feet by 6 feet 6 inches, with a gap of 2 feet between at the
body; the total area being 117 square feet. At the rear of the outer
ends are hinged ailerons, like those of the Farman biplane, to control
the lateral balance. The tail is 12 feet in the rear, and is of the
“box” type, with two horizontal surfaces and two vertical surfaces.
This is mounted with a universal joint, so that it can be moved in any
desired direction. The complete structure, without the motor, weighs
but 60 pounds.
The Chauviere monoplane is distinct in having a rigid spar for the
front of the plane, but no ribs. The surface is allowed to spread out
as a sail and take form from the wind passing beneath. The rear edges
may be pulled down at will to control the lateral balance. It is driven
by twin screws set far back on the body, nearly to the tail.
[Illustration:
The Morok monoplane at the Boston Exhibition. It has the body of
the Bleriot, the wings of the Santos-Dumont, and the sliding wing
tips of the Pfitzner.]
The smallest and lightest monoplane in practical use is that of M.
Raoul Vendome. It is but 16 feet in spread, and is 16 feet fore and
aft. It is equipped with a 12 horse-power motor, and flies at a speed
of nearly 60 miles per hour. Without the pilot, its entire weight is
but 180 pounds. The wings are pivoted so that their whole structure may
be tilted to secure lateral balance.
The new Moisant monoplane is built wholly of metal. The structure
throughout is of steel, and the surfaces of sheet aluminum in a
succession of small arches from the centre to the tips. No authentic
reports of its performances are available.
In the Tatin monoplane, also called the Bayard-Clement, the main plane
is oval in outline, and the tail a smaller oval. The surfaces are
curved upward toward the tips for nearly half their length in both
the main plane and the tail. The propeller is 8½ feet in diameter,
and is turned by a Clerget motor, which can be made to develop 60
horse-power for starting the machine into the air, and then cut down to
30 horse-power to maintain the flight.
Chapter VII.
FLYING MACHINES: OTHER FORMS.
The triplane--The quadruplane--The multiplane--Helicopters--Their
principle--Obstacles to be overcome--The Cornu helicopter--The
Leger helicopter--The Davidson gyropter--The Breguet
gyroplane--The de la Hault ornithopter--The Bell
tetrahedrons--The Russ flyer.
While the efforts of inventors have been principally along the lines
of the successful monoplanes and biplanes, genius and energy have also
been active in other directions. Some of these other designs are not
much more than variations from prevailing types, however.
Among these is the English Roe triplane, which is but a biplane
with an extra plane added; the depths of all being reduced to give
approximately the same surface as the biplane of the same carrying
power. The tail is also of the triplane type, and has a combined area
of 160 square feet--just half that of the main planes. The triplane
type has long been familiar to Americans in the three-decker glider
used extensively by Octave Chanute in his long series of experiments
at Chicago.
[Illustration: The Roe triplane in flight.]
The quadruplane of Colonel Baden-Powell, also an English type, is
practically the biplane with unusually large forward and tail planes.
The multiplane of Sir Hiram Maxim should also be remembered, although
he never permitted it to have free flight. His new multiplane, modelled
after the former one, but equipped with an improved gasoline motor
instead of the heavy steam-engine of the first model, will doubtless be
put to a practical test when experiments with it are completed.
[Illustration: Sir Hiram Maxim standing beside his huge multiplane.]
Quite apart from these variants of the aeroplanes are the helicopters,
ornithopters, gyropters, gyroplanes, and tetrahedral machines.
HELICOPTERS.
The result aimed at in the helicopter is the ability to rise vertically
from the starting point, instead of first running along the ground
for from 100 to 300 feet before sufficient speed to rise is attained,
as the aeroplanes do. The device employed to accomplish this result is
a propeller, or propellers, revolving horizontally above the machine.
After the desired altitude is gained it is proposed to travel in any
direction by changing the plane in which the propellers revolve to one
having a small angle with the horizon.
[Illustration:
The force necessary to keep the aeroplane moving in its
horizontal path is the same as that required to move the
automobile of equal weight up the same gradient--much less than
its total weight.]
The great difficulty encountered with this type of machine is that the
propellers must lift the entire weight. In the case of the aeroplane,
the power of the engine is used to slide the plane up an incline of
air, and for this much less power is required. For instance, the weight
of a Curtiss biplane with the pilot on board is about 700 pounds,
and this weight is easily slid up an inclined plane of air with a
propeller thrust of about 240 pounds.
Another difficulty is that the helicopter screws, in running at the
start before they can attain speed sufficient to lift their load, have
established downward currents of air with great velocity, in which the
screws must run with much less efficiency. With the aeroplanes, on the
contrary, their running gear enables them to run forward on the ground
almost with the first revolution of the propeller, and as they increase
their speed the currents--technically called the “slip”--become less
and less as the engine speed increases.
In the Cornu helicopter, which perhaps has come nearer to successful
flight than any other, these downward currents are checked by
interposing planes below, set at an angle determined by the operator.
The glancing of the currents of air from the planes is expected to
drive the helicopter horizontally through the air. At the same time
these planes offer a large degree of resistance, and the engine power
must be still further increased to overcome this, while preserving the
lift of the entire weight. With an 8-cylinder Antoinette motor, said
to be but 24 horse-power, turning two 20-foot propellers, the machine
is reported as lifting itself and two persons--a total weight of 723
pounds--to a height of 5 feet, and sustaining itself for 1 minute. Upon
the interposing of the planes to produce the horizontal motion the
machine came immediately to the ground.
[Illustration: Diagram showing principle of the Cornu helicopter. _P_,
_P_, propelling planes. The arrow shows direction of travel with planes
at angle shown.]
This performance must necessarily be compared with that of the
aeroplanes, as, for instance, the Wright machine, which, with a 25 to
30 horse-power motor operating two 8-foot propellers, raises a weight
of 1,050 pounds and propels it at a speed of 40 miles an hour for
upward of 2 hours.
Another form of helicopter is the Leger machine, so named after its
French inventor. It has two propellers which revolve on the same
vertical axis, the shaft of one being tubular, encasing that of the
other. By suitable gearing this vertical shaft may be inclined after
the machine is in the air in the direction in which it is desired to
travel.
[Illustration: The Vitton-Huber helicopter at the Paris aeronautical
salon in 1909. It has the double concentric axis of the Leger
helicopter and the propelling planes of the Cornu machine.]
The gyropter differs from the Cornu type of helicopter in degree rather
than in kind. In the Scotch machine, known as the Davidson gyropter,
the propellers have the form of immense umbrellas made up of curving
slats. The frame of the structure has the shape of a T, one of the
gyropters being attached to each of the arms of the T. The axes upon
which the gyropters revolve may be inclined so that their power may be
exerted to draw the apparatus along in a horizontal direction after it
has been raised to the desired altitude.
The gyropters of the Davidson machine are 28 feet in diameter, the
entire structure being 67 feet long, and weighing 3 tons. It has been
calculated that with the proposed pair of 50 horse-power engines the
gyropters will lift 5 tons. Upon a trial with a 10 horse-power motor
connected to one of the gyropters, that end of the apparatus was lifted
from the ground at 55 revolutions per minute--the boiler pressure being
800 lbs. to the square inch, at which pressure it burst, wrecking the
machine.
An example of the gyroplane is the French Breguet apparatus, a blend of
the aeroplane and the helicopter. It combines the fixed wing-planes of
the one with the revolving vanes of the other. The revolving surfaces
have an area of 82 square feet, and the fixed surfaces 376 square feet.
The total weight of machine and operator is about 1,350 lbs. Fitted
with a 40 horse-power motor, it rose freely into the air.
The ornithopter, or flapping-wing type of flying machine, though the
object of experiment and research for years, must still be regarded as
unsuccessful. The apparatus of M. de la Hault may be taken as typical
of the best effort in that line, and it is yet in the experimental
stage. The throbbing beat of the mechanism, in imitation of the bird’s
wings, has always proved disastrous to the structure before sufficient
power was developed to lift the apparatus.
The most prominent exponent of the tetrahedral type--that made up of
numbers of small cells set one upon another--is the _Cygnet_ of Dr.
Alexander Graham Bell, which perhaps is more a kite than a true flying
machine. The first _Cygnet_ had 3,000 cells, and lifted its pilot to a
height of 176 feet. The _Cygnet II_. has 5,000 tetrahedral cells, and
is propelled by a 50 horse-power motor. It has yet to make its record.
One of the most recently devised machines is that known as the Fritz
Russ flyer. It has two wings, each in the form of half a cylinder, the
convex curve upward. It is driven by two immense helical screws, or
spirals, set within the semi-cylinders. No details of its performances
are obtainable.
Chapter VIII.
FLYING MACHINES: HOW TO OPERATE.
Instinctive balance--When the motor skips--Progressive
experience--Plum Island School methods--Lilienthal’s
conclusions--The Curtiss mechanism and controls--Speed
records--Cross-country flying--Landing--Essential
qualifications--Ground practice--Future relief.
Any one who has learned to ride a bicycle will recall the great
difficulty at first experienced to preserve equilibrium. But once the
knack was gained, how simple the matter seemed! Balancing became a
second nature, which came into play instinctively, without conscious
thought or effort. On smooth roads it was not even necessary to grasp
the handle-bars. The swaying of the body was sufficient to guide the
machine in the desired direction.
Much of this experience is paralleled by that of the would-be aviator.
First, he must acquire the art of balancing himself and his machine in
the air without conscious effort. Unfortunately, this is even harder
than in the case of the bicycle. The cases would be more nearly alike
if the road beneath and ahead of the bicyclist were heaving and falling
as in an earthquake, with no light to guide him; for the air currents
on which the aviator must ride are in constant and irregular motion,
and are as wholly invisible to him as would be the road at night to the
rider of the wheel.
And there are other things to distract the attention of the pilot of an
aeroplane--notably the roar of the propeller, and the rush of wind in
his face, comparable only to the ceaseless and breath-taking force of
the hurricane.
The well-known aviator, Charles K. Hamilton, says:--“So far as the air
currents are concerned, I rely entirely on instinctive action; but my
ear is always on the alert. The danger signal of the aviator is when
he hears his motor miss an explosion. Then he knows that trouble is
in store. Sometimes he can speed up his engine, just as an automobile
driver does, and get it to renew its normal action. But if he fails
in this, and the motor stops, he must dip his deflecting planes, and
try to negotiate a landing in open country. Sometimes there is no
preliminary warning from the motor that it is going to cease working.
That is the time when the aviator must be prepared to act quickly.
Unless the deflecting planes are manipulated instantly, aviator and
aeroplane will rapidly land a tangled mass on the ground.”
[Illustration: Result of a failure to deflect the planes quickly enough
when the engine stopped. The operator fortunately escaped with but a
few bruises.]
At the same time, Mr. Hamilton says: “Driving an aeroplane at a speed
of 120 miles an hour is not nearly so difficult a task as driving an
automobile 60 miles an hour. In running an automobile at high speed
the driver must be on the job every second. Nothing but untiring
vigilance can protect him from danger. There are turns in the road, bad
stretches of pavement, and other like difficulties, and he can never
tell at what moment he is to encounter some vehicle, perhaps travelling
in the opposite direction. But with an aeroplane it is a different
proposition. Once a man becomes accustomed to aeroplaning, it is a
matter of unconscious attention.... He has no obstacles to encounter
except cross-currents of air. Air and wind are much quicker than a man
can think and put his thought into action. Unless experience has taught
the aviator to maintain his equilibrium instinctively, he is sure to
come to grief.”
The Wright brothers spent years in learning the art of balancing in
the air before they appeared in public as aviators. And their method
of teaching pupils is evidence that they believe the only road to
successful aviation is through progressive experience, leading up from
the use of gliders for short flights to the actual machines with motors
only after one has become an instinctive equilibrist.
At the Plum Island school of the Herring-Burgess Company the learner is
compelled to begin at the beginning and work the thing out for himself.
He is placed in a glider which rests on the ground. The glider is
locked down by a catch which may be released by pulling a string. To
the front end of the glider is attached a long elastic which may be
stretched more or less, according to the pull desired. The beginner
starts with the elastic stretched but a little. When all is ready he
pulls the catch free, and is thrown forward for a few feet. As practice
gains for him better control, he makes a longer flight; and when he
can show a perfect mastery of his craft for a flight of 300 feet, and
not till then, he is permitted to begin practice with a motor-driven
machine.
[Illustration: A French apparatus for instructing pupils in aviation.]
The lamented Otto Lilienthal, whose experience in more than 2,000
flights gives his instructions unquestionable weight, urges that the
“gradual development of flight should begin with the simplest apparatus
and movements, and without the complication of dynamic means. With
simple wing surfaces ... man can carry out limited flights ... by
gliding through the air from elevated points in paths more or less
descending. The peculiarities of wind effects can best be learned by
such exercises.... The maintenance of equilibrium in forward flight
is a matter of practice, and can be learned only by repeated personal
experiment.... Actual practice in individual flight presents the best
prospects for developing our capacity until it leads to perfected free
flight.”
The essential importance of thorough preparation in the school of
experience could scarcely be made plainer or stronger. If it seems that
undue emphasis has been laid upon this point, the explanation must be
found in the deplorable death record among aviators from accidents in
the air. With few exceptions, the cause of accident has been reported
as, “The aviator seemed to lose control of his machine.” If this is
the case with professional flyers, the need for thorough preliminary
training cannot be too strongly insisted upon.
Having attained the art of balancing, the aviator has to learn
the mechanism by which he may control his machine. While all of
the principal machines are but different embodiments of the same
principles, there is a diversity of design in the arrangement of the
means of control. We shall describe that of the Curtiss biplane, as
largely typical of them all.
In general, the biplane consists of two large sustaining planes, one
above the other. Between the planes is the motor which operates a
propeller located in the rear of the planes. Projecting behind the
planes, and held by a framework of bamboo rods, is a small horizontal
plane, called the tail. The rudder which guides the aeroplane to the
right or the left is partially bisected by the tail. This rudder is
worked by wires which run to a steering wheel located in front of
the pilot’s seat. This wheel is similar in size and appearance to
the steering wheel of an automobile, and is used in the same way for
guiding the aeroplane to the right or left. (See illustration of the
Curtiss machine in Chapter V.)
In front of the planes, supported on a shorter projecting framework,
is the altitude rudder, a pair of planes hinged horizontally, so that
their front edges may tip up or down. When they tilt up, the air
through which the machine is passing catches on the under sides and
lifts them up, thus elevating the front of the whole aeroplane and
causing it to glide upward. The opposite action takes place when these
altitude planes are tilted downward. This altitude rudder is controlled
by a long rod which runs to the steering wheel. By pushing on the wheel
the rod is shoved forward and turns the altitude planes upward. Pulling
the wheel turns the rudder planes downward. This rod has a backward and
forward thrust of over two feet, but the usual movement in ordinary
wind currents is rarely more than an inch. In climbing to high levels
or swooping down rapidly the extreme play of the rod is about four or
five inches.
Thus the steering wheel controls both the horizontal and vertical
movements of the aeroplane. More than this, it is a feeler to the
aviator, warning him of the condition of the air currents, and for
this reason must not be grasped too firmly. It is to be held steady,
yet loosely enough to transmit any wavering force in the air to the
sensitive touch of the pilot, enabling him instinctively to rise or dip
as the current compels.
[Illustration: _Courtesy N. Y. Times._
View of the centre of the new Wright machine, showing method of
operating. Archibald Hoxsey in the pilot’s seat. In his right
hand he holds a lever with two handles, one operating the warping
of the wing tips, and the other the rudder. Both handles may be
grasped at once, operating both rudder and wing tips at the same
moment. In his left hand Hoxsey grasps the lever operating the
elevating plane--at the rear in this type. The passenger’s seat
is shown at the pilot’s right.]
The preserving of an even keel is accomplished in the Curtiss machine
by small planes hinged between the main planes at the outer ends.
They serve to prevent the machine from tipping over sideways. They
are operated by arms, projecting from the back of the aviator’s seat,
which embrace his shoulders on each side, and are moved by the swaying
of his body. In a measure, they are automatic in action, for when the
aeroplane sags downward on one side, the pilot naturally leans the
other way to preserve his balance, and that motion swings the ailerons
(as these small stabilizing planes are called) in such a way that the
pressure of the wind restores the aeroplane to an even keel. The wires
which connect them with the back of the seat are so arranged that when
one aileron is being pulled down at its rear edge the rear of the
other one is being raised, thus doubling the effect. As the machine is
righted the aviator comes back to an upright position, and the ailerons
become level once more.
[Illustration: Starting a Wright machine. When the word is given both
assistants pull vigorously downward on the propeller blades.]
There are other controls which the pilot must operate consciously.
In the Curtiss machine these are levers moved by the feet. With a
pressure of the right foot he short-circuits the magneto, thus cutting
off the spark in the engine cylinders and stopping the motor. This
lever also puts a brake on the forward landing wheels, and checks the
speed of the machine as it touches the ground. The right foot also
controls the pump which forces the lubricating oil faster or slower to
the points where it is needed.
The left foot operates the lever which controls the throttle by which
the aviator can regulate the flow of gas to the engine cylinders. The
average speed of the 7-foot propeller is 1,100 revolutions per minute.
With the throttle it may be cut down to 100 revolutions per minute,
which is not fast enough to keep afloat, but will help along when
gliding.
Obviously, travelling with the wind enables the aviator to make his
best speed records, for the speed of the wind is added to that of his
machine through the air. Again, since the wind is always slower near
the ground, the aviator making a speed record will climb up to a level
where the surface currents no longer affect his machine. But over hilly
and wooded country the air is often flowing or rushing in conflicting
channels, and the aviator does not know what he may be called upon to
face from one moment to the next. If the aeroplane starts to drop, it
is only necessary to push the steering wheel forward a little--perhaps
half an inch--to bring it up again. Usually, the machine will drop
on an even keel. Then, in addition to the motion just described, the
aviator will lean toward the higher side, thus moving the ailerons by
the seat-back, and at the same time he will turn the steering wheel
toward the lower side. This movement of the seat-back is rarely more
than 2 inches.
[Illustration:
Diagram showing action of wind on flight of aeroplane. The force
and direction of the wind being represented by the line _A B_,
and the propelling force and steered direction being _A C_, the
actual path travelled will be _A D_.]
In flying across country a sharp lookout is kept on the land below. If
it be of a character unfit for landing, as woods, or thickly settled
towns, the aviator must keep high up in the air, lest his engine stop
and he be compelled to glide to the earth. A machine will glide forward
3 feet for each foot that it drops, if skilfully handled. If he is up
200 feet, he will have to find a landing ground within 600 feet. If
he is up 500 feet, he may choose his alighting ground anywhere within
1,500 feet. Over a city like New York, a less altitude than 1,500 feet
would hardly be safe, if a glide became necessary.
Mr. Clifford B. Harmon, who was an aeronaut of distinction before he
became an aviator, under the instruction of Paulhan, has this to say:
“It is like riding a bicycle, or running an automobile. You have to try
it alone to really learn how. When one first handles a flying machine
it is advisable to keep on the ground, just rolling along. This is a
harder mental trial than you will imagine. As soon as one is seated in
a flying machine he wishes to fly. It is almost impossible to submit to
staying near the earth. But until the manipulation of the levers and
the steering gear has become second nature, this must be done. It is
best to go very slow in the beginning. Skipping along the ground will
teach a driver much. When one first gets up in the air it is necessary
to keep far from all obstacles, like buildings, trees, or crowds. There
is the same tendency to run into them that an amateur bicycle rider
has in regard to stones and ruts on the ground. When he keeps his eye
on them and tries with all his might to steer clear of them, he runs
right into them.”
[Illustration: Practicing with a monoplane, 20 feet above the ground.]
When asked what he regarded the fundamental requirements in an aviator,
Mr. Harmon said: “First, he must be muscularly strong; so that he
will not tire. Second, he should have a thorough understanding of the
mechanism of the machine he drives. Third, mental poise--the ability to
think quick and to act instantly upon your thought. Fourth, a feeling
of confidence in the air, so that he will not feel strange or out of
place. This familiarity with the air can be best obtained by first
being a passenger in a balloon, then by controlling one alone, and
lastly going up in a flying machine.”
[Illustration: Grahame-White on his Bleriot No. XII. The lever in front
of him operates all the controls through the movement of the drum at
its base.]
Mr. Claude Grahame-White, the noted English aviator, has this to say of
his first experience with his big “No. XII.” Bleriot monoplane--which
differs in many important features from the “No. XI.” machine in which
M. Bleriot crossed the English Channel: “After several disappointments,
I eventually obtained the delivery of my machine in working order....
As I had gathered a good deal of information from watching the antics
and profiting by the errors made by other beginners on Bleriot
monoplanes, I had a good idea of what _not_ to do when the engine
was started up and we were ready for our first trial.... It was a
cold morning, but the engine started up at the first quarter turn.
After many warnings from M. Bleriot’s foreman not on any account to
accelerate my engine too much, I mounted the machine along with my
friend as passenger, and immediately gave the word to let go, and we
were soon speeding along the ground at a good sixty kilometers (about
37 miles) per hour.... Being very anxious to see whether the machine
would lift off the ground, I gave a slight jerk to the elevating
plane, and soon felt the machine rise into the air; but remembering
the warnings of the foreman, and being anxious not to risk breaking
the machine, I closed the throttle and contented myself with running
around on the ground to familiarize myself with the handling of the
machine.... The next day we got down to Issy about five o’clock in
the morning, some two hours before the Bleriot mechanics turned up.
However, we got the machine out, and tied it to some railings, and then
I had my first experience of starting an engine, which to a novice
at first sight appears a most hazardous undertaking; for unless the
machine is either firmly held by several men, or is strongly tied up,
it has a tendency to immediately leap forward. We successfully started
the engine, and then rigged up a leash, and when we had mounted the
machine, we let go; and before eight o’clock we had accomplished
several very successful flights, both with and against the wind. These
experiences we continued throughout the day, and by nightfall I felt
quite capable of an extended flight, if only the ground had been large
enough.... The following day M. Bleriot returned, and he sent for me
and strongly urged me not to use the aeroplane any more at Issy, as he
said the ground was far too small for such a powerful machine.”
[Illustration:
Diagram of Bleriot monoplane, showing controlling lever _L_
and bell-shaped drum _C_, to which all controlling wires are
attached. When the bell is rocked back and forward the elevator
tips on the rear plane are moved; rocking from side to side moves
the stabilizing tips of the main plane. Turning the bell around
moves the rudder.]
[Illustration:
The Marmonier gyroscopic pendulum, devised to secure automatic
stability of aeroplanes. The wheels are driven by the aeroplane
motor at high speed. The pendulum rod is extended upward above
the axis and carries a vane which is engaged by any gust of wind
from either side of the aeroplane, tending to tilt the pendulum,
and bringing its gyroscopic resistance into play to warp the
wings, or operate ailerons.]
The caution shown by these experienced aviators cannot be too closely
followed by a novice. These men do not say that their assiduous
practice on the ground was the fruit of timidity. On the contrary,
although they are long past the preliminary stages, their advice to
beginners is uniformly in the line of caution and thorough practice.
[Illustration:
When the aeroplane is steered to the left, the pendulum swings to
the right and depresses the right side of the plane, as in (_c_).
The reaction of the air raises the right side of the plane until
both surfaces are perpendicular to the inclined pendulum, as in
(_d_).
Diagrams showing action of Marmonier gyroscopic pendulum.]
Even after one has become an expert, the battle is not won, by any
means. While flying in calm weather is extremely pleasurable, a
protracted flight is very fatiguing; and when it is necessary to
wrestle with gusts of high wind and fickle air currents, the strain
upon the strongest nerve is a serious source of danger in that the
aviator is liable to be suddenly overcome by weariness when he most
needs to be on the alert.
[Illustration:
In that inclined position the aeroplane makes the turn, and
when the course again becomes straight, both the gyroscopic and
centrifugal forces cease, and the pendulum under the influence
of gravity becomes vertical. In this position it is inclined to
the left with respect to the planes, on which its effect is to
depress the left wing and so right the aeroplane, as in (_e_).
Diagram showing action of Marmonier gyroscopic pendulum.]
Engine troubles are much fewer than they used to be, and a more
dependable form of motor relieves the mind of the aviator from such
mental disturbance. Some device in the line of a wind-shield would be
a real boon, for even in the best weather there is the ceaseless rush
of air into one’s face at 45 to 50 miles an hour. The endurance of this
for hours is of itself a tax upon the most vigorous physique.
With the passing of the present spectacular stage of the art of flying
there will doubtless come a more reliable form of machine, with
corresponding relief to the operator. Automatic mechanism will supplant
the intense and continual mental attention now demanded; and as this
demand decreases, the joys of flying will be considerably enhanced.
[Illustration:
If, when pursuing a straight course, the aeroplane is tilted by
a sideways wind (_b_), the action of the pendulum as described
above restores it to an even keel, as in (_a_).
Diagrams showing action of Marmonier gyroscopic pendulum.]
Chapter IX.
FLYING MACHINES: HOW TO BUILD.
Santos-Dumont’s gift--_La Demoiselle_--Mechanical skill
required--Preparatory practice--General dimensions--The
frame--The motor--The main planes--The rudder-tail--The
propeller--Shaping the blades--Maxim’s experience--The running
gear--The controls--Scrupulous workmanship.
When Santos-Dumont in 1909 gave to the world the unrestricted
privilege of building monoplanes after the plans of his famous No.
20--afterward named _La Demoiselle_--he gave not only the best he knew,
but as much as any one knows about the building of flying machines.
Santos-Dumont has chosen the monoplane for himself because his long
experience commends it above others, and _La Demoiselle_ was the
crowning achievement of years spent in the construction and operation
of airships of all types. In view of Santos-Dumont’s notable successes
in his chosen field of activity, no one will go astray in following his
advice.
Of course, the possession of plans and specifications for an aeroplane
does not make any man a skilled mechanic. It is well to understand at
the start that a certain degree of mechanical ability is required in
building a machine which will be entirely safe. Nor does the possession
of a successful machine make one an aeronaut. As in the case of
bicycling, there is no substitute for actual experience, while in the
airship the art of balancing is of even greater importance than on the
bicycle.
The would-be aviator is therefore advised to put himself through a
course of training of mind and body.
Intelligent experimenting with some one of the models described in
Chapter XI. will teach much of the action of aeroplanes in calms
and when winds are blowing; and practice with an easily constructed
glider (see Chapter XII.) will give experience in balancing which
will be of the greatest value when one launches into the air for the
first time with a power-driven machine. An expert acquaintance with
gasoline motors and magnetos is a prime necessity. In short, every bit
of information on the subject of flying machines and their operation
cannot fail to be useful in some degree.
The dimensions of the various parts of the Santos-Dumont monoplane are
given on the original plans according to the metric system. In reducing
these to “long measure” inches, all measurements have been given to the
nearest eighth of an inch.
In general, we may note some of the peculiarities of _La Demoiselle_.
The spread of the plane is 18 feet from tip to tip, and it is 20 feet
over all from bow to stern. In height, it is about 4 feet 2 inches when
the propeller blades are in a horizontal position. The total weight
of the machine is 265 lbs., of which the engine weighs about 66 lbs.
The area of the plane is 115 square feet, so that the total weight
supported by each square foot with Santos-Dumont (weighing 110 lbs.) on
board is a trifle over 3 lbs.
The frame of the body of the monoplane is largely of bamboo, the three
main poles being 2 inches in diameter at the front, and tapering to
about 1 inch at the rear. They are jointed with brass sockets just back
of the plane, for convenience of taking apart for transportation. Two
of these poles extend from the axle of the wheels backward and slightly
upward to the rudder-post. The third extends from the middle of the
plane between the wings, backward and downward to the rudder-post.
In cross-section the three form a triangle with the apex at the top.
These bamboo poles are braced about every 2 feet with struts of steel
tubing of oval section, and the panels so formed are tied by diagonals
of piano wire fitted with turn-buckles to draw them taut.
[Illustration:
Side view of the Santos-Dumont monoplane. _MP_, main plane with
radiator, _R_, hung underneath; _RP_, rudder plane worked by
wires _HC_, attached to lever _L_; _VC_, vertical control wires;
_WT_, tube through which run the warping wires worked by lever
_K_, in a pocket of the pilot’s coat; _B_, _B_, bamboo poles of
frame; _S_, _S_, brass, or aluminum sockets; _D_, _D_, struts
of bicycle tubing; _G_, gasoline; _RG_, reserve gasoline; _M_,
motor; _P_, propeller; _Q_, _Q_, outer rib of plane, showing
camber; _N_, skid.]
In the Santos-Dumont machine a 2-cylinder, opposed Darracq motor of
30 horse-power was used. It is of the water-cooled type, the cooling
radiator being a gridiron of very thin ⅛-inch copper tubing, and hung
up on the under side of the plane on either side of the engine. The
cylinders have a bore of about 4⅛ inches, and a stroke of about 4¾
inches. The propeller is 2-bladed, 6½ feet across, and is run at 1,400
revolutions per minute, at which speed it exerts a pull of 242 lbs.
Each wing of the main plane is built upon 2 transverse spars extending
outward from the upper bamboo pole, starting at a slight angle upward
and bending downward nearly to the horizontal as they approach the
outer extremities. These spars are of ash, 2 inches wide, and tapering
in thickness from 1⅛ inches at the central bamboo to about ⅞ inch at
the tips of the wings. They are bent into shape by immersion in hot
water, and straining them around blocks nailed to the floor of the
workshop, in the form shown at QQ, p. 177.
[Illustration:
Front view of the Santos-Dumont monoplane, showing position
of tubular struts supporting the engine and the wings; also
the guys, and warping wires entering the tubes inside the
wheels. _MP_, the main plane; _TP_, tail plane in the rear;
_R_, radiators; _M_, motor; _P_, propeller, the arrow showing
direction of revolution.]
The front spar is set about 9 inches back from the front edge of the
plane, and the rear one about 12 inches forward of the back edge of
the plane. Across these spars, and beneath them, running fore and aft,
are bamboo rods about ¾ of an inch in diameter at the forward end,
and tapering toward the rear. They are set 8½ inches apart (centre
to centre), except at the tips of the wings. The two outer panels
are 10¼ inches from centre to centre of the rods, to give greater
elasticity in warping. These fore-and-aft rods are 6 feet 5 inches
long, except directly back of the propeller, where they are 5 feet 8
inches long; they are bound to the spars with brass wire No. 25, at the
intersections. They also are bent to a curved form, as shown in the
plans, by the aid of the hot-water bath. Diagonal guys of piano wire
are used to truss the frame in two panels in each wing.
Around the outer free ends of the rods runs a piano wire No. 20, which
is let into the tips of the rods in a slot ⅜ inch deep. To prevent
the splitting of the bamboo, a turn or two of the brass wire may be
made around the rod just back of the slot; but it is much better to
provide thin brass caps for the ends of the rods, and to cut the slots
in the metal as well as in the rods. Instead of caps, ferrules will do.
When the slots are cut, let the tongue formed in the cutting be bent
down across the bamboo to form the floor to the slot, upon which the
piano wire may rest. The difference in weight and cost is very little,
and the damage that may result from a split rod may be serious.
[Illustration: Plan and details of construction of _La Demoiselle_.]
After the frame of the plane is completed it is to be covered with
cloth on both sides, so as entirely to enclose the frame, except only
the tips of the rods, as shown in the plans. In the Santos-Dumont
monoplane the cloth used is of closely woven silk, but a strong,
unbleached muslin will do--the kind made especially for aeroplanes is
best.
Both upper and lower surfaces must be stretched taut, the edges front
and back being turned over the piano wire, and the wire hemmed in.
The upper and lower surfaces are then sewed together--“through and
through,” as a seamstress would say--along both sides of each rod, so
that the rods are practically in “pockets.” Nothing must be slighted,
if safety in flying is to be assured.
[Illustration: Sectional diagram of 2-cylinder Darracq opposed motor.]
[Illustration: Diagram of 4-cylinder Darracq opposed motor.]
[Illustration: Diagram of 3-cylinder Anzani motor.
Motors suitable for _La Demoiselle_ monoplane.]
The tail of the monoplane is a rigid combination of two planes
intersecting each other at right angles along a central bamboo pole
which extends back 3 feet 5½ inches from the rudder-post, to which it
is attached by a double joint, permitting it to move upon either the
vertical or the horizontal axis.
Although this tail, or rudder, may seem at first glance somewhat
complicated in the plans, it will not be found so if the frame of the
upright or vertical plane be first constructed, and that of the level
or horizontal plane afterward built fast to it at right angles.
As with the main plane, the tail is to be covered on both sides with
cloth, the vertical part first; the horizontal halves on either side so
covered that the cloth of the latter may be sewed above and below the
central pole. All of the ribs in the tail are to be stitched in with
“pockets,” as directed for the rods of the main plane.
The construction of the motor is possible to an expert machinist only,
and the aeroplane builder will save time and money by buying his engine
from a reliable maker. It is not necessary to send to France for a
Darracq motor. Any good gasoline engine of equal power, and about the
same weight, will serve the purpose.
The making of the propeller is practicable for a careful workman. The
illustrations will give a better idea than words of how it should be
done. It should be remembered, however, that the safety of the aviator
depends as much upon the propeller as upon any other part of the
machine. The splitting of the blades when in motion has been the cause
of serious accidents. The utmost care, therefore, should be exercised
in the selection of the wood, and in the glueing of the several
sections into one solid mass, allowing the work to dry thoroughly under
heavy pressure.
[Illustration:
Diagram showing how the layers of wood are placed for glueing:
_A_, at the hub; _B_, half way to the tip of the blade; _C_, at
the tip. The dotted lines show the form of the blade at these
points.]
The forming of the blades requires a good deal of skill, and some
careful preliminary study. It is apparent that the speed of a point
at the tip of a revolving blade is much greater than that of a point
near the hub, for it traverses a larger circle in the same period of
time. But if the propeller is to do effective work without unequal
strain, the twist in the blade must be such that each point in the
length of the blade is exerting an equal pull on the air. It is
necessary, therefore, that the slower-moving part of the blade, near
the hub, or axis, shall cut “deeper” into the air than the more swiftly
moving tip of the blade. Consequently the blade becomes continually
“flatter” (approaching the plane in which it revolves) as we work
from the hub outward toward the tip. This “flattening” is well shown
in the nearly finished blade clamped to the bench at the right of the
illustration--which shows a four-bladed propeller, instead of the
two-bladed type needed for the monoplane.
The propeller used for propulsion in air differs from the
propeller-wheel used for ships in water, in that the blades are curved
laterally; the forward face of the blade being convex, and the rearward
face concave. The object of this shaping is the same as for curving the
surface of the plane--to secure smoother entry into the air forward,
and a compression in the rear which adds to the holding power on
the substance of the air. It is extremely difficult to describe this
complex shape, and the amateur builder of a propeller will do well to
inspect one made by a professional, or to buy it ready made with his
engine.
[Illustration: Forming a 4-blade propeller out of 8 layers of wood
glued firmly together.]
The following quotation from Sir Hiram Maxim’s account of his most
effective propeller may aid the ambitious aeroplane builder: “My large
screws were made with a great degree of accuracy; they were perfectly
smooth and even on both sides, the blades being thin and held in
position by a strip of rigid wood on the back of the blade.... Like
the small screws, they were made of the very best kind of seasoned
American white pine, and when finished were varnished on both sides
with hot glue. When this was thoroughly dry, they were sand-papered
again, and made perfectly smooth and even. The blades were then covered
with strong Irish linen fabric of the smoothest and best make. Glue
was used for attaching the fabric, and when dry another coat of glue
was applied, the surface rubbed down again, and then painted with
zinc white in the ordinary way and varnished. These screws worked
exceedingly well.”
The covering of the blades with linen glued fast commends itself to the
careful workman as affording precaution against the splintering of the
blades when in rapid motion. Some propellers have their wooden blades
encased with thin sheet aluminum to accomplish the same purpose, but
for the amateur builder linen is far easier to apply.
[Illustration:
This method of mounting the wheels of the chassis has been found
the most satisfactory. The spring takes up the shock of a sudden
landing and the pivot working in the hollow post allows the
entire mounting to swing like a caster, and adapt itself to any
direction at which the machine may strike the ground.]
The wheels are of the bicycle type, with wire spokes, but with hubs six
inches long. The axle is bent to incline upward at the ends, so that
the wheels incline outward at the ground, the better to take the shock
of a sideways thrust when landing. The usual metal or wood rims may be
used, but special tires of exceptionally light construction, made for
aeroplanes, should be purchased.
The controlling wires or cords for moving the rudder (or tail) and for
warping the tips of the wings are of flexible wire cable, such as is
made for use as steering rope on small boats. The cable controlling
the horizontal plane of the rudder-tail is fastened to a lever at the
right hand of the operator. The cable governing the vertical plane
of the rudder-tail is attached to a wheel at the left hand of the
operator. The cables which warp the tips of the wings are fastened to
a lever which projects upward just back of the operator’s seat, and
which is slipped into a long pocket sewed to the back of his coat, so
that the swaying of his body in response to the fling of the tipping
machine tends to restore it to an even keel. Springs are attached to
all of these controlling wires, strong enough to bring them back to a
normal position when the operator removes his hands from the steering
apparatus.
The brass sockets used in connecting the tubular struts to the main
bamboos and the rudder-post, and in fastening the axle of the wheels to
the lower bamboos and elsewhere, should be thoroughly made and brazed
by a good mechanic, for no one should risk the chance of a faulty
joint at a critical spot, when an accident may mean the loss of life.
[Illustration: Diagram of Bleriot monoplane showing sizes of parts, in
metres. Reduced to feet and inches these measurements are:
0.60 metres 1 ft. 11½ in.
1.50 metres 4 ft. 11 in.
2.10 metres 6 ft. 10½ in.
3.50 metres 11 ft. 6 in.
8.00 metres 26 ft. 3 in.
8.60 metres 28 ft. 2½ in.
The diagram being drawn to scale other dimensions may be found.
In both the plan (upper figure) and elevation (lower figure),
_A_, _A_, is the main plane; _B_, tail plane; _C_, body; _D_,
elevator wing-tips; _E_, rudder; _a_, _a_, rigid spar; _b_, _b_,
flexible spar; _r_, _r_, points of attachment for warping-wires;
_h_, _h_, guys; _H_, propeller; _M_, motor; _R_, radiator; _S_,
pilot’s seat; _P_, chassis.]
For the rest, it has seemed better to put the details of construction
on the plans themselves, where they will be available to the aeroplane
builder without the trouble of continually consulting the text.
Some of the work on an aeroplane will be found simple and easy; some of
it, difficult and requiring much patience; and some impracticable to
any one but a trained mechanic. But in all of it, the worker’s motto
should be, “Fidelity in every detail.”
Chapter X.
FLYING MACHINES: MOTORS.
Early use of steam--Reliability necessary--The gasoline
motor--Carburetion--Compression--Ignition--Air-cooling--Water-cooling--Lubrication--The
magneto--Weight--Types of motors--The propeller--Form, size, and
pitch--Slip--Materials--Construction.
The possibility of the existence of the flying machine as we have it
to-day has been ascribed to the invention of the gasoline motor. While
this is not to be denied, it is also true that the gasoline motors
designed and built for automobiles and motor-boats have had to be
wellnigh revolutionized to make them suitable for use in the various
forms of aircraft. And it is to be remembered, doubtless to their
greater credit, that Henson, Hargrave, Langley, and Maxim had all
succeeded in adapting steam to the problem of the flight of models, the
two latter using gasoline to produce the steam.
Perhaps the one predominant qualification demanded of the aeroplane
motor is reliability. A motor-car or motor-boat can be stopped, and
engine troubles attended to with comparatively little inconvenience.
The aeroplane simply cannot stop without peril. It is possible for
a skilful pilot to reach the earth when his engine stops, if he is
fortunately high enough to have space for the downward glide which will
gain for him the necessary headway for steering. At a lesser height he
is sure to crash to the earth.
An understanding of the principles on which the gasoline motor works
is essential to a fair estimate of the comparative advantages of the
different types used to propel aeroplanes. In the first place, the
radical difference between the gasoline motor and other engines is the
method of using the fuel. It is not burned in ordinary fashion, but the
gasoline is first vaporized and mixed with a certain proportion of air,
in a contrivance called a carburetor. This gaseous mixture is pumped
into the cylinder of the motor by the action of the motor itself,
compressed into about one-tenth of its normal volume, and then exploded
by a strong electric spark at just the right moment to have its force
act most advantageously to drive the machinery onward.
[Illustration: The “Fiat” 8-cylinder air-cooled motor, of the “V” type,
made in France.]
It is apparent that there are several chances for failure in this
series. The carburetor may not do its part accurately. The mixture of
air and vapor may not be in such proportions that it will explode; in
that case, the power from that stroke will be missing, and the engine
will falter and slow down. Or a leakage in the cylinder may prevent
the proper compression of the mixture, the force from the explosion
will be greatly reduced, with a corresponding loss of power and speed.
Or the electric spark may not be “fat” enough--that is, of sufficient
volume and heat to fire the mixture; or it may not “spark” at just
the right moment; if too soon, it will exert its force against the
onward motion: if too late, it will not deliver the full power of the
explosion at the time when its force is most useful. The necessity for
absolute perfection in these operations is obvious.
[Illustration: A near view of the Holmes engine from the driving side.]
[Illustration: The Holmes rotative engine, 7-cylinder 35 horse-power,
weighing 160 pounds.
An American engine built in Chicago, Ill.]
Other peculiarities of the gasoline motor affect considerably its
use for aeroplanes. The continual and oft-repeated explosions of the
gaseous mixture inside of the cylinder generate great heat, and this
not only interferes with its regularity of movement, but within a
very brief time checks it altogether. To keep the cylinder cool enough
to be serviceable, two methods are in use: the air-cooling system and
the water-cooling system. In the first, flanges of very thin metal
are cast on the outside of the cylinder wall. These flanges take up
the intense heat, and being spread out over a large surface in this
way, the rushing of the air through them as the machine flies (or
sometimes blown through them with a rotary fan) cools them to some
degree. With the water-cooling system, the cylinder has an external
jacket, the space between being filled with water which is made to
circulate constantly by a small pump. In its course the water which
has just taken up the heat from the cylinder travels through a radiator
in which it is spread out very thin, and this radiator is so placed
in the machine that it receives the full draught from the air rushing
through the machine as it flies. The amount of water required for
cooling a motor is about 1⅕ lbs. per horse-power. With an 8-cylinder 50
horse-power motor, this water would add the very considerable item of
60 lbs. to the weight the machine has to carry. As noted in a previous
chapter, the McCurdy biplane has its radiator formed into a sustaining
plane, and supports its own weight when travelling in the air.
[Illustration: The 180 horse-power engine of Sir Hiram Maxim; of the
“opposed” type, compound, and driven by steam.]
[Illustration:
The Anzani motor and propeller which carried M. Bleriot across
the English Channel. The curved edge of the propeller blades is
the entering edge, the propeller turning from the right of the
picture over to the left. The Anzani is of the “radiant” type and
is of French build.]
It is an unsettled point with manufacturers whether the greater
efficiency (generally acknowledged) of the water-cooled engine more
than compensates for the extra weight of the water.
Another feature peculiar to the gasoline motor is the necessity for
such continual oiling that it is styled “lubrication,” and various
devices have been invented to do the work automatically, without
attention from the pilot further than the watching of his oil-gauge to
see that a full flow of oil is being pumped through the oiling system.
The electric current which produces the spark inside of the cylinder
is supplied by a magneto, a machine formed of permanent magnets of
horseshoe form, between the poles of which a magnetized armature is
made to revolve rapidly by the machinery which turns the propeller.
This magneto is often connected with a small storage battery, or
accumulator, which stores up a certain amount of current for use when
starting, or in case the magneto gives out.
[Illustration: Sectional drawings showing details of construction of
the Anzani motor. The flanges of the air-cooling system are distinctly
shown. The section at the left is from the side; that at the right,
from the front. All measurements are in millimètres. A millimètre is
0.039 inch.]
The great rivalry of the builders of motors has been in cutting down
the weight per horse-power to the lowest possible figure. It goes
without saying that useless weight is a disadvantage in an aeroplane,
but it has not been proven that the very lightest engines have made a
better showing than those of sturdier build.
[Illustration: The “Gobron” engine of the “double opposed,” or
cross-shaped type. A water-cooled engine, with 8 cylinders.]
One of the items in the weight of an engine has been the fly-wheel
found necessary on all motors of 4 cylinders or less to give steadiness
to the running. With a larger number of cylinders, and a consequently
larger number of impulses in the circuit of the propeller, the
vibration is so reduced that the fly-wheel has been dispensed with.
[Illustration: The Emerson 6-cylinder aviation engine, of the “tandem”
type, water-cooled; 60 horse-power; made at Alexandria, Va.]
There are several distinct types of aircraft engines, based on the
arrangement of the cylinders. The “tandem” type has the cylinders
standing upright in a row, one behind another. There may be as many as
eight in a row. The Curtiss and Wright engines are examples. Another
type is the “opposed” arrangement, the cylinders being placed in a
horizontal position and in two sets, one working opposite the other.
An example of this type is seen in the Darracq motor used on the
Santos-Dumont monoplane. Another type is the “V” arrangement, the
cylinders set alternately leaning to right and to left, as seen in
the “Fiat” engine. Still another type is the “radiant,” in which the
cylinders are all above the horizontal, and disposed like rays from
the rising sun. The 3-cylinder Anzani engine and the 5- and 7-cylinder
R-E-P engines are examples. The “star” type is exemplified in the 5
and 7-cylinder engines in which the cylinders radiate at equal angles
all around the circle. The “double opposed” or cross-shaped type is
shown in the “Gobron” engine. In all of these types the cylinders are
stationary, and turn the propeller shaft either by cranks or by gearing.
[Illustration: The Elbridge engine, of the “tandem” type and
water-cooled. It is an American engine, built at Rochester, N. Y.]
An entirely distinct type of engine, and one which has been devised
solely for the aeroplane, is the rotative--often miscalled the rotary,
which is totally different. The rotative type may be illustrated by the
Gnome motor. In this engine the seven cylinders turn around the shaft,
which is stationary. The propeller is fastened to the cylinders, and
revolves with them. This ingenious effect is produced by an offset
of the crank-shaft of half the stroke of the pistons, whose rods are
all connected with the crank-shaft. The entire system revolves around
the main shaft as a centre, the crank-shaft being also stationary.
[Illustration:
The famous Gnome motor; 50 horse-power, 7-cylinder, air-cooled;
of the rotative type; made in France. This illustration shows the
Gnome steel propeller.]
[Illustration: Sectional diagram of the 5-cylinder R-E-P motor; of the
“radiant” type.]
[Illustration: Sectional diagram of the 5-cylinder Bayard-Clement
motor; of the “star” type.]
Strictly speaking, the propeller is not a part of the motor of the
flying machine, but it is so intimately connected with it in the
utilization of the power created by the motor, that it will be treated
of briefly in this chapter.
The form of the air-propeller has passed through a long and varied
development, starting with that of the marine propeller, which was
found to be very inefficient in so loose a medium as air. On account
of this lack of density in the air, it was found necessary to act on
large masses of it at practically the same time to gain the thrust
needed to propel the aeroplane swiftly, and this led to increasing the
diameter of the propeller to secure action on a proportionally larger
area of air. The principle involved is simply the geometric rule that
the areas of circles are to each other as the squares of their radii.
Thus the surface of air acted on by two propellers, one of 6 feet
diameter and the other of 8 feet diameter, would be in the proportion
of 9 to 16; and as the central part of a propeller has practically no
thrust effect, the efficiency of the 8-foot propeller is nearly twice
that of the 6-foot propeller--other factors being equal. But these
other factors may be made to vary widely. For instance, the number of
revolutions may be increased for the smaller propeller, thus engaging
more air than the larger one at a lower speed; and, in practice, it is
possible to run a small propeller at a speed that would not be safe for
a large one. Another factor is the pitch of the propeller, which may
be described as the distance the hub of the propeller would advance in
one complete revolution if the blades moved in an unyielding medium,
as a section of the thread of an ordinary bolt moves in its nut. In
the yielding mass of the air the propeller advances only a part of its
pitch, in some cases not more than half. The difference between the
theoretical advance and the actual advance is called the “slip.”
[Illustration:
The Call Aviation Engine, of the opposed type; water-cooled. The
cylinders are large and few in number. The 100 horse-power engine
has but 4 cylinders, and weighs only 250 pounds. (The Gnome 100
horse-power engine has 14 cylinders.) This is an American engine,
built at Girard, Kansas.]
In practical work the number of blades which have been found to be most
effective is two. More blades than two seem to so disturb the air that
there is no hold for the propeller. In the case of slowly revolving
propellers, as in most airship mechanisms, four-bladed propellers are
used with good effect. But where the diameter of the propeller is
about 8 feet, and the number of revolutions about 1,200 per minute, the
two-bladed type is used almost exclusively.
The many differing forms of the blades of the propeller is evidence
that the manufacturers have not decided upon any definite shape as
being the best. Some have straight edges nearly or quite parallel;
others have the entering edge straight and the rear edge curved; in
others the entering edge is curved, and the rear edge straight; or
both edges may be curved. The majority of the wooden propellers are
of the third-mentioned type, and the curve is fashioned so that at
each section of its length the blade presents the same area of surface
in the same time. Hence the outer tip, travelling the fastest, is
narrower than the middle of the blade, and it is also much thinner to
lessen the centrifugal force acting upon it at great speeds. Near the
hub, however, where the travel is slowest, the constructional problem
demands that the blade contract in width and be made stout. In fact, it
becomes almost round in section.
Many propellers are made of metal, with tubular shanks and blades of
sheet metal, the latter either solid sheets or formed with a double
surface and hollow inside. Still others have a frame of metal with
blades of fabric put on loosely, so that it may adapt itself to the
pressure of the air in revolving. That great strength is requisite
becomes plain when it is considered that the speed of the tip of
a propeller blade often reaches seven miles a minute! And at this
velocity the centrifugal force excited--tending to tear the blades to
splinters--is prodigious.
Just as the curved surface of the planes of an aeroplane is more
effective than a flat surface in compressing the air beneath them,
and thus securing a firmer medium on which to glide, so the propeller
blades are curved laterally (across their width) to compress the air
behind them and thus secure a better hold. The advancing side of the
blade is formed with a still greater curve, to gain the advantage due
to the unexplained lift of the paradox aeroplane.
Where the propeller is built of wood it is made of several layers,
usually of different kinds of wood, with the grain running in slightly
different directions, and all carefully glued together into a solid
block. Ash, spruce, and mahogany, in alternating layers, are a favorite
combination. In some instances the wooden propeller is sheathed in
sheet aluminum; in others, it is well coated with glue which is
sandpapered down very smooth, then varnished, and then polished to the
highest lustre--to reduce the effect of the viscosity of the air to the
minimum.
[Illustration:
Two propellers, the one on the left of left-hand pitch; the
other of right-hand pitch. Both are thrusting propellers, and
are viewed from the rear. These fine models are of the laminated
type, and are of American make; the one to the left a Paragon
propeller made in Washington, D. C.; the other a Brauner
propeller made in New York.]
In order to get the best results, the propeller and the motor must be
suited to each other. Some motors which “race” with a propeller which
is slightly too small, work admirably with one a little heavier, or
with a longer diameter.
The question as to whether one propeller, or two, is the better
practice, has not been decided. The majority of aeroplanes have but
one. The Wright and the Cody machines have two. The certainty of
serious consequences to a machine having two, should one of them be
disabled, or even broken so as to reduce the area, seems to favor the
use of but one.