FIRST FRUITS OF STUDY
The building of large machines--Sir Hiram Maxim’s
costly work--A steam-driven French craft which
flew--Professor Langley’s research in America.
Of the way research next tended, it may be said that it was the first
putting into practice of the theories science had laid down; for now,
having an idea as to the shape of planes, and knowing that these planes
could be made to carry a load through the air, there were engineers who
began to build man-carrying, power-driven machines. In so doing,
however, they may be said to have tried to run before they could walk.
What they did was to provide the world with powerful flying craft before
there were men who could handle them.
One of the most interesting and ambitious designs was that of Sir Hiram
Maxim; and it was one to which he devoted years of labour and large sums
of money. He is said, indeed, to have expended £20,000 upon aerial
research. After a number of experiments with plane shapes, following the
theories of Phillips, he began to build a very large machine, which he
set upon a miniature railway as Phillips had done, using the same
precaution of a check-rail to prevent it from rising more than a certain
distance in the air. His apparatus, when built at Baldwin’s Park, Kent,
weighed 8000 lbs.: it was, in fact, the largest machine ever built. The
span of its planes was 105 feet, and they offered a total supporting
surface of 6000 square feet.
[Illustration: FIG. 13.
A. Elevating Plane; B.B. Outriggers; C.C. Operating Wires; D.D. Position
for ascending; E.E. Position for descending.]
The inventor employed the suggestion made by Wenham, and fitted his
lifting planes one above the other; while he used a horizontal plane in
front of the machine to act as an elevator. This plane could be tilted
up and down; and the idea was that, when it was tilted upward as the
machine ran forward upon its rails, it would exercise such a lifting
influence that the front of the craft itself would be raised, and so
cause the main-planes to assume a steeper angle to the air; and the
result of the planes being inclined thus more steeply would be to give
them a greater lift, and so induce the whole machine to raise itself
from the ground. This system is explained in Fig. 13, and is important
because such lifting planes, for rising or descending, have now come
into general use.
Sir Hiram Maxim employed another controlling surface which has become a
feature of present-day aircraft, and this was an upright plane, which
could be swung from side to side, and by which his craft was to be
steered. Such a rudder-plane is illustrated in Fig. 14. By this means,
as will be shown later, practically all aeroplanes are steered to-day.
The action of the aerial rudder, when it is moved from side to side, is
like that of swinging the rudder of a ship; but for the same reason that
propellers have to be made large--owing to the small density of the
air--so an aeroplane rudder needs to be a comparatively large plane, in
proportion to the size of the craft, before it will exercise an adequate
turning influence.
[Illustration: FIG. 14.
A. Vertical steering rudder; B.B. Outriggers; C.C. Operating wires;
D.D., E.E. Positions assumed in turning.]
To drive his machine Sir Hiram used two specially-built and lightened
steam engines, which developed a total of 360 h.p., and yet weighed only
640 lbs.; that is to say, they gave one h.p. of energy for each 1-3/4
lb. of weight. But they were only suitable for purposes of experiment.
Sir Hiram himself wrote:
“The quantity of water consumed was so large that the machine
could only remain in the air for a few minutes, even if I had had
room to manœuvre and learn the knack of balancing it in the air.
It was only too evident to me that it was no use to go on with the
steam engine.”
The engines drove two canvas-covered wooden screws, each 18 feet in
length, and the general appearance of the machine is indicated by Fig.
15. In these trials, although it was always captive, the aeroplane
demonstrated much that its inventor had set himself to prove. In Sir
Hiram Maxim’s own words, it showed that it had “a lifting effect of more
than a ton, in addition to the weight of three men and 600 lbs. of
water.” He adds: “My machine demonstrated one very important fact, and
that was that very large aeroplanes had a fair degree of lifting power
for their area.”
[Illustration: FIG. 15.--The Maxim Machine.]
So unmistakably did this craft show its lifting power, that--in one
fierce effort to rise--it broke a check rail which kept it upon its
metals, with the consequence that it became unmanageable, swerved
sideways, and was wrecked. At this stage Sir Hiram, having no faith in
the future of such steam engines as he was using, and having spent a
large sum of money, was compelled to relinquish his tests. His trouble
was that he was, as the saying goes, “before his time.” The machine was
too ambitious and too large. That it would have lifted itself into the
air was proved; but there was no man living who could have controlled
it. To put in charge of such a craft a man who knew nothing of the
navigation of the air, would have been like placing a novice at the
levers of a 60-mile-an-hour express. Picture such a huge aircraft in the
hands of a man who had never flown. It would rise, it is true; but how
could one who was not an expert so adjust the angle of its lifting plane
that it would glide smoothly from the ground and not rear itself upward
and fall with a crash? A machine is struck by wind-gusts, too, when it
is aloft; and there is the delicate art of making a descent, without
damaging one’s craft by a rough contact with the ground. Besides, it
would have been unlikely that this machine, being purely experimental,
would have been perfectly balanced as it flew: it might have shown a
tendency to slip sideways when in the air, or dive steeply. All of which
goes to show this: that the inventor might have wrecked one costly
machine after another before he obtained a practical model, even were he
lucky enough to escape with his life. Sir Hiram Maxim’s machine, while
it settled problems as to weight-lifting and power, lacked the man who
could fly it; and so did others of these man-lifting craft which were
built before their time. A child must learn to walk before it can run,
and must learn to crawl before it can walk. And what had not been
realised, at this stage of the conquest, was that there must be some
stage between building a model and a full-sized, motor-driven machine:
some step, in a word, by which a man might learn, without too great a
risk of death, to balance himself when in the air.
While Sir Hiram Maxim in England was devoting time and money to the
quest, there was another skilled engineer, a Frenchman, who was working
at the problem, and also by means of large machines. This was Clement
Ader, one of the European pioneers of the telephone, and he experimented
for many years. One of his first machines had wings like those of a
bird, and these the would-be flier was to operate by his own muscular
power. But this failed, seeing that men are not provided with sufficient
power, by their unaided efforts, to wing their way through the air in a
flapping flight. As Giovanni Borelli, a seventeenth century writer,
quaintly puts it: “It is impossible that men should be able to fly
craftily by their own strength.”
[Illustration: PLATE I.--THE LANGLEY MACHINE.
This craft, a double monoplane, was launched from a platform over the
river Potomac, loaded with a weight equivalent to that of a man. The
trials were unsuccessful; but recently--after a lapse of many years--the
Langley machine has been tested again, and has proved its ability to
fly.]
Ader next turned to steam-driven craft, and built a series of queer,
bat-like machines, which he called “Avions,” one of which is illustrated
in Fig. 16. Its wings were built up lightly and with great strength by
means of hollow wooden spars, and had a span of 54 feet, being deeply
arched. The whole machine weighed 1100 lbs., and was thus far smaller
and lighter than Maxim’s mighty craft. To propel it, Ader used a couple
of horizontal, compound steam engines, which gave 20 h.p. each and drew
the machine through the air by means of two 4-bladed screws. The craft
was controlled by altering the inclination of its wings, and also by a
rudder, the pilot sitting in a carriage below the planes. In 1890, after
its inventor had spent a large sum of money, the machine--which, unlike
those of Phillips and Maxim, ran upon wheels and was free to rise--did
actually make a flight, or rather a leap into the air, covering a
distance of about fifty yards. But then, on coming into contact with the
ground again, it was wrecked. Ader’s experiments were regarded by the
French Government as being so important that he received a grant
equalling £20,000 to assist him in continuing his tests; and this goes
to show how, even from the first, the French nation was--by reason of
its enthusiasm and imagination--able to appreciate what its inventors
were striving to attain, and eager to encourage them in their quest. For
just an opposite reason--because, that is to say, it had not this
imagination nor intuition--England neglected her experimenters, or
merely regarded their efforts with an amused tolerance, as though they
were children playing with toys.
[Illustration: FIG. 16.--Ader’s “Avion.”]
Ader’s greatest success came in 1897. With an improved machine, he
obtained a flight through the air of nearly 300 yards; and this goes
down to history as being the first ascent by a power-driven aeroplane
having a man on board. Ader’s name will never be forgotten, and one of
his machines is exhibited, as a relic beyond price, at the Institute of
Arts and Science in Paris. But the flight ended in damage to the
machine, as the other had done. A wind gust threatened to overturn the
craft, its engines were shut off, and it descended so heavily that it
was wrecked. Through constant difficulties in regard to motive power,
and the heavy cost of his experimental work, Ader was unable to make a
definite success, or produce a machine which could be called a practical
craft. In his case again, as in that of Maxim, there was a great and
apparently insurmountable defect. The aeroplane would rise; its engines
and propellers would drive it through the air; but the steersman had not
his machine under control: he had not, in a word, learned to fly. The
prospect, therefore, was unpromising, because one machine after another
might share the same fate--rising into the air, flying a hundred yards
or so, and then over-balancing and crashing to earth: thus, in fact,
might thousands of pounds be squandered.
But this stage of putting into practice what science had taught,
although disheartening for those who passed through it, was still of
value; it made a stepping-stone to the next. One of the men who thus
laboured, without himself seeing his work brought to the goal of
success, was Professor S. P. Langley, an American scientist connected
with the Smithsonian Institution, and a man of original ideas and great
resource. He made a methodical investigation of the action of lifting
planes and the shape of propellers, using a large revolving table so
that he could test the latter while they were moving through the air.
Then he began building models which took a double monoplane form, as
indicated by Fig. 17, with wings set at dihedral or upturned angle. This
uptilting of the wings was to give the models stability while in flight:
and the fixing of planes at the dihedral angle was tested, by later
experimenters, in regard to full-sized machines. But while it gave an
undoubted stability when a craft was flying under fair conditions, it
was declared by some experts to be a disadvantage in gusty winds. There
seemed also a risk that a machine so built might slip sideways when upon
a turn. But in some machines to-day a modified dihedral angle is used,
and with satisfactory results.
[Illustration: FIG. 17.--Langley’s Steam-driven Model.]
Professor Langley’s models, tested over the river Potomac, flew many
times for distances of half a mile. One, weighing 25 lbs., flew for
appreciably more than half a mile, and at a speed of 20 miles an hour;
and with another, which was slightly larger and weighed 30 lbs., a
three-quarters of a mile flight was obtained. This model measured a
little more than 12 feet across its wing tips, and was about 16 feet
long. The miniature steam engine which drove it, developing 1-1/2 h.p.,
weighed about 7 lbs., and operated a couple of two-bladed propellers
which were fitted behind the main wings, and turned in opposite
directions at the rate of 1200 revolutions a minute.
So successful were Professor Langley’s models that the United States War
Department became interested; and the result was that an official grant
was made for the building, according to the Professor’s plans, of a
machine of man-carrying size. But with this craft, which weighed 830
lbs., and was driven by a 52 h.p. engine--and is shown in Plate I--there
was a record of failure: launched from the roof of a house-boat over the
Potomac, it fell several times into the water; and ultimately, and
largely owing to the heavy cost of tests with such large machines, the
trials had to be abandoned.
But that the Langley machine would have flown, had it been launched more
carefully, has been demonstrated recently, and in a remarkable way. On
June 28th, 1914, obtaining permission to make tests with the actual
Langley machine, which had been preserved as a relic. Mr. Glenn Curtiss
fitted the craft with floats, and drove it across the surface of the
water at Hammondsport, New York, using the same engine that had been in
the machine during its early and unsuccessful trials. After skimming the
water for a short distance the monoplane rose, flying steadily and well,
and vindicating its constructor’s theories, although he himself was
dead.