We are very sure to be informed of the fact when an aviator is
killed. Comparatively little stir is made nowadays over an automobile
fatality, and the ordinary railroad accident receives bare mention. For
instruction and warning, accidents to air craft cannot be given too
much publicity; but if we wish any accurate conception of the danger we
must pay regard to factors of proportion. There are perhaps a thousand
aeroplanes and about sixty dirigible balloons in the world. About 500
men--amateurs and professionals--are continuously engaged in aviation.
The Aero Club of France has issued in that country nearly 300 licenses.
In the United States, licenses are held by about thirty individuals.
We can form no intelligent estimate as to the number of unlicensed
amateurs of all ages who are constantly experimenting with gliders at
more or less peril to life and limb.
A French authority has ascertained the death rate among air-men to
have been--to date--about 6%. This is equivalent to about one life for
4000 miles of flight: but we must remember that accidents will vary
rather with the number of ascents and descents than with the mileage.
Four thousand miles in 100 flights would be much less perilous, under
present conditions, than 4000 miles in 1000 flights.
[Illustration: THE AVIATOR]
There were 26 fatal aeroplane accidents between September 17, 1908,
and December 3, 1910. Yet in that period there were many thousands of
ascents: 1300 were made in one week at the Rheims tournament alone.
Of the 26 accidents, 1 was due to a wind squall, 3 to collision,
6 (apparently) to confusion of the aviator, and 12 to mechanical
breakage. An analysis of 40 British accidents shows 13 to have been
due to engine failures, 10 to alighting on bad ground, 6 to wind
gusts, 5 to breakage of the propeller, and 6 to fire and miscellaneous
causes. These casualties were not all fatal, although the percentage of
fatalities in aeronautic accidents is high. The most serious results
were those due to alighting on bad ground; long grass and standing
grain being very likely to trip the machine and throw the occupant.
French aviators are now strapping themselves to their seats in order to
avoid this last danger.
[Illustration: THE SANTOS-DUMONT "DEMOISELLE"
(From _The Aeroplane_, by Hubbard, Ledeboer and Turner)]
Practically all of the accidents occur to those who are flying; but
spectators may endanger themselves. During one of the flights of
Mauvais at Madrid, in March of the present year, the bystanders rushed
through the barriers and out on the field before the machine had well
started. A woman was decapitated by the propeller, and four other
persons were seriously injured.
Nearly all accidents result from one of three causes: bad design,
inferior mechanical construction, and the taking of unnecessary risks
by the operator. Scientific design at the present writing is perhaps
impossible. Our knowledge of the laws of air resistance and sustention
is neither accurate nor complete. Much additional study and experiment
must be carried on; and some better method of experimenting must be
devised than that which sends a man up in the air and waits to see what
happens. A thorough scientific analysis will not only make aviation
safer, it will aid toward making it commercially important. Further
data on propeller proportions and efficiencies, and on strains in the
material of screws under aerial conditions, will do much to standardize
power plant equipment. The excessive number of engine breakdowns
is obviously related to the extremely light weight of the engines
employed: better design may actually increase these weights over those
customary at present. Great weight reduction is no longer regarded
as essential at present speeds in aerial navigation: we have perhaps
already gone too far in this respect.
Bad workmanship has been more or less unavoidable, since no one has
yet had ten years' experience in building aeroplanes. The men who have
developed the art have usually been sportsmen rather than mechanics,
and only time is necessary to show the impropriety of using "safety
pins" and bent wire nails for connections.
The taking of risks has been an essential feature. When one man earns
$100,000 in a year by dare-devil flights, when the public flocks in
hordes--and pays good prices--to see a man risk his neck, he will
usually aim to satisfy it. This is not developing aerial navigation:
this is circus riding--looping-the-loop performances which appeal to
some savage instinct in us but lead us nowhere. Men have climbed two
miles into the clouds, for no good purpose whatever. All that we need
to know of high altitude conditions is already known or may be learned
by ascents in anchored balloons. Records up to heights of sixteen miles
have been obtained by sounding balloons.
If these high altitudes may under certain conditions be desirable for
particular types of balloon, they are essentially undesirable for the
aeroplane. The supporting power of a heavier-than-air machine decreases
in precisely inverse ratio with the altitude. To fly high will then
involve either more supporting surface and therefore a structurally
weaker machine, or greater speed and consequently a larger motor. It
is true that the resistance to propulsion decreases at high altitudes,
just as the supporting power decreases: and on this account, given only
a sufficient margin of supporting power, we might expect a standard
machine to work about as well at a two-mile elevation as at a height of
200 feet; but rarefaction of the air at the higher altitudes decreases
the weight of carbureted mixture drawn into the motor, and consequently
its output. Any air-man who attempts to reach great heights in a
machine not built for such purpose is courting disaster.
Flights over cities, spectacular as they are, and popular as they are
likely to remain, are doubly dangerous on account of the irregular air
currents and absence of safe landing places. They have at last been
officially discountenanced as not likely to advance the sport.
All flights are exhibition flights. The day of a quiet,
mind-your-own-business type of aerial journey has not yet arrived.
Exhibition performances of any sort are generally hazardous. There
were nine men killed in one recent automobile meet. If the automobile
were used exclusively for races and contests, the percentage of
fatalities might easily exceed that in aviation. It is claimed that no
inexperienced aviator has ever been killed. This may not be true, but
there is no doubt that the larger number of accidents has occurred to
the better-known men from whom the public expects something daring.
Probably the best summing up of the danger of aviation may be obtained
from the insurance companies. The courts have decided that an
individual does not forfeit his life insurance by making an occasional
balloon trip. Regular classified rates for aeroplane and balloon
operators are in force in France and Germany. It is reported that Mr.
Grahame-White carries a life insurance policy at 35% premium--about
the same rate as that paid by a "crowned head." Another aviator of a
less professional type has been refused insurance even at 40% premium.
Policies of insurance may be obtained covering damage to machines by
fire or during transportation and by collisions with other machines;
and covering liability for injuries to persons other than the aviator.
On the whole, flying is an ultra-hazardous _occupation_; but an
_occasional_ flight by a competent person or by a passenger with a
careful pilot is simply a thrilling experience, practically no more
dangerous than many things we do without hesitation. Nearly all
accidents have been due to preventable causes; and it is simply a
matter of science, skill, perseverance, and determination to make an
aerial excursion under proper conditions as safe as a journey in a
motor car. Men who for valuable prizes undertake spectacular feats will
be killed as frequently in aviation as in bicycle or even in automobile
racing; but probably not very much more frequently, after design and
workmanship in flying machines shall have been perfected. The total
number of deaths in aviation up to February 9, 1911, is stated to have
been forty-two.