High Flying. Mastery of the Air.

Progress, Volume V, Issue 6, 1 April 1910, Page 191

High Flying.

Mastery of the Air.

The question of height has lately assume! very different proportion from those attained at the beginning of last year. When Wilbur Wright reached at Berlin the height of 564 feet he was acclaimed as having performed a desperate feat. He replied the month following (October) by rising to the height of 1100 feet. Paulhan in November fell short of that performance, getting no higher than 997 feet. In the month of November Latham got as high as 1330 feet, and in December Paulhan reached the height of 1950 feet. But this was thrown into the shade by his attainment of the height of 4156 feet at the Los Angeles meeting. Presently there can be little doubt that the dirigible record (Capazza's 4929) will be beaten. Thus it is plain that the swifter aeroplane will always in war, if both types ever become used for war purposes, get the better of the dirigible. The effect of the rarer atmosphere on the propellers and engines and the difficulty of descending with a spent engine, are questions receiving attention from aviators as of enormous importance. As to the power of the engine, it is supposed that it must diminish necessarily in proportion to the density of the atmosphere. So long ago as 1898 the French scientific weekly periodical La Nature published an article on the loss of power of ordinary paraffin motors employed on mountains. It estimated the loss at* 10 per cent, at an altitude of 2,625 feet, 20 per cent, at 5741 feet, 30 per cent, at 9184 feet, 40 per cent, at 13,120 feet, and 50 per cent, at 18,040 feet. Those are the figures on which, for instance, the Gnome Company bases its calculations for ordinary stationary paraffin motors destined to be used on mountains. It has one working on the Himalayas at an altitude of 13,120 feet, but it does not lose more than between 'SO per cent, and 35 per cent, of its power on sea level. It is, however, very evident the motor on an aeroplane must lose a small fraction of its power with every foot it ascends. Therefore the aviator who may seek to attain, as Paulhan did 'on his Farman biplane furnished with a 50-h.p. Gnome rotary motor, the altitude of nearly 5,000 feet must have on his machine an engine giving a much greater power than is required to raise the aeroplane off the ground. There are also the questions of the diminished thrust of the propeller in a thinner element, the decreased capacity of the bearing surfaces to support the flying apparatus in a rarefied atmosphere, and the diminished resistance to the progress of the machine through the less dense air, which may, however, offer some compensation for the loss of power of the motor and the diminished thrust of the propeller. These problems', like so many others connected with aviation, are not yet solved. On the other question of the descent with a broken engine, a distinguished authority has placed his views on record. "Most people," he says, "especially those who do not follow very closely all the ex-

ploits of the men engaged in the conquest of the air, imagine that if, for instance, Paulhan's motor had stopped suddenly when he was flying at an altitude of 4000 feet the aeroplane would have fallen to the earth with such tremendous force that the bold pilot would infallibly have been killed on the spot. Though, of course, the situation would have been full of peril, nevertheless it is by no means certain that the result of such an accident would have been so tragic. Numerous aviators have purposely stopped their motors when flying at a considerable height, and have reached the ground safely b.y utilising the force of the fall to keep up the necessary speed to continue the forward movement of the aeroplane. Paulhan has himself practised that means of descent, called in French vol plane. When flying at Brooklands last autumn he stopped his motor at an altitude estimated at over 900 1 feet He first allowed his machine to sweep downwards, and then, checking the descent by a skilful play of the horizontal rudder, used the force of the fall to propel the machine in a horizontal direction. Repeating that manoeuvre more than once, he brought the machine to the ground as gently as if the

motor had been working all the time. The descent would of course, be much longer from the height of 5,000 feet, but if it can be effected safely from the altitude of 900 feet, I see no reason why it should be impossible to accomplish it from five, six, or even ten times that height, as the result of the unchecked fall of an. aeroplane weighing half a ton must be identical if it came from 900 or 9000 feet."