HOLES IN THE AIR.

Dominion, Volume 5, Issue 1398, 26 March 1912, Page 8

HOLES IN THE AIR.

WHAT THEY ARE. The mysterious and fatal "holes in (lie air ' that have puzzled all aviators and have been the death of some of them, are nothing, according to D. \V. Starrett in "Aircraft" (\"ew York, Fcbrunry), but regions in the atmosphere where iho wind happens to be Viewing in the same diree•tion as the aeroplane's flight and with equal speed. The <\ir and the plane are then relatively at rest, just as a man is at rest in an express train, though both are travelling n mile a minuto. And as the plane must be moving through or against tho air, nut v;ith it, to obtain the necessary support, it falls until it gets into a nioro favourable stratum. The sensation felt by the aviator is the same 'as if ho had been coasting on a smooth surface, nnd that supporting surface hail suddenly vanished, lotting him drop as into a chasm. Hence hn naturally talks about "holes in tho air." I-nvs Mr. Starret h-

"I'rofessor Langley, under his law, has given to the world tho reason why « heavier-than-air machine can l.'o mado to ily. At present tho aeroplane depends entirely upon speed for its buoyancy. The lav.; lias demonstrated that the ' more square feet of air it passes over per second of timo the more weight it can carrv. . . .

"Aviators have found that facing the wind is the best position from which to make a start. The reason for this is that more square feet of air surface, is flowing to the machine, which is equivalent to more speed of the machine. Increase the wind's speed, and, theoroticolly, tho time will come -when a sufficient number of square feet of air will pass under the planes Jo overcome gravitation. This will be accomplished by the centrifugal force of the wind, even though the planes are level and at rest.

"Tho results, therefore, of speeding the wind ami machine, each acting upon the other separately, are identical. Now assume the machine and the wind having speed and moving against each other; according to tho Langley lav; tho buoyancy of the machine, over that when acting separately, .will bo increased. But if eacn has the .same speed and moves in tho same direction, the buoyancy will ho r>stroy<><l and the machine will fall to the earth unless this condition is speedily changed. "It is plain, then, that if a machino strikes a descending current of air with a spend that will ovorcome gravitation, according to the law, there can be no danger of falling any more than in a head wind, if tho aviator has had the practice that will instantly tell him to elevate his planes. "No one has ever heard of an aviator falling upward, which would occur if on ascending current of air caught, his machine and he could not steer it on its course.. It is true that upon entering up and down curients there would bo tome momentary rise and fall. And if one bad an engine with gyroscopic force, there would bo grave danger, no doubt, if one was not prepared for the sudden change. "So the only reasonable explanation of the 'arc-hole- , trouble is the one given below.

"It will make no difference whether the aviator is flying in a straight line or circling; if he passes into a current of air that is moving with the same speed and in the same direction as his machine, it is bound, under tho Langley law, to fall.

"His supporting surface will bo gene in an instant, and if he is ignorant of the cause of his danger, and unless his momentum takes him from this region, nothing can save him. If his momentum dors not take him out he must fall out and take his chance?. But if he understands the principle he can speed his engine so that he may pass over the requisite number of snuare fret of air per second, when his rudder will act. Or he can slow his engine, when the greater speed of tho air will allow it to act. vihen ho ran steer and float.

"Naturally, in circling, an aviator is certain to encounter moro frequently airwhen he should be particularly on guard."