Building and Flying an Aeroplane / A practical handbook covering the design, construction, and operation of aeroplanes and gliders

by Charles B. Hayward

h = (V - v)/2g

If, as before, g be taken as 22 miles per hour, the equation reduces to the convenient formula

h = (V-v)/30

in which V and v are taken in miles per hour. Assuming various values for V and v, Table V has been found for the corresponding values of h in feet: For example, if the natural speed of the aeroplane in level flight be 50 miles per hour, and the aviator wishes to increase the speed by 20 miles per hour, he must dive at least 80 feet, assuming that the aeroplane falls freely, like a body in vacuo, or that its propeller overcomes the air resistance completely; otherwise the fall must be rather more than 80 feet.

It has been suggested that a contest be arranged to determine which aviator could dive most swiftly and rebound most suddenly, the prize going to the one who should stress his machine most as indicated by the accelerograph above proposed. But to avoid danger, the contest would have to be supervised by competent experimentalists, and would be best conducted over water. It is safe to say that more than one well-known aeroplane would be denied entry in such a contest because of lack of a sufficient factor of safety in its construction.

Dirigible Accidents. Because its wrecks are spectacular and the loss involved tremendous, the dirigible has probably earned an undeserved reputation, though it must be admitted that the big airships have come to grief with surprising regularity. The fact must be noted, however, that when an airplane is wrecked, the aviator seldom escapes with his life, while the spectators' lives are endangered to an even greater extent, whereas in the case of the dirigible, the loss is simply financial, both the crew and passengers usually escaping without a scratch. This is largely due to the fact that the majority of accidents to dirigibles have happened on the ground, and have been caused by lack of facilities for properly handling or "docking" the huge gas bag. Of course, lack of flotation or an accident to the motors, or both combined, have brought two of the numerous Zeppelins to earth in a very hazardous manner, though no one was killed, while four French army officers lost their lives in the Republique disaster, the exact cause of which was never definitely ascertained. This was likewise the case with Erbsloeh and his companion who were dropped from the sky, their airship having taken fire. It was thought that ignition was caused by atmospheric electricity, in this instance.

By far the great majority of later dirigible accidents have been due solely to the crude methods of handling the airships on the ground, and the frequency with which these have occurred should certainly have been responsible for the adoption of improvements in this respect at an earlier day.

For instance, the Morning Post, a big Lebaudy type bought for English use, had the envelope ripped open by an iron girder projecting from its shed. Repairs took several months, and at the end of the first trial thereafter, the ship was again Wrecked in landing. A company of soldiers failed to hold the big craft and it drifted broadside into a clump of trees, hopelessly wrecking it. In attempting to dock the Deutschland I, 200 men were unable to hold it down, a heavy gust of wand catching the big airship and pounding it down on top of a wind break that had been specially erected at the entrance of the shed for protection. A similar accident happened to the big Parseval, a violent gust of wind casting it against the shed and tearing such a hole in the envelope that the gas rushed out and the car dropped 30 feet to the ground. The big British naval dirigible of the rigid type, the Mayfly, was broken in half in attempting to take it out of the shed the first time. A cross wind was blowing and the gas bag of one of the central sections was torn, deflating it and showing in a striking manner that the solidity of a rigid dirigible results chiefly from the aerostatic pressure of the gas in its various compartments. Without the gas lift, a rigid frame is so in reality only for certain limited distances, as was shown by the total collapse of the Mayfly's frame after having been subjected to the opposed leverage of the parts on either side of the original break. This, of course, was an error in design, as the frame of a rigid dirigible should certainly not be so weak in itself as to collapse upon the deflation of a single one of the central compartments. The incident on the trip of the Zeppelin III to Berlin, in 1909, when the flying blades of a broken propeller pierced the hull without causing an accident, shows how much resistance it may offer.

[1]	This is exactly what occured at the Chicago Meet, August 15, 1911, when Badger's Baldwin biplane collapsed at the end of a long dive, causing the death of the aviator.