GLIDING IN GERMANY — GEORGH 275 



The Djalvar Anamm/i ("Devil take it") is of this type and its 

 main characteristics are: Braced monoplane wings, simple gjirder, 

 tail hook, and boat-shaped cockjiit below the winn:s. Plate 3, 

 Figure 3, shows a standard glider of this type. 



It has a good duration performance in light winds but a restricted 

 range on account of its slow air speed. In the school type the 

 aerodynamical (jualities are sacrificed to more robust construction, 

 simplified for ease of repair; the cockpit is not covered so that the 

 pilot may fall clear in a smash, and restricted gliding and soaring 

 powers are desirable for training purposes. The best known of this 

 derived type is the ZoegUng, shown in Plate 4, Figure 1. 



Once the princii)los of successful soaring were recognized, results 

 soon followed. In V^i^l^ Hentzen and Martens, both students, car- 

 lied out the first soaring flights, lasting over an hour, on the Vampyr. 

 Ilentzen's record flight of 3 hovirs 10 minutes, attaining an altitude of 

 3."»0 m., made the activities at the AVasserkuppe world famous. 



It elucidated the problem of soaring flight by using the energy in 

 the air's motion. In accordance with the laws of motion soaring is 

 possible in an ascending current of air, and in a horizontal air 

 current of variable velocity. 



When the rate of ascent of the air current equals or exceeds the 

 rate of descent of the glider, " static soaring " is possible. When 

 the horizontal wind is variable, the pilot gains height as the velocity 

 increases and loses height as the velocity decreases. As the air forces 

 are proportional to the .square of the air speed, it is possible in prin- 

 ciple to obtain a net gain. If the net rate of gain equals or exceeds 

 the sinking speed, this " dynamic flight " becomes possible. It is 

 quite probable that some dynamic gain was obtained in the earlier 

 flights, but not by any systematic use of the wind fluctuations. 



The extensive efforts made from 1921 to 1923 to connect pulsating 

 dynamical effects with the performance of man-carrying gliders did 

 more harm than good to the development and reputation of soaring, 

 the possibilities of which, apart from any such effects, have been 

 fully shown by the subsequent years. 



To revert to static soaring, local rising currents are produced by 

 every irregularity of the earth's surface — knolls, dunes, woods, the 

 waves of the sea — and may be utilized for soaring flight. The 

 following photograplis show well-known soaring grounds: 



The Wasserkuppe in the Rhoen (pi. 5, figs. 1, 2) ; the French soar- 

 ing grounds at Vauville (pi. G, fig. 1) ; and the soaring grounds at 

 Rossitten on the Kurisch Lagoon (at the mouth of the Memel in 

 East Prussia) (pi. 4, fig. 2). 



