GLIDIXO IN GERMAN Y — GEORGII 281 



hilly country alike, independently of the consideration of the 

 surface. 



The niobt important result is the ease with which great heights 

 can bo reached in the iip-currents of cumulus-cloud formations. The 

 second part of the llight gives fresh evidence of the value of the 

 older established method of flying in the up-currents from hills. 



A more recent development of cloud flying is the use of up-currents 

 at tiie cold air fronts of line squalls, of which measurements with an 

 engined aeroplane have been referred to. In this t3'^pe of atmos- 

 pheric disturbance masses of warm air are pushed uj) by the inrush 

 of cold air along the surface of the earth. Plate 14, Figure 1, shows 

 motion of the air caused by cold air flowing in under warm air 

 (W. Sclimidt). The lines of flow show the local direction of the 

 wind. In front of the line squall the air rises almost vertically and 

 offers the best soaring region. 



Plate 15, Figures 1, 2, and 3, shows Kronfeld's flight in front of a 

 line squall (143 km.), the region of up-currents before the cold front, 

 the barogram of the flight and the time changes in the line squall 

 along the course. 



Kronfeld started at the moment when the wind was freshening, 

 just before the passage of the line squall, and by utilizing the rising 

 currents before the cold front rose 2,000 m. above the starting point. 

 The middle part of the barogram shows that he then maintained 

 steady flight. 



The meteorological records determine the motion of the storm 

 accurately, and in conjunction with the pilot's account lead to the 

 conclusion that he flew about 2 km. in front of the squall, rising 

 or falling slightly as he was nearer or farther. After turning away 

 from the front the glider rapidly lost height and landed 143 km. 

 from the Wasserkuppe after 4V^ hours flight. 



The knowledge gained as to the configuration of line squalls, leads 

 to the conclusion that there is no danger if the pilot keeps some 

 distance before the advancing front. 



It appears from recent investigations at the research institute of 

 the Khoen-Hossitten Gesellschaft that heights of 4,000 to 4,500 m. 

 above the starting point may well be attained, in comparison with 

 the existing record of 2,150, and that the cross-country record of 

 150 km. may be increased in like proportion. 



Plate 6, Figure 2, shows a flight with towed glider at the Wasser- 

 kuppe. Systematic experiments have been carried out by the society 

 with gliders towed by power airplanes and released at a suflicient 

 height to reach regions of up-currents and to continue independent 

 cloud flying. Plate 2, Figure 1, siiows a flight with towed glider at 

 Darmstadt. 



