WELLNER'S SAIL-WHEEL FLYING MACHINE. 627 



WELLNER'S SAIL-WHEEL FLYING MACHINE. 



By Miss IIELENE BONFOKT. 



ONE of the latest and most ingenious schemes for solving the 

 problem of aerial navigation is that devised by Prof. G. 

 Wellner, of Brunn, Moravia, who has sought to bring in the ap- 

 plication of a new principle. He calls his apparatus the " sail- 

 wheel flying machine" {Segelrad-Flugmascliine) , and regards the 

 mechanism of it as a kind of cross between those of the screw- 

 propeller and of the kite, combining the advantages and avoiding 

 the inconveniences of both. His system has won approval and 

 confidence from eminent engineers and experts in aerial naviga- 

 tion to such an extent that the Vienna Association of Engineers 

 and Architects is having experiments and observations made 

 which will show very soon the degree of practicability and value 

 possessed by his invention. 



In his paper on the subject, Prof. Wellner describes his line of 

 thought and the result of his researches, prefacing them with a 

 summary of the experiments and investigations of his co-workers. 



The oblong form of balloons chosen by Giffard in Paris in 

 1852, by Dupuy de Lome in Vincennes in 1872, by Tissandier in 

 1883, and by Renard and 

 Krebs at Chalais in 1885 

 for their balloon " La 

 France," conquered to a 

 considerable degree the 

 resistance of the air and 

 thus increased the veloci- 

 ty (Fig. 1). They con- 

 tained electro-dynamic motors with a galvanic column so admi- 

 rably suited to the apparatus as to secure the greatest possible 

 power with the least weight. Various improvements made obvi- 

 ated the danger of pitching. The " La France " almost completely 

 fulfilled the condition that the balloon must return to its point of 

 departure ; in seven ascents a return was five times made to the 

 starting point, showing that five times a complete control of direc- 

 tion had been gained. A speed of 6 '5 metres per second (about 

 fourteen miles per hour) was reached. Efi:"orts have been made 

 by the French military department to double this velocity, mak- 

 ing it thirteen metres per second. This would be important, as 

 in aerial navigation direction can be controlled only by velocity. 

 But the weight of the motor required for such great power must 

 constitute a serious embarrassment. Moreover, the pressure of 

 air currents and the resistance of the wind endanger the balloon 

 constructed of light material. 



Fig. j. AiR-siiip La France. 



