I 



220 Dr Hankin, The Problem of Soaring Flight 



simple and elementary forms. Instead of the complicated sup- 

 porting plus propelling mechanism of the wing of varying plan form 

 and cross section the aeroplane was developed with a wing of simple 

 geometrical shape which was used for support only and with a screw 

 propelling mechanism quite distinct from its wings. 



Great progress has been made in the design of aircraft based on 

 mechanical methods of investigation in wind channels, where the 

 air is driven at uniform speed with little or no turbulence against 

 the model to be tested. There still remains a vast amount to be 

 discovered in the actual air structure in which aircraft fly and in the 

 aerodynamical design best suited to fit the conditions discovered. 

 Here, without a doubt, lies the value of a careful and considered 

 study of soaring flight. In this country, owing to the complicated 

 and ever-changing meteorological conditions, research is difficult. 

 In continental and particularly tropical climates conditions arelj 

 more stable and investigation easier. In India Dr Hankin has been" 

 particularly fortunate in having most favourable conditions for 

 observation and in bringing to bear on the problem observing 

 powers trained to a high degree of accuracy by long years of 

 practice. 



The measurements made and the facts discovered relating to 

 soaring flight are so extraordinary as to awaken suspicions at once 

 as to their accuracy. Were they but chance observations of an 

 observer made a;t odd intervals such criticisms would be just, but 

 the careful system of investigation and re-investigation continued 

 by Dr Hankin over a long period of years makes his results worthy 

 of consideration by all interested in flight phenomena and open up 

 an entirely new field for aviation and meteorological research. 



The high soaring speed of 50 miles per hour over the plains of 

 India without any discoverable wing movement brings up visions ■ 

 of possible motorless flight in tropical climates, where conditions! 

 of visibility and weather are ideal for this form of transport. To all 

 those who are interested in aviation development in India and other 

 tropical countries, Dr Hankin's discoveries must be of the greatest 

 interest and his published results well worthy of most careful 

 study. 



The results are by no means on all fours with present aircraft 

 design. The wing sections of the best soaring birds and of the 

 soaring dragon-flies are characterised by ridges projecting on the 

 under side of the wing, forming to the eye of the aeroplane designer 

 a source of resistance entirely uncalled for. On the other hand, birds 

 of more streamline wing cross section, where these ridges are not 

 present to anything Hke the same extent, invariably fly by flapping 

 their wings, and have little or no power to soar. Can it be that the 

 more crude cross sections fit in with, and thus take advantage more 

 readily of, some form of air turbulence or movement and so allow 



