TRANSACTIONS OF SECTION G. 



269 



would be nearly normal, though the whole machine would be coming down at 

 a steyp angle. This latter would be an advantage in the hands of an inexperienced 

 pilot in that he would be less likely to stall the machine in flattening out. 



The data obtained may be summarised by the following comparative figures, 

 taken from a large table of results compiled : — 



The aeroplane is assumed to come in at a height of 50 feet in each caee. 

 Distance run is calculated from equation 



S = 62-5 loge K^-lcge Ky 



K 



MKy 



fi being a friction factor. 



From the above it is seen that airbrakes alone are not of much effect. 

 Vai"ying camber, however, seems likely, to afford a better solution of the problem. 



In the afternoon a Sectional Visit was paid to the Bournemouth Gas and 

 Water Company's Works. 



FBI DAY, SEPTEMBER 12. 

 The following Papers were read : — 



1. Wireless Navigation for Aircraft. By Captain J. Eobinson, R.A.F. 



Navigation for aircraft duffers from that at sea because of the great 

 importance of drift. This prevents dead reckoning methods from being reliable. 

 In fogs and at night it is thus desirable to be able to fix one's position, and 

 the use of wireless bearings is the most hopeful method of progress. There are 

 two distinct methods of employing wireless bearings in order to determine 

 position : 



(a) By the first method the machine transmits, and the direction-finding 

 stations are on the ground. Each direction-finding station finds the bearing 

 on the moving object and communicates its bearing to a central station. There 

 the position of the moving object is worked out from the various bearings and 

 retransmitted to it. 



(6) By the second method the moving object, either aircraft or ship, has 

 its own direction-finding apparatus, and finds bearings on fixed transmitting 

 stations. 



Method {a) has considerable draw-backs ; the first being that in case of war 

 when the aircraft transmits to ask for its position this is also disclosed to the 

 enemy. 



Secondly, only very few aircraft can be dealt with, as a considerable amount 

 of transmission is required for a single aircraft to find its position. In con- 

 sequence, it was decided to attempt to use method {b) in the British Air Service. 



Most of the methods known at the beginning of the war for determining 

 bearings were minimum methods ; that is, for accuracy, it was necessary to find 



