Manchester Memoirs, Vol lix. (191 5), No. %. 5 



same method could have been followed through, the only 

 modification being that the height of the characteristic 

 points instead of being taken as two-thirds the maximum 

 ordinate of the parabola would have been calculated from 

 the expression given above. 



Bending Moment Diagrams for Aeroplanes having zvires 

 attached at points away from the neutral axis. 



The usual points of attachment of bracing wires are 

 arranged as near as possible to the under surface of the 

 spar, and they therefore lie at a minimum distance equal 

 to half the depth of the spar from the neutral axis. 

 Bending moments of considerable magnitude are induced 

 thereby, and it is necessary to provide for these moments 

 when calculating the scantlings required. This system of 

 attachment has probably been adopted in order to allow 

 the canvas to lie smoothly along the bottom surface of 

 the spar, but there appears to be no reason why a light 

 aluminium housing should not be provided round which 

 the fabric might be trimmed, and which would allow the 

 wire to pass through the plane of the lower surface of the 

 wing and be attached in the correct position. In a num- 

 ber of existing machines the theoretical factor of safety on 

 the greater proportion of the length of the spar would be 

 nearly doubled thereby. Where, however, the standard 

 method of attachment is adopted it becomes imperative 

 to calculate the additional moments, and for this purpose 

 the following extension of Claxton Fidler's method is 

 suggested as effecting that object with a minimum of time 

 and labour. Analytical determinations can be used, but 

 they will be found to be long and tedious. 



The forces in each wire can be looked upon as the 

 resultant of two components, one vertical, the sum of which 



