Milgram 



J 4h '^ r"2 



COS n(p' d0' [Q(0)-x/q2(0)-i] " 



(cos + COS0') 

 u 



where 



Q(0) = 2 + ^- cos (0) . (21) 



Using Eqs. (19) and (20), the expression for the downwash becomes 



w (y) = 



u„ V n A illll^ - [Q(^)-/q'(^)-i]" ] . (22) 



In the linearized theory the induced angle, o.^(y), is given by 

 and the induced drag distribution d • ( y ) is 



di(y) = Uy) aj (y) . (24) 



Hence, . ■ : 



cli(y) = Pr(y)w'(y) . (25) 



The total induced drag is 



D; = - /or(0) w'(.A) J sin V d0 . (26) 



Using Eqs. (9) and (22) and carrying out the integration for the part of the 

 downwash due to the trailing vortex sheet gives 



{CO CO CO TT r , — T in 



n=l n=l m=l ^/7^27V^^—, 



V^('/') - 1 



d0 



(27) 



Using the notation 



,„ = r sin .. sin . [^(^) - ^^Q^7^T^ lr ,, , (28) 



\/o2(0) - 1 



then 



1402 



