Brard 



The four last terms in the z-component are due to the velocities induced by the 

 wake on the plane; a^g and h^^ are positive dimensionless coefficients. Conse- 

 quently, in such a quasi -steady motion; the effective angle of attack is 



Let us assume that we are in the case "3^^": 



At t ' = 0+, the velocity induced by the wake is null; at t ' =+», it is ajgCw/U)^^. 

 At t' >0, it is 



^ ^ '0 + 



where 4>^^ is an increasing function equal to zero at t ' = 0+, and to 1 at t ' = +«». 

 In the general case, when (w/U) ^ , is a given function f^ j( t ') , the velocity in- 

 duced by the wake generated by f 1( t ') is 



(g)^/iB(t') + I ^ (J)^^0,BCt'-r')dr' = J f o / - ' ) ^ <^ib( ^ ' " r ' )dr ' 



t ' 



= [ foi(^') '^iB^t' -r')dr' . 



Finally, when 



'Lq 



the effective angle of attack becomes 



^e = ^Mn),,- (ir),,^B-/ t -kBfok(-')^^kB(t'--')dr'. (1) 

 The square of the incident velocity is 



"4' ^ ^ (0).. * ^ fel ^4 • <^' 



862 



