 experiment investig aerodynam wing slipstream experiment investig aerodynam wing slipstream experiment studi wing propel slipstream order determin spanwis distribut lift increas slipstream angl attack wing free stream slipstream veloc ratio intend evalu basi theoret treatment problem compar span load curv support evid substanti lift increment produc slipstream destal boundari-layer-control integr remain lift increment subtract destal lift agre well potenti flow theori empir evalu destal effect specif configur experi 