Installation effects on performance of multiple model V/STOL lift fans

Abstract

I IThe location and appendages of a l i f t f a n on a Such i n s t a l l a t i o n vari-V/STOL a i r c r a f t are expected t o have a measurable I effect on fan performance. ables as i n l e t and e x i t cover door design and loca-I tion, fan proximity t o the fuselage, and the prox-I 5mity of other fans or engines are all l i k e l y t o a f f e c t the t h r u s t of individual fans during takeoff and landing ( s t a t i c case) and during the t r a n s i t i o n t o fully-wingborne f l i g h t (crossflow case).To study such i n s t a l l a t i o n effects, an experimental program was performed i n which the individual performance of multiple VTOL model l i f t fans was masured. The model t e s t e d consisted of three 13.97 cm ( 5 , 5 i n . 1 diameter tip-turbine driven model VTOL l i f t Sans mounted chordwise i n a twodimensional wing t o simulate a pod-type array.The performance data provided significant inw sight i n t o possible t h r u s t variations and losses caused by the presence of cover doors, adjacent fuselage panels, and adjacent fansThe e f f e c t of a p a r t i a l l o s s of drive air supply (simulated gas generator f a i l u r e ) on fan performance was a l s o investigated. The r e s u l t s of the t e s t s demonstrated t h a t l i f t fan i n s t a l l a t i o n variables and hardware can have a significant e f f e c t on the thrust of the individual Sans. Hence, for v a l i d results, fan t e s t models should provide a close scaling o r simul a t i o n of the complete r e a l installation.