William A. Newsom, Jr.
An experimental investigation has been made to study the feasibility, from considerations of lateral trim, of having all the propellers of a tilting-wing vertical-take-off-and-landing (VTOL) airplane rotate in the same direction since this is a desirable feature from practical considerations. The model was a wing with four propellers, the slipstream from which covered practically the entire span of the wing. Tests were made at angles of attack up to 90 degrees for various differential flap deflections and differential blade pitch settings on the outboard propellers. Analysis of the data indicates that it is not quite possible to obtain lateral trim of a complete tilting-wing VTOL airplane with this wing-propeller combination by using differential flap deflection and differential outboard-propeller pitch. Complete trim could be obtained, however, if the control effectiveness of the wing flaps and propellers were augmented by the use of a rudder and a jet-reaction control at the rear of the fuselage capable of producing a side force of about 1 percent of the airplane weight. Since the lateral trim of the particular configuration represented by this model is marginal, it seems likely that some airplanes of this type could be trimmed with all the propellers rotating in the same direction whereas others could not.
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