Low-speed wind-tunnel tests on the effects of tailplane and nacelle position on the superstall characteristics of transport aircraft

Abstract

Summary. Measurements of lift, drag and pitching moment have been made on several model configurations for wing incidences up to 53 °. Tailplane and nacelle size and position were varied independently and the results confirmed that aircraft with engines mounted at the rear of the body and a high-tailplane position face severe superstall problems. For such layouts deep penetration of the stall could lead to a stable trimmed condition at a high incidence where the tailplane is in the wake of the wing and nacelles and is incapable of ensuring a recovery to normal flying attitudes. The advantage of using low-tailplane positions and of increasing the tail arm to allay the superstall problem was clearly demonstrated by the tests. Several other trends which it is considered will be of guidance to the future designer were also noted; but because of the complexity of the flow at the tailplane it is recommended that the wind-tunnel programmes on all future layouts should include some tests at very high incidence.