POA * ONLINE SUBSCRIPTION ONLY

ESDU 80020 contains a simple method for estimating the average downwash angle at the tailplane for subsonic speeds and low angles of attack where the lift, pitching moment and downwash characteristics are linear, i.e. where the flow is wholly attached. The method, which is semi-empirical, is a first order one allowing for the major effects of wing planform, body, wing-body interference and tailplane height. Moderate amounts of wing twist are acceptable in the method. The method applies only to wing-body-tail combinations although some assessment of the effect of rear-fuselage mounted nacelles is given. A computer program of the method is provided as ESDUpac A8020. ESDU 97021 provides a method for estimating the effect of flap deployment on the average downwash angle at the tailplane low speeds.