IHS ESDU Fuselage interference effects on flap characteristics. 97003

ESDU 97003 provides an empirical method to allow for the fuselage interference effects on the lift, pitching moment and drag coefficient increments predicted for the isolated wing due to deflection of part-span trailing-edge flaps with central cut-out corresponding to the fuselage width. The methods in the Series for estimating those increments give predictions for full-span flaps that are then factored to account for flaps that do not extend from the tip to the centreline. Those factors, which differ with flap type, depend primarily on the inboard and outboard limits of the flap panel and, to a lesser extent, on the wing geometry or spanwise loading. To account for fuselage interference, the flap is extended inboard by a fictitious amount and the part-span factors are evaluated for the new spanwise extent. There was considerable scatter in the data but definite trends were exhibited with variation of wing height. The interference effects were predicted to within 0.04 for lift and pitching moment coefficients, and within 0.005 for drag coefficient. The method applies for flaps that, when deflected, fit closely to the fuselage sides. If the minimum gap between the deflected flap and the fuselage exceeds 5 per cent of the wing semi-span, interference will be negligible.