IHS ESDU Effect of unshielded and shielded horn balances on hinge moment coefficients for controls at low speeds. 88003

ESDU 88003 gives a semi-empirical method for predicting the increments in the rates of change of hinge moment with incidence and with control deflection for controls fitted with unshielded and shielded horns at their tips. The increments are functions of control and horn planform geometry and thickness/chord ratio over the horn span for unswept or moderately swept hinge lines (except that for shielded horns the increment with control deflection was found to depend also on the nose shape, being larger for round-nosed horns than for elliptically-nosed horns). The results of predictions are compared with a range of experimental data extracted from the literature; the rates of change of hinge moment coefficient (based on control area and chord, both measured aft of the hinge line) with incidence and with control deflection are predicted to within 0.025 per radian for shielded horns and to within respectively 0.05 and 0.03 per radian for unshielded horns.