Control of autorotational characteristics of light-airplane fuselages

Abstract

Single-degree-of-freedom, free-to-roll, autorotational tests in a low-speed wind tunnel are conducted to explore the effects of windward strakes on the autorotational characteristics of typical light-airplane fuselage models. The results indicate that the autorotational speeds are very sensitive to strake height and location. With this technique, it is demonstrated that a large degree of control can be obtained over the autorotational behavior of such light-airplane Nomenclature 6 0 = width of the model C y = sectional side-force coefficient, = side h -strake height = length of the model r = distance measured along the bottom surface from vertical side to strake location R = corner radius V = freestream velocity a = angle of attack Aco 0 = increase/decrease of autorotational speed for strake configuration over the basic model n = r/b 0 £ =h/b 0 p = density of air (p = two-dimensional crossflow angle Q = angular velocity of the model about the wind axis co 0 = autorotational speed = Q//2F