Studies on the Gust Response of a Wing

In the previous report the response of a two-dimensional rigid wing, which has NACA-0012 airfoil section, to the sinusoidal gust has been investigated experimentally and the results show that the variation of the lift force acting on the wing is smaller than the value calculated with Sears' theory.Since one of the reasons of this phenomenon is considered to be the thickness effects of the wing section, in this report the effects of the wing thickness to the sinusoidal gust response are investigated more generally by the use of the method in which the integral equations for the circulation distribution are solved numerically. As the result, variations of lift force acting on the wing are obtained at the broader range of k (reduced frequency) and for the several kinds of airfoil sections (NACA 4 digit series). The following results are also obtained;(i) The thickness effects are observed remarkably even at k=0.01, and both the real part and the imaginary part of the lift force are smaller than the same terms of Sears'function. Therefore, the phase difference to the gust becomes larger.(ii) The thicker the airfoil section is, the more remarkable the tendency expressed in (i) becomes.