A smoke wind-tunnel, 1, 500mm×200mm×2, 000 mm in the inner dimensions of the test section, has been constructed at the Meiji University. The wind-tunnel enables us not only to observe the flow pattern around the model through the conventional stde-wall window but also to observe upstream by means of another window located at the diffuser section. A cyclone-type diffuser, whch is specially designed for this tunnel, is convenient for the latter observation mentioned above, and is also effective in obtaining a good diffuser performance in a limited space. The thickness of the boundary layer along the inner surface of the test section is minimized by the natural bleed of air from the narrow gap provided along the inlet part of the test section. Characteristics of the tunnel and several examples of flow pattern obtained are described.

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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.

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This paper presents the results of the low speed flutter model test and the flutter calculation of a wing with one engine supported by a flexible pylon.
These results show the effect of spanwise and chordwise position of engine and, horizontal and vertical stiffness of pylon.
The interesting result is that wing flutter mode (symmetry or anti-symmetry) and speed are varied by the value of pylon horizontal stiffness.

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