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necessary for the calculation of the coefficient to the well-known curves representing the qualities of the wing section. This is done by making use of the recent results of modern aerodynamics. All formulas and relations necessary for the calculation are contained in the paper. They give sometimes only an approximation of the real values. An example of calculation is added in order to illustrate the applications of the method. The coefficient indicates not only whether the effect of the tail plane is great enough, but also whether it is not too great. It appears that the designer has to avoid a certain critical length of the fuselage, which inevitably gives rise to periodical oscillations of the airplane. The discussion also shows the way and in what direction to carry out experimental work. Report No. I37, Point Drag and Total Drag of Navy Struts No. I Modified. By A. F. Zahm, R. H. Smith and G. C. Hill. I5 pages, illustrations, quarto. Washington, Government Printing Office, I922.
In this report are recorded the results of tests on struts conducted at the Washingtou Navy Yard.
Two models of the modified Navy strut, No. I, were tested in the 8 by 8 foot wind tunnel. The tests were made to determine the total resistance, and effect, and the pressure distribution at various wind tunnel speeds with the length of the strut transverse to the current. Only the measurements made at zero pitch and yaw are given in this report.
Report No. I4o, Lift and Drag Effects of Wing-tip Rake. By A. F. Zahm, R. M. Bear and G. C. Hill. 9 pages, illustrations, quarto. Washington, Government Printing Office, I9e2.
This pamphlet describes the tests carried out at the Washington Navy Yard on models of the RAF-6, Albatross, and Sloane aerofoils to determine the effectiveness of the conventional wing-tip rake in improving aerofoil characteristics. Two degrees of rake were tested on each model; the trailing edge being always longer than the leading edge. The results are compared with the values computed by standard formulae in use at the time the tests were conducted.
Report No. 142, General Theory of Thin Wing Sections. By Max M. Munk. 19 pages, illustrations, quarto. Washington, Government Printing Office, I922.
This report deals with a new, simple method of calculating the air forces to which thin wings are subjected at small angles of attack, if their curvature is not too great. Two simple integrals are the result. They contain only the co6rdinates of the wing section. The first integral gives the angle of attack at which the lift of the wing is zero, the second integral gives the moment experienced by the wing when the angle is zero. The two constants thus obtained are sufficient to determine the lift and moment for any other angle of attack. This refers primarily to a two-dimensional flow in a non-viscous fluid. However, in combination with the theory of the aerodynamical induction, and with our empirical knowledge of the drag due to friction, the results are valuable for actual wings also. A particular result obtained is the calculation of the elevator effect.
๐ SIMILAR VOLUMES
In this report prepared for publication by the National Advisory Committee for Aeronautics, in June, 1927, are outlined the three current methods of comparing dynamically similar motions, more especially of fluids, initiated respectively by Newton, Stokes (or Helmholtz), and Rayleigh. These three me