An Evalution Of Some Approximate Methods Of Computing Landing Stresses In Aircraft

The landing of a simplified airplane structure, consisting of a uniform beam for the wings, a concentrated mass for the fuselage, and a linear spring for the landing gear, is analyzed exactly and is compared with several approximate solutions. The approximate solutions which neglect elasticity in the determination of landing-gear reaction but consider elasticity in computations of stresses give results of good accuracy and indicate that drop tests in which rigid masses are used may be a satisfactory approach to the landing problem.

The method of computing velocity and pressure distributions along wing profiles under the assumption of the simplified density-speed relation, outlined in NACA Technical Note 1006, is extended to the case of a nonsymmetrical profile and a flow with circulation. The shape of the profile, the speed of the undisturbed flow, and a parameter determing the angle of attack may be prescribed. The problem is reduced to a nonlinear integral equation which can be solved numerical by an iteration method. A numerical example is given.