Search results

THE aim of this paper is to calculate the natural frequencies and to consider the influence of the damping parameter on a wing's natural flexural and torsional vibration. The author took into account only the elastic hysteresis of the material because the structural damping, depending on the type of the aeroplane, cannot be taken into account in a general consideration.

Further Correspondence On This Controversial Subject. Dear Sir, The purpose of this letter is to comment on M. Jaumotte's contribution to the September 1946 issue of AIRCRAFT ENGINEERING, arising from the earlier remarks of Mr. Mallinson and myself on rocket propulsive efficiencies.

AN aeroplane wing and fuselage may be treated from an analytic standpoint as two elastic beams, rigidly connected. In the present note the equations for the natural frequency, derived on the basis of Rayleigh's principle and Ritz's method, are extended to the case of free vibration of a set composed of two such beams with a number of concentrated loads elastically suspended.

THE general theorems given in Sections 4 and 6 include, from the fundamental point of view, all that is required for the analysis of redundant structures. However, to facilitate practical calculations it is helpful to develop more explicit methods and formulae. To find these is the purpose of this Section.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United States National Advisory Committee for Aeronautics and publications of other similar Research Bodies as issued.

THE steady increase in speed and use of thin aerofoils compels a deeper consideration of the problem of oscillation. In recent years there has been a tendency to the building of large aeroplanes. This is closely connected with the problem of oscillation. The author in a first approximation tries to solve, from a proportionality point of view, the question of influence of kind of material and size of aeroplane on wing flexural and torsional natural frequencies. Following the idea of solving this problem from a qualitative and not from a quantitative point of view, the conception of proportionality instead of equality is introduced. The idea of “wing torsional rigidity” is created, being inversely proportional to the angle of twist at the end of wing. Applying Newton's Law, at first the flexural and torsional natural frequency of an oscillating rod is found. Afterwards the method is used in the case of an oscillating tubular member. The results are checked by Rayleigh's Method. Lastly, the influence of size of wings having similar shape is taken into consideration.

ASSUME an aeroplane in pure dive, i.e. the motion of the centre of gravity of the aeroplane is purely vertical. The airscrew is stopped and the diving aeroplane may be treated like a diving glider. The only difference is in the value of drag. It is assumed that the aeroplane is infinitely stiff, wings are not subject to twisting, etc. The aeroplane starts to dive from a certain height h with a certain initial velocity vi which in a special case may be equal to zero. To calculate the velocity which the aeroplane will reach at the height x the Neumark formula is applied:

DEAR SIR, I have read with interest the article “Fluid Flow through Restrictions” by L. S. Greenland, published in the June issue of your journal, but feel obliged to comment on two things.