Aeronautics; a class text

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 Excerpt: ...of the suspension; for in this case there is also motion of the center of gravity backward and forward, which contributes the final term (the motion of the center of gravity in the normal direction being negligible if the oscillation be sufficiently small). But w = Iq = Id6/dt, and hence Therefore, the solution of this equation in 6 would give for the model except for mechanical friction the two quantities dM/dq and dX/du in combination. By making the experiment with two different values of I, for example, with / = 0 in one case, it would be possible to determine not only dM/dq but dX/du, without using the method of forced oscillations. In like manner, if the model were oscillating about a center at a distance / to the rear of the center of gravity, the differential equation obtained would involve dM/dq and dZ/dw. The rule for scaling up a quantity like dX/du or dZ/dw calls for the first power of the velocity ratio and the square of the linear dimension, whereas the rule for dM/dq calls for the first power of the velocity ratio and the fourth power of the linear dimension. It, therefore, follows that if the experiments were made with a sized model the value of dX/ du for model _, dXfdu for machine dM/dq for model dM/dq for machine Now, for the machine dX/du is very small, whereas dM/dq is large, and if it were necessary to perform the oscillating experiment upon the full-sized machine it is probable that dX/du occurring in the same equation with dM/dq would escape detection; but when the experiment is performed on the model the values of dX/du and dM/dq are not so dissimilar that one would entirely mask the other (owing to the different scale ratio 1: 576). (e) There have now been treated the following lateral coefficients: d(Y, L, N) d(L, N) d(L, N) dv' dp...