Prevention of jump in inertia-coupled roll maneuvers of aircraft

Hypersonic Flutter of a Cantilever Wing Consider the hypersonic flutter of the cantilever wing studied in Ref. 7 and reported in Ref. 1. This model has been analyzed with great details in Ref. 4 using in-quadrature air loads. The pioneering and now classical work of Ref. 7, made well before the advent of high computational devices, was performed using the classical k method of flutter analysis. The main purpose of analyzing this example here is to show that the traditional V-g-co plots using the k or p-k methods can miss some mild mode instabilities, since the solution is made at discreet values of reduced frequencies or velocities. The data of the model are given in the cited references. We consider only one case of A3 (the ratio of chordwise to torsion frequency), namely, A3 = 1.833, in this section. The results of the analysis are shown in Fig. 2. As can be seen from this figure, the problem presents two critical modes, the first one being a mild bending-torsion flutter mode, and the second being a violent torsion-chordwise flutter mode. The present formulation shows that the first instability occurs for the mild mode at a value of U/ba)2 = 9.72 and a flutter frequency ratio o)la)2 = 0.7058. This mode becomes stable again at a value of Ulbo)2 = 12.92 and a frequency ratio of 0.643. The second mode becomes unstable at a value of U/ba)2 = 12.97 and a frequency ratio of 1.273. The analysis of Ref. 7 made for discrete values of reduced frequency jumps the first instability and only detects the second one.