Abstract:
The rigid body short-period mode of flying-wing aircrafts is prone to couple with the first-order elastic bending mode, which will result in the body freedom flutter that is still not well understood yet. The influence of inertia parameters (pitching inertia and center of gravity) on characteristics (flutter velocity and flutter frequency) of the body freedom flutter of a flying-wing aircraft is studied by wind tunnel experiments and frequency domain calculations. The results of experiments and calculations, which agree well with each other, show that the pitching inertia and the center of gravity can change the frequency and velocity of the body freedom flutter substantially. With the increasing of the pitching inertia, the frequency of the pitching mode decreases. While the flutter velocity remaines unchanged under the constraint of plunge degrees of freedom and increases otherwise. When the center of gravity moves forward, the frequency and damping of the pitching mode both increase. The pitching mode and the first-order elastic bending mode are more likely to couple. But the damping of the divergent mode branches is larger, so that the flutter velocity first decreases and then increases, while the flutter frequency increases monotonously.