Experimental Study on the Application of Flat Spin to Vertical Landing of a Fixed-Wing Small UAV

The flat spin of a fixed-wing airplane is usually considered to be dangerous, and should be avoided by all means. However, an airplane in a flat spin descends almost vertically and relatively slowly. It can be used as a means of vertical landing, especially for a small fixed-wing unmanned aerial vehicle. Controlling the impact speed to the ground and touchdown position is necessary to realize the application of flat-spin landing. A large pitch-up moment generated by the combination of an allflying tail and the gyro precession due to the yawing motion generated by the so-called P-factor of the propeller rotation was found to be effective not only for the rapid entry into flat spin, but also to control the pitch attitude and rate of descent during a flat spin. In this paper, the results regarding the relationships among the deflection angle of the all-flying tail, the rotational speed of the propeller, the spin rate, and the rate of descent obtained by flight tests using a small unmanned aerial vehicle are presented as fundamental knowledge towards the realization of practical flat-spin landing

フラットスピンを用いた小型固定翼無人機の定点垂直着陸法の基礎研究

A runway for the operation of a fixed-wind UAV cannot be always available in practical missions and there is no handy method for landing in confined space while a catapult can be used for launch. The purpose of this paper is to develop a new vertical landing method using the flat spin. Flat spin is the motion that an aircraft rotates horizontally while it is descending vertically. In order to control its touchdown position to a desired position, it is necessary to generate centripetal force to control UAV's descent path to target direction while descending vertically. This paper shows the method to change the path during vertical descent, as well as the result of flight tests and wind tunnel tests