RT Journal Article
SR 00
ID 10.2514/1.16746
A1 Nadal Mora, Vicente J.
A1 Sanz Andres, Angel Pedro
T1 Stability analysis of a free falling pararotor
JF Journal of Aircraft
YR 2006
FD 2006
VO 43
IS 4
SP 980
OP 986
AB The pararotor is a decelerator device based on the autorotation of a rotating wing. When it is dropped, it generates  an aerodynamic force parallel to the main motion direction, acting as a decelerating force. In this paper, the  rotational motion equations are shown for the vertical flight without any lateral wind component and some  simplifying assumptions are introduced to obtain analytic solutions of the motion. First, the equilibrium state is  obtained as a function of the main parameters. Then the equilibrium stability is analyzed. The motion stability  depends on two nondimensional parameters, which contain geometric, inertia, and aerodynamic characteristics of  the device. Based on these two parameters a stability diagram can be defined. Some stability regions with different  types of stability trajectories (nodes, spirals, focuses) can be identified for spinning motion around axes close to the major, minor, and intermediate principal axes. It is found that the blades contribute to stability in a case of spin around the intermediate principal inertia axis, which is otherwise unstable. Subsequently, the equations for  determining the angles of nutation and spin of the body are obtained, thus defining the orientation of the body for a  stationary motion and the parameters on which that position depends.
PB AIAA
SN 0021-8669
LK https://oa.upm.es/39721/
UL http://arc.aiaa.org/doi/abs/10.2514/1.16746