-M
-
MO
-
80
-
6
-
61
Static Preload Moment (oscillations occur about this moment). Static Moment required to deflect store to breakout value; 678 N m ( 6 0 0 0 in.lb). Amplitude of store pitch oscillation. Pitch Angle at which store breaks friction (0.03804 degrees). Describing function ( 6 = Ke/K) where Ke is the equivalent linear spring constant of the nonlinear spring.
The analysis indicates that there are small changes in the flutter speed as a function of large variations of the ratio
-
M/Mo. This is due to the small angular range over which the pylon is below breakout.
Aeroservoelastic Analyses
Symmetric and antisymmetric aeroservoelastic analyses were conducted using the pylon simulation based on ground test data. Both analyses were made at a Mach number of 0.9 and at an altitude of sea level. The symmetric analysis was conducted with the pitch loop open. At 305 m/s ( 5 9 4 kts) at sea level the pitch loop has a large gain and phase margin. Since the pitch loop margins were large, the analysis was not conducted at additional velocities. The antisymmetric analysis was conducted with the yaw loop closed and the gain and phase margins were determined from the open loop roll response. The analysis was conducted with the unsteady aerodynamic terms computed for a Mach number of 0.9. The gain and phase margins were determined for a series of velocities. By conducting the analysis with t h e yaw loop closed, the stability of the yaw l o o p is 9
