Proposal of Static Margin Limit during Launch Phase for the VS-30 Orion Sounding Rocket

Unguided rockets must be stable to fly the planned trajectory. During the launch phase the velocity of the rocket is relatively low and, consequently, the wind has more influence on the trajectory. After the vehicle lives the launch rail it encounters a horizontal wind. In this event, known as lift-off, the rocket is disturbed by the wind and opens the maximum angle of attack (AoA). If the center of pressure (CP) - point of application of aerodynamic force - moves forward as the AoA increases from zero, the vehicle may become unstable depending on the velocity of the wind. For each rocket, there is a corresponding range of AoA for which the vehicle remains stable. The maximum value within this range is the angle at which the center of pressure coincides with the center of gravity, situation that corresponds to the limit of stability of the vehicle. The objective of this study is to ascertain the minimum wind intensity that can produce an unstable condition during the lift-off phase. The knowledge of the wind intensity that could make the vehicle to reach its limit of stability is very important information for flight safety and decision making. The vehicle considered in this study is the VS-30 Orion.