Fin Damage and Rod Eccentricity for Spin/Pitch Lock-in for Antiarmor Kinetic Energy Projectiles
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
Pagination or Media Count:
A study and a general model for the rollpitch frequency lock-in phenomenon are made for antitank long kinetic energy projectiles and missiles in general, to quantify the necessary projectile damagedefect required to cause the lock-in. Lock-in is a persistent resonance for the flight duration of the vehicle i.e., projectile. Fin damage and body mass offset are modeled as the forcing forces and moments asymmetries causing the lock-in. Idealized fin damage is modeled. The corresponding pitch, side slip, and roll equations are numerically integrated. The resulting yaw is largest when the projectile is spinning near the pitching frequency, and yaw diminishes when the spin rate attributable to fin damage is away from it. The nonlinear induced roll moment is essential in coupling the pitchingyawing motions with the moment of the roll motion. A specific and complete projectile case study is presented, in which quantified fin damage and rod mass offset are found to cause such lock-in. Computed flight motion history pitch, side slip, and roll, and yaw amplification factor provide insight into this lock-in behavior. The model is general and can be applied to any finned projectile or missile.
- Ammunition and Explosives