In aerobatics, Pugachev’s Cobra (or Pugachev Cobra) is a dramatic and demanding maneuver in which an airplane flying at a moderate speed suddenly raises the nose momentarily to the vertical position and slightly beyond, before dropping it back to normal flight.
It uses potent engine thrust to maintain approximately constant altitude through the entire move. Some have speculated that the maneuver may have used in close range combat, although it has never been used.
It is an impressive trick to demonstrate an aircraft’s pitch control authority, high angle of attack (AOA) stability and engine-versus-inlet compatibility, as well as the pilot’s skill. The maneuver is named after the Soviet test pilot Viktor Pugachev, who performed it in 1989 at the Le Bourget Paris air show.
But Igor Volk was the first who tested aircraft behaviour at high super-critical angles of attack (around 90°) and performed aerobatics such as the “cobra” manoeuvre.
Description
In the case of the Su-27, the pilot initially disengages the angle of attack limiter of the plane, normally set at 26°.This action also disengages the g limiter. After that the pilot pulls back on the stick hard.
The aircraft reaches 90–120° angle of attack with a slight gain of altitude and a significant loss of speed. When the elevator is centered, the drag at the rear of the plane causes torque, thus making the aircraft pitch forward. At that time the pilot adds power to compensate for the lift loss. In a properly performed Pugachev’s Cobra, the plane maintains almost straight flight throughout the maneuver; the plane does not roll or yaw in either direction.
Proper entry speed is significant because, if entering at too low a speed, the pilot might not be able to accomplish the maneuver; entering at too high a speed might result in airframe damage due to the high g-force or for the pilot to lose consciousness.
While Pugachev’s Cobra can be executed using only standard aerodynamic controls, it could be achieved more easily with modern thrust vectoring such as the case of F-22 Raptor which utilizes 2D thrust vectoring. In the latter case it would be an example of supermaneuverability,specifically poststall maneuvering.
The Herbst maneuvering and the helicopter maneuver are other examples of the recent growing use of vectored thrust in 4.5 and fifth-generation jet fighters, manned as well as unmanned.
