Pugachev's Cobra Maneuver



Pugachev Cobra is a fighter aircraft maneuver. It is a demonstration of the pitch control authority, high angle of attack (AOA) stability and engine/inlet compatibility at high angles of attack of the aircraft.

The maneuver allows for very quick turns which can make an attack fail or put the pilot in a position to execute an attack. It is an example of air combat manoeuvering (ACM). Many Western experts on ACM believe this maneuver has absolutely no value in actual air combat; nonetheless, the Pugachev Cobra is known to be one of the most aesthetic, dramatic, demanding and beautiful maneuvers performed at air shows worldwide. The maneuver is so named after the Sukhoi OKB (design bureau) test pilot Viktor Pugachev, who first performed the maneuver.

 

 

In order to perform the Cobra (in this example, in a Su-27 Flanker) the pilot reduces speed to approximately 275 knots in level flight. S/he then must disable the AOA limiter on the Flight Control System, as this serves to limit the airplane to angles of attack not exceeding 30 degrees in normal flight. Once this is accomplished, the pilot sharply pitches up the nose of the airplane. If the speeds are right and the pitchup is done properly, the aircraft will rotate around its horizontal axis until the nose is past vertical - the single-seat Flanker can achieve between 110 and 120 degree AOA! - while continuing to move in its prior flight path as the maneuver is too quick and there isn't enough energy to allow the airplane to climb as it pitches up. Once the pilot has reached the desired attitude, s/he sharply increases throttle and releases the stick. The airplane has managed to rotate back past vertical on the initial rotational energy of the pitchup maneuver; once it approaches vertical, however, the rear half of the aircraft (now the 'lower' half) generates much more drag than the front (or 'top') half due to the larger cross-section of the wings and stabilizers. This will cause the rotation to stop and then reverse, the nose pitching sharply 'down' relative to the airframe, back into level flight. The throttle added during the maneuver will, if done properly, prevent the airplane from losing any altitude during the process. In sum, the maneuver should take no more than a few seconds. The aircraft will exit the maneuver at around 135 knots, which means it is in a fairly precarious position until it gains airspeed. The MiG-29 and Su-27 are both designed to have extremely large tolerances for airflow deviation into the engine inlets. This is what permits them to perform this maneuver without suffering an engine unstart (normally). In addition, their postive lateral stability and clean lines reduce the risk of a full stall during the procedure. They have high thrust-to-weight ratios as well. The MiG-29 must enter a climb of around 30 degrees before performing the Cobra as it will not recover quickly enough to avoid losing altitude. Vehicles known to be able to make the cobra maneuver are the Sukhoi Su-27 Flanker family (from horizontal flight), and Mikoyan MiG-29 (from a 30 degree up angle). Thrust vectoring aircraft (such as the Sukhoi Su-30, Su-37, Su-47, MiG 1.42, F-22, F-15 ACTIVE, F-16 MATV/VISTA, and NASA's X-31) should be able to perform this maneuver more easily, though note that the air intake still needs to be able to handle the air inflow. The Eurofighter Typhoon should be able to perform this maneuver, as long as the engines stay lit.



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