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Cobra maneuver

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In aerobatics, Pugachev's Cobra (or Pugachev Cobra) is a dramatic and demanding manoeuvre in which a plane 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 a potent engine thrust to maintain approximately constant altitude through the entire move.[1] The figure has several combat uses[citation needed] including spoofing doppler radar, and is also an impressive trick to demonstrate aircraft's pitch control authority, high angle of attack (AOA) stability and engine-versus-inlet compatibility, as well as the pilot's skill. The manoeuvre is named after the Soviet test pilot Viktor Pugachev, who first performed the manoeuvre publicly in 1989 at the Paris Le Bourget air show.[2] Initially the Cobra was performed by Sukhoi's test pilot Igor Volk while testing the new Sukhoi Su-27 fighter.[3]

Description

A Su-27 performing the Cobra manoeuvre

In case of the Su-27, initially the pilot disengages the angle of attack limiter of the plane, normally set at 26°.[1] 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 manoeuvre; 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 manoeuvre; entering at too high a speed might result in the g-force sufficient[clarification needed] for the airframe to be damaged, or for the pilot to lose consciousness.[4][verification needed]

While Pugachev's Cobra can be executed using only standard aerodynamic controls, it could be achieved more easily with modern thrust vectoring. In the latter case it would be an example of supermanoevreability,[5] specifically poststall manoeuvreing. The Herbst manoeuvre and the helicopter manoeuvre are other examples of the recent growing use of vectored thrust in 4.5 and 5th generation aircraft, manned as well as unmanned.[6]

Examples of aircraft capable of the manoeuvre

See also

References

  1. ^ a b c d William C. Davis (2002). The illustrated directory of the Old West. St. Paul, Minnesotta: MBI Publishing Company. p. 442. ISBN 0760313431. Retrieved 23 March 2011.
  2. ^ The Illustrated Directory of Fighters By Mike Spick
  3. ^ Из космоса — на самолёт!
  4. ^ What is cobra?, AeroWeb.Lucia.it
  5. ^ Malcolm J. Abzug. Airplane stability and control: a history of the technologies that made aviation possible. pp. 157–161. ISBN 9780521809924. Retrieved 23 March 2011. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  6. ^ Benjamin Gal-Or, "Vectored Propulsion, Supermanoeuvreability, and Robot Aircraft", Springer Verlag, 1990, ISBN 0-387-97161-0, 3-540-97161-0
  7. ^ a b c International journal of turbo & jet-engines: Volume 11 http://books.google.com/books?id=0SxQAAAAYAAJ&q=Pugachev+Cobra&dq=Pugachev+Cobra&hl=en&ei=s8-JTbKLIZK2hAet042nDg&sa=X&oi=book_result&ct=result&resnum=5&ved=0CDkQ6AEwBA. Retrieved 23 March 2011. {{cite journal}}: Missing or empty |title= (help)
  8. ^ Cobra and Kulbit by F-22
  9. ^ Sk35C Draken trainers doing high-alpha manouvers

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