page_title: Three-surface aircraft
section_title: Manoeuvrability beyond the stall
hierarchical_section_title: Three-surface aircraft / History / Manoeuvrability beyond the stall
caption_attribution_description: English: This photo shows the X-29 during a 1991 research flight. Smoke generators in the nose of the aircraft were used to help researchers see the behavior of the air flowing over the aircraft. The smoke here is demonstrating forebody vortex flow. This mission was flown September 10, 1991, by NASA research pilot Rogers Smith.
context_page_description: A three-surface aircraft or sometimes three-lifting-surface aircraft has a foreplane, a central wing and a tailplane. The central wing surface always provides lift and is usually the largest, while the functions of the fore and aft planes may vary between types and may include lift, control and/or stability.
  In civil aircraft the three surface configuration may be used to give safe stalling characteristics and short takeoff and landing performance. It is also claimed to allow minimizing the total wing surface area, reducing the accompanying skin drag. In combat aircraft this configuration may also be used to enhance maneuverability both before and beyond the stall, often in conjunction with vectored thrust.
context_section_description: Around 1979, military jet designers began studying three-surface configurations as a way to provide enhanced manoeuvrability and control, especially at low speeds and high angles of attack such as during takeoff and combat. In the United States the experimental Grumman X-29 flew in 1984 and a modified McDonnell Douglas F-15, the F-15 STOL/MTD, in 1988 but these designs were not followed up. In the Soviet Union a Sukhoi Su-27 modified with canard foreplanes flew in 1985 and derivatives of this design became the only military types to enter production.
caption: Grumman X-29, rear strake flaps deflected
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