Editing Compression lift (section)

{{Short description|Phenomenon allowing supersonic aircraft to ride their own shockwave}}
[[File:North American XB-70A Valkyrie in flight 061122-F-1234P-022.jpg|thumb|right|250px|The [[North American XB-70 Valkyrie|XB-70]] had [[Folding wing|folding wingtips]] to enhance both compression lift and directional stability at high speeds.]]
[[File:Hp scan0021.jpg|thumb|right|250px|Rear view of the [[Grumman F-14 Tomcat|F-14 Tomcat]] showing the area between the engine nacelles. The area referred as the "pancake" provided compression lift in flight.]]

In [[aerodynamics]], '''compression lift''' refers to the increased pressure under an [[aircraft]] that uses [[shock wave]]s generated by its own [[supersonic]] flight to generate [[Lift (force)|lift]]. This can lead to dramatic improvements in lift for [[supersonic]]/[[hypersonic]] aircraft. [[Clarence Syvertson]] and [[Alfred J. Eggers]] discovered this phenomenon in 1956 as they analyzed abnormalities at the reentry of [[nuclear warhead]]s.<ref name="Compression Lift">[http://www.aerospaceweb.org/design/waverider/design.shtml Compression Lift]</ref>

The basic concept of compression lift is well known; "[[planing (boat)|planing]]" boats reduce drag by "[[surfing]]" on their own [[bow wave]] in exactly the same fashion. Using this effect in aircraft is more difficult, however, because the "wake" is not generated until supersonic speeds are reached, and is highly angled. Aircraft have to be carefully shaped to take full advantage of this effect. In addition, the angle of the [[shock wave]]s varies greatly with speed, making it even more difficult to design a craft that gains significant lift over a wide range of speeds.

Higher speed designs using compression lift, [[waverider]]s, remain an interesting possibility for [[hypersonic]] vehicle designs, although only testbed models have been flown.<ref name="Compression Lift"/> The [[Boeing X-51 Waverider|Boeing X-51 (Waverider)]] also uses compression lift.