An air speed record is the highest airspeed attained by an aircraft of a particular class. The rules for all official aviation records are defined by Fédération Aéronautique Internationale (FAI), which also ratifies any claims. Speed records are divided into multiple classes with sub-divisions. There are three classes of aircraft: landplanes, seaplanes, and amphibians; then within these classes, there are records for aircraft in a number of weight categories. There are still further subdivisions for piston-engined, turbojet, turboprop, and rocket-engined aircraft. Within each of these groups, records are defined for speed over a straight course and for closed circuits of various sizes carrying various payloads. Timeline Gray text indicates unofficial records, including unconfirmed or unpublicized war secrets. Official records versus unofficial The Lockheed SR-71 Blackbird holds the official Air Speed Record for a manned airbreathing jet engine aircraft with a speed of . The record was set on 28 July 1976 by Eldon W. Joersz and George T. Morgan Jr. near Beale Air Force Base, California, USA. It was able to take off and land unassisted on conventional runways. SR-71 pilot Brian Shul claimed in The Untouchables that he flew in excess of Mach 3.5 on 15 April 1986, over Libya, in order to avoid a missile. Although the official record for fastest piston-engined aeroplane in level flight was held by a Grumman F8F Bearcat, the Rare Bear, with a speed of , the unofficial record for fastest piston-engined aeroplane in level flight is held by a British Hawker Sea Fury at . Both were demilitarised and modified fighters, while the fastest stock (original, factory-built) piston-engined aeroplane was unofficially the German Dornier Do 335 Pfeil, with a maximum speed of in level flight. The unofficial record for fastest piston-engined aeroplane (not in level flight) is held by a Supermarine Spitfire Mk.XIX, which was calculated to have achieved a speed of in a dive on 5 February 1952. The last new speed record ratified before the outbreak of World War II was set on 26 April 1939 with a Me 209 V1, at . The chaos and secrecy of World War II meant that new speed breakthroughs were neither publicized nor ratified. In October 1941, an unofficial speed record of was secretly set by a Messerschmitt Me 163A "V4" rocket aircraft. Continued research during the war extended the secret, unofficial speed record to by July 1944, achieved by a Messerschmitt Me