X-Plane 9.70+ Lockheed XFV-1 Salmon. The American Lockheed XFV (sometimes referred to as the Salmon) was an experimental tailsitter prototype aircraft built by Lockheed in the early 1950s to demonstrate the operation of a vertical takeoff and landing fighter for protecting convoys. With the realization that the XFV's top speeds would be eclipsed by contemporary fighters and that only highly-experienced pilots could fly the aircraft, the project was cancelled in June 1955. The Readme file gives advice on how to fly the aircraft. By Vasco Ribeiro.