The last SR-71, the SR-71C, was nicknamed “The Bastard.” The name was partly due to the Frankenstein-like creation of the aircraft. After one SR-71B trainer crashed in January 1968, it was determined that another trainer plane should be constructed.

The project began with a wrecked YF-12A that was utilized for the rear part of the fuselage, and the front came from a static, but functional, SR-71A mockup. It was apparently a “bastard” to fly as well, considering it was said to have a “yaw at supersonic speeds” due to the joined fuselage not being quite straight