The first flight of YP3V-1 prototype came on 25 November 1959 at the Lockheed plant in Burbank, California, where most of the aircraft would be built. The nickname Orion was officially adopted in late 1960, keeping with the Lockheed tradition of naming aircraft after mythological figures or celestial bodies.

Lockheed Martin Aeronautics Company – Palmdale, CA
P-3 Orion
YP3V-1
10-14-1960
Lockheed Martin Photo by Larivee