March 1955
From The Space Library
Feasibility of F-1 rocket engine developing a million pounds of thrust in a single chamber established at Rocketdyne.
Rocketdyne Division of North American Aviation, Inc. (NAA), established the feasibility of a million-pound-thrust liquid-fueled rocket engine for the U.S. Air Force.
Rocketdyne Skywriter, May 20, 1960, p. 1.