Two aircraft companies have borne the name Northrop Corporation. The first was started by designer Jack Northrop as the Avion Corp. in 1929, persisting as a division of the United Aircraft Corp. until 1937. The second, again founded by Jack Northrop, started in 1939 and continues to the present day, now called the Northrop Grumman Corp. after its purchase of Grumman in 1994.
The products of Jack Northrop and his companies were consistently innovative. Northrop began by working for Lockheed, but split to pursue aircraft of all-metal construction rather than the wood monocoque that Lockheed continued to favor. In his first company, he produced an influential series of four aircraft named after the first four letters of the Greek alphabet: Alpha, Beta, Delta and Gamma. Each was a single-engined, all-metal aircraft employing “stressed-skin” (i.e. the outer skin of the airplane bears structural loads rather than just being hung on the internal structure for aerodynamics) “semi-monocoque” (i.e. the aircraft’s skin is part of the primary structure, but is supported by some internal structure) construction. They also employed Northrop’s “cellular wing” concept in which the wings were built in three sections, a center section and two bolted-on, removable outer sections. Northrop’s construction methods were not the lightest, but they were very strong and resulted in aircraft that were prized for their durability. Not very many of these “Greek-letter” types were made, but their technologies found their way into such iconic aircraft as the North American T-6 and Douglas DC-3.
In the second incarnation of Northrop Corp., the company focused on tail-less “flying wing” designs, which had become a preoccupation of Jack Northrop’s. Its development of several small, experimental flying wings led by the end of the war into a contract for a large all-wing bomber, the B-35, of which two were built. A further three examples were built of a jet-powered version, the B-49. The projects were cancelled in the late 1940s in favor of the Convair B-36, which featured more conventional construction and whose manufacturer was better-connected with the government and senior Air Force officers.
Northrop’s one successful World War II design, the P-61 night fighter, served as a springboard into fighter design during the jet age, and Northrop continued to innovate in aerodynamics and stealth technology. Its most recent successful aircraft design has been the B-2 Spirit stealth bomber.