Rocketdyne
The Rocketdyne Division was founded by North American Aviation (NAA) in 1955, and was later part of Rockwell International (1967-1996) and Boeing (1996-2005). In 2005, the Rocketdyne Division was sold to United Technologies Corporation, becoming Pratt & Whitney Rocketdyne as part of Pratt & Whitney. In 2013, Pratt & Whitney Rocketdyne was sold to GenCorp, which merged it with Aerojet to form Aerojet Rocketdyne.
Rocketplane XP
On January 24, 2006 Rocketplane Limited announced a Space Act agreement with NASA Johnson Space Center for the loan of a Rocketdyne RS-88 rocket engine for three years, for use in flight tests of the XP vehicle.