original question: What's the development status of the rocket engine, designed by [Rocketdyne], whose Isp (sea level) is no more than [255.0]?
answer: flown
answer type: Rocket engine development status.
auxiliary information: Rocketdyne was an American rocket engine design and production company headquartered in Canoga Park, located in the western San Fernando Valley of suburban Los Angeles, in southern California. The Rocketdyne Division was founded by North American Aviation in 1955, and was later part of Rockwell International and Boeing. 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.
What is the development update of the rocket engine that has an Isp (sea level) that is no more than [255.0] and is designed by [Rocketdyne]?