Rolls-Royce RB401
The Rolls-Royce RB.401 was a British two-spool business jet engine which Rolls-Royce started to develop in the mid-1970s as a replacement for the Viper. RB.401-06 prototype engines were already being manufactured when a decision to develop the higher thrust RB.401-07 was taken.
Although ground testing of both the -06 and -07 continued into the early 1980s, a lack of funds caused the project to be cancelled.