Another example of a rocket-powered aircraft is the Douglas D-558-2 Skyrocket. Normally carried aloft by a mother ship, the Skyrocket made several take-offs with the aid of JATO in order to determine rate of climb, which was poor. The machine illustrated is an early Skyrocket powered by a Westinghouse J34-WE-22 turbojet and a 6,000-lb. thrust Reaction Motors XLR-8 bi-fuel rocket.
Typical of the present trend of fighter design is the SO.9050 Trident II. The wingtip-mounted Armstrong Siddeley Viper turbojets are used for economic cruising, and the twin-barrel rocket boosts the machine to supersonic speed in a matter of seconds.
The Bell X-1A possessed one of the essential features of a modern interceptor - speed (it reached a speed of 1,650 m.p.h. - Mach 2.5), but the enormous fuel consumption of the rocket motor restricted the duration of flight.
The Republic XF-91 Thunderceptor was a compromise between the pure jet and the rocket-powered interceptor. Although it never entered large-scale production, It provided a glimpse of the fighter of the future.