The next, natural step forward from the EZ-Rocket is an improved rocketplane called the X-Racer, being developed by XCOR Aerospace for the RRL. Using a modified Long-EZ, the X-Racer will have a single liquid-propellant engine, the XR-4K14, burning kerosene and LOX, which are delivered to the thrust chamber by XCOR's own piston-pumps. This automatically eliminates the expensive helium-pressurized belly fuel tank used on the EZ-Rocket. Instead, the X-Racer will carry unpressurized kerosene in strake tanks built into the sides of the fuselage. The heavy LOX is carried in an insulated tank of its own, just behind the pilot and close to the center of gravity. Rather than a pair of 400-lb thrust engines, the X-Racer sports a single 1,500-lb thrust rocket, which can be shut down and electrically restarted in flight numerous times. The maximum speed - determined by the airframe, not the engine - will be 230 mph. The X-Racer will have about 3^ min of intermittent powered flight capability together with a total of some 15 min of power-off glide. This will allow the X-Racer to complete 8-9 laps around a three-dimensional aerial race track during rocket racing competition. Refueling of both the kerosene and the cryogenic oxygen will take only 5-10 min, enabling the X-Racer to get back into the race quickly.
The X-Racer and other similar rocketplanes will compete in regular events sponsored by the RRL (Fig. 1.21). This venue promises to combine the thrill of rocketry with the excitement and competition of racing. The RRL is a partner-
ship of space enthusiasts and racing expertise. It was conceived by X Prize founder, Peter Diamandis, and two-time Indianapolis 500 champion team partner, Granger Whitelaw. The idea is to bring key talents together in order to "advance the technology and increase public awareness of space travel." All rocket racers will, of course, be top pilots.25
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