Pioneer Rocketplane Inc. have two designs up their corporate sleeve. One is called "Pathfinder" and may possibly not qualify for the X-Prize, as it is intended to refuel at high altitude, before travelling on to its maximum height, where payload doors open and a rocket is released, taking the payload into low earth orbit. The other is called "Rocketplane XP" and has the familiar configuration of jet engines plus a rocket motor. It is, presumably, intended to take the X-Prize with this vehicle. Currently, the website has a statement that it is intended to fly the Pioneer XP, "soon", affordably and safely. According to their "History" section, Pioneer have been awarded contracts for studies. As of April 2004, there is a reference to static engine tests, which is indicative of progress, but things seem to be a long way behind Scaled Composites, the field leader.

Here is what they say about the XP: "The XP is a four-seat fighter-sized vehicle powered by two jet engines and one rocket engine, enabling it to reach altitudes of 350,000 feet (106.7 kilometres). It has military applications, research and observation platforms and promotional and sponsorship opportunities".