PIONEER ROCKETPLANE is planning to fly its Pathfinder transatmospheric launch vehicle in three years time, to be available for initial deployment of the proposed Teledesic constellation of some 840 small communications satellites. Denver, Colorado-based Pioneer is seeking $6 million in funding for detail design of the Pathfinder and will need $100 million to build, test and begin operations with its first vehicle.
The two-crew Pathfinder combines air-breathing and rocket propulsion. After a conventional take-off under turbofan power, carrying its kerosene fuel, the vehicle will rendezvous with an aerial-refuelling tanker to take on liquid oxygen, then make a brief suborbital flight under rocket power to deploy its payload on a small upper-stage, before re-entering for a conventional landing under turbofan power, says co-founder Dr Robert Zubrin.
The company is aiming for a launch price of $4.5 million to place a 1,000kg payload into low-Earth orbit. That compares with $23 million for a launch by Orbital Sciences' Taurus expendable booster, says Zubrin. The vehicle uses off-the-shelf components, he explains, including two Pratt & Whitney F100-200 turbofans and a Russian RD-120 rocket motor.
The aerial tanker would be a modified ex-military Boeing KC-135 or a commercial airliner,converted for probe-and-drogue refuelling, Zubrin says. To be built by Burt Rutan's Scaled Composites, the Pathfinder would have an all-composite structure and alumina-enhanced thermal-protection tiles. The vehicle would re-enter at Mach 12, about half the speed of the Space Shuttle, he says.
The Pathfinder is seen as the forerunner of a transoceanic package-delivery freighter able to carry 1,800kg over 8,300km (4,500nm) in under 50min. In the longer term, the company hopes to develop a passenger version, says president Larry Hecker, a former deputy administrator of the US Federal Aviation Administration.
Source: Flight International
