GRAHAM WARWICK / WASHINGTON DC
Development work to focus on reducing risk from hydrocarbon-fuelled powerplants
Boeing's Rocketdyne division is winding down work on its RS-83 reusable cryogenic rocket engine, as NASA focuses on kerosene-fuelled powerplants under its Space Launch Initiative (SLI) to develop technology for a second-generation reusable launch vehicle (RLV).
NASA has already ordered Pratt & Whitney and partner Aerojet to halt work on the Cobra cryogenic reusable engine. Work on the rival RS-83 will stop by year-end, says Rocketdyne SLI programme director John Vilja. The company will continue development of the RS-84, one of two kerosene-fuelled rocket engines being funded by NASA. TRW, meanwhile, is working on the kerosene-fuelled TR107.
Vilja says NASA's decision to stop work on liquid-hydrogen/liquid-oxygen engines is a result of an assessment "that the risk level with reusable high-power kerosene engines is higher, and that it is better to focus on the area where they get the most risk reduction". NASA plans to ground-test at least one prototype engine before making a decision in 2006 on whether to proceed into full-scale development of a second-generation RLV.
While hydrogen engine tests were planned for 2005, prototype kerosene engine tests are not scheduled until the first half of 2006. "That allows NASA to take a year off [from hydrogen engine development] and still meet the 2006 decision date," says Vilja. The space agency could restart cryogenic engine work in a year and still meet its deadline, although a decision on developing a second-generation RLV is almost certain to be delayed.
Rocketdyne's RS-84 is a 1.05 million lb thrust (4,700kN) staged-combustion rocket engine, which evolved from work on high-power kerosene engines for the stillborn Space Shuttle liquid fly-back booster.
Under this programme, Vilja says, the company conducted small-scale tests of turbine materials that could operate in an oxidiser-rich environment without coatings, improving reusability. That work is now being scaled up.
NASA, meanwhile, has delayed an SLI system requirements review set for this month. The agency is expected to divert funds from a second-generation RLV to development of an orbital spaceplane that can be launched on an expendable booster to provide crew rescue for the International Space Station.
Source: Flight International
