Guy Norris/LOS ANGELES

THE BOEING AND McDonnell Douglas (MDC) X-33 team is studying Russian as well as US-made rocket engines for use in its proposed re-useable launch vehicle (RLV) demonstrator.

Paul Klevatt, Boeing-MDC X-33 programme manager, says: "We're looking at existing engines, as well as a whole cadre of Russian engines. We have all three [US] rocket makers involved - Aerojet, Pratt & Whitney and Rocketdyne - and most have Russian connections." The Boeing/MDC team will use liquid-oxygen/liquid-hydrogen rocket engines.

Boeing/MDC is competing against teams led by Lockheed Martin and Rockwell for a single NASA technology-demonstration contract expected to be awarded in June or July 1996. The winning X-33 design will be flown in the first quarter of 1999, with the ultimate goal of fielding an unmanned, fully re-useable, single-stage-to-orbit launch vehicle in 2005.

Giving new details about its bid, the team says that the vertical take-off and landing vehicle will be around 30m (100ft) tall, with a 9m diameter, compared with the 12m-tall, 4m-diameter, MDC DC-X testbed. It will have a gross lift-off weight of 227,000kg, compared with just 18,160kg for the DC-X.

Livingston Holder, deputy programme manager, says that the final design "...was a major team decision. We had narrowed it down to three, two vertical landers - one nose first and one base first - and a horizontal lander. All could be made to work, but the vertical lander is the best technology testbed."

One of the critical technologies to be tested on the X-33 will be a durable thermal-protection system (TPS). Boeing/MDC believes that designing its vehicle so that it re-enters the atmosphere nose-first, and then turns base-first for landing, reduces the heat concentration, and the technology risks, associated with the the TPS. "We're looking at a TPS that does not require more than a quick look-see," says Klevatt.

A Lockheed Martin SR-71 is being modified at the company's "Skunk Works" site in Palmdale, California, to carry a linear, "aerospike" rocket engine on top of the fuselage. The first research flights scheduled for April 1996, are in support of the Lockheed Martin-led X-33 team, which is studying a lifting-body design.

Source: Flight International