Tim Furniss/LONDON
Boeing is reiterating that it is "on track" to launch the first Delta IV in May 2002. The launcher will carry a Defense Space Communications System (DSCS) satellite for the US Air Force under the Evolved Expendable Launch Vehicle (EELV) programme. The launch confirmation follows reports that a Lockheed Martin Atlas V has been lined up for the mission following problems with the Boeing Rocketdyne RS-68 engine which powers the Delta IV.
The confusion has arisen as Boeing and Lockheed will back each other up for the provision of some launches, depending on the payload. The EELV programme allows either contractor to give USAF assured access to space. "In December 2000 as a standard precaution, the service asked Lockheed Martin to begin initial integration activities to support DSCS as needed," Boeing says.
Lockheed Martin has already begun integration of the first Atlas V EELV as a back-up in case the USAF opts to take the mission away from Boeing. "We have not been notified by the US Air Force of any intention to reassign the launch," says Boeing.
The Delta IV EELV mission will be preceded in the first quarter of 2002 by a demonstration mission, carrying a commercial communications satellite or a dummy payload.
Boeing says that the Delta IV maiden flight schedule is paced by the development of the RS-68 cryogenic liquid oxygen-liquid hydrogen first stage engine. The company has recently completed four successful tests of the engine totalling 800s over seven days, which validated design fixes after earlier problems with the engine.
Problems occurred during an engine static firing test at the Stennis Space Centre, Mississippi, in November which caused damage to turbine blades due to a "component failure" possibly as a result of "high cycle fatigue". The problems centred on the single blade and disc assemblies, or bliscs, in the turbopumps. Boeing says the problem was eliminated by adjusting "the natural frequency of the blisc to operate the engine at the desired levels".
The RS-68 is the first cryogenic engine to be built in the USA as a first stage powerplant since the Space Shuttle Main Engine. "The tests are evidence that we overcame the issues seen to date and will be ready to support a commercial launch in early 2002," says Boeing.
Boeing was awarded a $1.38 billion contract to build 19 Delta IV EELVs for the USAF, an order increased to 21 last year, at the expense of the Atlas V, which lost two launches, bringing to seven those for the USAF under its original $650 million contract.
Source: Flight International