Thiokol Propulsion is to begin fabrication later this month of the first exit cone for Boeing's new RS-68 low-cost cryogenic engine which will power the Delta IV Evolved Expendable Launch Vehicle (EELV) for the US Air Force.

The phenolic exit cone will be delivered to Boeing for a full static test firing in February 1999. Three development units have already been delivered and one will be used for an initial static test in October.

The US Air Force is expected to announce formally this month that Boeing and Lockheed Martin have been picked to build a fleet of small, medium and large EELV models.

Boeing's Delta IV EELV fleet will be based on a common core booster powered by the RS-68. The cryogenic engine will be the first new motor built by the USA since the Space Shuttle Main Engine (SSME).

It will be the most powerful liquid hydrogen/liquid oxygen engine in the world - 50% more powerful than the SSME. Thiokol applied its experience as the world's largest solid-rocket motor company to produce the simple four-piece ablative design that replaces more complex multi-piece exit-cone configurations.

Source: Flight International