Aerojet and Boeing's Rocketdyne division are competitively studying an improved nozzle for the Space Shuttle Main Engine (SSME).

The companies have received eight-month NASA contracts to study the feasibility of developing a "channel wall" nozzle with increased reliability and reduced cost. The nozzle could be part of the next SSME upgrade, which could also include a larger-throat combustion chamber to lower operating pressures and temperatures.

The present Rocketdyne-designed SSME nozzle is formed by brazing together more than 1,000 tubes, through which liquid hydrogen is pumped to cool the nozzle. In the channel wall design, slots milled into the nozzle structure become coolant channels when an outer jacket is attached.

Aerojet says the channel wall design offers a significant increase in SSME nozzle reliability and promises faster, cheaper and more consistent production. NASA requires the new nozzle to be capable of 55 flights and one abort.

Meanwhile, under a $7.6 million NASA Space Launch Initiative contract, Aerojet will demonstrate a dual-thrust reaction control engine for a second-generation reusable launch vehicle.

The engine will use the company's platelet injector technology to provide both high and low thrust levels for up to 100 missions, burning liquid oxygen and ethanol. Aerojet will build three engines for testing in 2004.

Source: Flight International