Aerojet has won an eight-month, $5 million contract from NASA to study the feasibility of developing a channel wall nozzle to replace the tube nozzle in the Space Shuttle Main Engine (SSME).

The existing tube nozzle is constructed by brazing together more than 1,000 specially shaped tubes to form the nozzle. During engine operation, hydrogen flows through the inside of these tubes to cool the nozzle and gasify the hydrogen.

Current Space Shuttle Main Engine. Photo: NASA-KSC

Channel wall nozzles feature very few components and incorporate cooling slots milled directly into the nozzle structure that are transformed into individual hydrogen coolant channels when an outer jacket is attached. Channel wall nozzles could offer a significant increase in SSME nozzle reliability and could potentially be produced faster, more consistently and at lower cost than tube nozzles. NASA's requirements are that the channel wall nozzle be capable of 55 flights, 27,000 seconds of operation and one abort flight.

"In this study, we will identify design and process risks associated with developing a robust channel wall nozzle and develop solutions for eliminating or reducing those risks," said Robert Werling, Aerojet program manager.

Aerojet is competing with Rocketdyne for possible selection to design and fabricate nozzles for the next SSME upgrade. Other elements in the potential SSME upgrade project include a new larger throat combustion chamber that reduces system operating pressures and temperatures, and an Advanced Health Management System that enhances anomaly detection and mitigation during engine operation.

Aerojet's study contract was awarded through NASA's contracting office at George C. Marshall Space Flight Center in Huntsville, Ala.

Aerojet, a GenCorp company, is a world-recognized aerospace and defense leader principally serving the space electronics, missile and space propulsion, and smart munitions and armaments markets.