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

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.

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

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. Aerojet’s Web site
address is