NASA will partner with the US Air Force (USAF) to study next-generation upper stage propulsion, formalizing the agencies joint interests in a new upper stage engine to replace the venerable Pratt & Whitney Rocketdyne RL-10.

"We know the list price on an RL-10.if you look at cost over time, a very large portion of the unit cost of the EELVs is attributable to the propulsion systems, and the RL-10 is a very old engine, and there's a lot of craftwork associated with its manufacture," says Dale Thomas, associate director of technical issues at NASA Marshall. "That's what this study will figure out, is it worthwhile to build an RL-10 replacement?"

From the study, NASA hopes to find a less expensive RL-10-class engine for a third stage of the Space Launch System (SLS), which is on track to become the most powerful rocket ever built. Atop the Space Shuttle Main Engines (SSME)-powered first stage and Pratt & Whitney Rocketdyne J-2X second stage, a third stage is required to push massive payloads beyond Earth orbit.

USAF hopes to replace the Rocketdyne RL-10 engines used on the upper stage of both the Lockheed Martin Atlas V and the Boeing Delta IV, known as evolved expendable launch vehicles (EELV) that are the primary method of putting US satellites into space. While NASA frequently uses EELVs to launch large scientific payloads, the programme's administration is largely run through other channels.

 Delta IV rocket launch


"In recent years, it's become apparent that the rocket propulsion industry is in a state of distress," says Dale Thomas, associate director at Marshall. "Collaborating -- especially in a time of declining budgets -- helps to grow and strengthen the knowledge base which is important for our nation's technical preeminence."

Several companies have announced work on an RL-10 replacement, including, including an Xcor/United Launch Alliance (ULA) team and Rocketdyne itself. Rocketdyne is also working on an updated RL-10, called the RL-10C.

Source: Flight International