A 1/6 scale model of the AR1 engine currently in development by Aerojet Rocketdyne as a replacement for the Russian-built RD-180 engine that powers United Launch Alliance's Atlas 5 rocket. Credit: Aerojet Rocketdyne

WASHINGTON — Aerojet Rocketdyne said Dec. 17 that the AR1 engine it hopes to build for United Launch Alliance’s next-generation rocket has completed a key design review.

The review, similar to a preliminary design review used in government acquisition, clears the way for further development of the kerosene-fueled engine.

Aerojet Rocketdyne officials have said the AR1 engine could be ready for the test stand by 2017 and certified for flight by 2019.

“This is one of the most important design reviews the program will undergo during its development,” Julie Van Kleeck, Aerojet Rocketdyne’s vice president of advanced space and launch programs, said in a Dec. 17 press release. “We apply rigorous design reviews as part of our overall development program, minimizing risk and helping ensure that we will meet the delivery schedule on a program of such national significance as AR1.”

The review included an examination of 18 subsystems and components that make up the engine to ensure they work properly by themselves and within the engine.

Congress has given the U.S. Air Force a 2019 deadline for fielding an American-made propulsion system capable of ending the Defense Department’s dependence on the Russian-made RD-180 engine that powers ULA’s Atlas 5 rocket.

Aerojet Rocketdyne is developing the AR1 as a replacement for the RD-180. While ULA is supporting AR1 development, ULA has indicated that Blue Origin’s BE-4 engine is the leading candidate to replace the RD-180 and power Vulcan.

In June, Tory Bruno, ULA’s chief executive, told Congress that Blue Origin’s BE-4 engine development program is 16 months ahead of Aerojet Rocketdyne’s AR1 effort. ULA expects to make a final decision on which engine to pursue in late 2016.

However, Bruno said in Aerojet Rockedyne’s Dec. 17 press release that the Sacramento, California-based propulsion house “is making excellent progress” on the engine.

Meanwhile, the Air Force is expected to award as many as four contracts in the coming weeks worth a combined $160 million for new prototype rocket propulsions systems. Aerojet Rocketdyne is vying for one of those contracts.

Mike Gruss covers military space issues, including the U.S. Air Force and Missile Defense Agency, for SpaceNews. He is a graduate of Miami University in Oxford, Ohio.