Aerojet Rocketdyne has won the lion’s share of new government work to develop a U.S. alternative to Russia’s RD-180 hydrocarbon rocket engine, taking a $115.3 million “other transaction agreement” (OTA) for continued development of its AR1 prototype main-stage engine under the Air Force Evolved Expendable Launch Vehicle (EELV) program.                                                                       

United Launch Alliance received an OTA worth $46.6 million for work on the BE-4 engine it is developing with Blue Origin, and for the Advanced Cryogenic Evolved Stage (Aces) upper-stage propulsion system.  The two companies will join Orbital ATK and SpaceX in OTAs the service’s Space and Missile Systems Center (SMC) hopes will give the U.S. an alternative to ULA’s RD-180-powered Atlas V in the Centennial, Colorado-based company’s planned Vulcan launch vehicle.

Aerojet Rocketdyne noted that its AR1 can also power the Atlas V, and some of the work funded under the new OTA will go to designing the engine to power the older ULA vehicle that now uses the RD-180.

“ULA is fully committed to transitioning as quickly and affordably as possible to a domestic engine,” stated ULA President and CEO Tory Bruno, in a release issued by Aerojet Rocketdyne. “Our supplier, Aerojet Rocketdyne, is moving us toward one of two viable options with the excellent progress on the AR1 engine development.”

The BE-4, which Blue Origin is developing for its own orbital launch vehicle as well, is being designed to use liquid natural gas as a fuel, requiring longer tanks in the main stage of the proposed Vulcan vehicle than the rocket-grade kerosene the RD-180 burns. Aerojet Rocketdyne has billed the kerosene-fueled AR1 as a drop-in replacement for the RD-180 on the Atlas V.

“The AR1 engine is the option with the least technical risk that allows the United States to quickly and efficiently transition off its use of Russian-supplied engines currently used on the Atlas V launch vehicle,” stated Eileen Drake, CEO and president of Aerojet Rocketdyne.

Work under the two OTAs announced Monday is due to be completed by the end of 2019. Aerojet Rocketdyne is to contribute $57.7 million initially under its arrangement with SMC, which has a total potential government investment of $536 million. If all options are exercised, the Canoga Park, California, company will invest $268 million in AR1 development.

ULA will invest $40.8 million initially, of a total potential company investment of $134.2 million. The total potential government investment with ULA is $201.7 million.

“Having two or more domestic, commercially viable launch providers that also meet national security space requirements continues to be our end goal,” stated Lt. Gen. Samuel Greaves, SMC commander and the service’s program executive officer for space.  “These innovative public-private partnerships with industry as they develop their rocket propulsion systems are a key part of the EELV acquisition strategy to assure access to space and address the urgent need to transition away from strategic foreign reliance.”