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Backup engine for ULA’s Vulcan rocket completes design review

United Launch Alliance Vulcan Next Generation Launch System rocket ULA image posted on SpaceFlight Insider

ULA’s “Vulcan” Next Generation Launch System. Image Credit: ULA

United Launch Alliance’s (ULA) new Next Generation Launch System “Vulcan” booster has been developed to be reliable; as such, some of its key systems have backups. While ULA has tapped Blue Origin’s BE-4 rocket engine to power the new rocket’s first stage, the firm has also been developing a backup engine for the rocket as well – Aerojet Rocketdyne’s AR-1. That engine has recently completed a milestone in its development.

While restrictions on the import of the Russian-made RD-180 might have lessened, Aerojet Rocketdyne has stated that the AR-1 has been designed to be a “direct replacement” of the NPO Energomash-produced RD-180.

The RD-180 has become a lightning rod in political circles ever since the Russian government’s military actions in the Ukraine. The requirement for a domestically-produced replacement has been the source of pressure applied to the Launch Service Provider community.

“ULA performed a comprehensive trade study of all the options evaluating technical and business parameters,” ULA’s Lyn Chassagne told SpaceFlight Insider. “The BE-4 scored well across the board, and that is why we are moving forward with development. However, as we stated previously, ULA is prepared to pursue other options as necessary.”

Aerojet Rocketdyne AR-1 rocket engine Aerojet Rocketdyne image posted on SpaceFlight Insider

The AR-1 rocket engine. Photo Credit: Aerojet Rocketdyne

Chassagne noted that while the BE-4 was the engine-of-choice for Vulcan, the company is keeping its options open.

“We are currently developing the BE-4 to fly on Vulcan. Yes, AR1 is a backup engine option for Vulcan,” Chassagne said.

For their part, representatives with Aerojet Rocketdyne worked to highlight the progress they have made toward having the AR-1 enter service.

“This is one of the most important design reviews the program will undergo during its development,” said Julie Van Kleeck, vice president of Advanced Space & Launch Programs at Aerojet Rocketdyne.

“United Launch Alliance and Aerojet Rocketdyne have enjoyed a long relationship that spans decades,” said United Launch Alliance President and CEO, Tory Bruno. “Aerojet Rocketdyne continues to be a valued supplier and is making excellent progress on the AR1 engine development.”

The AR-1’s 18 components and subsystems were checked out during the design review to ensure that they would work as advertised once integrated onto the Vulcan booster.

The AR-1 is currently slated to undergo full-scale engine testing as early as 2017, with the engine potentially being certified as soon as 2019.

In total, the AR-1 has conducted some 155 staged-combustion tests as well as turbomachinery and valve tests and has even carried out hot-fire tests of additively manufactured (3-D printed) elements of the rocket.

“Our experience and proven track record of delivering highly reliable large liquid rocket engines, like the RS-25 for NASA’s Space Launch System and the RS-68 for the Delta IV launch vehicle, protects U.S. national security,” said Aerojet Rocketdyne CEO and President Eileen Drake. “We have achieved every milestone in our AR1 schedule to be ready for 2019 – we have in place the production facilities, tools, equipment, supply base and, most importantly, highly skilled employees to manufacture the AR1 engine to meet the national security needs of our nation.”

The RS-68A and AJ-60A solid rocket motor could soon join the company’s AJ26 rocket engine in being an engine without a customer. ULA has already selected Orbital ATK’s GEM 63 to replace the AJ-60A for use on the Atlas V family of rockets and the GEM 63XL for use on Vulcan. The RS-68A – currently used on ULA’s Delta IV boosters – will not have a customer once that rocket is retired sometime in the early-to-mid 2020s.

“We have been investing in the AR1 booster engine to maintain 2019 for the nation,” Drake added. “AR1 is the right fit for the problem confronting the United States, which is ending reliance on Russian rocket engines.”

Whereas the BE-4 burns liquid methane with liquid oxygen, the AR-1 utilizes kerosene and liquid oxygen propellants. The AR-1 is capable of generating some 500,000 pounds-force (2.2MN) of thrust – each. With the Atlas V requiring two of these engines (if selected), this means the engines could impart one million pounds-force (4.45 MN) of thrust in total. At present, ULA is working to phase out the Atlas V, sometime by the end of this decade – or the early part of the next. The AR-1 is designed to be compatible with an array of other rockets.

Video courtesy of United Launch Alliance


Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology,, The Mars Society and Universe Today.

Reader Comments

What array of other rockets are looking at the AR1? Does anyone/USAF really believe the AR1 will be ready for certification by 2019? Ready for certification is different from being certified which I do not think will happen in 2019. Would you put your money into Aerojet???

Well, Antares could potentially take advantage of it. Assuming the price is right, of course. And assuming that Yuzhmash doesn’t go bankrupt in the meantime. Those are two really big ifs, of course.

I’m not sure if this qualifies as Reinventing The Wheel or just being smart enough to use 2 or four of them , but… the license to build the RD-180 entirely in the US domestically was granted by AMROSS to Pratt & Whitney Rocketdyne et al back in 2008 , but never acted on . It was said to be too expensive to tool and start up a whole new engine assembly line .

Well, here we are tooling up whole new assembly lines… just sayin’.

Yes, but I’d think that the new AR-1 design must be much less labor-intensive. That could make all the difference if you have to pay American salaries and not ~$10k as they do in Russia. It’s perfectly plausible that the RD-180 is indeed unviable for US manufacturing.

— except the US salaries are a constant whichever engine is being built. But there would be no development costs ( ~ $ 500,000,000 ) and allow the RD-180 to be phased out / amortized over a longer time frame.

Where would we be if Senator-ULA Crony Shelby hadn’t lifted the US embargo on RD-180’s as McCain wanted ? You can’t believe that was a coincidence tucked into last week’s federal budget bill….

The salaries may be but the man-hours per each engine unit built surely aren’t if the AR-1 is improved. And that no initial costs would be involved seems dubious since just launching the new RD-180 production line was quoted fairly high (a billion?), from what I can recall.

Vulcan will never get made.

Double, double, toil and trouble;
Fire burn and cauldron bubble.

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