By Kendra Chamberlain

Defense and Aerospace contractor Aerojet Rocketdyne is designing a new large liquid propellant engine that it says will help the US remain competitive in space launches. Aerojet hopes its new rocket booster engine, called the AR1, will help the US move away from using Russian parts for space flight vehicles.

Aerojet promises its new AR1 engine will also be affordable — thanks to additive manufacturing (aka 3D printing) and modular design, which helps keep production costs down. The AR1 will be capable of delivering 500,000 lbf of thrust at sea level, and will have a modular design that means the engine can be used for a range of vehicles, including the Atlas V and NASA’s new Space Launch System (SLS).

Aerojet is using 3D printing for the development of engine components such as the element injectors — components of the AR1 “preburner,” which is part of the staged combustion cycle of the engine.  Aerojet said it would take the company six months to manufacture one element injector prototype, using traditional manufacturing techniques.  With the help of additive manufacturing, the company was able to design, manufacture and test the element injector in just one month. Aerojet is now looking into devising ways to 3D print the hardware that will actually be used in the engine.

“Our world-class workforce is very excited to rapidly bring the AR1 engine into production — it will support the Trump administration’s efforts to make our military strong again,” said Aerojet Rocketdyne president and CEO Eileen Drake, in a statement. “The AR1 rocket engine is crucial to ensuring America’s assured access to space and making US launch vehicles competitive across the globe.”

The large liquid propellant AR1 engine. Image source: Aerojet Rocketdyne
The large liquid propellant AR1 engine. Image source: Aerojet Rocketdyne



Aerojet Rocketdyne will manufacture its AR1 booster engines in Huntsville, Alabama — where NASA’s Marshall Space Flight Center is located.  It’ll bring 100 new jobs to Huntsville, the company said.

The engine system is still under development, but Aerojet Rocketdyne said it’ll have the engine ready by 2019, in order to meet the deadline Congress imposed on the US to stop using foreign suppliers for rocket engines.

The company describes the AR1 engine as the “lowest risk, lowest cost to the taxpayer and fastest path to eliminating our dependence on Russian-built rocket engines for US National Security space launches.” Aerojet hopes its AR1 will replace the Russian-built RD-180 engine by 2019.

Russia's RD-180 engine. Image source: NPO Energomash
Russia’s RD-180 engine. Image source: NPO Energomash

The RD-180 engine is currently used in the first stage of the Atlas V.

The Russian government sells the RD-180 to the US for $5-8 million per engine pair. But according to a report released by the George C. Marshall Institute, the true production cost of the engine is between $11-15 million.  Estimates peg the AR1 at $25 million per pair.

The geopolitical climate between Russia and the US grew a bit sour as a result of Russia’s 2014 annexation of Crimea from Ukraine, which briefly threatened the US’s ability to source the Russian engines. After the US government imposed sanctions on the Russia in 2014, Russia’s Deputy Prime Minister Dmitry Rogozin declared that “Russia will ban the United States from using Russian-made rocket engines for military launches.” That, in turn, spurred US Congress to mandate that the US government be able to source rocket engines from local suppliers. Aerojet Rocketdyne stepped up to the challenge, and will receive up to $1 billion in government funding for the development of the AR1.

There may be good reason to do so. While Russia is currently the only nation that can send manned vehicles to space, there are some concerns about the manufacturing protocols and safety standards in place. This week, Russia’s government decided to delay the release of its Proton rockets due to faulty materials. After a failed launch in December, an investigation revealed that a critical heat-resistant part had been swapped in assembly for a less heat-resistant material at the manufacturing plant Voronezh. Russia’s Deputy PM Rogozin, apparently under the impression that some employees had intentionally swapped the parts, made a statement yesterday that those found responsible would be “severely punished.” The week prior, the head of the Voronezh facility stepped down, citing “unsatisfactory work and product quality,” as his reason for resigning.

Aerojet has a long history in US flight advancements. During World War II, the company supplied US Armed Forces with Jet Assisted Take Off (JATO) units; during the space race of the 1960s, the company’s liquid rocket boosters propelled the TITAN vehicle to deliver the first manned Gemini flight into orbit in 1965; the company designed the Orbital Maneuvering System engines for the US’s space shuttles; and its thrusters were used to help guide NASA’s Mars Science Laboratory (MSL) to its landing on the surface of Mars in 2012. In 2013, Aerojet acquired Pratt & Whitney’s Rocketdyne division to create Aerojet Rocketdyne.

The company is the only US suppliers of large liquid propellant rocket engines. Aerojet claims its RS-68 engine is the most powerful liquid rocket engine available today, delivering 700,000 lbf of thrust to launch. The RS-68 is the engine used on the Delta IV launch vehicle. Its RL10 engine has powered upper stages on both the Delta IV and Atlas V launch vehicles — and has been selected by NASA to power the upper stage of its new SLS. NASA’s SLS will use four RL10 rockets, delivering some 2 million pounds of thrust, to power the massive 322 foot tall rocket launch off the pad. The SLS is expected to be launch-ready in 2018.

Aerojet Rocketdyne displays the NASA Space Launch System rocket’s upper-stage engine, the RL10, at Future Flight in Houston, TX, this week. Image source: Aerojet Rocketdyne
Aerojet Rocketdyne displays the NASA Space Launch System rocket’s upper-stage engine, the RL10, at Future Flight in Houston, TX, this week. Image source: Aerojet Rocketdyne

Aerojet is assembling and hot fire testing the AR1 engine at NASA’s Stennis Space Center in Mississippi.


Kendra R Chamberlain
Editor and analyst at The Enterprise Orbit, covering new space business and technology developments; freelance journalist covering telecom, renewable energy technology & smart infrastructure.

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