Spaceflight Insider

3-D printed components for AR1 rocket engine undergo hot-fire testing

AR1 Test with Additive Manufacturing Photo #1

Photo Credit: Aerojet Rocketdyne

As Launch Service Providers and other aerospace firms develop new technology or utilize existing systems to increase their capabilities, decrease their production rates, and lower the cost of delivering payloads to orbit, there is one technology in particular that has surged to the forefront of producing hardware for use in spaceflight operations: additive manufacturing, more commonly known as “3-D printing”. Recent hot-fire tests conducted by Aerojet Rocktdyne on elements of the company’s AR1 booster engine help to demonstrate just how far the technology has progressed.

The tests, carried out at Aerojet Rocketdyne’s Sacremento test site, were conducted on the AR1’s main injector elements. A series of hot fires were carried out in the hopes that the AR1 booster engine can go into production sometime in 2019.

According to Aerojet Rocketdyne, the AR1 is a 500,000 lbf (2.2 MN) thrust-class liquid oxygen/kerosene booster engine, one being developed to provide the US market with an additional rocket engine. With the political issues that surround the Russian-made RD-180, having domestically-produced engines is considered a requirement.

Aerojet Rocketdyne 3D printed injector undergoes hot-fire testing photo credit Aerojet Rocketdyne posted on SpaceFlight Insider

Aerojet Rocketdyne 3-D printed injector undergoes hot-fire testing. Photo Credit: Aerojet Rocketdyne

“We believe the AR1 is the best, most affordable option to eliminate U.S. dependence on foreign sources of propulsion while maintaining assured access to space for our nation’s critical national security and civil space assets,” said Linda Cova, executive director of Hydrocarbon Engine Programs at Aerojet Rocketdyne. The AR1 is designed to integrate with the Atlas V launch vehicle, as well as provide a versatile propulsion solution for multiple current and future launch vehicle applications. “When you consider the minimal changes to the Atlas V launch vehicle, launch pad and related infrastructure that are required with an AR1 solution, this approach is clearly the best path toward finding a replacement for the RD-180 and meeting the launch needs of our nation,” said Cova. “We look forward to working with the U.S. government in a competitive procurement environment to bring this engine to market.”

“Aerojet Rocketdyne is committed to delivering an RD-180 replacement by 2019, which is why the company is investing in the engine and inviting the Air Force, ULA, and other key stakeholders to all major reviews so that engine certification can occur in parallel,” added Cova. The company has made progress toward utilizing this technology to “print” rocket engines. Some milestones the company has met include the following:

Completion of System Requirements Review;

Full-scale single-element main injector hot-fire testing;

Subscale preburner testing;

Turbopump inducer testing.

Last year, after the turmoil caused by Russia’s military actions in the Ukraine, the 2015 National Defense Authorization Act was initiated. The act specifically calls for the RD-180 to be phased out in preference to a US-produced rocket engine for use on missions relating to national defense. The AR1 matches the Act’s requirements in that this new engine is supposed to be on the assembly line by the document’s timeline of 2019.

Aerojet Rocketdyne AR1 rocket engine image credit Aerojet Rocketdyne

The AR1 twin booster. (Click to enlarge) Image Credit: Aerojet Rocketdyne

It is hoped that a vehicle-level concept review as well as a Preliminary Design Review of the main propulsion system will be completed by the end of this year. Considering that the effort to develop this engine began last year, the engine’s development appears to be taking place at an increased pace.

The AR1 will serve as a backup for Blue Origin’s BE-4 rocket engine, which is planned for use on United Launch Alliance’s Next Generation Launch System, or “NGLS”.

The main injector hot fire test was carried out in order to validate different design features of the component. The performance of the injector is not the only aspect of the test that was scrutinized. The overall design of the injector as well as the methods of fabrication were reviewed.

Aerojet Rocketdyne stated in a release that it had produced several injectors via what the company calls Selective Laser Melting (SLM). SLM is another form of 3-D printing.

Aerojet Rocketdyne is one of many aerospace firms that is adding 3-D printing methods to their tool kits. The process of additive manufacturing has shown promise in rapidly producing parts at about 70 percent less than traditional methods.

The injector was hot fire tested at pressures in excess of 2,000 psi (13.8 MPa), the company has stated that this represents the highest pressure hot-fire test conducted to date, especially one that was conducted during an exercise that the engine would encounter during an actual mission.



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

Maybe they can sell it to Orbital for the Antares.

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