Capitalizing on Aerojet Rocketdyne’s decades of engine development experience, the AR1 program is leveraging the latest technology — including advanced materials, world-leading 3-D printing techniques and proven rocket engine manufacturing capabilities — to deliver an affordable propulsion solution that is the right fit for our nation’s space launch needs.
The AR1 design was chosen specifically to be able to replace the Russian-made RD-180 used on current launch vehicles and provide a long-term advanced booster propulsion option for the United States launch industry. AR1 accomplishes this because it operates with the same engine cycle, known as oxidizer-rich staged combustion (ORSC), as does the RD-180.
In its essence, ORSC is quite simple: hot oxygen-rich exhaust products from the preburner power the turbomachinery and burn the majority of the fuel in the main combustion chamber of the engine. By contrast, current U.S. engines, like the Merlin and the RS-68A, use a gas generator engine cycle that dumps the preburner gases overboard. To create an ‘oxidizer-rich’ exhaust, a small amount of fuel is burned with all of the oxygen the engine will consume. Only a small amount of the oxygen burns with the fuel. The rest is simply heated up and used to power the turbopump.
The ORSC cycle makes the engine significantly more efficient for two main reasons: no propellant is wasted by dumping it overboard and all propellant passes through the combustion chamber to generate thrust, and a much higher chamber pressure is enabled. Efficiency is extremely important in rocket engines, as every pound of additional propellant decreases payload capability.
A second major ORSC benefit, owing to the higher chamber pressures, is that the resulting engine is physically more compact, making it easier to handle, test and incorporate into a launch system. Highly efficient, compact engines translate into smaller, cheaper and more robust launch systems.
While the ORSC engine cycle appears simple, the particulars such as the preburner are not. Because the preburner and its function are critical to the success of the AR1’s overall design and performance, it is a major target of the AR1 development program. Testing has already begun on the preburner at NASA’s Stennis Space Center and we are beginning to validate our design.
This truly is rocket science, and extensive knowledge and experience is needed to solve complex engineering challenges, like developing materials capable of handling hot, oxygen-rich gases. Aerojet Rocketdyne — with its proven track record of building very large, complex, reliable engines such as the F1, RS-25 and RS-68 — has the experience to design a mature ORSC engine for our nation.