Sierra Space and Agile Space successfully collaborate on the largest ever in-space bi-prop hydrazine engine.
Agile Space Industries has designed, developed, manufactured, tested, and delivered the experimental AX19 preburner for Sierra Space in 19 weeks.
Durango, Colorado (11/14/2023) – Agile Space Industries – Sierra Space contracted with Agile Space to design, develop, manufacture, and test a hydrazine-rich preburner for their VRM5500-H engine. This was done on a timeline of only 19 weeks and it is likely that this is the first time a hydrazine-rich preburner has been developed or used in an engine, at least as far as the public record is concerned. The first prototype unit that was produced demonstrated stable operation across a 6:1 throttle range with high combustion efficiency. This is yet another example of Agile Space successfully developing new technology in record time.
Why was it developed?
Large, high efficiency rocket engines used on large spacecraft need a power source to drive the pumps that take the low-pressure propellants in the tanks to the high pressures needed to run the engine. The AX19 preburner facilitates this by combining all the engine’s hydrazine fuel with some of the engine’s MON-3 oxidizer to decompose the hydrazine into (mostly) hydrogen, ammonia, nitrogen, and water. This hot gas is used as the power to drive the engine’s high-pressure pumps.
Achieving high-efficiency combustion in a rocket engine requires a very efficient injector. There are several different methods for achieving this, but in general having one or both propellants injected as a gas instead of as a liquid will greatly improve mixing and create a higher performing engine. The AX19 preburner enables this capability for hydrazine by converting it into the gaseous products mentioned above.
How does it work?
Hydrazine is a monopropellant, which means that it doesn’t need any oxidizer to combust. This presents a challenge when attempting to design a fuel-rich preburner because partial combustion of the fuel as in a kerosene, methane, or hydrogen engine isn’t possible. Monopropellant combustion is typically difficult to keep stable without running it through a large amount of specialized catalyst, which is both very expensive and difficult to acquire in large quantities.
The AX19 was designed to use as little catalyst as possible while maintaining stable combustion. First, a small fraction of the hydrazine is sent to a catalyst reactor where it is decomposed and sent to the preburner main combustion chamber as a hot mix of ammonia, nitrogen, and hydrogen. Next the remaining liquid hydrazine, which is most of the fuel flow to the preburner, is injected as a liquid into the preburner combustion chamber. At the same time in the main combustion chamber a small amount of oxidizer is injected into the chamber, where it is fully combusted with a portion of the liquid hydrazine and decomposed gas. All the heat added to the chamber from both the reactor exhaust gas and oxidizer combustion is used for rapid thermal decomposition of the remaining, now thoroughly atomized, liquid hydrazine.
AX19 preburner after being delivered to Sierra Space integrated into the VRM-5500H engine, being hot fired at a test facility at Redstone Arsenal.
Does it work?
The AX19 preburner was successfully tested as a standalone component in October of 2022 in Durango, Colorado on Agile’s Animas test stand. After initial runs it was delivered to Sierra Space for further testing and was operated successfully both standalone and coupled to their full VRM-5500H engine in Q1 and Q2 of 2023. This testing covered the entire throttle range and verified stable operation of the preburner and successful operation of the VRM5500-H engine.
ARTICLE WRITTEN BY Charles Campbell ON NOV 14th, 2023
About Agile Space Industries
Agile Space Industries is an in-space propulsion solution provider, specializing in hypergolic chemical systems. Agile has industry leading expertise in the design of chemical-propulsion rocket thrusters. Rapid prototyping, development, qualification, and delivery is catalyzed by in-house additive manufacturing and engine test capability. The company employs more than 65 people between facilities in Durango, Colorado and Mount Pleasant, PA that specialize in component, system development, test, and additive manufacturing. Agile is working with numerous primes as well as the US Government on various spacecraft and launch vehicle propulsion projects.
About Sierra Space
Sierra Space is a leading, pureplay commercial space company at the forefront of innovation and the commercialization of space in the Orbital Age™, building an end-to-end business and technology platform in space to benefit life on Earth. With more than 30 years and 500 missions of space flight heritage, the company is enabling the future of space transportation with Dream Chaser®, the world’s only commercial spaceplane, and is bringing LIFE™ (Large Integrated Flexible Environment) to low-Earth orbit with its modular, three-story commercial habitation and science platform. Both Dream Chaser and LIFE are central components to Orbital Reef, a mixed-use business park in LEO being developed by principal partners Sierra Space and Blue Origin, which is expected to be operational by the end of the decade. Sierra Space also builds and delivers a host of systems and subsystems across solar power, mechanics and motion control, environmental control, life support, propulsion and thermal control, offering myriad space-as-a-service solutions for the new space economy.
MEDIA CONTACTS:
Juleah Kaliski, Agile Space Industries
(530) 351-2179 | juleah.kaliski@agilespaceindustries.com
