NASA's 3D

What is a Rotating Detonating Engine?

Detonative combustion engines are known for their ability to generate flame fronts that expand at supersonic speeds. This approach is much more efficient than the combustion used in internal combustion engines of vehicles. A rotating detonating engine takes this a step further by using one or more detonations to carry out combustion around an annular channel.

In the RDE approach, the fuel and oxidizer are mixed into the channel through small holes. Detonation is brought about using an igniter. Following which subsequent detonations become self-sustaining. The combustion products are pushed outside the channel by new incoming fuel and oxidizer, generating thrust and allowing the engine to operate continuously.

Research in this area has demonstrated the potential of RDE in transportation, and institutions across the world have been working to incorporate it into military and space applications.

"The RDRE enables a huge leap in design efficiency," said Thomas Teasley, the lead of RDRE operations at Marshall Space Flight Center.

"It demonstrates we are closer to making lightweight propulsion systems that will allow us to send more mass and payload further into deep space, a critical component to NASA's Moon to Mars vision."

NASA's 3D-printed RDRE

To overcome the complexity of manufacturing the engine with subscale injector orifices, NASA turned to additive manufacturing or 3D printing. The manufacturing uses NASA's developed copper-alloy GRCop-42, which allows it to operate under extreme conditions without overheating.

Last year, engineers at the Marshall Space Flight Center tested the engine by firing it more than a dozen times in 10 minutes. When operating at full capacity, the engine generated 4,000 pounds of thrust.

A year later, the team carried out another test, continuously firing the engine for 251 seconds (more than four minutes). This time, the RDRE generated more than 5,800 pounds of thrust. "That kind of sustained burn emulates typical requirements for a lander touchdown or a deep-space burn that could set a spacecraft on course from the Moon to Mars," said Thomas Teasley, lead at RDRE, in a press release.

According to Teasley, the latest test will help the engineers understand how the combustor can be scaled to meet the requirements of different engine systems and their thrust requirements. This will allow the engine to serve a wide range of missions, such as landers, upper-stage engines, and supersonic retropropulsion, the technique used to decelerate large payloads before they can land on the ground.