WASHINGTON — Sierra Space won an Air Force contract to proceed development of an engine that may very well be utilized in the upper stage of future launch vehicles.
Colorado-based Sierra Space received a $22.6 million contract from the Air Force Test Center July 25 to mature the design of its VR35K-A engine. The contract will allow continued work on the engine, equivalent to development of “flight-weight engine component design,” in line with a Defense Department procurement notice.
Sierra Space and its corporate parent, Sierra Nevada Corporation, have been working on the VR35K-A engine design for several years with support from the Air Force Research Laboratory. That included completing a critical design review for the engine in August 2022.
The engine, using liquid hydrogen and liquid oxygen propellants, is designed to supply 35,000 pounds-force of thrust. In a press release to SpaceNews, Sierra Space said the engine achieved “high thrust efficiency” during recent tests at an organization facility in Wisconsin.
“Compared with other upper-stage engines currently in the marketplace, the VR35K-A provides more thrust and better performance in a smaller package,” said Rusty Thomas, Sierra Space’s chief technology officer and vice chairman and general manager for the corporate’s Space Applications business sector.
The corporate has previously outlined several benefits of the engine design, including its use of a fuel-rich staged combustion cycle for increased specific impulse, a measure of engine efficiency. The engine also uses thrust chamber assembly design called VORTEX for increased pressure in a smaller volume.
“Once complete, the VR35K-A will allow our launch vehicle teammates and partners to deliver as much as 30% more payload mass to orbit,” Thomas said. “It’s going to drive technology across all propulsion products at Sierra Space, from our applications and destinations sectors to space transportation with our Dream Chaser spaceplane.”
Sierra Space has not disclosed any customers for the VR35K-A engine. While intended to be used on launch vehicle upper stages, corporations designing or operating large launch vehicles today are either developing their very own engines or are buying engines from other suppliers, as United Launch Alliance is with the RL10 engine from Aerojet Rocketdyne used on its Atlas, Delta and Vulcan vehicles.
At an investor conference June 27, though, Tom Vice, chief executive of Sierra Space, said the corporate was examining long-term options for developing propulsion systems that may allow Dream Chaser to succeed in orbit without counting on other corporations’ launch vehicles.
“We’re enthusiastic about investigating the fitting technologies in thermal and propulsion and materials that permits us to potentially think in regards to the staging options that may allow us, for the primary time, have horizontal takeoff,” he said, but didn’t offer a schedule or other details about those plans.