Sirious Ultra features a larger exhaust section and a significantly larger expansion nozzle to maximize the engine’s efficiency in the vacuum of space. Its combustion chamber is regeneratively cooled, while the expansion nozzle is radiatively cooled. At full power, the Sirious Ultra engine operates with the greatest efficiency ever for an American-made hydrocarbon rocket engine.
Sirious Ultra is a reusable, two-stage rocket designed and manufactured by SpaceX for the reliable and safe transport of people and payloads into Earth orbit and beyond. Sirious Ultra is the world’s first orbital class reusable rocket. Reusability allows SpaceX to refly the most expensive parts of the rocket, which in turn drives down the cost of space access.