Rocket Lab said it's taking the next major step in evolving the Electron launch vehicle into a reusable rocket by launching a pre-flown Rutherford engine.
The 3D printed engine, previously flown on the ‘There and Back Again’ mission launched in May 2022, has undergone extensive qualification and acceptance testing to certify it for re-flight, including multiple full mission duration hot fires where the pre-flown engine performed flawlessly and on par with a new Rutherford engine. With Rocket Lab’s propulsion team now giving the engine the green light for re-flight, it will be launched on an upcoming commercial mission scheduled for lift-off in the third quarter of this year. While the engine is ready for re-flight now, the Electron rockets scheduled for launch in the second quarter are already built with complete Rutherford powerpack assemblies so this pre-flown engine will join the production line to be integrated with an in-progress rocket. The engine is one of several recovered Rutherford engines that collectively have now been through many successful full duration hot fires to support testing and R&D efforts for recovery. The engine joins multiple systems that have been re-flown on Electron including helium press systems.
Re-flying this engine is the latest milestone in an iterative and methodical reusability program that has seen Rocket Lab recover hardware and first stages from six Electron missions to date, with the latest stage recovered on 24 March 2023 following ‘The Beat Goes On’ mission launched from Rocket Lab Launch Complex 1 in New Zealand. Rocket Lab has been iteratively developing and testing two recovery methods in parallel; marine recovery where Electron’s first stage returns to Earth under a parachute for a soft ocean splashdown and recovery by boat, and mid-air recovery where Electron’s first stage is caught in the air by a specialized helicopter as the stage descends back to Earth under parachute. Extensive analysis of returned stages shows that Electron withstands an ocean splashdown and engineers expect future complete stages to pass qualification and acceptance testing for re-flight with minimal refurbishment. As a result, Rocket Lab is moving forward with marine operations as the primary method of recovering Electron for re-flight. This is expected to take the number of Electron missions suitable for recovery from around 50% to between 60-70% of missions due to fewer weather constraints faced by marine recovery vs mid-air capture, while also reducing costs associated with helicopter operations. Rocket Lab will assess the opportunities for flying a complete pre-flown first stage booster following the launch of the pre-flown Rutherford engine in the third quarter this year.
Designed and built by Rocket Lab, the Rutherford engine is the world’s first 3D printed and electric pump-fed orbital rocket engine. A total of 350 Rutherford engines have been launched to space since Rocket Lab’s first Electron launch in 2017, making it one of the most reliable and frequently flown U.S. orbital rocket engines.
The Rutherford engine’s production scalability is facilitated by additively manufactured, or 3D printed, primary components. With a 3D printed combustion chamber, injectors, pumps, and main propellant valves, Rutherford has the most 3D printed components of any rocket engine in the world. These primary components can be printed in 24 hours, drastically reducing production timelines compared with traditional production methods.
Rutherford engines are used as both first stage and second stage engines on the Electron launch vehicle, with nine engines on the first stage and a single vacuum optimized engine on the second stage. The sea level versions on Electron’s first stage produce 24 kN (5,500 lbf) of thrust each and with a specific impulse of 311 seconds, while the vacuum optimized version on Electron’s second stage produces a max thrust of 24 kN (5,500 lbf) of thrust and a specific impulse of 343 seconds.
Instead of being powered by traditional gas turbine pumps, Rutherford uses a cycle of brushless DC electric motors and high-performance lithium polymer batteries to drive its propellant pumps. This cuts down on much of the complex turbomachinery typically required for gas generator cycle engines, meaning that the Rutherford is simpler to build than a traditional engine but still can achieve 90% efficiency.
Rutherford engines are manufactured at Rocket Lab’s headquarters in Long Beach, California.