Country of origin New Zealand Associated L/V Electron Propellant LOX / RP-1 | Designer Rocket Lab Status Certified for flight | |
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Application First and second stage engine | ||
Rutherford is a liquid propellant rocket engine, designed in New Zealand by Rocket Lab. It uses LOX and kerosene as propellants and is the first flight-ready engine to use the electric pump feed cycle. It will be used on the company's own rocket, Electron. This is a similar arrangement to the Falcon 9, using nine identical engines on the first stage and one, optimized for vacuum with a longer nozzle, on the second stage. The vacuum optimized version produces 22,000 N (5,000 lbf) and has a specific impulse of 327 s (3.21 km/s).
It was qualified for flight in March 2016 and is expected to debut in early 2017.
Description
Rutherford, named after New Zealand scientist Ernest Rutherford, is a small liquid propellant rocket engine designed to be simple and cheap to produce. It is used as both a first stage and as a second stage engine, which simplifies logistics and improves economies of scale. To reduce its cost, it uses the electric pump feed cycle, being the first flight ready engine of such type. It uses kerosene and LOX as propellant, and is fabricated largely by 3D printing, via electron beam melting. Its engine chamber, injector, pumps, and main propellant valves are all printed.
As with all pump-fed engines, the Rutherford uses a rotodynamic pump to increase the pressure from the tanks to that needed by the combustion chamber. The use of a pump avoids the need for heavy tanks capable of holding high pressures and the high amount of gas needed to pressurize them, and replaces them with a pump.
In the case of the electric pump feed engines, the pumps (one for the fuel and one for the oxidizer) are actuated by an electric motor. In Rutherford's case, it uses a dual brushless DC electric motor and a Lithium polymer battery bank. This improves efficiency from 50% for a typical gas-generator cycle to 95% achieved by Rutherford. However it increases the dry mass of the battery pack.
Each engine has two small motors that generate 50 hp (37 kW) while spinning at 40,000 rpm. The first stage battery bank, which has to power the pumps of nine engines simultaneously, can provide over 1 MW of electric power.
The engine is regenerative cooled, which means that it first passes the fuel through channels that cool the combustion chamber and nozzle before injecting them for combustion. The first stage version of the rocket has a thrust at sea level of 16.89 kN (3,800 lbf) and in vacuum of 20.33 kN (4,570 lbf). The vacuum version, with a vacuum optimized nozzle shape, has a thrust of 22 kN (5,000 lbf) with a specific impulse of 327 s (3.21 km/s).