Country of origin |
United States New Zealand |
---|---|
Designer | Rocket Lab |
Manufacturer | Rocket Lab |
Application | First- and second-stage engine |
Status | Active |
Liquid-fuel engine | |
Propellant | LOX [1] / RP-1 [1] |
Cycle | Electric pump-fed engine |
Pumps | 2 electric pumps |
Configuration | |
Chamber | 1 |
Performance | |
Thrust, vacuum | |
Thrust, sea-level |
|
Thrust-to-weight ratio | 72.8 |
Specific impulse, vacuum | 343 s (3.36 km/s) [2] [1] |
Specific impulse, sea-level | 311 s (3.05 km/s) [2] [1] |
Dimensions | |
Diameter | 25 cm (9.8 in) |
Dry weight | 35 kg (77 lb) [3] |
Used in | |
Electron, HASTE | |
References | |
References | [4] [5] [6] [7] |
Rutherford is a liquid-propellant rocket engine designed by aerospace company Rocket Lab [8] and manufactured in Long Beach, California. [9] The engine is used on the company's own rocket, Electron. It uses LOX (liquid oxygen) and RP-1 (refined kerosene) as its propellants and is the first flight-ready engine to use the electric-pump feed cycle. The rocket uses a similar engine arrangement to the Falcon 9; a two-stage rocket using a cluster of nine identical engines on the first stage, and one vacuum-optimized version with a longer nozzle on the second stage. This arrangement is also known as an octaweb. [10] [6] [7] The sea-level version produces 24.9 kN (5,600 lbf) of thrust and has a specific impulse of 311 s (3.05 km/s), while the vacuum optimized-version produces 25.8 kN (5,800 lbf) of thrust and has a specific impulse of 343 s (3.36 km/s). [11]
First test-firing took place in 2013. [12] The engine was qualified for flight in March 2016 [13] and had its first flight on 25 May 2017. [14] As of April 2024, the engine has powered 47 Electron flights in total, making the count of flown engines 369, including one engine flown twice. [15]
Rutherford is named after renowned New Zealand-born scientist Ernest Rutherford. It is a small liquid-propellant rocket engine designed to be simple and cheap to produce. It is used as both a first-stage and a second-stage engine, which simplifies logistics and improves economies of scale. [6] [7] To reduce its cost, it uses the electric-pump feed cycle, being the first flight-ready engine of such type. [5] It is fabricated largely by 3D printing, using a method called laser powder bed fusion, and more specifically Direct Metal Laser Solidification (DMLS®). Its combustion chamber, injectors, pumps, and main propellant valves are all 3D-printed. [16] [17] [18]
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. [5] The use of a pump avoids the need for heavy tanks capable of holding high pressures and the high amounts of inert gas needed to keep the tanks pressurized during flight. [19]
The pumps (one for the fuel and one for the oxidizer) in electric-pump feed engines are driven by an electric motor. [19] The Rutherford engine uses dual brushless DC electric motors and a lithium polymer battery. It is claimed that this improves efficiency from the 50% of a typical gas-generator cycle to 95%. [20] However, the battery pack increases the weight of the complete engine and presents an energy conversion issue. [19]
Each engine has two small motors that generate 37 kW (50 hp) while spinning at 40 000 rpm. [20] The first-stage battery, which has to power the pumps of nine engines simultaneously, can provide over 1 MW (1,300 hp) of electric power. [21]
The engine is regeneratively cooled, meaning that before injection some of the cold RP-1 is passed through cooling channels embedded in the combustion chamber and nozzle structure, transferring heat away from them, before finally being injected into the combustion chamber.