rocket engine
A rocket engine is a reaction engine, producing thrust in accordance with Newton's third law by ejecting reaction mass rearward, usually a high-speed Jet (fluid), jet of high-temperature gas produced by the combustion of rocket propellants stor ...
burning
liquid oxygen
Liquid oxygen, sometimes abbreviated as LOX or LOXygen, is a clear cyan liquid form of dioxygen . It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an application which is ongoing.
Physical ...
and
liquid methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth make ...
in an oxidizer-rich
staged combustion cycle
The staged combustion cycle (sometimes known as topping cycle, preburner cycle, or closed cycle) is a power cycle of a bipropellant rocket engine. In the staged combustion cycle, propellant flows through multiple combustion chambers, and is th ...
. It is designed by aerospace company
Rocket Lab
Rocket Lab Corporation is a Public company, publicly traded aerospace manufacturer and List of launch service providers, launch service provider. Its Rocket Lab Electron, Electron orbital rocket launches Small satellite, small satellites, and ha ...
for its
Neutron
The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nucle ...
rocket.
History
Archimedes was presented on December 2, 2021, in a webcast by Rocket Lab CEO Peter Beck as a fully reusable,
gas generator
A gas generator is a device for generating gas. A gas generator may create gas by a chemical reaction or from a solid or liquid source, when storing a pressurized gas is undesirable or impractical.
The term often refers to a device that uses a ...
engine using liquid oxygen (LOX) and methane as propellant, a departure from the company's previous Rutherford, which is electrically pump fed. He then stated that it had a thrust of and 320 seconds of
specific impulse
Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine, such as a rocket engine, rocket using propellant or a jet engine using fuel, generates thrust. In general, this is a ratio of the ''Impulse (physics), ...
. The same day, the Neutron page on Rocket Lab's website was updated specifying the thrust of the nine Archimedes engines used on the first stage as at sea level and a maximum thrust of and the upper stage's single vacuum optimized Archimedes at . It was expected to have its first hot-fire test during May 2024. In an interview published on the CNBC website, Beck stated that Archimedes would be manufactured in New Zealand and its very simple design had "all the things you want when you have to build an engine that can be reused over and over again."
In the September 21st, 2022 Investor Day Presentation, the engine design had changed to an oxidizer-rich
staged combustion cycle
The staged combustion cycle (sometimes known as topping cycle, preburner cycle, or closed cycle) is a power cycle of a bipropellant rocket engine. In the staged combustion cycle, propellant flows through multiple combustion chambers, and is th ...
. The presentation stated that the sea level version would have a maximum thrust of with a specific impulse of 329 seconds and would be able to throttle to 50% of maximum thrust.
Meanwhile, the vacuum optimized version would have a maximum thrust of , a specific impulse of 367 s and the same throttling capabilities of 50% of maximum thrust. It was also implied, but not confirmed, that the engine would be built in the Virginia, USA factory. It was disclosed they would use the Stennis Space Center A-3 Test stand for development testing. They expected to start preburner testing in that or the following quarter, hopefully starting full engine testing at Stennis before the end of 2023, and hoped to be able to launch by mid 2025.
Design
Archimedes is presented as a highly reusable liquid-propellant engine using methane and liquid oxygen in an oxidizer-rich staged combustion cycle. There are both sea-level and vacuum variants. The engine is mostly 3D printed, with some of the biggest 3D printers in the world. The rationale for the cycle change from the original gas generator was that they could not get the performance they needed through all the throttle points that a reusable rocket needs, without pushing the turbine temperature and other factors beyond their preset limits. By changing to the higher performing cycle but with lower performance requirements, they were able to lower temperatures and other stress factors and increase margins everywhere, making reusability more attainable.
Rutherford (rocket engine)
Rutherford is a liquid-fuel rocket, liquid-propellant rocket engine designed by aerospace company Rocket Lab and manufactured in Long Beach, California. The engine is used on the company's own rocket, Electron (rocket), Electron. It uses LOX (li ...
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Curie (rocket engine)
Curie is a liquid-propellant rocket engine designed and manufactured by Rocket Lab. A bipropellant is used for the propulsion of the third stage/kick stage of the Electron rocket, as well as the Photon. The composition of the propellant is a tra ...
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Merlin (rocket engine family)
Merlin is a family of rocket engines developed by SpaceX. They are currently a part of the Falcon 9 and Falcon Heavy launch vehicles, and were formerly used on the Falcon 1. Merlin engines use RP-1 and liquid oxygen as rocket propellants in a ...
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SpaceX Raptor
Raptor is a family of rocket engines developed and manufactured by SpaceX. It is the third rocket engine in history designed with a Staged combustion cycle#Full-flow staged combustion cycle, full-flow staged combustion fuel cycle, and the first ...
Archimedes
Archimedes of Syracuse ( ; ) was an Ancient Greece, Ancient Greek Greek mathematics, mathematician, physicist, engineer, astronomer, and Invention, inventor from the ancient city of Syracuse, Sicily, Syracuse in History of Greek and Hellenis ...