rocket engine
A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive Jet (fluid), jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, i ...
burning
liquid oxygen
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an a ...
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 relative abundance of methane on Ear ...
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 ...
. It is designed by aerospace company
Rocket Lab
Rocket Lab is a public American aerospace manufacturer and launch service provider, with a New Zealand subsidiary. The company operates lightweight Electron orbital rockets, which provide dedicated launches for small satellites. Rocket Lab al ...
for its
Neutron
The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behav ...
rocket.
History
Archimedes was presented on December 2, 2021 in a webcast by Rocket Lab CEO Peter Beck. It was presented 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 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 (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse is ...
. The same day, the Neutron page on Rocket Lab's website was updated specifying the thrust of the seven Archimedes 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 is expected to have its first hot-fire test during 2022.
In an interview published on CNBC website, Mr. 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 ...
. It was then stated that the sea level version would have a maximum thrust of with a vacuum isp of 329s and would be able to throttle to a 50% of maximum thrust. Meanwhile the vacuum optimized version, would have a maximum thrust of , an isp o 367s 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 also disclosed they would use the Stennis Space Center A-3 Test stand for development testing. They expected to start preburner testing in that or following quarter, hopefully starting full engine testing at Stennis before 2023 ends, and hoped to be able to launch in 2024.
Design
Archimedes is presented as a highly reusable liquid-propellant engine using methane and liquid oxygen in a 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 much more attainable.
Merlin (rocket engine family)
Merlin ( cy, Myrddin, kw, Marzhin, br, Merzhin) is a mythical figure prominently featured in the legend of King Arthur and best known as a mage, with several other main roles. His usual depiction, based on an amalgamation of historic and l ...
Archimedes
Archimedes of Syracuse (;; ) was a Greek mathematician, physicist, engineer, astronomer, and inventor from the ancient city of Syracuse in Sicily. Although few details of his life are known, he is regarded as one of the leading scienti ...