TRI-D is a 3D printed metal rocket engine. Students from the Students for the Exploration and Development of Space at UCSD students test fire 3D-printed metal rocket engine
gizmag, October 12, 2013.
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Space.com, October 08 2013.

University of California, San Diego The University of California, San Diego (UC San Diego or colloquially, UCSD) is a public university, public Land-grant university, land-grant research university in San Diego, California. Established in 1960 near the pre-existing Scripps Insti ...

(SEDS at UC San Diego) built the metal rocket engine using a technique previously confined to

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

, using a GPI Prototype and Manufacturing Services printer via the

Direct metal laser sintering Selective laser sintering (SLS) is an additive manufacturing (AM) technique that uses a laser as the power and heat source to sinter powdered material (typically nylon or polyamide), aiming the laser automatically at points in space defined b ...

(DMLS) method. UCSD students were the first group in the world to 3D print a rocket engine of its size, other than NASA as of February 2014.UCSD group plans second 3-D printed rocket engine test to gather more data - 10News.com KGTV ABC10 San Diego
10News, February 25, 2014.
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The Tri-D engine cost US$6,800.
3Ders, October 7, 2013.

Students successfully hot test 3D printed rocket engine
design-engineering, October 10, 2013.
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Development

The Tri-D rocket engine was designed and built with the cooperation of NASA’s Marshall Space Flight Center, to explore the feasibility of printed rocket components. It was designed to power the third stage of a Nanosat or Cubesat launcher, i.e. an engine capable of launching satellites that weigh less than 1.33 kg (2.93 lb).

Specifications

Tri-D is around 17.7 cm long and weighs around 4.5 kg. It was fabricated using a chromium-cobalt alloy powder. The

propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or other motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the e ...

s are kerosene and liquid oxygen. The engine produces about thrust. According to Gizmag "the injector has a Fuel-Oxidizer-Oxidizer-Fuel inlet arrangement with two outer fuel orifices converging with two inner oxidizer orifices". The engine has a

regenerative cooling Regenerative cooling is a method of cooling gases in which compressed gas is cooled by allowing it to expand and thereby take heat from the surroundings. The cooled expanded gas then passes through a heat exchanger where it cools the incoming comp ...

jacket that extends to the

nozzle A nozzle is a device designed to control the direction or characteristics of a fluid flow (specially to increase velocity) as it exits (or enters) an enclosed chamber or pipe. A nozzle is often a pipe or tube of varying cross sectional area, a ...

to prevent the engine from overheating while firing. The

combustion chamber A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process. Intern ...

was designed to burn the propellants in the middle of the chamber and keep as much heat generated as possible away from its chamber walls, while at the same time insulating the wall with a

film A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, feelings, beauty, or atmosphere ...

of cooler gases.

Printer

The engine was printed with a GPI Prototype and Manufacturing Services printer using a technique called

(DMLS). In the process of printing, a powder of the chromium-cobalt alloy is spread in a thin layer. Then computer-controlled laser fuses the powders into a cross section of the engine component. The machine then spreads a second layer of powder and the process continuously repeats until each component is complete. Any excess powder is removed as are temporary supports that were printed to hold the components together during printing process. Finally it is hardened, polished and assembled.

Test firing

The test firing at Mojave went without any problems and the engine exhaust achieved thrust. The team claimed "it was a resounding success and could be the next step in the development of cheaper propulsion systems and a commercializing of space".

Injector test

On a separate engine, a 3D printed

injector An injector is a system of ducting and nozzles used to direct the flow of a high-pressure fluid in such a way that a lower pressure fluid is entrained in the jet and carried through a duct to a region of higher pressure. It is a fluid-dynamic ...

was test fired in a conventionally manufactured engine. In the test of the injector on August 22, 2014, the engine generated thrust.

References

{{Reflist 3D printing Rocket engines using kerosene propellant