Partnership Uses Additive Manufacturing to Build Aerospike Engine

A version of the engine developed by Monash University and Amaero takes advantage of design freedoms from metal 3D printing.

An aerospike rocket engine has the ability to maintain thrust efficiency from ground level into outer space, meaning it is capable of leaving the earth’s atmosphere without the need for multiple-stage boosters. But you may never have heard of it; despite the engine’s benefits and years of R&D work, an aerospike engine has never entered service because of manufacturing difficulties. 

The engine features an inverted bell shape with complex cooling channels that are difficult to produce through conventional means. Problems related to this design, coupled with organizational changes, forced NASA to abandon an aerospike engine project in the early 2000s. But recently, a partnership between Monash University and Amaero successfully built a functional aerospike engine using the design freedoms of additive manufacturing (AM).

The Amaero team redesigned the aerospike with an emphasis on manufacturability. They took into consideration both the additive manufacturing of the part and the need for postprocessing, making choices that would result in a successful build and also minimize the amount of machining necessary.  The additive method—selective laser melting (SLM)—placed restrictions on the design in terms of size, materials, thicknesses of features and other parameters. However, working within these parameters from the beginning helped the team to realize the advantages of the method.

The SLM process enabled building the entire engine in one piece, and also supported features that would not have been practical with conventional machining. The conformal cooling channels, shown in the rendering above, cater to local heat flux with changes in their size and orientation throughout the part, something that would be difficult to achieve through machining and brazing the tubes together.

The result of this project is a functional aerospike engine that has been successfully tested, as shown in the video below (skip ahead to 3:40 to see it fire). Learn more about the aerospike engine in this blog post from Additive Manufacturing.