POLARIS Spaceplanes Tests a 3D Printed Aerospike Rocket Engine

German aerospace start-up POLARIS Spaceplanes, based in Bremen, has achieved a key milestone by successfully testing a 3D printed Aerospike rocket engine. This achievement highlights the growing importance of 3D printing technology in the aerospace sector. During the tests, the five-meter-long MIRA II prototype completed taxi and flight tests, distinguishing itself by its innovative LOX/Kerosin-AS-1 engine produced by additive manufacturing. The company expects the prototype to be operational in scheduled flights as early as 2028.

How was MIRA II built? The MIRA II prototype was developed from the original MIRA demonstrator, which crashed during a test flight in May 2024. Since this incident, POLARIS has made progress. The new prototype has completed a three-hour engine test on an airstrip and successfully passed unmanned flight tests over the Baltic Sea. In the final test, the demonstrator took off from Peenemünde airport with four turbojets. Once ignition was reached, the AS-1 engine produced a three-second burn, generating 900 newtons of thrust and an acceleration of 4 m/s².

The demo unit MIRA II. (Photo: POLARIS Spaceplanes)

What’s more, the Aerospike engine represents a more efficient alternative to traditional rocket engines with bell-shaped nozzles. The MIRA II incorporates a dart-shaped nozzle, offering several advantages. One of the main advantages is weight reduction, thanks to a compact, mass-saving design. The engine can also adapt to different altitudes and pressures, guaranteeing optimum performance at all times and effectively adjusting thrust to suit conditions.

However, one drawback of Aerospike thrusters is the intense heat they generate during operation, requiring sophisticated cooling systems. To meet this challenge, POLARIS used additive manufacturing technologies from AM Global. The company plans to continue optimizing the Aerospike engine, with an extensive flight test program designed to assess the operational capability of this 3D printed technology. To find out more about the start-up and its flight tests, click HERE.

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*Cover Photo: POLARIS Spaceplanes