German startup space launch company Rocket Factory Augsburg (RFA) announced on Wednesday that it had successfully concluded the first test campaign on its Helix rocket motor. The Helix is a staged combustion engine and it was tested in its flight configuration, at Kiruna, in Sweden.

“Helix operated perfectly for a total duration of 74 seconds – including three ignition and shut-down sequences without the need to replace any components on the engine,” enthused RFA COO Dr Stefan Brieschenk. “This first qualification campaign also included up-throttling the engine to 130% of the nominal design point for a brief period. We are truly excited that our design has proven so reliable and performant [sic].”

In a more conventional liquid-fuelled rocket motor, the pumps that control the flow of fuel and oxydiser into the engine’s main combustion chamber are themselves powered by turbines (the combined units are called turbopumps); the exhaust gases from these turbines (turbopumps) are effectively ‘dumped overboard’. In a staged combustion engine, these exhaust gases, which include unburnt fuel, are captured and then fed into the main combustion chamber, where the unburnt fuel is then ignited.

Staged combustion thus increases thrust, increases efficiency, reduces carbon emissions and reduces launch costs. On the other hand, staged combustion engines are more complex and more difficult to build. (Rocket science is dead easy; it is rocket engineering that is fiendishly difficult, owing to the enormous stresses experienced during launch). RFA is only the third commercial company in the world, and the very first in the European Union, to successfully develop and test a staged combustion rocket engine. The intellectual property for the Helix belongs entirely to RFA.

The test campaign involved a very short initial burn of the Helix, which lasted just four seconds. The second and third ‘hot firings’ were relatively long-duration tests. The second lasted 30 seconds, while the third ran for 40 seconds. All three tests used the same engine and lasted for their planned durations. Each time, the engine was safely shut down at the end of the test.

“We [now] have enough data to focus our attention on the next milestone, the integrated systems test of the upper stage,” he reported. “In this test, Helix will fire for a full duration of an upper stage flight. We have just made a huge leap towards our first launch by completing this first qualification campaign of Helix.”

RFA seeks to be able to launch payloads of up to 1 300 kg into low Earth orbit, and beyond. The company was founded in 2018.