Why we lit this candle

The production hall in Neuenstadt am Kocher looks less like the future and more like a very serious workshop. Carbon fiber casings on racks, test rigs, people with rolled-up sleeves. And in the middle of it all, a twelve meter rocket. »When I walk into a rocket hall, I am right back in my Airbus years,« says Aimo Bülte, who spent a good part of his career in aerospace before co-founding Räuberleiter, and who releases weather balloons into the stratosphere for fun. »This is where I want to be.«

He is not the only one at Räuberleiter who feels at home here. Our founding team grew up professionally around aircraft and launchers, at Airbus and on programs from Ariane to the A380, first as consultants and engineers, later building umlaut into one of the industry’s go-to partners. Aerospace is not a new market for us. It is where we come from. Which is why this investment, our first in New Space, feels less like a departure and more like a homecoming.

HyImpulse builds rockets around an idea so simple it sounds like a joke: candle wax. The SR75 burns solid paraffin with liquid oxygen, and that changes almost everything about how a rocket behaves. The paraffin-based fuel is non-explosive; if a flight has to be aborted, the oxygen is vented and the wax simply stops burning. The fuel segments can sit in storage for years and travel like ordinary freight. And because the system is so much easier to handle, it does not need the vast, expensive infrastructure that conventional launchers depend on. A modest launch pad will do.

The people behind it have been refining this idea for a long time. As students in Stuttgart, they built a hybrid rocket that set a world altitude record in 2016. In 2018 they spun out of the German Aerospace Center to turn their research into a company. And in May 2024 their SR75 lifted off from the Koonibba Test Range in Australia, successfully completed its inaugural flight campaign and came home by parachute. It was the first time that a German company has achieved the lift-off of a commercially viable launch vehicle. The mission’s name, a nod to an old astronaut’s line, could not have been better chosen: Light this Candle.

German New Space has two famous names, and HyImpulse is usually mentioned third, if at all. The others raised bigger rounds and built conventional rockets. HyImpulse took the harder route, developed its own propulsion technology, and kept its head down. We will not pretend to be neutral here: that is exactly the kind of company we find hard to resist. Not the loudest, not the best funded. The ones with the better idea, who then go out and prove it in flight. Days before we published this, German New Space reached orbit for the first time. We could not be happier about it: the door to space is open, the market is proven, and HyImpulse is next in line, holding a different key.

Was there debate at Räuberleiter before we signed? Of course. Venture investments are bets, and rockets are unforgiving. But the conditions here are unusually good: a technology already proven in flight, a market that urgently needs affordable European launch capacity, and a company whose next challenges happen to be the ones we know best. At some point the discussion settled itself.

Because that is the real story of this investment. HyImpulse today is more than a hundred people from all over the world, most of them in their thirties, many of them with the company since its research days. They have a flying rocket, a growing order book, and all the homework that comes with sudden scale: serial production, governance, finance, hiring, telling their story to the world. The threshold from brilliant engineering organization to grown-up company is exactly where a Räuberleiter belongs, and it is the work our team has done before, at umlaut and elsewhere.

HyImpulse sees it the same way. Although we are not among the largest investors in this round, the company gave us an observer seat on its advisory board. They did not just take our money. They pulled up a chair.

A second SR75 flight is in preparation at SaxaVord Spaceport in Scotland, their first from European soil. After that comes SL1, the orbital launcher that bundles the proven SR75 propulsion into a rocket carrying up to 600 kg into Low Earth Orbit. Step by step, launch by launch, toward something Europe has talked about for twenty years and now badly needs: its own affordable way to orbit.

A Räuberleiter, after all, is the simplest technology ever invented for getting someone higher than they could get alone. A rocket is the complicated version of the same idea. We are proud to hold the ladder for this one.

Photos: HyImpulse