A four-person rocket startup working out of Dresden just announced $400 million in launch reservations for a heavy-lift vehicle that hasn't yet flown. The unconventional part: an engine design that tosses out the turbopump entirely, rotating the entire combustion chamber to pressurize propellant instead.
RATLOG, which Y Combinator accepted into its Fall 2026 cohort, says it hot-fired its first prototype in four months on a budget under $30,000. Now the team is angling to carve out a niche somewhere between Europe's expendable Ariane 6 and SpaceX's reusable Falcon 9, targeting payloads up to 20 tonnes.
The technical gamble centers on what CEO Charlie Weise and his co-founders see as an Achilles' heel in conventional rocket engines. Turbopumps, which spin at tens of thousands of revolutions per minute to force fuel and oxidizer into the combustion chamber, represent some of the most failure-prone and expensive components in liquid rocketry. RATLOG's solution is to spin the entire engine, building centrifugal pressure without the elaborate plumbing. Parts count drops by roughly 90%, the company claims, though the approach demands heavy-duty bearings capable of withstanding extreme loads.
"Every launch company wants to catch SpaceX," Weise said in an interview with Payload Space published Tuesday.
Whether that ambition translates into actual flights remains an open question. RATLOG says it has booked more than 10 missions and is in discussions with over 70 potential customers, including operators planning orbital data centers and satellite constellations. The startup intends to sell capacity by the kilogram as a rideshare service. The company is exploring potential launch sites in Oman and the United Arab Emirates, Payload reported.
Weise and co-founder Paul Kunhart, who serves as CTO, both cut their teeth on the European Space Agency's Argonaut Moon Lander project at TU Dresden's Aerospace Institute. The pair previously launched Innuendo, a venture that developed an air-breathing cruise missile powered by a rotating detonation engine. Kunhart brought nozzle design experience from his ESA work.
The team's COO, Matty Driesnack, arrived from Lio, a YC Summer 2023 company backed by Andreessen Horowitz. Driesnack first learned about Y Combinator in a venture capital financing course at TU Dresden, according to the university's October announcement of RATLOG's YC acceptance. Felix Kelm, the fourth co-founder and chief avionics officer, handled electronics development at Innuendo after studying electrical engineering at TU Dresden and telecommunications at INSA Lyon.
Prototyping began in April with a €30,000 grant from the German government. The first successful hot-fire test came in early September. RATLOG had already picked up support from Dresden's YETI Fellowship and Munich's Schub accelerator before landing at YC, which invested its standard $500,000 package: $125,000 for 7% equity plus $375,000 on an uncapped safe note.
The startup's November agenda includes testing an engine with 200 times the thrust of that initial prototype. Flight-ready hardware is slated for 2027, followed by a first-stage hopper hot-fire in 2028 and commercial launches targeting 2030, Weise told Payload. Those timelines assume everything goes smoothly, a notably optimistic view in an industry where schedules tend to slip.
RATLOG is pitching itself as a "cheaper and more available Ariane 6" for European customers while taking on SpaceX in the global market. Ariane 6, Europe's newest heavy-lift rocket, is expendable rather than reusable, which puts it at an economic disadvantage against Falcon 9's recovery-and-refly model. RATLOG shares its YC batch with Inflection Space Systems, which is targeting production of tens of thousands of spacecraft annually with a first launch scheduled for Q1 2028, and Orca Aerospace, focused on AI-driven spacecraft operations.
Y Combinator's Fall 2026 Demo Day is set for December 2 in San Francisco, where somewhere between 1,000 and 1,500 investors and journalists are expected to show up.
Note: Some details in this article reference events or timelines that may have been superseded; readers should verify current company status independently.
