Hop Aero Lands $11M to Build Suborbital Cargo Rocket

Hop Aero closed an $11 million SAFE round to fund its suborbital delivery rocket, the company said Tuesday, with proceeds backing the development of a full-scale vehicle targeting a mid-2027 debut.

The seven-person startup, fresh out of Y Combinator's summer batch, raised the capital through Simple Agreements for Future Equity, blending pre-program and in-program commitments. Initialized Capital led the round. The seed-stage firm previously backed AstroForge, Kayhan Space, and Star Catcher.

CEO and cofounder Matija Milenovic said demand from investors outstripped the company's original target. "We ended up raising more than we initially planned," Milenovic told Payload. "We were really fortunate to be able to turn down a lot of really good funds, so I think it sets us up to be in a great position for our Series A."

What did Hop actually test?

The capital arrives after a dense ground-test campaign at Oklahoma's Infinity One spaceport, run during the YC batch to de-risk propulsion and payload systems. Three phases made up the program:

• Engineers designed and 3D-metal-printed an engine using Hop's "hopOS" software, then hot-fired four internal variants ranging from conservative designs to ones the team expected might explode. None detonated.
• Hop dropped that engine into a roughly half-scale Rook prototype and ran a full static fire, validating fuel tanks, plumbing, and harnessing together.
• Four drones slid out of the payload bay on a rail, a ground demonstration of the deployment mechanism the startup is pitching to defense customers.

Milenovic identified the defense market as Hop's strongest commercial pull. "Where we have the most demand is being able to take a swarm of autonomous systems, put them in a rocket, [send] them hundreds of miles away into a contested environment, and then deploy them there," he said.

What does the round actually fund?

The $11 million will bankroll Rook 2, a larger vehicle Milenovic said will use a different engine and propulsion architecture than its predecessor. Hop has yet to fly any vehicle untethered. Its first untethered launch is targeted for mid-2027.

"We're going to be moving into our full-scale Rooks," Milenovic said. "Obviously, it's a different engine, different propulsion architecture. So we're going to be just going full speed on de-risking a lot of those elements."

What hasn't Hop solved yet?

The startup has not tested rocket recovery. Setting a vehicle down intact and on target after a hypersonic reentry is the unsolved problem that has kept suborbital cargo delivery on the drawing board for years. Static firing addressed propulsion risk. The drone drop addressed payload risk. Sticking the booster landing remains on the to-do list.

Where does the team stand operationally?

Hop Aero is expanding at the Oklahoma Spaceport, where the team plans to pour concrete by year-end to support the larger Rook 2 airframe. The site faced drought conditions during testing that raised the prospect of a statewide fire ban, which would have shut operations down. The startup compressed its schedule by two weeks and worked 20-hour days to finish before any ban could take effect.

So what?

An $11M SAFE round does not buy a hypersonic-reentry program. It buys engine development, infrastructure expansion, and a credible shot at a mid-2027 maiden flight. Rook 2's first untethered launch will be the moment investors, the Pentagon, and rival point-to-point players measure whether suborbital cargo delivery graduates from the drawing board to the launch manifest.