Hermeus raises $350M and flies its second aircraft in nine months, pushing toward Mach 5

Summary

Hermeus raises $350M, flies second aircraft in nine months

Hermeus has closed a $350 million round at a unicorn valuation, timed to the first flight of its Mark Two "Eagle" aircraft — an F-16-sized unmanned vehicle powered by a 30,000-pound-thrust engine, roughly 10x the thrust of the collaborative combat aircraft programs it's designed to surpass.

The round follows a rapid build cycle. Hermeus flew its first jet-powered aircraft, called Turkey, at Edwards Air Force Base in May 2025. Nine months later, it flew Eagle at White Sands. Zach Shore, the company's president, says a second Eagle flight is scheduled for the following Friday. That pace — two distinct aircraft in under a year — is the central pitch to investors: hardware iteration at software-like cadence.

The propulsion stack

Eagle's near-term goal is getting through transonic, the Mach 0.99 to 1.2 window where shock waves and aerodynamic instability create the highest risk before supersonic flight. Once through that, the second aircraft in the Eagle series — currently in production in Atlanta — adds Hermeus's proprietary precooler, targeting Mach 2-plus, roughly matching an F-15 at full speed in level flight rather than a dive.

The third aircraft, targeting Mach 3, will be built at a new El Segundo facility and is expected to fly around 2027. Mach 3 is the critical unlock, not because it's the endpoint, but because demonstrating sustained Mach 3 flight with the F100-229 turbine engine — the same engine used in the F-16 — is what allows Hermeus to light its ramjet and transition into what it calls turbine-based combined cycle (TBCC) propulsion.

The TBCC concept is not new. NASA developed the framework, and Shore says Hermeus and DARPA are the only two organizations to have demonstrated the propulsion cycle on the ground. The lineage traces back further: the SR-71 Blackbird carried a ramjet-powered drone called the D-21 that flew Mach 3-plus over 3,500 nautical miles after being released above Mach 3. Hermeus is essentially modernizing that 1960s concept using mature materials — titanium, Inconel, steel — rather than the exotic ceramics required for scramjet-territory above Mach 6.

The stated ceiling is Mach 5. Shore argues going higher crosses into science problems — novel materials, unproven physics, scramjet territory — rather than engineering problems, and the survivability analysis doesn't justify the added complexity.

Unmanned as a development accelerant

Removing the pilot does more than reduce operational risk. Shore describes being able to strip out oxygen systems, ejection seats, cockpit interfaces, and human-machine controls, redirecting that weight and volume into payload and fuel. More practically, unmanned flight allows Hermeus to deliberately push an aircraft to its performance limits in ways that would be unacceptable with a person on board, compressing the risk envelope on each test cycle.

El Segundo expansion

The company is adding a second headquarters in El Segundo to access the engineering talent concentrated around Los Angeles aerospace. Shore is direct that the talent pool he needs — engineers who know how to iterate quickly on high-speed hardware — barely exists outside that geography. The closest analogue is the rocket iteration culture built by SpaceX and its neighbors, and Shore wants to redirect that capability toward aircraft. He summarizes the strategic logic as "talent and tacos."

Defense first, commercial later

Shore frames commercial aviation as a genuine long-term destination, but not an operational focus. FAA certification for a new airframe and engine combination is expensive and slow, and making it economically viable requires a stable defense business first. Hermeus's stated identity is unmanned, high-Mach, high-altitude systems for the U.S. military — and Shore says that remains true north, with commercial applications a downstream possibility once the core platform matures.

The next concrete milestone is supersonic flight with the first Eagle aircraft, followed by Mach 2-plus with the Atlanta-built second aircraft, and Mach 3 out of El Segundo in 2027.