Hermeus secures licence to build Pratt & Whitney F100 engines

Pratt & Whitney, a subsidiary of RTX, has signed a licensing agreement allowing the startup Hermeus to assemble the F100-PW-229 engine. According to a press release issued on September 15, 2026, Hermeus said the deal is the first of its kind for the engine maker.

Hermeus is developing hypersonic platforms. Its Quarterhorse family of unmanned aircraft uses the F100, the powerplant for the F-15 and F-16 fighter series. The company is also building its own engine, named Chimera, which pairs a precooled F100 with a ramjet. A ramjet has no moving parts and is designed for very high supersonic speeds, but it needs acceleration before it can produce thrust.

Once complete, Chimera is expected to power later versions of Quarterhorse. Hermeus has already tested Quarterhorse Mk 1, which uses a GE J85 engine, and Quarterhorse Mk 2 and Mk 2.1, which carry a precooled F100 without a ramjet component. On May 26, 2026, Quarterhorse Mk 2.1 exceeded Mach 1 for the first time, reaching Mach 1.21 over the White Sands Missile Range in New Mexico.

Both companies framed the agreement as a way to broaden and diversify US advanced manufacturing capacity for defense. Zach Shore, chief executive of Hermeus, said meeting future operational needs requires expanding the country's ability to produce the engines its warfighters depend on. He added that Hermeus becomes one of a small number of vertically integrated airframers with in-house propulsion capability needed to scale Quarterhorse.