Hermeus has selected the Pratt & Whitney F100 turbofan to integrate into its larger hypersonic engine. The company says that securing an off-the-shelf turbine engine will save it billions of dollars in research and development costs and years of schedule.

Pratt & Whitney's F100 turbofan, which is used in the F-15 and F-16 aircraft, will act as the turbine portion of Hermeus' turbine-based combined cycle engine named Chimera II.

“The F100 is a legendary turbine engine that will fit within our larger engine architecture extremely well,” says Hermeus CTO Glenn Case. “We chose it for its reliability, performance, and because it's currently in production. We're thrilled to have Pratt & Whitney as a partner on our journey to making hypersonic flight a reality.”

Chimera II will power Hermeus' aircraft, Darkhorse, a hypersonic uncrewed aerial system designed for defense and intelligence customers. The aircraft has multi-mission flexibility and is fully reusable.

This engine contract keeps the Darkhorse program on track for engine testing in 2024.

“The F100 engine recently celebrated 50 years of service and 30 million flight hours, demonstrating its dependability and capabilities,” reports Chris Johnson, VP of Fighter and Mobility Programs at Pratt & Whitney. “Pratt & Whitney's participation with Hermeus' Darkhorse program is a great example of creating innovative partnerships in aviation and will play a crucial role in addressing our national security challenges.”

Chimera II is a hypersonic turbine-based combined cycle (TBCC) engine. Put simply, a TBCC is a hybrid between a turbine engine and a ramjet. This allows for both low-speed and high-speed operation.

The benefit of this engine architecture is the ability for aircraft to takeoff from traditional airports using existing infrastructure – something that rocket-based hypersonic vehicles can't do.

Chimera II is a more powerful version of Chimera, which is designed for use in Hermeus' smaller aircraft, Quarterhorse.

Darkhorse is a hypersonic UAS (uncrewed aerial system) designed for defense and intelligence customers. The aircraft has multi-mission flexibility and is fully reusable.

Darkhorse is the second vehicle in the company's roadmap to commercial hypersonic flight. With lessons learned from flying its first aircraft, Quarterhorse, and subsequently Darkhorse, Hermeus will build Halcyon – a 20 passenger hypersonic aircraft.