Hermeus continues its march toward hypersonic development with the testing of its precooler technology on the Pratt & Whitney F100. The precooler lowers the temperature of incoming air, enabling an increase in the maximum speed of the turbine engine. Hermeus called the launch of such testing the first major propulsion milestone for what will be its second Quarterhorse flying prototype, Mk 2.
The company rolled out Quarterhorse Mk 1 in March with plans to begin flight trials later this year to test high-speed takeoff and landing at Edwards Air Force Base. That aircraft, an uncrewed, remotely piloted demonstrator, uses the GE J85 for its engine base.
As part of Hermeus’ plans to progressively build on complexity and lessons learned from each aircraft, Quarterhorse Mk 2—which incorporates the F100 with the precooler technology—will fly at supersonic speeds next year.
The precooler testing is taking place at sea-level static conditions at Edwards in California. Hermeus is examining how the F100 handles the precooler under various loads, leading to testing with heated air that simulates high-Mach flight conditions.
“The F100 is one of aviation’s most reliable engines, having clocked more than 30 million flight hours,” said Josh Goodman, senior director of the F100 program at Pratt & Whitney. “The F100 is taking on new life as Hermeus extracts even more performance out of our storied engine.”
Hermeus is developing a turbine-based combined cycle Chimera air-breathing engine that combines a turbine with a ramjet. Ultimately, Chimera will operate in turbine mode with the F100 at low speeds and transition to ramjet mode at higher speeds. The precooler is designed to help bridge the two modes by increasing the turbine performance.
Plans call to test Quarterhorse Mk 2 at speeds exceeding Mach 2.5. Hermeus will fit a full Chimera engine, including a ramjet, in the next aircraft, Quarterhorse Mk 3, which is anticipated to approach Mach 4.
“Airbreathing engines are critical to Hermeus’ goal of operationalizing hypersonic aircraft,” said Hermeus co-founder and chief technologist Glenn Case. “By making a full-range, air-breathing hypersonic engine, Hermeus is setting the stage for aircraft that are capable of taking off from a regular runway and accelerating up to hypersonic speeds. No rockets or motherships required.”