Hermeus hits hypersonic engine goal thanks to Additive Manufacturing

December 2, 2022

The transition from turbojet to ramjet of Hermeus’ Chimera engine has been demonstrated repeatedly (Courtesy Hermeus)
The transition from turbojet to ramjet of Hermeus’ Chimera engine has been demonstrated repeatedly (Courtesy Hermeus)

Hermeus, an aerospace company headquartered in Atlanta, Georgia, USA, has demonstrated turbojet to ramjet transition within its Chimera engine. The cost and speed at which the Hermeus team achieved this milestone is notable: Hermeus designed, built, and tested Chimera in twenty-one months for $18 million.

Manufacturing in-house allows for a tight feedback loop between engineers and technicians which is key to the company’s ability to iterate quickly. Additionally, vertical integration eases reliance on outside vendors and allows for better control of the supply chain. Another important factor in building Chimera is Additive Manufacturing; reportedly about 15% of the engine is produced via AM, which enabled rapid development.

Chimera is a turbine-based combined cycle engine (TBCC) – which basically means it’s a hybrid between a turbojet and a ramjet. The ability to switch between these two modes allows Hermeus’ first aircraft, Quarterhorse, to take off from a regular runway and accelerate up to high-Mach speeds.

At low speeds, Chimera is in turbojet mode – just like any jet aircraft. But as the temperature and the speed of the incoming air increase, turbojets hit their performance limit. This happens at around Mach 2. Chimera has a pre-cooler that reduces the temperature of the air coming into the turbojet, allowing Hermeus to squeeze a bit more performance from the turbojet before transitioning to ramjet.

At around Mach 3, Chimera begins to bypass the incoming air around the turbojet and the ramjet takes over completely. A ramjet is a simple propulsion system which ‘rams’ the incoming high-pressure air to create compression. Fuel is mixed with this compressed air and ignited for thrust. Ramjets are optimal between Mach 3 and Mach 5.

“This achievement is a major technical milestone for Hermeus,” stated AJ Piplica, CEO. “But more than that, it’s a proof point that demonstrates how our small team can rapidly design, build, and test hardware with budgets significantly smaller than industry peers.”

The testing took place at the Notre Dame Turbomachinery Laboratory, which provides heated air to simulate high-Mach temperatures and pressures.

“The Notre Dame facility allowed us to create conditions similar to what we’ll see in flight,” said Glenn Case, CTO. “Completing this testing on the ground significantly de-risks our Quarterhorse flight test campaign which will begin late next year.”

Hermeus’ TBCC engine is unique in the field of hypersonics. Most hypersonic platforms are powered by a rocket engine. But this approach makes reusability much harder and inherently more dangerous for passenger flight.

By making a full-range air-breathing hypersonic engine that does not require a rocket to accelerate, Hermeus is setting the stage for operational hypersonic flight – meaning aircraft that can be rapidly re-used.

An additional benefit of this engine design is that it accommodates existing transportation infrastructure. Hermeus aircraft are designed to be operational at traditional airports. This is important not just for hypersonic testing, but reportedly critical to Hermeus’ goal of radically accelerating passenger travel through hypersonic flight.

www.hermeus.com

The transition from turbojet to ramjet of Hermeus’ Chimera engine has been demonstrated repeatedly (Courtesy Hermeus)

In the latest issue of Metal AM magazine

Download PDF
 

Extensive AM industry news coverage, as well as the following exclusive deep-dive articles:

  • What happens when you take the powder out of AM? Charting the rise of wire-based DED with WAAM3D
  • Smart sensor-integrated parts by AM: A look at a novel possibility with industrial applications
  • Tailored materials for AM: How a 'powder kit' can achieve greater material diversity with fewer resources in PBF-LB
  • QuesTek's ICMD: Faster, cheaper, and better alloy development for Additive Manufacturing
  • NanoAL: Alloy development on an open parameter PBF-LB machine, from installation through to Rapid Alloy Screening
  • Using the Six Sigma method to optimise metal powder spreading in PBF-LB
  • Insights from R&D to part production: How CT analysis can advance metal Binder Jetting
  • Corrosion and wear resistence of materials processed by beam-based AM technologies

The world of metal AM to your inbox

Don't miss any new issue of Metal AM magazine, and get the latest industry news. Sign up to our twice weekly newsletter.

Sign up

News from the industry…

    News from the industry…

    Discover our magazine archive…

    The free to access Metal Additive Manufacturing magazine archive offers unparalleled insight into the world of metal Additive Manufacturing from a commercial and technological perspective through:

    • Reports on visits to leading metal AM part manufacturers and industry suppliers
    • Articles on technology and application trends
    • Information on materials developments
    • Reviews of key technical presentations from the international conference circuit
    • International industry news

    All past issues are available to download as free PDFs or view in your browser.

    Browse the archive

    Looking for AM machines, metal powders or part manufacturing services?

    Discover suppliers of these and more in our comprehensive advertisers’ index and buyer’s guide, available in the back of Metal AM magazine.

    • AM machines
    • Process monitoring & calibration
    • Heat treatment & sintering
    • HIP systems & services
    • Pre- & post-processing technology
    • Powders, powder production and analysis
    • Part manufacturers
    • Consulting, training & market data
    Download PDF
    Share via
    Copy link
    Powered by Social Snap