Hermeus, a startup developing hypersonic aircraft to radically accelerate air travel, has demonstrated turbojet-to-ramjet transition within its engine, Chimera, which uses 3D printing for approximately 15% of its metal components, built on Velo3D printers. This turbojet-to-ramjet transition is one of the most important technological feats in the process of making operational hypersonic flight a reality.
Chimera is a turbine-based combined cycle engine (TBCC) – essentially 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 then accelerate up to high-Mach speeds.
Hermeus designed, built, and tested Chimera in only 21 months, for $18 million, with the aid of additive manufacturing. “This achievement is a major technical milestone for Hermeus,” said AJ Piplica, CEO of Hermeus. “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 of Hermeus. “Completing this testing on the ground significantly de-risks our Quarterhorse flight test campaign which will begin late next year.”
By making a full-range air-breathing hypersonic engine that does not require a rocket to accelerate, Hermeus is enabling operational hypersonic aircraft to be rapidly re-used.
This engine is also designed to accommodate existing transportation infrastructure, to be operational at traditional airports. This is critical considering Hermeus’ goal of radically accelerating passenger travel through operational hypersonic flight.
An essential manufacturing principle at Hermeus is vertical integration, though the use of 3D printing for manufacturing in-house. This 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 – where additive manufacturing plays its part.
The Hermeus team is now set to manufacture the first Quarterhorse aircraft that will begin flight testing in late 2023.