The high-thrust engine

Yesterday was the autumnal over our sister planet so, time to rake those leaves. In celebration: rocket post!

It's a commonplace that combustion engines, of which the jet-turbine is one, represent a controlled explosionburn. Here's controlled detonation. DEFINITIONS 3/19/22: Chris Combs explains that burn/conflagration is subsonic; detonation supersonic. The Orion Project going tactical-nuclear would be, er, supersonic.

Let's manage what Daniel Rosato et al. actually say in their paper, "Stabilized detonation for hypersonic propulsion". The University of Central Florida built them a hypersonic "high-enthalpy" reaction chamber. Herein was created an oblique detonation wave, which they formed by using an angled ramp inside the reaction chamber to create a detonation-inducing shock wave for propulsion. UPDATE 8/23 Apparently this differs from rotary detonation.

Reminds me of Princeton's Alfven: taking a powerful one-off force, controlling it, and making it run for longer. UCF say they got three seconds out of their own detonation. That means it can be studied. That does not mean Elon can use it in a Raptor - yet.

If anyone can run this big bang past three seconds this promises (far) beyond Rolls Royce' new Concorde. This looks to compete with freakin' scramjets and/or the fabled X-15 (UPDATE 8/9: which don't last long anyway). Although I bet when it's time for commercial flight, the aerodynamics of it all will favour Rolls. "Mach 17!" is laughable. And - yeah, three seconds is not the thirty minutes hyped for NY/LA.

As an engine technology, it doesn't have to be a turbine. Which means it has applications in (chemical) rocketry as well. In fact, I'd say foremost. Elon has to be looking into this, to replace his Raptors. Although again, Elon needs more than three seconds.

For now, and for our delta-V needs in space itself: we got a high-thrust-but-still-low-impulse engine. We got orbital transfer options and we got Oberth; we don't even need to go nuclear.

Sadly the blame for the hype must fall upon Rosato, as principal author. An engine operating with a Mach 5 flow path corresponds to a vehicle flight Mach number of 6 to 17. That is comparable to a half-hour flight from New York to London and is 5 times faster than the average time it took the legendary Concorde to complete the same journey. You should have stopped at the first sentence, bro. Manage our expectations with the rest.

And to be fair to the hype, the article does mention that latter. I'd have advised that they started with that, but, hypesters gotta hype.

BACKDATE 5/17. Also, radio signals in the ionosphere.

HYPE 5/28/22: Combs is on this day mocking this take, back from the grave.