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In the US, a rotating detonation rocket engine takes flight

arstechnica.com

11–20 of 77 posts

Re: In the US, a rotating detonation rocket engine takes flight

#11
>Sassie Duggleby and her husband, Andrew Duggleby, founded Venus Aerospace nearly five years ago with the long-term goal of developing powerful rotating detonation engines and building a hypersonic aircraft that could carry perhaps a dozen passengers and travel at astonishingly fast speeds worldwide.

As an engineering project it sounds really cool, but is the application really commercial travel? I would have thought the military would be far more interested and much better funded.

Re: In the US, a rotating detonation rocket engine takes flight

#12
post #9

From the article: "In contrast to a traditional rocket engine, in which a highly pressurized propellant and an oxidizer are injected into a combustion chamber where they burn and produce an energetic exhaust plume, a rotating detonation engine is different in that a wave of detonation travels around a circular channel. This is sustained by the injection of fuel and oxidizer and produces a shockwave that travels outwa…

Those descriptions are actually both correct, but one is describing the elephant's trunk and another the elephant's ear.

To be a bit more clear, the detonation is racing around a circular track in one plane, but the net thrust is in the direction perpendicular to that plane. Fuel and oxidiser are continuously pumped in all along the track, dropping to ~0 after a detonation and rising afterwards until the detonation front arrives again. Since you don't have to pump into a continual high pressure deflagration like in a conventional rocket engine this looks like it should be easier in terms of pump power.

Rocket engine efficiency, like all heat engine efficiency[1], governed by the difference in temperature between hot and cold in the cycle. Because at any given point in a detonation engine the combustion engine only comes in pulses it can reach temperatures that would otherwise melt the rocket engine. That's true of regular rocket engines too, which use active cooling, but seems more true of a detonation engine. And I would guess that the exhaust, already being supersonic, needs less of a chock on the de Laval nozzle to ensure laminar flow.

[1] Strictly speaking this only applies to combustion rocket engines. An ion engine, for instance, is a rocket engine but not a heat engine.

Re: In the US, a rotating detonation rocket engine takes flight

#14
post #7

2 hours? What's the point? It could be 0 minutes with a 0% explosion rate and the total travel time would probably be longer.

The point is reduced fuel use and faster response times (either emergencies or warfare).

Maintaining a detonation (as opposed to deflagration) is quite a technical challenge. If nothing else, it pushes mechanical engineering and material science forward.

Re: In the US, a rotating detonation rocket engine takes flight

#15

From the article: "In contrast to a traditional rocket engine, in which a highly pressurized propellant and an oxidizer are injected into a combustion chamber where they burn and produce an energetic exhaust plume, a rotating detonation engine is different in that a wave of detonation travels around a circular channel. This is sustained by the injection of fuel and oxidizer and produces a shockwave that travels outwa…

The first reference in the wiki article has a nice animation

https://www.rtx.com/news/2025/03/04/more-power-no-moving-par...

Re: In the US, a rotating detonation rocket engine takes flight

#16
post #7

2 hours? What's the point? It could be 0 minutes with a 0% explosion rate and the total travel time would probably be longer.

Fuel efficiency is the answer for "why would you do this?" That's really important for rockets, since to launch each gram of fuel you have to have some more fuel which you also have to lift.

Re: In the US, a rotating detonation rocket engine takes flight

#17
post #11

>Sassie Duggleby and her husband, Andrew Duggleby, founded Venus Aerospace nearly five years ago with the long-term goal of developing powerful rotating detonation engines and building a hypersonic aircraft that could carry perhaps a dozen passengers and travel at astonishingly fast speeds worldwide. As an engineering project it sounds really cool, but is the application really commercial travel? I would have thought…

From the bottom of the article:

"We're actively engaged with US defense and national security agencies as well as commercial partners exploring hypersonic applications in logistics, aerospace, and future mobility—including large primes," she said. "The enthusiasm we’re seeing reflects a broad recognition that Venus’s technology can unlock new operational and economic possibilities across multiple markets."

Re: In the US, a rotating detonation rocket engine takes flight

#20
post #19

Still trying to wrap my head around this. Doesn’t this cause insane stresses with basically all explosions being off axis? Or are there multiple sets of explosions moving at same the on opposites sides?

The main drawback is that RDEs need substantially stronger structure to smooth out the forces. It's still worth it, the force of the detonation (it's not separate explosions, it's a single continuous detonation front moving in a circular channel) is small enough to be containable.

There have been tests with multiple detonation fronts, but controlling them is much harder. It's very hard to have them go around the channel at exactly the same speed, so their positions relative to each other remain fixed.

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