61–70 of 77 posts
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Basically it's a turbine engine but the rotating blades are replaced with orbiting shockwaves instead.
That makes no sense at all. How do you think a turbine engine works?
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…
Basically it's a turbine engine but the rotating blades are replaced with orbiting shockwaves instead.
That sounds like something out of sci-fi, amazing.
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…
>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…
It's a smokescreen for hypersonic missile development. It's a common tactic. I knew someone who worked on a novel satellite surveillance system. Their pitch was that it would allow them to engage in futures trading because the resolution of their satellites would allow unique insights into global trade for certain markets using realtime optical imaging. The guy was former Lockheed. One night at dinner I told him to c…
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What about noise? So far all we have gotten is companies trying to build planes that still are very loud and produce audible booms all the way along their travel path. Pitched to the empathetic heros that are billionaires. And to sway public opinion they fly test planes at slightly over mach one in specific weather and altitude setting that avoids having the sonic booms reach the ground. While marketing and selling t…
Flying it the high limits of the atmosphere reduces sonic boom intensity due to both the extremely low density of the air and the distance from the ground. Ultimately, sonic boom is a sign of wasted energy, so if (big if) we can make aircraft that conform to the required aerodynamic ideals for efficient hypersonic flight, they will be relatively quiet. Just like with regular air travel, though, I would expect a few d…
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 rotating part is a solution to the problem that forcing a continuous sustained explosion inside an engine can be complicated. By letting the explosion constantly happening, expanding, and traveling radially across a thin cylindrical gap, it solves such problems as sustained combus-^H^H^H detonation, fuel supply, etc. It's not the only possible type of an engine based on detonation principle, but so far the most promising. Detonating piston engines for cars, for example, are much less promising.
Engine part is just regular reaction rocket. It shoots the gas out the back. The faster and heavier the gas, the more reaction force it creates.
This isn't the first RDE ever to have been built, fired, or fired in a freefall, but it's finicky and experimental enough that it warrants a news story like this.
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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.
At supersonic speeds, the efficiency of an engine like this can be very high, and at high altitudes, travel is very efficient. People don’t seem to get that there is potential for more efficient transport at supersonic speeds/ hypersonic speeds. The ultimate example of this a satellite. How many times does it circle the world every 45 min, all on that initial fuel it took to get it up there? It seems wasteful, but it…
In energetic terms this is clearly true, but that leaves you at the end of the descent with very high speed / lots of kinetic energy. Great for missiles, because you dump the energy into the target. But I'm struggling to see how it's useful for any other application?
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…
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Integza made a YouTube video[1] where he visited a lab where they had a RDE, and includes some nice explanations, animations and slow-mos of the prototype in action. His channel has a certain flavor, but at least the video is informative. [1]: https://www.youtube.com/watch?v=fRMMSyCcTDI
> His channel has a certain flavor It's kind of an anti-tomato flavor.
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At supersonic speeds, the efficiency of an engine like this can be very high, and at high altitudes, travel is very efficient. People don’t seem to get that there is potential for more efficient transport at supersonic speeds/ hypersonic speeds. The ultimate example of this a satellite. How many times does it circle the world every 45 min, all on that initial fuel it took to get it up there? It seems wasteful, but it…
> the fuel cost of getting to altitude is mostly returned in the descent In energetic terms this is clearly true, but that leaves you at the end of the descent with very high speed / lots of kinetic energy. Great for missiles, because you dump the energy into the target. But I'm struggling to see how it's useful for any other application?
For the same reasons that theoretically possible doesn’t mean necessarily practical, theoretically difficult doesn’t mean practically impossible. We just won’t know until we significantly advance the state of the art. We might find out that atmospheric flight is a waste of time and that exoatmopheric ballistic trajectories are where it’s at. Or we might find out that zeppelins were the way all along.
We are still a long way off from having engines that can operate any where near theoretical efficiencies except within very narrow parameters and altitudes. Until we sort that we will have difficulty traversing a wide speed envelope without waste.