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In the US, a rotating detonation rocket engine takes flight

arstechnica.com

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

#31

Post by hammock »

ColinWright wrote: post #2

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…

I imagine an internal combustion engine with a ring of spark plugs firing rapidly in sequence into a nozzle that has fuel/air injected uniformly

That is my naive attempt to grok with an analogue, that is probably wrong.

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

#32

Post by jrmg »

jcims wrote: post #17
verzali wrote: 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."

What are ‘large primes’ here?

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

#33

Post by hermitcrab »

K0balt wrote: post #21
zdragnar wrote: post #14

Earlier quoted context omitted.

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…

Presumably, you have to be travelling quite a distance before hypersonic/high-altitude flight becomes more efficient than current commercial airliners.

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

#35

Post by mannykannot »

twic wrote: post #24
kd5bjo wrote: post #8

Earlier quoted context omitted.

From my understanding, it's more that the explosion phase of a detonation is more fuel-efficient than the burning phase, but can't last very long under normal circumstances because the flame front is moving so fast-- This is a trick to continue fueling the explosion to sustain it over an indefinite time period. Think about it in terms of an old-fashioned gunpowder line fuse: If you lay it out in a ring and have some…

What i've never understood is how detonation can be more efficient than deflagration. What does that mean? Both types of engine take a mix of fuel and oxidiser and turn it into hot combustion products. The hot combustion products then expand through a nozzle to produce thrust. How is that process different between the two? Does a deflagration engine leave some fuel unburnt, that a detonation engine burns? Does the co…

This is mentioned in the introduction here [1]. The version I'm looking at is an image, so I cannot easily copy-paste the relevant passage, but it seems to say that the efficiency gain comes from detonation causing the combustion to occur at a higher pressure than in the case of deflagration. Generally speaking, higher peak pressures increase the efficiency of heat engines, as this allows for greater expansion of the working fluid, and thus more work being done for the same fuel consumption.

With regard to your comparison, I guess this means that the detonation engine can have a higher pressure in the combustion chamber, together with a larger bell, a faster-moving exhaust, or some combination.

[1] https://arc.aiaa.org/doi/10.2514/6.2013-3971

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

#36

Post by cookingmyserver »

jrmg wrote: post #32
jcims wrote: post #17

Earlier quoted context omitted.

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."

What are ‘large primes’ here?

Primary defense contractors. Lockheed, Boeing, Raytheon, etc.

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

#37

Post by xeonmc »

ColinWright wrote: post #2

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.

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

#38

Post by twothreeone »

jrmg wrote: post #32
jcims wrote: post #17

Earlier quoted context omitted.

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."

What are ‘large primes’ here?

M136,279,841 is pretty big..

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

#39

Post by deelowe »

verzali wrote: 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…

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 cut the BS and that their real goal was to target military/government contracts. He said "off the record" this is correct. This an unspoken goal by everyone involved - management, investors, etc.

My understanding is it can be hard to position yourself as a defense company as a start up if you don't already have a foothold in the space.

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