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NASA validates revolutionary propulsion design for deep space missions

nasa.gov

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Re: NASA validates revolutionary propulsion design for deep space missions

#11

Post by kossTKR »

mdorazio wrote: post #5
vanattab wrote: post #3

In the theoretical limit how much improvement in efficiency could such engines provide?

Up to 25% improvement compared to conventional rocket engines according to the Wikipedia page. I haven’t found an actual ISP measurement for this NASA engine, though.

25% sounds super disappointing from a laymans perspective and not very "revolutionary" in the grand scheme of time and space.

Can't wait until AI will be able to iterate advanced engineering designs in simulation space at incredible speed.

Re: NASA validates revolutionary propulsion design for deep space missions

#13

Post by grogenaut »

kossTKR wrote: post #11
mdorazio wrote: post #5

Earlier quoted context omitted.

Up to 25% improvement compared to conventional rocket engines according to the Wikipedia page. I haven’t found an actual ISP measurement for this NASA engine, though.

25% sounds super disappointing from a laymans perspective and not very "revolutionary" in the grand scheme of time and space. Can't wait until AI will be able to iterate advanced engineering designs in simulation space at incredible speed.

From 10% to 35% is a 25% improvement, you're still at 35%... From 70 to 95% is a 25% improvement, but it's a lot more. Going from 98 to 99% is only 1% but also like really a 10x improvment.

Rockets are operating at pretty decent efficiency, 25% improvment on an internal combusion engine would be mind blowing and make EVs way less interetsting.

There are theoretical maximum efficencies for various types of engines due to thermodynamics. You always lose energy to heat. Entropy is a b**.

Re: NASA validates revolutionary propulsion design for deep space missions

#14

Post by sounds »

out_of_protocol wrote: post #6

Anybody know what Specific impulse we are talking about? According to wikipedia, current values for rockets are around 300s

This was a smaller prototype. Unless they release a theoretical Isp model for scaling up the engine (which, would we believe them if they did?) we can't know for certain yet.

Re: NASA validates revolutionary propulsion design for deep space missions

#15

Post by drtgh »

messe wrote: post #7
mdorazio wrote: post #5

Earlier quoted context omitted.

Up to 25% improvement compared to conventional rocket engines according to the Wikipedia page. I haven’t found an actual ISP measurement for this NASA engine, though.

Is that a 25% improvement in ISP/exhaust velocity or another metric?

It seems that 25% paragraph on wikipedia cites a non-technical article[1] from 2018:

    "Theoretical calculations have shown that detonation combustion is 25% more efficient than the isobaric combustion cycle, which corresponds to constant-pressure combustion, which is implemented in the chambers of of modern liquid propulsion engines."
From another article[2] of the same year:

    "Conservatively speaking, a rotating detonation combustor, or RDC, should reduce specific fuel consumption by about 5% compared to a conventional engine. This measure of fuel efficiency is calculated by dividing fuel consumption by power output. A rotating detonation engine generates more power, which drives down specific fuel consumption. A reduction on the order of 5 percent would be a breakthrough, given that designers of conventional engines “try to eke out fractions of a percent,” says Scott Claflin, director of advanced concepts at the Rocket Shop, Aerojet Rocketdyne’s innovation organization."
[1] https://rg.ru/2018/01/18/levochkin-vozmozhnost-sozdaniia-det...

[2] https://aerospaceamerica.aiaa.org/departments/increasing-eng...

Re: NASA validates revolutionary propulsion design for deep space missions

#16

Post by Lichtso »

grogenaut wrote: post #13
kossTKR wrote: post #11

Earlier quoted context omitted.

25% sounds super disappointing from a laymans perspective and not very "revolutionary" in the grand scheme of time and space. Can't wait until AI will be able to iterate advanced engineering designs in simulation space at incredible speed.

From 10% to 35% is a 25% improvement, you're still at 35%... From 70 to 95% is a 25% improvement, but it's a lot more. Going from 98 to 99% is only 1% but also like really a 10x improvment. Rockets are operating at pretty decent efficiency, 25% improvment on an internal combusion engine would be mind blowing and make EVs way less interetsting. There are theoretical maximum efficencies for various types of engines due…

Technically, from 10% of something to 35% of something is a 350% improvement or a 25 percent point improvement.

https://en.wikipedia.org/wiki/Percentage_point

Re: NASA validates revolutionary propulsion design for deep space missions

#17

Post by dotnet00 »

kossTKR wrote: post #11
mdorazio wrote: post #5

Earlier quoted context omitted.

Up to 25% improvement compared to conventional rocket engines according to the Wikipedia page. I haven’t found an actual ISP measurement for this NASA engine, though.

25% sounds super disappointing from a laymans perspective and not very "revolutionary" in the grand scheme of time and space. Can't wait until AI will be able to iterate advanced engineering designs in simulation space at incredible speed.

Simulations aren't really the limiter on engine efficiency, SpaceX etc already lean heavily on simulations.

The limiters on engine efficiency at this point are mostly materials and costs, and even the latter are coming down with better fuels (eg Methane, which is extremely popular with rockets debuting this decade) and different design philosophies (eg SpaceX's Raptor engine, which is supposedly under $1M per engine while being the most advanced flight tested rocket engine out there).

Re: NASA validates revolutionary propulsion design for deep space missions

#18

Post by phkahler »

out_of_protocol wrote: post #6

Anybody know what Specific impulse we are talking about? According to wikipedia, current values for rockets are around 300s

Not sure the relationship, but they say 600PSI chamber pressure, or about 20 bar. Spacex is push 200 to 300 bar pressures. I would think this means they're currently at a low ISP. The challenge with RDEs has been keeping them lit, I e. Keeping the detonation wave going indefinitely. Once that's done they can work of efficiency. Seems like they're at that point now.

Re: NASA validates revolutionary propulsion design for deep space missions

#19

Post by dotancohen »

Lichtso wrote: post #16
grogenaut wrote: post #13

Earlier quoted context omitted.

From 10% to 35% is a 25% improvement, you're still at 35%... From 70 to 95% is a 25% improvement, but it's a lot more. Going from 98 to 99% is only 1% but also like really a 10x improvment. Rockets are operating at pretty decent efficiency, 25% improvment on an internal combusion engine would be mind blowing and make EVs way less interetsting. There are theoretical maximum efficencies for various types of engines due…

Technically, from 10% of something to 35% of something is a 350% improvement or a 25 percent point improvement. https://en.wikipedia.org/wiki/Percentage_point

Actually, from 10% of something to 35% of something is a 250% improvement. You already had the first 10%.

Re: NASA validates revolutionary propulsion design for deep space missions

#20

Post by wolfram74 »

phkahler wrote: post #18
out_of_protocol wrote: post #6

Anybody know what Specific impulse we are talking about? According to wikipedia, current values for rockets are around 300s

Not sure the relationship, but they say 600PSI chamber pressure, or about 20 bar. Spacex is push 200 to 300 bar pressures. I would think this means they're currently at a low ISP. The challenge with RDEs has been keeping them lit, I e. Keeping the detonation wave going indefinitely. Once that's done they can work of efficiency. Seems like they're at that point now.

Pressure can tell you about thrust, but I don't think its as strongly linked to specific impulse. However looking at the wiki article on the RS25 which is pretty high up there being a hydrolox engine, I see it's also got a chamber pressure in the 200+ bar range.
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