Author Topic: The Reaction Engines Skylon/SABRE Master Thread (7)  (Read 354463 times)

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #760 on: 02/07/2023 06:08 pm »
The announcement of a Department of Science, Innovation and Technology seems to, prima facie, be a good thing, SABRE fitting at least two of those aspects.

Of course, if it's just deck chair shuffling, and no money, it'll be business as usual.
Yes, that is the question.  :(
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline t43562

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #761 on: 02/08/2023 10:48 am »
The announcement of a Department of Science, Innovation and Technology seems to, prima facie, be a good thing, SABRE fitting at least two of those aspects.

Of course, if it's just deck chair shuffling, and no money, it'll be business as usual.

I read that the money spent on setting it up the department was in the 10s of millions. I think it would probably have been enough to provide a big jump for REL but it's going on politics and re-organisation.  The economic situation feels a bit grim to me - we cannot even apparently support blindingly obvious strategic things like battery factories.
« Last Edit: 02/08/2023 10:50 am by t43562 »

Offline lkm

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #762 on: 02/08/2023 07:27 pm »
To return  to RE I don't think the latest patents have been posted to the thread yet.

https://worldwide.espacenet.com/patent/search/family/069726073/publication/GB2578262A?q=nftxt%20%3D%20%22REACTION%20ENGINES%20LTD%22

The  THERMALLY INTEGRATED AMMONIA FUELLED ENGINE patent was just published and details a dozen different configurations for ammonia cracked turbojets and turbofans including precooled high mach configurations but interestingly no rocket based combined cylces ala SABRE which seems like an oversight patent wise.
 A tripropellent SABRE would perhaps be an interesting proposition, is it possible for a single rocket chamber to have an ammonia/hydrogen mix that adjusts with ascent?

GB2601367A Engines details the integration of turbojets with precooling with the addition of mass injection for peak cooling.

Both of these patents seem relevant to RR and their high mach work and net zero.

Offline matthewkantar

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #763 on: 02/08/2023 08:07 pm »
Curiosity had me locate the first thread for RE on this forum. It is 13 years old now. RE seems farther away from flying anything now than they did back then. I find it very unlikely the ownership of this company matters at all to the UK’s economy.

Offline lkm

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #764 on: 02/08/2023 08:58 pm »
Curiosity had me locate the first thread for RE on this forum. It is 13 years old now. RE seems farther away from flying anything now than they did back then. I find it very unlikely the ownership of this company matters at all to the UK’s economy.

We were actually discussing the ownership of Rolls-Royce in light of the new chief executive's "burning platform" speech, and by relation how that might impact Reaction Engines.

Offline matthewkantar

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #765 on: 02/08/2023 11:52 pm »
Curiosity had me locate the first thread for RE on this forum. It is 13 years old now. RE seems farther away from flying anything now than they did back then. I find it very unlikely the ownership of this company matters at all to the UK’s economy.

We were actually discussing the ownership of Rolls-Royce in light of the new chief executive's "burning platform" speech, and by relation how that might impact Reaction Engines.

Er, yes you were, and that has what to do with RE?

Offline Asteroza

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #766 on: 02/09/2023 12:06 am »
To return  to RE I don't think the latest patents have been posted to the thread yet.

https://worldwide.espacenet.com/patent/search/family/069726073/publication/GB2578262A?q=nftxt%20%3D%20%22REACTION%20ENGINES%20LTD%22

The  THERMALLY INTEGRATED AMMONIA FUELLED ENGINE patent was just published and details a dozen different configurations for ammonia cracked turbojets and turbofans including precooled high mach configurations but interestingly no rocket based combined cylces ala SABRE which seems like an oversight patent wise.
 A tripropellent SABRE would perhaps be an interesting proposition, is it possible for a single rocket chamber to have an ammonia/hydrogen mix that adjusts with ascent?

GB2601367A Engines details the integration of turbojets with precooling with the addition of mass injection for peak cooling.

Both of these patents seem relevant to RR and their high mach work and net zero.

Are you suggesting somehow integrating an ammonia precooler/cracker in addition to the helium precooler/hydrogen heat exchanger for a SABRE engine?
As in, the cracked ammonia yields hydrogen and nitrogen for pumping into the fuel side of SABRE, whereas regular SABRE is running air (oxygen+nitrogen) on the oxidizer side of the rocket engine, thus from the rocket chamber perspective it looks like oxygen+nitrogen and nitrogen+hydrogen, rather than the normal oxygen+nitrogen and hydrogen setup?

Regular SABRE is to an extent adjusting nitrogen injection during ascent to the oxidizer side of the engine by varying the amount of precooled air versus onboard LOx entering the rocket compressor.


Offline lkm

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #767 on: 02/09/2023 12:16 pm »
Curiosity had me locate the first thread for RE on this forum. It is 13 years old now. RE seems farther away from flying anything now than they did back then. I find it very unlikely the ownership of this company matters at all to the UK’s economy.

We were actually discussing the ownership of Rolls-Royce in light of the new chief executive's "burning platform" speech, and by relation how that might impact Reaction Engines.

Er, yes you were, and that has what to do with RE?

Well RR is an investor in RE and a strategic partner. They are working together on the HTX programme, among other things, which will presumably feed into future defense work. Currently RR Space (https://www.rolls-royce.com/innovation/space.aspx) is essentially reaction engines and in space nuclear.
 The inference is that if/when a full up SABRE engine is built RR will be taking the turbomachinery work and that RE thermal management is going to find it's way into RR engines. If RR is sold all that may become more or less likely depending on the buyer.

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #768 on: 02/09/2023 07:15 pm »
Are you suggesting somehow integrating an ammonia precooler/cracker in addition to the helium precooler/hydrogen heat exchanger for a SABRE engine?
As in, the cracked ammonia yields hydrogen and nitrogen for pumping into the fuel side of SABRE, whereas regular SABRE is running air (oxygen+nitrogen) on the oxidizer side of the rocket engine, thus from the rocket chamber perspective it looks like oxygen+nitrogen and nitrogen+hydrogen, rather than the normal oxygen+nitrogen and hydrogen setup?
No. This is part of Reactions non- SABRE work.

Basically if you want to de-carbonise, or eliminate CO2 emissions you have to use a fuel without carbon in it. There are only 2 of these in common use (do any chemists reading this know others? I know about the hydrazines, but they are WMD level toxic  :( ). Ammonia and Hydrogen. *

 Hydrogen is the scientists choice. But it's a massive PITA to use, unless there is simply no alternative.  :(

Ammonia is more of the engieers choice. Fairly easy to liquify by either temperature (10s, not 100s of deg C below zero) or pressure (more butane lighter than divers breathing tank). So while it's energy intensive to make  you won't use 3x that level to liquify it or get enough in a tank as a gas (IE 5Ksi) to store a useful quantity. Ammonia is also relatively safe to handle (an ammonia leak is pretty obvious if you have any sense of smell)

But Ammonia is difficult to ignite. However if you run it over a catalyst (even at room temperature, with the right catalyst) you can get enough of it to decompose to GH2 and GN2. The H2 will get the igntion process started

So most of these patents are about how to make this work.
Quote from: Asteroza
Regular SABRE is to an extent adjusting nitrogen injection during ascent to the oxidizer side of the engine by varying the amount of precooled air versus onboard LOx entering the rocket compressor.
I'm not sure how many people realise SABRE is a triprollent engine already, it's just that unlike most of them it has different oxidisers, not fuels. BTW AFAIK SABRE does not use LO2 until rocket mode. All the conbustion O2 comes from the air it ingests (along with the 80% inert "reaction mass"  ;)  )


*If you're thinking "what about batteries" outside of moving something the size and mass of a couple of human beings they just don't have it. There are electric 18 wheelers but their range is 250mils (gasoline powered more like 1-2000) and take hours to recharge.  What about container ships? Long haul aircraft? Simpley nowhere near what's needed for those tasks. I mean orders of magnitude.
« Last Edit: 02/09/2023 08:04 pm by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline DanClemmensen

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #769 on: 02/09/2023 07:23 pm »
Basically if you want to de-carbonise, or eliminate CO2 emissions you have to use a fuel without carbon in it.
You can use hydrocarbon fuels (methane or heavier) as long as you produce it from Atmospheric CO2 and renewable electricity. Yes, you will emit CO2, but you will remove as much as you emit.

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #770 on: 02/09/2023 08:18 pm »
Basically if you want to de-carbonise, or eliminate CO2 emissions you have to use a fuel without carbon in it.
You can use hydrocarbon fuels (methane or heavier) as long as you produce it from Atmospheric CO2 and renewable electricity. Yes, you will emit CO2, but you will remove as much as you emit.
No you won't.  That requires a 100% efficient system, which doesnt exist, so the CO2 level continues to rise, although the rate (if done on a sufficient scale), would be lower. Switching to H2 or NH3 elimnates that combustion issue (provided the supply material sources are carefully considered of course).

However given that CO2 has an atmospheric lifetime of 300-1000 years even if all CO2 production stopped tomorrow it would take a minimum of 3 centuries to return to a CO2 level apropriate to the size of the current global population, which has grown a bit since the late 1600s.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline DanClemmensen

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #771 on: 02/09/2023 08:32 pm »
Basically if you want to de-carbonise, or eliminate CO2 emissions you have to use a fuel without carbon in it.
You can use hydrocarbon fuels (methane or heavier) as long as you produce it from Atmospheric CO2 and renewable electricity. Yes, you will emit CO2, but you will remove as much as you emit.
No you won't.  That requires a 100% efficient system, which doesnt exist, so the CO2 level continues to rise, although the rate (if done on a sufficient scale), would be lower. Switching to H2 or NH3 elimnates that combustion issue (provided the supply material sources are carefully considered of course).

However given that CO2 has an atmospheric lifetime of 300-1000 years even if all CO2 production stopped tomorrow it would take a minimum of 3 centuries to return to a CO2 level apropriate to the size of the current global population, which has grown a bit since the late 1600s.
Sorry, no. If you do not use fossil carbon, then you do not add carbon to the atmosphere, regardless of your efficiency. Your H2 or NH2 systems can also be inefficient, and they also do not affect the carbon balance. No different. If 100% of the carbon atoms are taken from atmospheric CO2, then the net addition of carbon to the atmosphere is zero, regardless of the efficiency. If any fossil carbon is used in the production cycle of any fuel (H2, NH2, or hydrocarbon) then there will be a net addition of carbon to the atmosphere.

Of course we need to quit adding fossil carbon to the atmosphere as soon as we possibly can: no argument at all with that. If there were a way to stop tomorrow, we should do it tomorrow, complaints by fossil carbon producers and consumers notwithstanding.

Offline lkm

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #772 on: 02/09/2023 09:30 pm »
To return  to RE I don't think the latest patents have been posted to the thread yet.

https://worldwide.espacenet.com/patent/search/family/069726073/publication/GB2578262A?q=nftxt%20%3D%20%22REACTION%20ENGINES%20LTD%22

The  THERMALLY INTEGRATED AMMONIA FUELLED ENGINE patent was just published and details a dozen different configurations for ammonia cracked turbojets and turbofans including precooled high mach configurations but interestingly no rocket based combined cylces ala SABRE which seems like an oversight patent wise.
 A tripropellent SABRE would perhaps be an interesting proposition, is it possible for a single rocket chamber to have an ammonia/hydrogen mix that adjusts with ascent?

GB2601367A Engines details the integration of turbojets with precooling with the addition of mass injection for peak cooling.

Both of these patents seem relevant to RR and their high mach work and net zero.

Are you suggesting somehow integrating an ammonia precooler/cracker in addition to the helium precooler/hydrogen heat exchanger for a SABRE engine?
As in, the cracked ammonia yields hydrogen and nitrogen for pumping into the fuel side of SABRE, whereas regular SABRE is running air (oxygen+nitrogen) on the oxidizer side of the rocket engine, thus from the rocket chamber perspective it looks like oxygen+nitrogen and nitrogen+hydrogen, rather than the normal oxygen+nitrogen and hydrogen setup?

Regular SABRE is to an extent adjusting nitrogen injection during ascent to the oxidizer side of the engine by varying the amount of precooled air versus onboard LOx entering the rocket compressor.



My thinking went like this.
Given that the patent includes a cycle for an ammonia precooled high mach turbine with ramjet bypass this suggests that an ammonia precooled airbreathing rocket cycle is similarly possible and according to the SABRE 4 patent the rocket mode is mechanically independent of the airbreathing mode, utilizing it own turbo-machinery and rocket chamber thus it should be possible for it use a different fuel than the airbreathing mode.

So this was my thought. Skylon is a very large aircraft, could it successfully trade an increased fuel density and lower Isp for the reduced dry mass and reduced drag of a smaller vehicle and come out ahead?
This could be done in one of two ways. Either the SABRE operates in airbreathing mode ammonia fueled and then operates in rocket mode Hydrogen fueled ( this seems like it should be very possible) or, it operates in airbreathing mode ammonia fueled and then operates in rocket mode on an ammonia/ hydrogen mix that adjusts with ascent for maximum performance. My question was whether this second option is actually possible in a single chamber.
My assumption with option 2 is that with the Skylon mass and aerodynamic model you could possibly iterate a solution that outperforms pure hydrogen with a smaller vehicle and a larger GTOW.

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #773 on: 02/10/2023 06:22 am »

My thinking went like this.
Given that the patent includes a cycle for an ammonia precooled high mach turbine with ramjet bypass this suggests that an ammonia precooled airbreathing rocket cycle is similarly possible and according to the SABRE 4 patent the rocket mode is mechanically independent of the airbreathing mode, utilizing it own turbo-machinery and rocket chamber thus it should be possible for it use a different fuel than the airbreathing mode.

So this was my thought. Skylon is a very large aircraft, could it successfully trade an increased fuel density and lower Isp for the reduced dry mass and reduced drag of a smaller vehicle and come out ahead?
This could be done in one of two ways. Either the SABRE operates in airbreathing mode ammonia fueled and then operates in rocket mode Hydrogen fueled ( this seems like it should be very possible) or, it operates in airbreathing mode ammonia fueled and then operates in rocket mode on an ammonia/ hydrogen mix that adjusts with ascent for maximum performance. My question was whether this second option is actually possible in a single chamber.
My assumption with option 2 is that with the Skylon mass and aerodynamic model you could possibly iterate a solution that outperforms pure hydrogen with a smaller vehicle and a larger GTOW.
That is an interesting idea. Ammonia is a (light) cryogen. OTOH so are any of the short chain alkanes (starting with methane). And if you're doing insulation for LH2 (in fact Reaction's plan is to use sub-cooled LH2) you're OK with that anyway.

As always with an SSTO the question you should always be asking is "Does my cunning plan improve performance/mass/manufacturability/whatever enough across the whole mission to make it viable"?

Upside is still no additional CO2, and (potentially) smaller, lighter tanks.

The question is wheather that reduction of tank volume is enough to wrap a smaller Sears-Haake body around everything :(
That would be a win. But then you've got to consider the increased plumbing and complexity to accomodate ammonia in the pre-burner.

Is this what you want in an X-plane?

OTOH Ammonia for conventional aviation (and shipping)  has a lot going for it. In turn Reaction have strong skillset that can leverage that. In countries with abundant sustainable energy it can be made with (literally) water and air.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #774 on: 02/10/2023 06:35 am »
Sorry, no. If you do not use fossil carbon, then you do not add carbon to the atmosphere, regardless of your efficiency. Your H2 or NH2 systems can also be inefficient, and they also do not affect the carbon balance. No different. If 100% of the carbon atoms are taken from atmospheric CO2, then the net addition of carbon to the atmosphere is zero, regardless of the efficiency. If any fossil carbon is used in the production cycle of any fuel (H2, NH2, or hydrocarbon) then there will be a net addition of carbon to the atmosphere.
Of course that assumes the energy you use to make the synthetic fuel does not use more fossile fuel to make it.  :( The whole "Blue" hydrogen nonsense.

There is also an assumption that the present leve of atmospheric CO2 is acceptable.
Quote from: DanClemmensen
Of course we need to quit adding fossil carbon to the atmosphere as soon as we possibly can: no argument at all with that. If there were a way to stop tomorrow, we should do it tomorrow, complaints by fossil carbon producers and consumers notwithstanding.
I personally don't have a problem with fossile carbon producers producing it.

Coal, oil and gas are remarkable chemical feedstocks. The discovery that microwave treatment can turn coal into graphite (re-discovering some of Liz Franklin's papers on the graphitisation of carbons, including PVC) without days at 3000c opens up a raft of possible applications.

The trouble is the #1 actual use of fossil carbon production is fuel, starting with the 10% of oil that Saudi Arabia pumps straight out of the ground and into the boilers of its chemical plants (making it the #1 CO2 emitter by head of population on the face of the planet, with Australia the #2)

If Saudia Arabia were to switch to using say solar or nuclear heat for their processing they'd have a lot fewer issues. Sadly the dominant reactor designs are quite poor for process heat needs  :(

This however is fairly OT for this thread. Perhaps "Power options for a Martian settlement" ?
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline lkm

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #775 on: 02/10/2023 11:58 am »

My thinking went like this.
Given that the patent includes a cycle for an ammonia precooled high mach turbine with ramjet bypass this suggests that an ammonia precooled airbreathing rocket cycle is similarly possible and according to the SABRE 4 patent the rocket mode is mechanically independent of the airbreathing mode, utilizing it own turbo-machinery and rocket chamber thus it should be possible for it use a different fuel than the airbreathing mode.

So this was my thought. Skylon is a very large aircraft, could it successfully trade an increased fuel density and lower Isp for the reduced dry mass and reduced drag of a smaller vehicle and come out ahead?
This could be done in one of two ways. Either the SABRE operates in airbreathing mode ammonia fueled and then operates in rocket mode Hydrogen fueled ( this seems like it should be very possible) or, it operates in airbreathing mode ammonia fueled and then operates in rocket mode on an ammonia/ hydrogen mix that adjusts with ascent for maximum performance. My question was whether this second option is actually possible in a single chamber.
My assumption with option 2 is that with the Skylon mass and aerodynamic model you could possibly iterate a solution that outperforms pure hydrogen with a smaller vehicle and a larger GTOW.
That is an interesting idea. Ammonia is a (light) cryogen. OTOH so are any of the short chain alkanes (starting with methane). And if you're doing insulation for LH2 (in fact Reaction's plan is to use sub-cooled LH2) you're OK with that anyway.

As always with an SSTO the question you should always be asking is "Does my cunning plan improve performance/mass/manufacturability/whatever enough across the whole mission to make it viable"?

Upside is still no additional CO2, and (potentially) smaller, lighter tanks.

The question is wheather that reduction of tank volume is enough to wrap a smaller Sears-Haake body around everything :(
That would be a win. But then you've got to consider the increased plumbing and complexity to accomodate ammonia in the pre-burner.

Is this what you want in an X-plane?

OTOH Ammonia for conventional aviation (and shipping)  has a lot going for it. In turn Reaction have strong skillset that can leverage that. In countries with abundant sustainable energy it can be made with (literally) water and air.

Ammonia in the RE patent is sub cooled at 200K and 1 bar with a density of 728kg/m3 so it has the benefit over methane of being significantly denser and it has a much better heat capacity as well as not being carbon based. I seem to recall the cycle works better for ammonia. There are a number of chinese papers on hydrocarbon precooling and they focus on chemical cooling using fuel mixes that endothermically crack at diferent temperatures. I think there's also an RE inc paper on one such fuel.

There's no doubt this makes for a more complicated engine but it could potentially make for a vehicle say 2/3 the size for the same payload mass, which may possibly  be worthwhile construction wise. Skylon is after all larger than an A380, size is a problem all of its own.
I think more likely though is in second generation applications once an initial vehicle has proven the technology where there is some room for vehicle specialisation for more bespoke use cases, at which point there might be some intrinsic value in having a smaller responsive launch vehicle for defense customers.

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #776 on: 02/10/2023 07:17 pm »
Curiosity had me locate the first thread for RE on this forum. It is 13 years old now. RE seems farther away from flying anything now than they did back then. I find it very unlikely the ownership of this company matters at all to the UK’s economy.
And how many other rocket companies have appeared in those 13 years?

How many have just blown aways like leaves on the wind?

Would you like to guess? 100s? A 1000?

Reaction has stayed in business because it a)Continues to make progress to its goals b)When fully funded delivers the results it promises (because it's doing engineering, not science) and c)It offers the prospect of a truly revolutionary transportation system that doesn't just change how you get to orbit but how you buy the method of how you get to orbit.

99% of their competitors just offered yet another
Two Stage To Orbit Expendable Launch Vehicle.
Yet another sole mfg/sole operator business model with it's obsession with the companies "Traffic model."
Yet another variation on the ICBM, which is exactly what they look like on EW radar.  :(

And guess what. The world does not need anymore of those.

As for Reaction's  progress you're not very well informed. In fact you have it backwards. But I'm ok with that.

So thank you for your time, but don't feel you need to spend a moment more of it reading this thread if your time is so valuable.
« Last Edit: 02/11/2023 10:45 am by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline lkm

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #777 on: 02/10/2023 10:51 pm »
Just another thought about the patents.
The second one I mentioned and posted utilized their frost control system to do mass injection of water for extra cooling for brief hypersonic sprints needing peak cooling.
It's my understanding from the SABRE papers that the biggest source of inefficiency in the cycle is the high temperature precooler having to operate at twice the matched capacity ratio to keep the precooler within material temperature limits.  Given a Skylon takeoff with a 1mt of water for brake cooling could it make performance sense to retain some for mass injection allowing a matched capacity ratio within the engine at high mach and a more efficient cycle?

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #778 on: 02/11/2023 11:01 am »
Just another thought about the patents.
It's my understanding from the SABRE papers that the biggest source of inefficiency in the cycle is the high temperature precooler having to operate at twice the matched capacity ratio to keep the precooler within material temperature limits.  Given a Skylon takeoff with a 1mt of water for brake cooling could it make performance sense to retain some for mass injection allowing a matched capacity ratio within the engine at high mach and a more efficient cycle?
Again an interesting idea. IIRC the water cooled brake system saves 1400Kg (going from memory on this) so it depends if you're thinking about keeping most of that or a fairly small amount. EG 200Kg.

Whch once again demonstrates how closely everything is linked together.  :(

Also temperature is relative. The GH2 coming out He/H2 HX might still be substantially cooler than the airstream. If injected into the incoming airstream it might actually cool the airflow. :)

No I haven't checked the thermodynamics of this. I'm just posing an option. Whatever happens will happen fast. I find it helps to think not in terms of m/s but of s/m. At roughly M5 (with M1 at 340m/s) that's roughly 588 microseconds/metre. OTOH chemical reactions are a lot faster at 1000c+.
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Offline lkm

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Re: The Reaction Engines Skylon/SABRE Master Thread (7)
« Reply #779 on: 02/11/2023 11:54 am »
Just another thought about the patents.
It's my understanding from the SABRE papers that the biggest source of inefficiency in the cycle is the high temperature precooler having to operate at twice the matched capacity ratio to keep the precooler within material temperature limits.  Given a Skylon takeoff with a 1mt of water for brake cooling could it make performance sense to retain some for mass injection allowing a matched capacity ratio within the engine at high mach and a more efficient cycle?
Again an interesting idea. IIRC the water cooled brake system saves 1400Kg (going from memory on this) so it depends if you're thinking about keeping most of that or a fairly small amount. EG 200Kg.

Whch once again demonstrates how closely everything is linked together.  :(

Also temperature is relative. The GH2 coming out He/H2 HX might still be substantially cooler than the airstream. If injected into the incoming airstream it might actually cool the airflow. :)

No I haven't checked the thermodynamics of this. I'm just posing an option. Whatever happens will happen fast. I find it helps to think not in terms of m/s but of s/m. At roughly M5 (with M1 at 340m/s) that's roughly 588 microseconds/metre. OTOH chemical reactions are a lot faster at 1000c+.

I think it's in the ballpark of 140kg based the numbers we have access to, but it depends on how this changes engine performance.
This is only necessary for about 5 minutes above mach 4 so the H2 coming out of the high temp He/H heat exchanger has already reach the temp limit of the precooler, as those numbers are thermodynamically linked so injected into the airstream it couldn't lower the average temperature to within the materials limit.

 

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