Author Topic: The Reaction Engines Skylon Master Thread (5)  (Read 420223 times)

Online dror

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #240 on: 04/16/2015 11:37 AM »
You CAN after all make a "SABRE" cycle LIKE engine with any cry-fluid but the deep cooling of the air pretty much takes LH2 to accomplish so using something else how accurate is the result?

Randy

So I don't realy understand. Is the SABRE cycle even possible with other cryogenic fuel or not?
Strictly theoretically, is it possible with deep cooled methan for instance,  or is it not cold enogh to "liquify" the air?

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Offline dasmoth

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #241 on: 04/16/2015 01:55 PM »
At LonCon last year, Alan Bond said LH2 was the only viable option.

Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #242 on: 04/16/2015 03:05 PM »
You CAN after all make a "SABRE" cycle LIKE engine with any cry-fluid but the deep cooling of the air pretty much takes LH2 to accomplish so using something else how accurate is the result?

So I don't realy understand. Is the SABRE cycle even possible with other cryogenic fuel or not?
Strictly theoretically, is it possible with deep cooled methane for instance,  or is it not cold enogh to "liquify" the air?

"SABRE-like" would mean a cycle that approximates but does not duplicate the SABRE. Off the top of my head I used an example of Mass Injection, Pre-Compressor Cooling or MIPCC which uses injected water and LOX to densify and concentrate the incoming air. You COULD use liquid methane and other cryo-fluids as injection fluids, (tests have been done with liquid nitrogen for verification of the MIPCC effects on turbo-machinery) but none of the really come to the point of DEEP cooling the air.

It actually DOES take liquid hydrogen to accomplish by the SABRE cycle. LH2 is what is know as a "hard" cryogen due to its VERY cold liquefaction temperature, (-252c/-423f) compared to other cryogenic fluids. For example methane FREEZES at -182c/-294f and its boiling point is higher as well at -161c/-258f. Your components of air (nitrogen/oxygen) liquefy at -196c/-320f and -182c/297f respectively. That's if we wanted to use something like a LACE (Liquid Air Cycle Engine) system though were we were actually making liquid oxygen for the engine, what we're talking about it simply "deep" cooling which require a lot less cooling. But we're also NOT talking about "normal" temperature air either. At Mach-5 the incoming air is going to be very hot BEFORE it's compressed and fed into the engine and only LH2 has the thermal capacity to reduce that temperature AND still drop the air temperature to a point where it can be dense enough to feed into the engine.

The main mechanical "sticking point" has always been the heat exchanger for deep cooling air for a turbo-machine application. Flow, Frost, and most other problem have been solved numerous times for various designs but mass was always an issue and REL has pretty much solved their problems with those factors with the current SABRE cycle. The OTHER more problematical issue has been that despite having worked out and proven in laboratory testing that deep cooling allowed all the advantages of LACE without most of the problems there was an industry and academic wide misunderstanding (blind spot really) that in order to run a ROCKET engine on "air" that propellant had to be made from a "gas" (which could be run in a turbo-compressor but not run through turbo-pump, the former being a jet engine the latter being "required" to inject propellant into an rocket engine) into a liquid.

I say this was a "blind spot" for the simple reason that even when it was PROVEN in lab testing that you in fact COULD deep cool air to a point where it could be run through a turbo-pump and fed into a rocket engine AS A GAS not only was this ignored by the majority of people working on the subject, the program that DID this mis-named the process by calling "turbo-LACE" which by definition would suggest that at some point the "air" becomes a "liquid" as its CALLED a version of the Liquid Air Cycle Engine...
(And in a classic case of the rocket engine people not talking to the jet engine people it was categorically stated in the literature of the time that you REQUIRED propellant to be liquid in order to run them through turbo-pumps to get high pressure in a rocket engine at the VERY same time the people producing what was to become the RL-10 LH2/LOX rocket engine were producing papers and studies showing how much MORE efficient it was to inject the propellants THROUGH A TURBO-PUMP as a GAS instead of a LIQUID! ::::doublefacepalm:::: Couple this with the obsession with the "perfect" air-breathing engine which {in theory} is the SCramjet and its pretty clear why its take REL going back and asking the "basic" questions again and NOT accepting the "common knowledge" to get to the point we are now)

You CAN do "SABRE-like" with other cryogen-propellants but the actual cycle(s) are very different and in most cases won't be as efficient at SABRE is supposed to be.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline SteveKelsey

Re: The Reaction Engines Skylon Master Thread (5)
« Reply #243 on: 04/16/2015 05:38 PM »
A lateral question at this point considering the detail of the discussion but with this

 "Furthermore, the heat exchanger technology also warrants further investigation for applications across the aerospace domain"

 indicating interest by the USAF,  will SABRE technology get snared in ITAR problems. I am delighted that SABRE has received the endorsement, but would hate to see Reaction Engine's IP inadvertently sequestered.
2001 is running a little late, but we are getting there.

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #244 on: 04/16/2015 06:46 PM »
indicating interest by the USAF,  will SABRE technology get snared in ITAR problems. I am delighted that SABRE has received the endorsement, but would hate to see Reaction Engine's IP inadvertently sequestered.
An excellent point.

The Official UK position on ITAR was described in the BSA's report on UK spaceports.

It makes depressing reading and you'd have to be very careful to ensure that any SABRE/Skylon IP is not "contaminated" by USAF work, effectively making the USG a business partner and giving it power of veto over your decisions.  :(

That might not be a position the British government is too bothered by but it should scare the hell out of any  British company that wants to be predominately  a supplier to the world in aerospace.  :(
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #245 on: 04/16/2015 07:17 PM »
indicating interest by the USAF,  will SABRE technology get snared in ITAR problems. I am delighted that SABRE has received the endorsement, but would hate to see Reaction Engine's IP inadvertently sequestered.
An excellent point.

The Official UK position on ITAR was described in the BSA's report on UK spaceports.

It makes depressing reading and you'd have to be very careful to ensure that any SABRE/Skylon IP is not "contaminated" by USAF work, effectively making the USG a business partner and giving it power of veto over your decisions.  :(

That might not be a position the British government is too bothered by but it should scare the hell out of any  British company that wants to be predominately  a supplier to the world in aerospace.  :(

The key phrase is "across the aerospace domain" rather than something directly applicable to "rocket/missile" technology. ITAR legally is about home made missiles not home made bombers and drones which is why model "rockets" get a hard time while GPS guided "autonomous and remote control" aircraft don't :)

As I asked earlier, one possible interesting application is a 'reverse' HE where heat is transferred FROM another source into an airstream, uses such as in turbo-heat-exchangers comes to mind as well.

It's not "just" for cooling anymore :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #246 on: 04/16/2015 07:27 PM »
Just to be clear what the CRADA says

The USAF accept that the SABRE 3 does work and at no point violates the laws of Thermodynamics provided the components can be be built to meet the thermal and structural requirements in different parts of the system.

NSF posters will already know that the core of the SABRE engines is the precooler and this has already been tested, due to it having the most demanding set of requirements in terms of airflow, temperature difference, frost control etc.

Some of the USAF's views are a bit odd. The SABRE cycle is specifically designed for flight to orbit. I think it would be superior for acceleration to M5 (during a launch) but if they wanted an engine for M5 they should have been aware of REL's LAPCAT work, which is a completely different cycle, optimized for M5 cruise.

I think it's very clear from their choice of the SABRE cycle and willingness to look at cryogens that this work is specifically aimed at launching payloads ASAP, the so called "responsive space" notion.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline flymetothemoon

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #247 on: 04/16/2015 07:59 PM »
May I at this point out that for the second time that 20 billion dollars (my random, but somewhat educated guess at current cost now) is not a lot of money in terms of US govt spending...

I am slightly concerned about IP having been already handed over in this CRADA process however...

Offline Star One

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #248 on: 04/16/2015 08:35 PM »

May I at this point out that for the second time that 20 billion dollars (my random, but somewhat educated guess at current cost now) is not a lot of money in terms of US govt spending...

I am slightly concerned about IP having been already handed over in this CRADA process however...

But it's not chicken feed either especially these days when even the USAF is feeling the pinch hence why they keep trying to retire various aircraft so they can fund things like the F-35.

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #249 on: 04/17/2015 01:17 AM »
It probably should be pointed out that the USAF is formulating proposals for a next generation bomber and a 6th generation fighter, with hypersonic.on the wish list for the latter.



DM

Offline Star One

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The Reaction Engines Skylon Master Thread (5)
« Reply #250 on: 04/17/2015 06:21 AM »
It probably should be pointed out that the USAF is formulating proposals for a next generation bomber and a 6th generation fighter, with hypersonic.on the wish list for the latter.

The bomber is well, well beyond formulating proposals being as they've effectively admitted to it being at the prototype stage so isn't relevant here.
« Last Edit: 04/17/2015 06:23 AM by Star One »

Offline momerathe

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #251 on: 04/17/2015 02:59 PM »
Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.

Could REL develop the two engines in parallel? I'm going to say no. Regardless of the similarities, I would expect the detailed engineering on either one would consume their entire energies.
thermodynamics will get you in the end

Offline flymetothemoon

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #252 on: 04/17/2015 05:17 PM »
Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.

Could REL develop the two engines in parallel? I'm going to say no. Regardless of the similarities, I would expect the detailed engineering on either one would consume their entire energies.

Actually I've always thought that too. The CRADA might have specified SABRE, but it seems extremely unlikely that the investigations didn't involve all types of uses they were interested in.

Offline Star One

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #253 on: 04/17/2015 06:41 PM »

Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.

Could REL develop the two engines in parallel? I'm going to say no. Regardless of the similarities, I would expect the detailed engineering on either one would consume their entire energies.

Totally agree that's what the USAF will be interested in not SABRE itself. There has been indications that the USAF would like to have some kind of hypersonic technological demonstrator in the air before the turn of the decade. How achievable that kind of target is for REL on the propulsion side whilst still trying to develop SABRE is anyone's guess.

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #254 on: 04/17/2015 06:45 PM »
Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.

Could REL develop the two engines in parallel? I'm going to say no. Regardless of the similarities, I would expect the detailed engineering on either one would consume their entire energies.
It's clear what the CRADA studied. It's equally clear that SABRE's focus is single stage to orbit launch and if the USAF chose to ignore that point that's their decision.

I will note that SABRE and Skylon are separate  designs. If the USAF were so minded they could look at a more conservative airframe that traded payload for more traditional aerospace materials.

How small I don't know. Part of it would depend on wheather they wanted orbit from a CONUS site, rather than an equatorial site. It would be an option.

Actually I've always thought that too. The CRADA might have specified SABRE, but it seems extremely unlikely that the investigations didn't involve all types of uses they were interested in.

It's not the use. LAPCAT's internals are completely different, with the turbine outside the core. IIRC it trades higher weight for better LH2 economy and of course eliminates all the air sealing system as it runs in atmosphere all the time.

May I at this point out that for the second time that 20 billion dollars (my random, but somewhat educated guess at current cost now) is not a lot of money in terms of US govt spending...

I am slightly concerned about IP having been already handed over in this CRADA process however...
The cargo transport contract to the ISS is about $18Bn

$20Bn is about a 66% rise on the last REL estimate I'm aware of ($12Bn.) That last rise was caused by including the Skylon Upper Stage to take payloads to GTO as part of the baseline development.

That's a lot of inflation compared to REL's estimate.  :(
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Online dror

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #255 on: 04/17/2015 07:00 PM »

$20Bn is about a 66% rise on the last REL estimate I'm aware of ($12Bn.) That last rise was caused by including the Skylon Upper Stage to take payloads to GTO as part of the baseline development.


Is that Skylon Upper Stage planned to be reusable and return to the Skylon befor reentry or expendable?
"If we crave some cosmic purpose, then let us find ourselves a worthy goal. "
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Offline flymetothemoon

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #256 on: 04/17/2015 07:07 PM »
Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.

Could REL develop the two engines in parallel? I'm going to say no. Regardless of the similarities, I would expect the detailed engineering on either one would consume their entire energies.
It's clear what the CRADA studied. It's equally clear that SABRE's focus is single stage to orbit launch and if the USAF chose to ignore that point that's their decision.

I will note that SABRE and Skylon are separate  designs. If the USAF were so minded they could look at a more conservative airframe that traded payload for more traditional aerospace materials.

How small I don't know. Part of it would depend on wheather they wanted orbit from a CONUS site, rather than an equatorial site. It would be an option.

Actually I've always thought that too. The CRADA might have specified SABRE, but it seems extremely unlikely that the investigations didn't involve all types of uses they were interested in.

It's not the use. LAPCAT's internals are completely different, with the turbine outside the core. IIRC it trades higher weight for better LH2 economy and of course eliminates all the air sealing system as it runs in atmosphere all the time.

Ok. But I am sure the USAF can use their imagination :)

May I at this point out that for the second time that 20 billion dollars (my random, but somewhat educated guess at current cost now) is not a lot of money in terms of US govt spending...

I am slightly concerned about IP having been already handed over in this CRADA process however...
The cargo transport contract to the ISS is about $18Bn

$20Bn is about a 66% rise on the last REL estimate I'm aware of ($12Bn.) That last rise was caused by including the Skylon Upper Stage to take payloads to GTO as part of the baseline development.

That's a lot of inflation compared to REL's estimate.  :(

You're right. I believe you are referring to last, fairly recent, estimates which included a reduction in price owing to potential new manufacturing approaches (was it manufacturing?). So I completely take that back. I was going by the old, old, oft quoted GBP price,  rounding up quite a lot for years passed and then adding a hefty conversion to dollars. Very back of envelope and prob very inaccurate.
« Last Edit: 04/17/2015 07:08 PM by flymetothemoon »

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #257 on: 04/17/2015 07:27 PM »
Is that Skylon Upper Stage planned to be reusable and return to the Skylon befor reentry or expendable?
It's designed for 10 reuses running on LH2/LO2 through a pair of the SOMA engines. It uses the idea of the duration for an orbit to near GEO being a sub multiple of the period of the Skylon's  orbit (so called "resonant" orbits) so it "falls" back to the Skylon orbit and the Skylon is in place to pick it up than bring it back.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline Star One

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #258 on: 04/17/2015 08:06 PM »

Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.

Could REL develop the two engines in parallel? I'm going to say no. Regardless of the similarities, I would expect the detailed engineering on either one would consume their entire energies.
It's clear what the CRADA studied. It's equally clear that SABRE's focus is single stage to orbit launch and if the USAF chose to ignore that point that's their decision.

I will note that SABRE and Skylon are separate  designs. If the USAF were so minded they could look at a more conservative airframe that traded payload for more traditional aerospace materials.

How small I don't know. Part of it would depend on wheather they wanted orbit from a CONUS site, rather than an equatorial site. It would be an option.

Actually I've always thought that too. The CRADA might have specified SABRE, but it seems extremely unlikely that the investigations didn't involve all types of uses they were interested in.

It's not the use. LAPCAT's internals are completely different, with the turbine outside the core. IIRC it trades higher weight for better LH2 economy and of course eliminates all the air sealing system as it runs in atmosphere all the time.

May I at this point out that for the second time that 20 billion dollars (my random, but somewhat educated guess at current cost now) is not a lot of money in terms of US govt spending...

I am slightly concerned about IP having been already handed over in this CRADA process however...
The cargo transport contract to the ISS is about $18Bn

$20Bn is about a 66% rise on the last REL estimate I'm aware of ($12Bn.) That last rise was caused by including the Skylon Upper Stage to take payloads to GTO as part of the baseline development.

That's a lot of inflation compared to REL's estimate.  :(

If you think everything that was studied was detailed in that press release then I would say that you would be mistaken.

Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #259 on: 04/17/2015 08:13 PM »
It IS important to note that the AF looked at the SABRE and its cycle specifically. As noted the HE itself has other uses that make the technology important to study but the cycle itself DOES actually have some uses beyond orbital launch, though NOT in a Skylon type vehicle :)

For example it could be used in a Hypersoar (http://en.wikipedia.org/wiki/HyperSoar) which does skip-glides at speeds of less than Mach-12. (Studies show a "sweet-spot" around Mach-6 actually) Or a deep cooled engine using another cycle is possible (http://www.secretprojects.co.uk/forum/index.php?topic=6422.0, http://www.secretprojects.co.uk/forum/index.php?topic=6422.0, etc) are possible as well.

The main point of contention is operationally the AF would rather avoid LH2 propellant if at all possible, however the CRADA makes it pretty clear that the entire operation of the SABRE cycle DEPENDS on using LH2 and deep cooling, (which it does) and so any consideration of using the technology has to take that into account.

That little item in and of itself is the main point of the whole exercise IMO. This points out very distinctly that while you can have other cycles that can possibly do what the SABRE does, the SABRE itself REQUIRES LH2 so any plans to utilize the cycle require the use of LH2. The AF has in the past has used H2O2, hydrazine, IRFNA, and other toxic and dangerous propellants but they have ONLY considered (and used) LH2 when they had no other choice for the mission they wanted. (And gladly dropped it if ANY other option was available) The wording tells me that someone, somewhere was of the mind that they could use the SABRE cycle without the LH2, ("Liquid Methane is cold, we really don't need LH2") and this pretty much puts the last nail in that coffin as it were. You want to use the SABRE cycle you have to use LH2, you don't want to do that then this cycle isn't for you.

So IF the AF wants this for a launch vehicle expect to hear more, if they are looking for anything else it won't be using the SABRE or LH2 :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

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