Author Topic: The Reaction Engines Skylon Master Thread (5)  (Read 419927 times)

Offline Radical_Ignorant

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1460 on: 04/04/2016 04:02 PM »
But to clarify: most of my criticism isn't aimed at REL, but at their fanbois. I'm sure REL would be happy to work on a TSTO. Hell, even developing a version of the pre-cooler for stationary generator gas turbines. It's the fanbois not REL itself who are screeching that any alternative proposal is "wrong" or "stupid", even when those proposing it are holding money.

I do think that in the early years, REL pushed Skylon too heavily and that actually harmed their ability to attract interest. It created the perception that they weren't open to other ideas: "We have this product that can only be used on one extremely high risk, extremely costly development. Plz send us ur monies"
{snip}

Can't disagree. As Space X, as I imagine it, didn't went to investors telling them "we want to colonize Mars somewhere 30-50 years down the road. Wanna give us few hundreds millions?" Space X goal is hard and then rarely even talked about. All focus is on next step, which in SX case is to make cheap space transport.

And here for REL they should/are focusing on engine. And if there is a way to generate revenue out of this engine then that's the way to go no matter if payer idea makes sense. If someone want to makes cats go to Internet faster using this engine let them do it if he pays btw for what REL guys and we all dream about :p

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1461 on: 04/04/2016 06:49 PM »

Can't disagree. As Space X, as I imagine it, didn't went to investors telling them "we want to colonize Mars somewhere 30-50 years down the road. Wanna give us few hundreds millions?" Space X goal is hard and then rarely even talked about. All focus is on next step, which in SX case is to make cheap space transport.
They didn't go to investors at all Musk was rich enough to fund F1 and F9.

REL have had to justify every penny they have been given.
Quote
And here for REL they should/are focusing on engine. And if there is a way to generate revenue out of this engine then that's the way to go no matter if payer idea makes sense. If someone want to makes cats go to Internet faster using this engine let them do it if he pays btw for what REL guys and we all dream about :p
A fair point.
"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 93143

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1462 on: 04/04/2016 11:26 PM »
Upper scale is existing infrastructure.

Skylon isn't intended to use existing infrastructure.  As I recall, REL were envisioning a new-built spaceport (or a new-built facility at an existing spaceport like Kourou) designed specifically to service it.

Offline Radical_Ignorant

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1463 on: 04/05/2016 07:32 AM »

Can't disagree. As Space X, as I imagine it, didn't went to investors telling them "we want to colonize Mars somewhere 30-50 years down the road. Wanna give us few hundreds millions?" Space X goal is hard and then rarely even talked about. All focus is on next step, which in SX case is to make cheap space transport.
They didn't go to investors at all Musk was rich enough to fund F1 and F9.

REL have had to justify every penny they have been given.

No, Musk money was not enough. https://www.quora.com/How-much-money-has-SpaceX-raised-and-who-from (and that's only the beginning) But yeah, you are right, they needed little more money, not all the money. So had much more freedom in how to operate. And the second difference is NASA - early contract allowed them to develop F9. IIRC Musk money was enough for three failed launches of F1 (and building company). At least that what he was saying at the very start.
But I'm getting little off topic.
« Last Edit: 04/05/2016 09:57 AM by Radical_Ignorant »

Offline Jim

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1464 on: 04/05/2016 11:34 AM »
(it really helps that Kourou has cleanroom standard vehicles with an airlock for moving things between buildings)

It isn't that great of idea. Just an unnecessary move.  Just put the fairing on the payload before bringing it to the launch vehicle.
« Last Edit: 04/05/2016 11:35 AM by Jim »

Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1465 on: 04/05/2016 10:19 PM »
The scramjet research and the people involved have no sensible bearing on space launch, so why the hell ask them to comment on SABRE?

Scramjet researchers may be biased.  But so might the people at REL.  Scramjet researchers are experts on propulsion at these speeds.  There's basically just them and REL.  Both could potentially have some bias, but if you want a perspective from outside REL, there's nobody better to give it than scramjet researchers.

Whether the goal is space launch or missiles, it's still propulsion at hypersonic speeds.

So, it makes sense to be wary of what scramjet researchers say about Skylon, and keep a critical frame of mind, but not to dismiss it out of hand.

Actually I have to disagree because SCramjet researches have a biased opinion BECAUSE SABRE is somewhat of a "hypersonic" propulsion system which therefore is directly in competition with them and they are pretty vocal about it. Yes REL has some bias' about SCramjets, so does anyone who's ever worked on or built subsonic combustion ramjets, including the majority of folks who initially worked the hardest ON SCramjet research.
(The same folks that actually BUILT operational ramjets all the way into the '90s before SCramjet research managed to convince everyone that ramjets were obsolete)

And ask yourself if you really get any good information from someone who has never researched or worked on anything BUT SCramjets on systems they therefore know nothing about? (Hint? While yes aero-propulsion systems are generally the same the devil is in the details and the people you're talking to in fact don't really know that much about anything BUT SCramjet propulsion)

The point, and it's quite a valid one, is that asking someone who works on SCramjets about a zero-to-hypersonic propulsion system is going to get you a vary biased and probably highly inaccurate answer because the person you're asking ONLY works with hypersonic to VERY-HIGH hypersonic propulsion and not anything that can start from zero and even go supersonic let alone reach hypersonic speeds on it's own. And you're asking the question of someone who very well knows that any positive answer can potentially cause their own research to lose funding, support, or interest.

SABRE barely touches hypersonic speed, (at most Mach-6 when "hypersonic" is at least Mach-5) it uses a compressor, it has rocket engines, and it takes off from a runway all of which a SCramjet doesn't do and frankly no one has been designing them to for almost 40 years. SCramjet researchers have all been concentrating on getting from Mach-7, (where a SCramjet starts working efficiently if at all) to higher speeds, the closest they have come in the last 20 years to addressing the "zero-to-" issue is suggesting an integral rocket/ramjet/SCramjet but since the 'duel-mode' SCramjet (a subsonic and supersonic combustion ramjet in one engine) never panned out and SCramjet research has sucked up all the money for integral rocket/ramjet research there has been nothing else but to launch SCramjet test articles by brute force rocket launch. Yet the same folks will tell you how wonderful the "theory" is that once we have SCramjets we can "easily" fly to Mach-26+ in the atmosphere and drift out into space for pennies per pound...

And you want their opinion on a possible competitor system?

Granted REL has their own issues but if you want an "outside" opinion you'd need to get one from someone who's probably at least in theory qualified to actually give you an accurate answer wouldn't you think?

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 Star One

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1466 on: 04/05/2016 10:36 PM »
The scramjet research and the people involved have no sensible bearing on space launch, so why the hell ask them to comment on SABRE?

Scramjet researchers may be biased.  But so might the people at REL.  Scramjet researchers are experts on propulsion at these speeds.  There's basically just them and REL.  Both could potentially have some bias, but if you want a perspective from outside REL, there's nobody better to give it than scramjet researchers.

Whether the goal is space launch or missiles, it's still propulsion at hypersonic speeds.

So, it makes sense to be wary of what scramjet researchers say about Skylon, and keep a critical frame of mind, but not to dismiss it out of hand.

Actually I have to disagree because SCramjet researches have a biased opinion BECAUSE SABRE is somewhat of a "hypersonic" propulsion system which therefore is directly in competition with them and they are pretty vocal about it. Yes REL has some bias' about SCramjets, so does anyone who's ever worked on or built subsonic combustion ramjets, including the majority of folks who initially worked the hardest ON SCramjet research.
(The same folks that actually BUILT operational ramjets all the way into the '90s before SCramjet research managed to convince everyone that ramjets were obsolete)

And ask yourself if you really get any good information from someone who has never researched or worked on anything BUT SCramjets on systems they therefore know nothing about? (Hint? While yes aero-propulsion systems are generally the same the devil is in the details and the people you're talking to in fact don't really know that much about anything BUT SCramjet propulsion)

The point, and it's quite a valid one, is that asking someone who works on SCramjets about a zero-to-hypersonic propulsion system is going to get you a vary biased and probably highly inaccurate answer because the person you're asking ONLY works with hypersonic to VERY-HIGH hypersonic propulsion and not anything that can start from zero and even go supersonic let alone reach hypersonic speeds on it's own. And you're asking the question of someone who very well knows that any positive answer can potentially cause their own research to lose funding, support, or interest.

SABRE barely touches hypersonic speed, (at most Mach-6 when "hypersonic" is at least Mach-5) it uses a compressor, it has rocket engines, and it takes off from a runway all of which a SCramjet doesn't do and frankly no one has been designing them to for almost 40 years. SCramjet researchers have all been concentrating on getting from Mach-7, (where a SCramjet starts working efficiently if at all) to higher speeds, the closest they have come in the last 20 years to addressing the "zero-to-" issue is suggesting an integral rocket/ramjet/SCramjet but since the 'duel-mode' SCramjet (a subsonic and supersonic combustion ramjet in one engine) never panned out and SCramjet research has sucked up all the money for integral rocket/ramjet research there has been nothing else but to launch SCramjet test articles by brute force rocket launch. Yet the same folks will tell you how wonderful the "theory" is that once we have SCramjets we can "easily" fly to Mach-26+ in the atmosphere and drift out into space for pennies per pound...

And you want their opinion on a possible competitor system?

Granted REL has their own issues but if you want an "outside" opinion you'd need to get one from someone who's probably at least in theory qualified to actually give you an accurate answer wouldn't you think?

Randy

Except what LM is looking into longer term for its air breathing vehicle isn't a pure scramjet.

Quote
Hewson also showed an image of a third hypersonic concept, similar to the HAWC but with a recoverable “turbine-based combined cycle” engine, Weiss explained. The HAWC’s booster is designed for a single use, he stressed. There is not yet a DARPA project for this capability, and Lockheed still needs to mature the propulsion technology, he said.

http://www.defensenews.com/story/defense/air-space/2016/03/16/lockheeds-marilyn-hewson-touts-breakthroughs-hypersonic-weapons/81836070/


Offline knowles2

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1467 on: 04/05/2016 11:09 PM »

Can't disagree. As Space X, as I imagine it, didn't went to investors telling them "we want to colonize Mars somewhere 30-50 years down the road. Wanna give us few hundreds millions?" Space X goal is hard and then rarely even talked about. All focus is on next step, which in SX case is to make cheap space transport.
They didn't go to investors at all Musk was rich enough to fund F1 and F9.

REL have had to justify every penny they have been given.
Quote
And here for REL they should/are focusing on engine. And if there is a way to generate revenue out of this engine then that's the way to go no matter if payer idea makes sense. If someone want to makes cats go to Internet faster using this engine let them do it if he pays btw for what REL guys and we all dream about :p
A fair point.
Musk wasn't rich enough, in fact he had to borrow money after the first three F1s blew up to fund the launch of the 4th and Spacex been borrowing money ever since.

But he had enough connections that he borrowed money of his rich silicon valley buddies, many of them I suspect thought it would just be fun to see if he could do it rather than as a series investment opportunity.

Offline oddbodd

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1468 on: 04/05/2016 11:11 PM »

Except what LM is looking into longer term for its air breathing vehicle isn't a pure scramjet.


If you follow the thread back I was the original person criticizing the article - that was only about Skylon - for quoting the opinions of scramjet researchers. The article (http://forum.nasaspaceflight.com/index.php?topic=36826.msg1508669#msg1508669) had nothing to do with LM except for referencing the LM X-33 program that never flew and was canceled some 15 years ago. No-one else mentioned LM, so I don't understand the relevance of your point/response to Randy, which I guess relates to the proposals for their new SR-72 program engines. I only seek enlightenment btw, not trying to start a flame fest.
« Last Edit: 04/05/2016 11:15 PM by oddbodd »

Offline ChrisWilson68

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1469 on: 04/06/2016 02:31 AM »

Except what LM is looking into longer term for its air breathing vehicle isn't a pure scramjet.


If you follow the thread back I was the original person criticizing the article - that was only about Skylon - for quoting the opinions of scramjet researchers. The article (http://forum.nasaspaceflight.com/index.php?topic=36826.msg1508669#msg1508669) had nothing to do with LM except for referencing the LM X-33 program that never flew and was canceled some 15 years ago. No-one else mentioned LM, so I don't understand the relevance of your point/response to Randy, which I guess relates to the proposals for their new SR-72 program engines. I only seek enlightenment btw, not trying to start a flame fest.

The article seemed pretty balanced between Skylon optimists and skeptics to me.  There were lots of quotes from a REL representative, and the non-Skylon people expressed a mix of skepticism and hope.  It was not a Skylon-bashing article.

If there are two main approaches, A and B, in any field, then the people working in the field who don't think A is the best approach will naturally be working on approach B.  Your argument seems to be that we should ignore all statements by people working on approach B.  I think that causes you to miss the opportunity to hear from the people most likely to have valid criticisms of approach A.  Sure, be aware that people working on B might have some bias, but listen and consider what they say, don't just dismiss it out of hand.  Unless, of course, you only want to hear opinions that confirm what you already believe.

Offline 93143

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1470 on: 04/06/2016 06:43 AM »
I'd suggest that people don't usually work on a particular project because they've expertly assessed all the options and chosen what they think is the best one.  They are more likely to favour an approach (and/or have a dim view of alternatives) because it's what they've been working on their whole careers, since long before they had the expertise to assess the options.

If these scramjet guys had expressed valid concerns, that would be one thing.  But as far as I can tell from the article's quotes, there was no substance to their skepticism at all.  A bit of generic information about why SSTOs have been hard to build, and how you make engineering decisions when designing one, but no actual analysis or reasoning to support their negativity on the subject of Skylon specifically.
« Last Edit: 04/06/2016 09:37 AM by 93143 »

Offline MIKKELH

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1471 on: 04/06/2016 09:38 AM »
Please forgive me if this has already been discussed, but I ven't had the time to read all the 77 pages of posts in this thread, let alone the previous threads. I have my own reservations about Skylon, not because it is not pausible, nor even because the economic model won't work. Rather, I tend to agree with the argument that they are not thinking incrementally enough. It is not so mich that they are tacklong too many unknowns... It is that they are not taking a good look at what their engine actually does. Skylon is not really a novel engine design. It is at most a novel arrangement of engine omponents. What IS new is that rather than carrying pre-processed oxidizer in a heavy tank, they are collecting and processing oxygen as they go up. Personally, I think this is brilliant, but they are spending too mich time looking at other things.
Why not stick with basic, well proven, rocket engine designs? For the most part, this is all the thrust producing part of a Saber engine actually is. They have a collection of small conventional thrust chambers and nozzles, which is rather silly because these small thrusters are much less efficient than a single thruster with the same thrust load would be.
Why not stick with a proven booster design? Okay, a horizontal lift rocket would have the benefit of being able to use unsophisticated airport runways.... You just need to add LH propellant storage facilities. But, for the short term, stick with rockets that get out of the atmosphere more quickly... And thus reduce the total deltas v loss resulting from aerodynamic and gravity drag.
Finally, instead of developing an engine that produces just the right amount of oxygen flow as it is needed, and weighing down your rocket with the oxidizer mass required for operations when the atmosphere is too rarified for collection, why not stick with an oversized air collector and processor? Instead of solid rocket boosters, have strap on air collectors capable of processing large quantities of air, extracting water vapour centrifugally before comprssion, cooling the remaining air down to liquid temperatures ( condensation issues no longer being a major development concern because you are no longer feeding the processed oxygen in directly) during the compression stage, and feeding the liquid air (perhaps after separating the oxygen from the nitrogen centrifugally) to an initially empty propellant tank (initially loaded with just enough gaseous oxygen to support sea level air pressure). The key is to have a large enough intake not only to collect the amount of oxygen required for combustion, but to also fill the oxidiser tank while on the way up. Once at an altitude too high for oxygen collection, these strap on units will be jettisoned for recovery. Not only does this dramatically decrease launch mass, it also means that you can jettison the mass of the air intakes and compressors. As a side note, the extracted water and nitrogen could either be jettisoned directly, or collected in another 'empty' tank for space station supply.

Offline francesco nicoli

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1472 on: 04/06/2016 02:32 PM »
US military to reveal Skylon-based launch vehicle

http://www.rocketeers.co.uk/node/4613

Offline Star One

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1473 on: 04/06/2016 02:53 PM »
US military to reveal Skylon-based launch vehicle

http://www.rocketeers.co.uk/node/4613

Can't see anything new in that, that hasn't already been reported up thread?

Offline MIKKELH

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1474 on: 04/06/2016 04:03 PM »
What IS new is that rather than carrying pre-processed oxidizer in a heavy tank, they are collecting and processing oxygen as they go up

They're not. SABRE is not a LACE
SABRE is an evolutional development of LACE. The principal responsible for SABRE was co-creator of LACE, and all the work on SABRE was a continuation of the lessons learnt from LACE research. The essential difference between the two is that LACE liquified the oxygen, whereas SABRE keeps the oxygen above the condensation point, which I have already alluded to. There is also a difference in the intended structural design of the host craft (Skylon vs HOTOL) in that the engines are moved forward to correct for a cascade of problems resulting from the original engine placement causing the CG to be moved too far back.

Offline ChrisWilson68

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1475 on: 04/06/2016 05:54 PM »
US military to reveal Skylon-based launch vehicle

http://www.rocketeers.co.uk/node/4613

You make it sound like they're about to pull a curtain back and show the world an operational vehicle that is ready to fly.

I think it's more accurate to say "A US military research lab is going to present a paper outlining a two-stage launch vehicle concept using SABRE engine technology."

There's a big difference between SABRE-based and Skylon-based.  And there's a big difference between presenting a concept for a vehicle and unveiling an actual vehicle, or even a funded vehicle development program.

The truth of this is a big positive for REL.  No need to exaggerate.

Offline oddbodd

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1476 on: 04/06/2016 06:11 PM »

Except what LM is looking into longer term for its air breathing vehicle isn't a pure scramjet.


If you follow the thread back I was the original person criticizing the article - that was only about Skylon - for quoting the opinions of scramjet researchers. The article (http://forum.nasaspaceflight.com/index.php?topic=36826.msg1508669#msg1508669) had nothing to do with LM except for referencing the LM X-33 program that never flew and was canceled some 15 years ago. No-one else mentioned LM, so I don't understand the relevance of your point/response to Randy, which I guess relates to the proposals for their new SR-72 program engines. I only seek enlightenment btw, not trying to start a flame fest.

The article seemed pretty balanced between Skylon optimists and skeptics to me.  There were lots of quotes from a REL representative, and the non-Skylon people expressed a mix of skepticism and hope.  It was not a Skylon-bashing article.

If there are two main approaches, A and B, in any field, then the people working in the field who don't think A is the best approach will naturally be working on approach B.  Your argument seems to be that we should ignore all statements by people working on approach B.  I think that causes you to miss the opportunity to hear from the people most likely to have valid criticisms of approach A.  Sure, be aware that people working on B might have some bias, but listen and consider what they say, don't just dismiss it out of hand.  Unless, of course, you only want to hear opinions that confirm what you already believe.

I have no problem with a countering view point, I'm just not convinced of the scramjet researchers as particularly good ones. A scramjet is (at least currently as far as I'm aware) a single mode engine more related to a pure jet (not turbine jet). If the article had quoted counterpoints from LACE, turbine jet, and/or rocket engine researchers/designers they would have made better skeptics. Instead only scramjet researchers were quoted, and as 93143 said, they weren't particularly good as skeptics.

Anyway, I think the horse is well and truly flogged on this.

[edited to remove the unintentional scamjet Freudian slip typo ;D]
« Last Edit: 04/06/2016 06:33 PM by oddbodd »

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1477 on: 04/06/2016 06:17 PM »
What IS new is that rather than carrying pre-processed oxidizer in a heavy tank, they are collecting and processing oxygen as they go up

They're not. SABRE is not a LACE
SABRE is an evolutional development of LACE. The principal responsible for SABRE was co-creator of LACE, and all the work on SABRE was a continuation of the lessons learnt from LACE research.
Who are you talking about? HOTOL was not a LACE system.
Quote
The essential difference between the two is that LACE liquified the oxygen, whereas SABRE keeps the oxygen above the condensation point, which I have already alluded to. There is also a difference in the intended structural design of the host craft (Skylon vs HOTOL) in that the engines are moved forward to correct for a cascade of problems resulting from the original engine placement causing the CG to be moved too far back.
What exactly is the question you were asking?

US military to reveal Skylon-based launch vehicle

http://www.rocketeers.co.uk/node/4613

Can't see anything new in that, that hasn't already been reported up thread?
No. TL:DR version. LM say they've made lots of improvements to make a hypersonic weapon system. Please give us the money to build one.
"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 john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1478 on: 04/06/2016 06:22 PM »
And there's a big difference between presenting a concept for a vehicle and unveiling an actual vehicle, or even a funded vehicle development program.
True.

LM continues their PR campaign to get build an "SR72," whatever that is.
"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 oddbodd

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1479 on: 04/06/2016 06:29 PM »
SABRE is an evolutional development of LACE. The principal responsible for SABRE was co-creator of LACE, and all the work on SABRE was a continuation of the lessons learnt from LACE research. The essential difference between the two is that LACE liquified the oxygen, whereas SABRE keeps the oxygen above the condensation point, which I have already alluded to. There is also a difference in the intended structural design of the host craft (Skylon vs HOTOL) in that the engines are moved forward to correct for a cascade of problems resulting from the original engine placement causing the CG to be moved too far back.

Huh? Maybe it's a language thing, but co-creator? It reads a bit like you are saying the same person who came up with LACE also came up with SABRE, which is not true. I think it is a lost-in-translation thing though. Yes, the SABRE learnt from the lessons of LACE, but they are substantially different. AIUI LACE is a single mode engine that collects and uses/stores liquid oxygen (discarding the 80% nitrogen) before powering out of the atmosphere meaning it has to cruise in atmosphere for some period of time to collect sufficient oxygen. SABRE is a dual-mode engine that uses atmospheric gaseous oxygen/nitrogen while in-atmosphere and ground loaded on-board liquid oxygen for the exit from the atmosphere, which means it does not need to cruise along collecting oxygen. I'd call SABRE a cousin rather than progeny of LACE.

LACE was never an option for HOTOL, so not sure why you bring up the difference between HOTOL and Skylon here. The RB545 was designed for HOTOL, and is still classified top secret. I'd love to know what the big deal was with that engine.
« Last Edit: 04/06/2016 06:36 PM by oddbodd »

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