Author Topic: The Reaction Engines Skylon/SABRE Master Thread (6)  (Read 298572 times)

Offline edzieba

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #980 on: 04/16/2018 01:25 PM »
Only air-breathing tests will be carried out at Westcott no lox will be used at the site. Full rocket tests will be carried out at a more remote site like Spadeadam.
That's a bit of a spanner in the works: it means that Wescott cannot host a full systems cycle test of SABRE. In order to test the transition from air-breathing to rocket operation and back again, a new test site would be needed with the same equipment as Wescott plus the ability to test the rocket portion. It's possible RE intend to test a non-rocket SABRE engine in flight first (a product that has some existing demand), before looking at a combined cycle version.

The only other question I would have liked to have answered was wheather this is going to demonstrate the E/D nozzle, or wheather that's one of the modules that's not needed.  :(
I think I added it to my notes on the earlier talk, but the E-D nozzle testing ('Demo-R') is no longer going to be public, and is behind Demo A in priority. E-D development is mainly going on in university partnerships rather than internally to RE.

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #981 on: 04/16/2018 04:14 PM »
Only air-breathing tests will be carried out at Westcott no lox will be used at the site. Full rocket tests will be carried out at a more remote site like Spadeadam.
That's a bit of a spanner in the works: it means that Wescott cannot host a full systems cycle test of SABRE. In order to test the transition from air-breathing to rocket operation and back again, a new test site would be needed with the same equipment as Wescott plus the ability to test the rocket portion. It's possible RE intend to test a non-rocket SABRE engine in flight first (a product that has some existing demand), before looking at a combined cycle version.
True. It's potentially quite a serious restriction. Unless (somehow) other companies bring their own oxidizer plumbing that limits you to Hydrogen fueled air breathing engines. I'm not sure how big a range of vehicle that is. 

Quote from: edzieba
The only other question I would have liked to have answered was wheather this is going to demonstrate the E/D nozzle, or wheather that's one of the modules that's not needed.  :(
I think I added it to my notes on the earlier talk, but the E-D nozzle testing ('Demo-R') is no longer going to be public, and is behind Demo A in priority. E-D development is mainly going on in university partnerships rather than internally to RE.
TBH that's pretty much how all the E/D nozzle work was done. Bristol U advanced degree candidates did the analysis and design. Airbourne Engineering have done the build.

Note that SABRE 4 no longer shares air breathing and rocket combustion in the same thrust chamber. In principle it might have no rocket combustion chamber and run entirely in AB mode, with TC(s) optimized to run at jet engine pressures (today 10, not 100 atm is high pressure in a jet engine).  This is (AFAIK) what lets them dispense with the high grade frost control system of SABREs 1-3. However while it has a pre-burner in the loop it will always need a LOX supply to operate.

This means any use of SABRE 4 can be leveraged to a full earth to orbit capable engine.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline JCRM

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #982 on: 04/17/2018 02:32 PM »
However while it has a pre-burner in the loop it will always need a LOX supply to operate.
That would make testing at Westcott tricky. All the SABRE diagrams with preburners show air being used in airbreathing mode.

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #983 on: 04/17/2018 03:22 PM »
However while it has a pre-burner in the loop it will always need a LOX supply to operate.
That would make testing at Westcott tricky. All the SABRE diagrams with preburners show air being used in airbreathing mode.
Well that changes things quite a lot. With the pre burner capable of running both with LOX and air you can (in principle) build a straight air breathing engine by just not including the rockets bits IE LOX tank, LOX pumps and and all their associated plumbing.

Still not good though unless there are many air/H2 engines around Europe looking for reasonably sized (and priced) test facilities. It's a safe bet REL know more than the average poster about such a market.

This raises a further interesting question.  The EU funded LAPCAT work developed a "Low NoX" burner for the Scimitar engine, but I think incorporating the burner design inside a rocket sized (and pressure) thrust chamber was going to be difficult. With separate chambers that may be a lot simpler.

Apparently NoX production is a concern for LH2 air breathing systems. IIRC they normally run a lot hotter than kerosene based engines and that makes them much better NoX producers, hurting their "Green" credentials. Given LAPCAT and LAPCAT[ II's goals for large civilian passenger transport this was a concern.
IIRC the combustion modelling (Pisa, or Turnin Universities IIRC) reckoned the REL design was much better at this. 10-100x lower than known systems.
« Last Edit: 04/17/2018 03:28 PM by john smith 19 »
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Star One

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #984 on: 04/18/2018 01:29 PM »
Read an article today in Flight International today about this additional investment and it was stated in it that the initial applications will be in space, so I sure did get that wrong thinking it would be military first. Though they also mentioned the application of the technology in non space & aviation industries.

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #985 on: 04/18/2018 04:02 PM »
Read an article today in Flight International today about this additional investment and it was stated in it that the initial applications will be in space, so I sure did get that wrong thinking it would be military first. Though they also mentioned the application of the technology in non space & aviation industries.
Yes it seems you did.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Star One

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The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #986 on: 04/18/2018 04:16 PM »
Read an article today in Flight International today about this additional investment and it was stated in it that the initial applications will be in space, so I sure did get that wrong thinking it would be military first. Though they also mentioned the application of the technology in non space & aviation industries.
Yes it seems you did.

Well thatís because I am more likely to take the word of a professionally written article in well respected publication than some random individual online.
« Last Edit: 04/18/2018 04:17 PM by Star One »

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #987 on: 04/18/2018 10:38 PM »
Read an article today in Flight International today about this additional investment and it was stated in it that the initial applications will be in space, so I sure did get that wrong thinking it would be military first. Though they also mentioned the application of the technology in non space & aviation industries.
Yes it seems you did.

Well thatís because I am more likely to take the word of a professionally written article in well respected publication than some random individual online.
Perhaps you shouldn't take the word of anyone and look for the evidence instead from the actual people involved?

BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline JCRM

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #988 on: 04/20/2018 11:16 AM »
Read an article [stating] the initial applications will be in space, so I sure did get that wrong thinking it would be military first.
REL do seem to suffer from writers biases, I don't know if this is more so than others or if it's just horizontal takeoff that does it - the Telegraph put the emphasis on hypersonic airliners.
When agreements are being signed with USAF, and the company's web site talks of "hypersonic mission applications," then not considering the military aspects of the technology would be a shocking oversight. It's certainly not certain whether the first application will be civilian or military -- even if the path to Skylon is REL's focus.
Quote from: Star One
Though they also mentioned the application of the technology in non space & aviation industries.
And REL tweeted about  the investment allowing commercialisation of proprietary thermal management

Speaking of tweets:

From the REI twitter:

I've not seen a layout of TF2 before, Perhaps the lilac bits are being shipped from the UK?

Offline ChrisWilson68

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #989 on: 04/20/2018 11:32 AM »

No, it doesn't.

The real effect on budget depends on many factors.  You're just taking one factor and ignoring the rest.

If each vehicle has more margin, each can be far cheaper to develop than a single vehicle.  And the two can potentially have commonality.  And one or the other can re-use some existing technology.  It's not just a "fully ready to go upper stage to drop in" or nothing -- there's a whole range of possibilities.  And the combined size of the two vehicles can potentially be smaller for the same payload to orbit when staging is used.
I fear I have not been explicit enough. I was talking about the development budget. You seem to be talking about the manufacturing budget.

No, I was talking about the development budget.
So by your thinking the more alike the two (or three) stages are the cheaper they will be?
Because that's exactly the thinking behind the Bi or Triamese, as GD/Convair proposed for STS and BAC with MUSTARD.  Identical stages with identical engines.

Except no one has ever gone that way.

No.  Again, not what I said, and not what I meant.

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #990 on: 04/20/2018 05:21 PM »

No, it doesn't.

The real effect on budget depends on many factors.  You're just taking one factor and ignoring the rest.

If each vehicle has more margin, each can be far cheaper to develop than a single vehicle.  And the two can potentially have commonality.  And one or the other can re-use some existing technology.  It's not just a "fully ready to go upper stage to drop in" or nothing -- there's a whole range of possibilities.  And the combined size of the two vehicles can potentially be smaller for the same payload to orbit when staging is used.
I fear I have not been explicit enough. I was talking about the development budget. You seem to be talking about the manufacturing budget.

No, I was talking about the development budget.
So by your thinking the more alike the two (or three) stages are the cheaper they will be?
Because that's exactly the thinking behind the Bi or Triamese, as GD/Convair proposed for STS and BAC with MUSTARD.  Identical stages with identical engines.

Except no one has ever gone that way.

No.  Again, not what I said, and not what I meant.
Actually it kind of is.   :(

The implication is that 2 complete vehicles will cost less than 1 complete vehicle to design, develop, test and mfg despite the fact one of those vehicles will cover the whole operating range of the single vehicle anyway and they will interact with each other (as well as both interacting with the environment) as they fly the trajectory.

But each will cost no more than 50% of the budget for 1 complete vehicle to do so.

Or maybe you'd like to think about what it is you are trying to say and y'know, say it?
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Jim Davis

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #991 on: 04/20/2018 10:41 PM »
The implication is that 2 complete vehicles will cost less than 1 complete vehicle to design, develop, test and mfg despite the fact one of those vehicles will cover the whole operating range of the single vehicle anyway and they will interact with each other (as well as both interacting with the environment) as they fly the trajectory.

Not only is it the implication, it has thus far been the reality. Every orbital launcher since the beginning of the space age has used 2 (or more) complete vehicles to achieve orbit and their designers, from many different nations and political and economic systems, have concluded that this would "cost less than 1 complete vehicle to design, develop, test and mfg despite the fact one of those vehicles will cover the whole operating range of the single vehicle anyway and they will interact with each other (as well as both interacting with the environment) as they fly the trajectory."

Are you suggesting that everyone has had it wrong since the '50s?

Online Steven Pietrobon

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #992 on: 04/21/2018 07:08 AM »
Not only is it the implication, it has thus far been the reality. Every orbital launcher since the beginning of the space age has used 2 (or more) complete vehicles to achieve orbit and their designers, from many different nations and political and economic systems, have concluded that this would "cost less than 1 complete vehicle to design, develop, test and mfg despite the fact one of those vehicles will cover the whole operating range of the single vehicle anyway and they will interact with each other (as well as both interacting with the environment) as they fly the trajectory."

Atlas B which launched SCORE was 1.5 vehicles. :-)

Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #993 on: 04/21/2018 08:10 AM »
Not only is it the implication, it has thus far been the reality. Every orbital launcher since the beginning of the space age has used 2 (or more) complete vehicles to achieve orbit and their designers, from many different nations and political and economic systems, have concluded that this would "cost less than 1 complete vehicle to design, develop, test and mfg despite the fact one of those vehicles will cover the whole operating range of the single vehicle anyway and they will interact with each other (as well as both interacting with the environment) as they fly the trajectory."

Are you suggesting that everyone has had it wrong since the '50s?
No, because once again context is very important in this question.  :(

Firstly let's be real and note that nuclear weapons delivery has been the driver of the technology so money has never been the issue, "performance" IE % of GTOW to drop on Moscow/Washington/Beijing/London/Paris has dominated the issue. The reliability (or otherwise) of second stage engine ignition and stage separation was not that high a priority because, bluntly, when you're dropping a few thousand nukes on someone a few dud launches does not matter.

So when you have

Unlimited budget (because it's national defense) x high propellant consumption(relative to air breathers) x vertical launch (for small defendable site and rockets viewed as "artillery") -->TSTO.

Note that money was not a constraint, post Sputnik.

Once you factor in the technology of the time TSTO (or "1 and 1/2" in the case of the Atlas) was inevitable.

The constraints that have persisted since then are
a) Poor payload fraction of rocket based SSTO concepts.
b) Very poor fuel consumption of rockets compared to air breathers.
c) Poor T/W ratio of air breathers relative to rockets.
d) Very little pressure to build relatively low mass fraction aircraft structures.

a) is the killer. "Sure we can (probably) do it but for the same GTOW we can get (with a TSTO) 2 or 3x the payload to orbit."
Now when you think about it about who cares about how much the GTOW is?
When you buy a car or boat do you (or have you?) worried it might be too heavy for your budget?

Because Cost Estimating Relationships (in aerospace), which "predict" what designs will cost, are dominated  by the mass of something.
Not number of parts. Not mfg complexity of parts.
Weight.

So, right there is the #1 killer of all previous SSTO concepts that needed exterior funding. As a result people keep doing what they've always done. As a consequence they get what they always got.

b, c & d Ensure if (by some miracle) you did convince (or you're rich enough to fund yourself) they will suffer with the following problems.
a) VTOL air breathers need very big engines due to poor T/W ratio. So still a TSTO but with more complexity.
b) HTOL with conventional air breathing and/or rockets means very big TSTO, but including a big hypersonic aircraft as the first stage (at least. As a data point the F9 booster separates at M6). But again it's going to be very  heavy and therefor (because our CER says so) very expensive.

tl;dr. Conventional engine technologies cannot deliver a SSTO that a) Delivers the same mass of payload to orbit as a TSTO b) Can be built with high confidence that weight growth won't eat all allowed margins.

When you put in all the constraints with existing technology the VTO TSTO is the obvious option and people have simply swallowed all the associated costs with it.  :(

So the real definition of a "better" LV is
a) Higher payload fraction to orbit (currently 2-3.5% of GTOW for TSTO.) How about say 6% of GTOW? That would be a serious improvement over the SoA or
b) Cut the number of stages.

a) can be done if 6% of the TSTO is structure and 6% is payload if the Isp is about 937secs, but AB engines have T/W ratios of 10:1 (at best. SCramjets are 2.5-5x worse than that). Can you do a rocket structure given the engine T/W has gone down from at least 6x (for LH2/LO2 engines) or > 13x for RP1/LO2)? Maybe if you get the high Isp over enough of the trajectory. But it's dubious.
b) Is possible for HTOL. Wings cancel most of the gravity losses for a start. Thrust can be less than GTOW.

That leaves the open question of wheather it's possible to build a SSTO HTOL plane within the necessary structural fraction. IMHO it's the area which has been least explored and which therefor has the most likelihood of being possible IE the least risk of failure.

Basically everything else results in yet another TSTO ELV, with a 50/50 of a successful first launch leading (if it launches enough and often enough with no major changes) to a loss rate of 1-2%

Would you get in your car if I could guarantee somewhere in every 50-100 engine starts the car will explode?

tl;dr No, rocket designers have done the best they could within the limits of the existing technology. SABRE opens those limits a lot. "Game changer" is a cliche. But it does change the rules you have to play by to win "the game".
« Last Edit: 04/21/2018 08:37 AM by john smith 19 »
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Online FutureSpaceTourist

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #994 on: 04/21/2018 02:07 PM »
Interesting article about the history of Westcott with a bit of current and planned uses including REL:

Quote
The return of a secret British rocket site
Westcott Venture Park was once the centre of the UKís Cold War rocket research. Left idle for years, itís now enjoying a second wind as British firms unveil new 21st Century designs.

By Paul Marks
19 April 2018

http://www.bbc.com/future/story/20180418-the-return-of-a-secret-british-rocket-site

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #995 on: 04/22/2018 10:54 AM »
When agreements are being signed with USAF, and the company's web site talks of "hypersonic mission applications," then not considering the military aspects of the technology would be a shocking oversight. It's certainly not certain whether the first application will be civilian or military -- even if the path to Skylon is REL's focus.
One of those "military missions" is the on demand launch of payloads to increase capability to do some things over certain areas of the globe that at short notice.

This is generically been called "Responsive Space," by the DoD who have hosted a few conferences on it. It's tough because you need to re-think how you build and source your payloads as well. A vehicle that can launch in a day is useless if the payload takes another 18 months to design.

ELV mfgs will tell you "No one wants to buy a launch vehicle" but that's quite deceptive. What they mean is
"No one wants to buy a very large object that costs a fortune, can only be used once, needs unique infrastructure that can't be used by any other vehicles of its capability and has a 1 in 50 failure rate and can only be launched by the mfg in countries designated by the government of the country they are based in."

And on that basis why would you?

OTOH quite a lot of people would buy a vehicle that can deliver X Kg to LEO (or GTO with the SUS) if its ground infrastructure could be shared by other vehicles (IE a large runway or aircraft maintenance systems), had a loss rate like more normal transport systems (by designing out multiple failure modes) that was under their direct control and that they could sell if they no longer needed (IE an actual asset, not a massive operating cost per launch).

IRL, given the labyrinthine ways of selling something to the US military it would be better to design a vehicle and sell it to an operator to operate it on the behalf of the US military. just as such a vehicle can be sold to an operator to use it for ESA launches or Russian launches.

But that's only possible with a fully reusable system and only if that system doesn't need an artillery range style operating process. No "Exclusion zones" for each flight for example.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline edzieba

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #996 on: 04/23/2018 09:29 AM »
With Reaction Engines Inc themselves explicitly stating that they are developing a two-stage-to-orbit design because it is cheaper and more achievable than an SSTO design, I'm going to take them at their word as they're the ones who have to actually do it!

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #997 on: 04/23/2018 11:49 AM »
With Reaction Engines Inc themselves explicitly stating that they are developing a two-stage-to-orbit design because it is cheaper and more achievable than an SSTO design, I'm going to take them at their word as they're the ones who have to actually do it!
I know the USAF AFRL have had SEI review a couple of concepts for TSTO's. Where did you see that REL Inc is looking at a design for this?
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Robotbeat

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #998 on: 04/23/2018 12:45 PM »
With Reaction Engines Inc themselves explicitly stating that they are developing a two-stage-to-orbit design because it is cheaper and more achievable than an SSTO design, I'm going to take them at their word as they're the ones who have to actually do it!
Glad to hear. Get flying!
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Offline chipguy

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #999 on: 04/23/2018 05:33 PM »
Would you get in your car if I could guarantee somewhere in every 50-100 engine starts the car will explode?

tl;dr No, rocket designers have done the best they could within the limits of the existing technology. SABRE opens those limits a lot. "Game changer" is a cliche. But it does change the rules you have to play by to win "the game".

What makes you think a SABRE engine will be less likely to explode than a traditional LRE?

It has an air breathing mode and a liquid oxidizer feed mode so it is much more complex
than a pure LRE which operates only in a single mode. More complexity and two different
operating regimes with a mid flight switchover suggests that SABRE has a lot more failure
modes.

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