The Reaction Engines Skylon/SABRE Master Thread (6)

[john smith 19]

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

Well for a start it's quad redundant in the pre cooler and dual redundant in the LO2 and LH2 pumps.
Damage to section of pre-cooler. Dump section.
Damage turbine. Switch out air breathing, switch to full rocket, abort mission.
Damage to a pump. Shut down it and its partner LH2 and continue with half engine.
All turbines are driven by GHe, not super heated steam and GH2 as in the SSME. Much more benign.

Obviously the turbo pumps will be highly stressed relative to normal jet engine practice but I don't know if they will be as highly stressed as the SSME's were.

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.

You should look at the SSME startup process. It in fact started in a wholly different engine cycle before becoming a staged combustion engine.

Basically the bits that spin fast are driven by a quite hot inert gas, while the bits that make it hot don't contain any large lumps of fast spinning metal.

Multiply in roughly 4 decades improvements in seals, bearings and engine management and fault detection and I'm pretty confident the engine can be made pretty reliable, although I'm sure they will have noted modern practice with XCOR (who started it) and SX's use of blast containment panels.

Note the explosion I talked about was for car.  I didn't say the engine. IRL the things that most end missions are still
a) Separation failure
b) Upper stage engine start or engine failure.

Not the highly dramatic engine RUD's that make such good videos on YT.

Note the AB/rocket transition is a mode transition, not a start. In fact there will be some LOX flow from the moment the wheels start rolling to "top up" the energy supplied by the pre cooler. There won't be a set of valves "slamming" shut, and another ripped open. Each will be more of a gradual ramp, which is much less stressful. [EDIT Oops. That was the SABRE 3 cycle. SABRE 4 expects to run with air in the pre burner as well. However the change over can be done gradually and again any failure (if it's a HTOL winged vehicle) can be quite benign ]

Likewise the use of deeply cooled air, switching to LOX, for the nozzle cooling lowers the stress on the coolant passages relative to the use of LH2, and eliminates the risk of coking from hydrocarbon fuel cooling of rocket nozzles.

[edzieba]

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?

Mark Wood did a guest lecture at the IET recently, summary here.

[john smith 19]

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?

Mark Wood did a guest lecture at the IET recently, summary here.

I reread it. The "SR72" is a M5 reconnaissance aircraft and the reference to them talking to someone about TSTO is pretty vague.

[Star One]

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?

Mark Wood did a guest lecture at the IET recently, summary here.

I reread it. The "SR72" is a M5 reconnaissance aircraft and the reference to them talking to someone about TSTO is pretty vague.

The same as the B-21 the SR-72 is a grey/black project therefore references in relation to it will necessarily be vague.

[john smith 19]

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?

Mark Wood did a guest lecture at the IET recently, summary here.

I reread it. The "SR72" is a M5 reconnaissance aircraft and the reference to them talking to someone about TSTO is pretty vague.

The same as the B-21 the SR-72 is a grey/black project therefore references in relation to it will necessarily be vague.

Apples and Oranges. The B21 is AFAIK funded and has Congressional support. The reason we're hearing very little about the SR72 is that there may just not be that much to hear.

And again LM were very keen to say they have been working with Orbital AJR on their Dual Mode Ram/SCRamjet engine.

All of which may be true but is probably better left in the General Hyperpsonics thread.

[JCRM]

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.

If a Skylon engine explodes, it would be unfortunate, but there should be a less than 1 in 20000 chance that the payload is lost. Still not great.

Note the AB/rocket transition is a mode transition, not a start. In fact there will be some LOX flow from the moment the wheels start rolling to "top up" the energy supplied by the pre cooler. There won't be a set of valves "slamming" shut, and another ripped open. Each will be more of a gradual ramp, which is much less stressful. [EDIT Oops. That was the SABRE 3 cycle. SABRE 4 expects to run with air in the pre burner as well. However the change over can be done gradually and again any failure (if it's a HTOL winged vehicle) can be quite benign ]

I don't think it was in SABRE 3 either

[edzieba]

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?

Mark Wood did a guest lecture at the IET recently, summary here.

I reread it. The "SR72" is a M5 reconnaissance aircraft and the reference to them talking to someone about TSTO is pretty vague.

It was pretty unequivocal, and in the first paragraph:

This also came with confirmation that while SSTO remains the 'holy grail' goal, RE are taking a much more pragmatic approach to development with TSTO being more viable.

[john smith 19]

If a Skylon engine explodes, it would be unfortunate, but there should be a less than 1 in 20000 chance that the payload is lost. Still not great.

By aircraft standards no.
By space launch standards that is a phenomenal level of safety. HTOL buys a lot of leeway for failure.

I don't think it was in SABRE 3 either

Tried to get that video to run. Didn't work.

[FutureSpaceTourist]

https://www.reactionengines.co.uk/westcott-test-site-tf1-1-year-construction/

[knowles2]

[recording]

It was good to hear Alan still taking an interest. Thanks for asking my question. I'm not surprised, but disappointed it'll be an airreathing onlyfacility. I'm intrigued by he notion it'll be useful to others in that state. - interesting times maybe.

Is it safe to say now that there will definitely be a functional working SABRE engine in a few years?

No. If all goes well, there will be a demonstration engine, which has all the componetns of a functional SABRE engine core working together - which has been the plan since that was funded by the UK government in 2016. While this would be functional and working in the technical sense I very much dout it would be considered so in a practical sense (could I stick this on a vehicle and go somewhere)- which is how I interpreted your question.






If there are no show-stoppers, then hopefully funding will be forthcoming for a fulll engine. OTS parts are being Frankensteined together to make the demonstrator, so apart from the precoolers very little of the demonstrator will fly.

A question was asked about ITAR and they said all data is protected from ITAR. A separate company in the USA has been set up to test hot air intake only and in no way does this compromise any SABRE design work at all.

Reaction Engines Inc wasn't set up to test the hot air intake only (did you mean heat exchangers, or is this a different company you're discussing?) but to interact at arms length passing requiremnet to the UK company where design work occurs outside of ITAR. It does seem a very difficult having your cake and eating it arrangement.

It seems as though Westcott is alive again rising  phoenix like back to the rocket engine testing  of the fifties and sixties

Except very quietly, so as not to upset the neighours. Westcott has been testing REL engines for over a decade, and LEROS engines have been developed tehre since the 90s

As far as I am aware Reaction Engines Inc at this stage will only be testing the pre-cooler under hot intake conditions. I suppose the question you have to ask is, why did they need to go to the USA to do this form of testing, is there a hidden agenda going on!.

  I think they just went there because their was a pot of Darpa money available to them to build a facility that they needed and doesn't really exist anywhere else, an DARPA was asking for something which only Reaction engines could delivered so it 100% guarantee of winning the money. I'm sure they counted on BAE to provide them with political cover as well. I'm sure as Sabre engine is slowly proven to be workable design forces within the US government will want to try and seek to control it, as they do with all new technological breakthroughs and will seek to use ITAR and other mechanisms to do so.

But what can the US actually do if Reaction Engines simply close up it US subsidiary after getting the data it wants, even if it just, hey guys in the UK your designs work perfectly, and then Reaction engines just build a engine in the UK made of 100% UK built parts?

[HMXHMX]

[recording]

It was good to hear Alan still taking an interest. Thanks for asking my question. I'm not surprised, but disappointed it'll be an airreathing onlyfacility. I'm intrigued by he notion it'll be useful to others in that state. - interesting times maybe.

Is it safe to say now that there will definitely be a functional working SABRE engine in a few years?

No. If all goes well, there will be a demonstration engine, which has all the componetns of a functional SABRE engine core working together - which has been the plan since that was funded by the UK government in 2016. While this would be functional and working in the technical sense I very much dout it would be considered so in a practical sense (could I stick this on a vehicle and go somewhere)- which is how I interpreted your question.






If there are no show-stoppers, then hopefully funding will be forthcoming for a fulll engine. OTS parts are being Frankensteined together to make the demonstrator, so apart from the precoolers very little of the demonstrator will fly.

A question was asked about ITAR and they said all data is protected from ITAR. A separate company in the USA has been set up to test hot air intake only and in no way does this compromise any SABRE design work at all.

Reaction Engines Inc wasn't set up to test the hot air intake only (did you mean heat exchangers, or is this a different company you're discussing?) but to interact at arms length passing requiremnet to the UK company where design work occurs outside of ITAR. It does seem a very difficult having your cake and eating it arrangement.

It seems as though Westcott is alive again rising  phoenix like back to the rocket engine testing  of the fifties and sixties

Except very quietly, so as not to upset the neighours. Westcott has been testing REL engines for over a decade, and LEROS engines have been developed tehre since the 90s

As far as I am aware Reaction Engines Inc at this stage will only be testing the pre-cooler under hot intake conditions. I suppose the question you have to ask is, why did they need to go to the USA to do this form of testing, is there a hidden agenda going on!.

  I think they just went there because their was a pot of Darpa money available to them to build a facility that they needed and doesn't really exist anywhere else, an DARPA was asking for something which only Reaction engines could delivered so it 100% guarantee of winning the money. I'm sure they counted on BAE to provide them with political cover as well. I'm sure as Sabre engine is slowly proven to be workable design forces within the US government will want to try and seek to control it, as they do with all new technological breakthroughs and will seek to use ITAR and other mechanisms to do so.

But what can the US actually do if Reaction Engines simply close up it US subsidiary after getting the data it wants, even if it just, hey guys in the UK your designs work perfectly, and then Reaction engines just build a engine in the UK made of 100% UK built parts?

Unless the law has changed in recent years, DARPA can't fund facilities.  When I built the HMX MIPCC Test Bench for a DARPA Phase 1/2 SBIR in the 2003 time frame, we were at great pains not to use the word facility, and HMX had to own all the equipment ourselves, not DARPA.  All we could sell to DARPA was data.  The MTB plenum and other hardware elements were later novated to another firm (one of our contractors) and have now been sold for the RM test rig, as described up thread.

[t43562]

But what can the US actually do if Reaction Engines simply close up it US subsidiary after getting the data it wants, even if it just, hey guys in the UK your designs work perfectly, and then Reaction engines just build a engine in the UK made of 100% UK built parts?

They can just ask for whatever they buy to be made in America like the Rocket Labs people are having to do. If not then.....well....there are other ways of going hypersonic.  They might e.g. demand that certain systems (e.g. engine management or something like that) be US designed such that REL would have to duplicate a lot of work for an ITAR free version. So I don't think there's a huge problem for them. The UK is simply not going to be the major market for this engine so it can't expect to organise things to entirely suit itself - unless it can play competing interests against each other and does it really want to do play that kind of game with a military ally? Who would be the counter balance? The EU that we just rejected?

[john smith 19]

They can just ask for whatever they buy to be made in America like the Rocket Labs people are having to do. If not then.....well....there are other ways of going hypersonic.  They might e.g. demand that certain systems (e.g. engine management or something like that) be US designed such that REL would have to duplicate a lot of work for an ITAR free version. So I don't think there's a huge problem for them. The UK is simply not going to be the major market for this engine so it can't expect to organise things to entirely suit itself - unless it can play competing interests against each other and does it really want to do play that kind of game with a military ally? Who would be the counter balance? The EU that we just rejected?

The situation is more complex than that.  Let's keep in mind the way the RD180 (essentially built in Russia) was "manufactured" in the USA by what was the Rocketdyne/Russian JV.

[john smith 19]

Unless the law has changed in recent years, DARPA can't fund facilities.  When I built the HMX MIPCC Test Bench for a DARPA Phase 1/2 SBIR in the 2003 time frame, we were at great pains not to use the word facility, and HMX had to own all the equipment ourselves, not DARPA.  All we could sell to DARPA was data.  The MTB plenum and other hardware elements were later novated to another firm (one of our contractors) and have now been sold for the RM test rig, as described up thread.

And yet how can something be novated to another contractor if a govt agency doesn't own it in the first place?

It seems where there is a will, there's a way.

BTW there is an REL Flight Test Vehicle thread in advanced concepts.  Do you know of any gaps in data for general hypersonics studies that such a vehicle might fill?

[Star One]

I originally posted this in the general hypersonic thread as this seems applicable here as it sounds more likely some technological breakthrough rather than any particular project.

We can expect an important announcement in a few weeks that “a significant acceleration is doable” of the Air Force’s hypersonic efforts. Roper said he’d completed a review of all the service’s work on hypersonic, one of the Pentagon’s top priorities

https://breakingdefense.com/2018/04/big-hypersonic-news-coming-faster-progress-likely-roper/

[john smith 19]

I originally posted this in the general hypersonic thread as this seems applicable here as it sounds more likely some technological breakthrough rather than any particular project.

https://breakingdefense.com/2018/04/big-hypersonic-news-coming-faster-progress-likely-roper/

True. Something by the end of June at the latest?

Although it seems a bit early for  those DARPA funded hot precooler tests to have borne fruit.

I'll note that that while it's probably too late for support from the European Investment Bank for REL it could still help REL's planned TPS supplier supplier, who are (AFAIK) French.

[Star One]

I originally posted this in the general hypersonic thread as this seems applicable here as it sounds more likely some technological breakthrough rather than any particular project.

https://breakingdefense.com/2018/04/big-hypersonic-news-coming-faster-progress-likely-roper/

True. Something by the end of June at the latest?

Although it seems a bit early for  those DARPA funded hot precooler tests to have borne fruit.

I'll note that that while it's probably too late for support from the European Investment Bank for REL it could still help REL's planned TPS supplier supplier, who are (AFAIK) French.

I imagine it also signals he’s probably rationalised hypersonic research as what’s the betting there has been a lot of duplications of effort up to now judging by the variety of projects we keep hearing about.

[HMXHMX]

Unless the law has changed in recent years, DARPA can't fund facilities.  When I built the HMX MIPCC Test Bench for a DARPA Phase 1/2 SBIR in the 2003 time frame, we were at great pains not to use the word facility, and HMX had to own all the equipment ourselves, not DARPA.  All we could sell to DARPA was data.  The MTB plenum and other hardware elements were later novated to another firm (one of our contractors) and have now been sold for the RM test rig, as described up thread.

And yet how can something be novated to another contractor if a govt agency doesn't own it in the first place?

It seems where there is a will, there's a way.

BTW there is an REL Flight Test Vehicle thread in advanced concepts.  Do you know of any gaps in data for general hypersonics studies that such a vehicle might fill?

Novation is simply replacing one contractor for another.  As part of doing that (we wanted to get out of the specific line of business) the hardware was given to the contractor we choose to replace us.  Hardware didn't go to the gov't.

[john smith 19]

Unless the law has changed in recent years, DARPA can't fund facilities.  When I built the HMX MIPCC Test Bench for a DARPA Phase 1/2 SBIR in the 2003 time frame, we were at great pains not to use the word facility, and HMX had to own all the equipment ourselves, not DARPA.  All we could sell to DARPA was data.  The MTB plenum and other hardware elements were later novated to another firm (one of our contractors) and have now been sold for the RM test rig, as described up thread.

And yet how can something be novated to another contractor if a govt agency doesn't own it in the first place?

It seems where there is a will, there's a way.

BTW there is an REL Flight Test Vehicle thread in advanced concepts.  Do you know of any gaps in data for general hypersonics studies that such a vehicle might fill?

Novation is simply replacing one contractor for another.  As part of doing that (we wanted to get out of the specific line of business) the hardware was given to the contractor we choose to replace us.  Hardware didn't go to the gov't.

I recently saw the term in connection with the contract for the Space Shuttle's software. Originally let to IBM Federal System by NAA but then shifted to come directly under NASA so they could have insight into all aspects of the Shuttle design, given how intimately software either monitored or controlled practically everything (starting with the 60+ fluid tanks on the orbiter).

That is very relevant to REL's funding issues.

It suggests (in principal) REL could negotiate with potential end users for Skylon. Binding contracts could be signed for delivery of those vehicles (subject to compliance with suitable performance specs and allowance for inflation). With a large enough number of contracts signed REL could then approach commercial funding organizations and be in a strong position to forma a consortium by novating the
contract to the consortium.

It would then be up to the mfg company ("Skylon PLC" to give it a name) to execute the order.

[JCRM]

It would then be up to the mfg company ("Skylon PLC" to give it a name) to execute the order.

On a tangent, Skylon Enterprise Ltd was dissolved just over a year ago