Reaction Engines SABRE engine (Skylon Spaceplane)

[Archibald]

Ammonia is easier usable for combustion engines than for turbines

Does that mean "piston engines" as in Super Constellation ? the irony, that would be. Should we bring back the Convair XC-99 or Lockheed Constitution ? Except with ammonia ?

 

[GTX]

 

[Flyaway]

https://twitter.com/x/status/1592155727854030848

View: https://twitter.com/ReactionEngines/status/1592155727854030848

Reaction Engines has officially formed a U.S. Board of Advisors! REI welcomes Dr. Mark Lewis and John “JV” Venable to the Reaction Engines Inc. U.S. Board of Advisors. They will be an excellent addition and provide us with strong guidance in our company strategy and growth

 

[Dagger]

We will get a lot of "good news" in the run up to the 2024 IPO
but REL is like Theranos and it will end the same way too.

 

[Nik]

Dagger, IMHO, REL is utterly unlike Theranos as their remarkable capillary heat exchanger has been proven to satisfaction of sponsors.

Also, REL does not exhibit the pathological behaviour of Theranos' management...

 

[Dagger]

Dagger, IMHO, REL is utterly unlike Theranos as their remarkable capillary heat exchanger has been proven to satisfaction of sponsors.

Also, REL does not exhibit the pathological behaviour of Theranos' management...

If you had any idea what heat transfer is about you would not be impressed by that rather simple tubular heat exchanger that they have been dancing around now for the past twenty years.
That the tubes are 1 mm in diameter does not make it remarkable. Others can and have done that before.
The basic theory and correlations for heat transfer apply in exactly the same way to exchangers with 1 mm tubes or with 1 inch tubes.

REL is like Theranos because it also used the same philosophy from the start: fake it till you make it.
Moreover like Theranos also REL has fanatic fanboys and cheergirls that are blinded by idolism and do not want to see reality: after 33 years REL has produced nothing but a few simple radiators.

And both companies try to enrich themselves by selling worthless shares to clueless retail investors.
However the visitors of this forum have been warned so they will not fall for that.

 

[Nik]

Dagger, what evidence would you accept to change your opinion ??

 

[Zoo Tycoon]

I challenged Dagger to provide evidence to support his claim that RE were switching LN2 for water. Of course nothing was produced.

 

[Jemiba]

Some of you believe in the claims of that company, some of you not . Ok, most readers of this thread
probably have understood. Getting too figurative ("...worthless shares to clueless retail investors.., etc")
shouldn't be necessary, I think, as are answers to individual members, instead of answers to arguments.
Allegations should be supported by evidence, otherwise they will lose credibility, at least, as long as they
aren't regarded as general understanding.
Please, back to normal tone, there's no need to challenge anybody. Most members are well able to
make up their minds without such tricks, I think !

 

[Dagger]

I challenged Dagger to provide evidence to support his claim that RE were switching LN2 for water. Of course nothing was produced.

What are you talking about? Which post are you referring to?

I have said in the past that I will post elaborate explanations why both the hot test and the cold test that REL has done, or claimed to have done, with that precooler are useless, prove nothing and are just a show to keep up appearances.
Contrary to REL I will keep my promise and it won't take me 33 years, but will be done well ahead of the 2024 IPO.

[.................] Most members are well able to make up their minds without such tricks, I think !

I am worried that most members are not able to make up their minds correctly, when it comes to deciding whether to buy REL shares or not at or after the IPO, hence my warnings about REL's claims, and the fact that they produced almost nothing in 33 years.

If one thing has become clear to me than it is that, except me, nobody on this forum seems to have any idea about the theory of heat transfer, or how heat exchangers actually work. Even the stakeholders don't seem sufficiently familiar with that. Apparently heat transfer is a mystery within the aerospace industry, which has made it easy for REL to make ridiculous claims about their precooler.

 

[Zoo Tycoon]

That’ll be this one;-

2. No they did not.
That "hypersonic" test was an even bigger farce. All they did was blow 1000 oC gas (jet engine exhaust) into a precooler that was cooled by atmospheric water inside the tubes. I don't think that the metal of the precooler got any warmer than 250 oC at the "hot" side and not colder than 100 oC at the "cold" side, while the pressure inside the tubes was only atmospheric. A far cry from the conditions the precooler metal would experience during actual hypersonic flight, which I estimate to be 950 oC at the hot side, -200 oC at the cold side, 200 bar inside, if the air would be cooled to -150 oC.
This test was just keeping up appearances. It had nothing to do with hypersonic.

I consider the claim above to be unverified. contrary to the RE issued report (contractual customer DRAPA as part of their Hypersonic research) and fundamental incorrect. As previously pointed out RE published report specifically records temperatures consistent with LN2 being on the “cold side”.

So please provide the RE test data that proves the RE published report is fraudulent.

If you’re claiming to be the world’s leading authority on cryo heat exchanger icing please provide one of your published works specifically into the subject at at least PhD level.

 

[TomcatViP]

Heat transfer is a fundamental of any engineering and scientific curriculum across the wold. At least, as early as 18/19 years old age, most of those students that have been learning Sciences have the necessary background to apply heat transfer equations.

Most would also have reached the end of thermodynamics at a Master level.

I fill confident that this can be discussed without fears that it would remain beyond the reach of too much said investors.

@Dagger : feel free to engage with us more specifically on the theme.

It is clearly fishy that REL have stayed so long on the cheap side of development (no expensive hardware built to test).

 

[Nik]

IIRC, REL 'farmed out' construction of the novel heat exchanger to a company with appropriate skills...

IMHO, REL still want to fly 'runway to orbit to runway'. If that means licensing solutions for heat exchangers and/or antipodal / sub-orbital hypersonics to commercial and friendly military use, that keeps the cash flowing until financial climate is clement...

I'd be really, really worried if tiny REL tried to raise money to actually build a flight-vehicle. Okay, a UK team may hold land-speed record, but that brave project showed how rapidly sponsorship may evaporate when business tide turns...

Perhaps a better analogy for REL would be ARM ? Design hyper-nimble RISC-CPUs, but not stuck with vast overheads of a chip foundry...

Disclosure: I used to know several of the 'old' RELs via our membership of BIS. IIRC, they've now retired. I do not know the new team..

 

[Nik]

Tangential, such capillary tubing is probably far outside scope of most engineering experience.

It's the square/cube thing taken to extreme, far, far beyond the 'familiar' HVAC or automotive 'radiator' core.

My modest experience is via HPLC, 'High Performance Liquid Chromatography', where we cheerfully connected pumps, injector, heated column, detector etc etc with stainless-steel or plastic (!!) capillary tubing, via finger-tight or mini-spanner fittings, at ~200 Bar and 2 ml/min.

Apparently, such modest pressures are now considered 'quaint', as 'state of art' has progressed...

Nearest 'familiar' equivalent would be 'fuel injection'...

 

[steelpillow]

Any sane startup developing new tech of this sophistication is essentially a design/R&D house, and will only bog itself down with prototype manufacture if that can not be outsourced and they are forced to develop the manufacturing technology in-house, alongside the product technology. REL are not among the insane.

Still, making stuff to deliver extreme performance at scale and in an extreme environment without breaking (Mach-5-plasma-to-liquid-helium in the thickness of a capillary tube, no cracking, wrinkling or snaking allowed!) is a pretty tall order for anybody. I remain utterly impressed by all concerned.

 

[Nicknick]

Well, why is nobody doing a calculation of the heat exchanger? According to my understanding, it’s a bundle of tubes which are rectangular to the air stream, this is pretty standard (I believe, the air is already subsonic before entering the heat exchanger).Everyone who knows why it could or could not work should know enough boundary conditions for his judgment.

If I would have a passion in that thing, I would do it myself…

 

[Dagger]

Everyone who knows why it could or could not work should know enough boundary conditions for his judgment.

Maybe some people should reread my previous posts.

Of course it is possible to use a simple tubular heat exchanger to cool air from 1000 oC to ambient.
It's just a matter of choosing the right alloy that can stand the high temperature, provide possibility of tube expansion, and provide sufficient tube area. Hundreds of companies in the world can do that. An smart engineering student could probably also do it.
However it is not possible to cool moist air to -150 oC without freezing up the exchanger if it is a design like the one REL has built, no matter what REL claims.

REL only exists today because they claimed they could cool to -150 oC without freezing up, and that bold statement got them financing. Then the FOMO effect drew in other financiers.
If REL had claimed from the start that they could only cool to ambient, as is nowadays on their website, then probably nobody would have financed that company and REL would not have existed very long.
It seems however that finally the present stakeholders decided to stop the financing. Maybe they also noticed that REL silently changed their tune from -150 oC to ambient.

To get more money an IPO is planned for 2024, but before that there will be what they call a pre-IPO to raise 35 million £ from private investors. Apparently the present stakeholders don't even want to provide that (which would be only 7 million for each of them) although according to the propaganda REL is valued at 1 to 2 billion £. An absurd value for a company that only makes a loss and rarely sells a radiator.

REL does not seem to realize that by announcing an IPO they will draw attention from the financial and public media to their actual performance which is ................. so I doubt there will be an IPO. The heat exchanger part of REL might be sold to another exchanger company, some other part might be absorbed by RR or BAe, the rest dissolved.

Each year thousands of heat exchangers are designed and built all over the world for use in the process industry.
Are each of them tested to check whether they will perform as intended? No. The design correlations to determine the required size of an exchanger are known and there is no need to check them in a test facility.
Are each of them tested to check whether they can withstand the temperature that they will have to endure during actual operation? No. The materials of each exchanger are selected based on the mechanical design temperature and corrosivity (if applicable). The mechanical properties of each alloy are well known. There are codes and standards that govern the material selection as well as what tensile strength (safety margin included) to be used for wall thickness calculations. There is no need to test them again and again.
Are each of them tested to check whether they can withstand the pressure that they will have to endure during actual operation? Sort of. They are tested at 1.5 to 2 times the mechanical design pressure using cold water. That's all. A simple, cheap test that takes little time. No test of simultaneous occurrence of high temperature and high pressure. That is covered by the factor 1.5 to 2. Following the codes and standards is all a designer and manufacturer needs to do.

The above is in a nutshell why that "hypersonic test facility" they built in the US is such nonsens. First of all there is nothing hypersonic going on there, but moreover the tests they are supposedly doing are useless as they reveal nothing that can't be calculated in a fraction of a second by appropriate software, or even by hand in a matter of hours.
Different flowrate of air or the medium inside the tubes? Different air temperature? Different ....... (whatever)? No test required, just do a software run.
A lot of money and years to build it, all just to drag it on as long as possible and at the same time pretend that something revolutionary is going on there. That precooler model is all they have to show after 33 years, and the show must go on, at least until the planned IPO.

 

[Nicknick]

Almost all companies which produce heat exchanger are using a simple software which helps to predict the heat flow rates.

Misbelieving a startup which claims mega superior technology is right in 95 % of all cases, but I don’t want to judge without fully understanding the limits of their approach. Is de-icing really impossible, or could it be done e.g., by switching of sections of the heat exchanger periodically? They might also use a device to scrap of the ice from the tubes or they might use something else which we might not know (Someone else on YouTube suggested vibration, but I don’t think this would work).

The entrance boundary conditions for the ambient air can be calculated with the speed, standard atmosphere for each height and the efficiency of the diffusor (probably working with at least three compression shocks to get subsonic). We know the tube diameter and the rough dimensions of the heat exchanger. Heat exchanger working with tube bundles are nothing new, there is a lot of literature about it. I know, it takes some hours to calculate that stuff (at least, if the last time you did it is decades ago…) but it is not an extremely complex problem.

For De -icing I would suggest to assume a certain maximum thickness of the ice on the tubes (lets say 0,2 mm). In this case, we know the tube diameter quite exactly (between 1.4 and 1 mm) and the surface temperature (0° C). Someone should do the job, but please not me....

Instead of de-icing by ambient air, the de-icing section could also be blocked from the air stream (by a rotating buffle) and the tubes could be used to pre cool the working fluid. This would be a more efficient solution because it requires less ambient air flow.

 

[Trident]

Well, is icing even such a serious concern for the very specific application this heat exchanger is intended for? I mean, absolute moisture content of stratospheric air (which is where the REL engine cycle would be operating in air-breathing mode) has to be vanishingly low compared to sea level, as a gut instinct?

 

[Zoo Tycoon]

The whole 33year and start up thing is being very miss represented. For 25years RE was a company with just 3 employees, obsessed with solving just one problem. This is where the Theranos comparison is utter tosh as their CEO was even that old when she started her scam. How many start up have a 25year long preparation behind them?

Theranos did everything inside their company with investor funds and was found to be fraud when they failed customers which were private citizens. The disappointed customers brought in the government regulators. With RE in Colorado the customer is the US government including their internal audit process. The US gov DRAPA sponsored hypersonic research conducted by RE in Colorado is reproducing the flow condition in a cryogenic heat exchanger at high Mach number. It’s frankly absurd to claim that such a purpose built facility conducting such a focused test could switch LN2 with water and the sponsor wouldn’t notice. .

Dagger you’ve again failed to supply any evidence of your alleged fraud.m

Maybe they’ve found a version of this and coated the tubes within the heat exchanger.

Anti-icing performance of hydrophobic material used for electromechanical drill applied in ice core drilling | Journal of Glaciology | Cambridge Core

Anti-icing performance of hydrophobic material used for electromechanical drill applied in ice core drilling - Volume 66 Issue 258

www.cambridge.org

 

[red admiral]

For me its simply that there is no product or income stream or apparent steps towards getting either. So where is any return on investment?

Novel and "Cool" technology might be exciting but that doesn't mean its useful or better than other approaches

 

[steelpillow]

Well, is icing even such a serious concern for the very specific application this heat exchanger is intended for? I mean, absolute moisture content of stratospheric air (which is where the REL engine cycle would be operating in air-breathing mode) has to be vanishingly low compared to sea level, as a gut instinct?

Yes, icing is always a problem for engines which fly through humid air at freezing temperatures, whether it be on the way up, down or cruise. Remember SABRE is intended as a ground-to-orbit powerplant, so it is going to spend time in that regime at some point. Also, the stratosphere may have a low density, but it can still have a high relative humidity and an awful lot flows through an engine at high speeds. You don't need much ice to break a delicate microtube at those speeds.
This was one of the key features that REL had to demonstrate on a working prototype that they were on top of, before the big investors would come in.

 

[Nicknick]

The whole 33year and start up thing is being very miss represented. For 25years RE was a company with just 3 employees, obsessed with solving just one problem. This is where the Theranos comparison is utter tosh as their CEO was even that old when she started her scam. How many start up have a 25year long preparation behind them?

Theranos did everything inside their company with investor funds and was found to be fraud when they failed customers which were private citizens. The disappointed customers brought in the government regulators. With RE in Colorado the customer is the US government including their internal audit process. The US gov DRAPA sponsored hypersonic research conducted by RE in Colorado is reproducing the flow condition in a cryogenic heat exchanger at high Mach number. It’s frankly absurd to claim that such a purpose built facility conducting such a focused test could switch LN2 for water and the sponsor wouldn’t notice. .

Dagger you’ve again failed to supply any evidence of your alleged fraud.m

Maybe they’ve found a version of this and coated the tubes within the heat exchanger.

Anti-icing performance of hydrophobic material used for electromechanical drill applied in ice core drilling | Journal of Glaciology | Cambridge Core

Anti-icing performance of hydrophobic material used for electromechanical drill applied in ice core drilling - Volume 66 Issue 258

www.cambridge.org

Another approach could be switching the direction of the air flow trough the heat exchanger (inside out to outside in and vise versa). The icing will only occure in the downstream section after the air is cooled below 0° C, by changing the direction of the air flow periodically, the ice will always be removed in split seconds. Since the air flow is allready slowed down before entering the heat exchanger, I don"t epect troubles with the tubes (which btw. are far more robust than ordinary coolers out of aluminium plates).

The relative humidity is quite irelevant, when the temperatures are very low, simply because even at 100 % relative humidity the absolute amount of water is extremely low (the temperature will be far below the triple point). At -50° C, the steam pressure of ice (water doesn2t exist here) is 0.03939 mbar.

http://anorganik.chemie.vias.org/dampfdruck_tabelle_wasser.html

 

[Dagger]

Is de-icing really impossible, or could it be done e.g., by switching of sections of the heat exchanger periodically? They might also use a device to scrap of the ice from the tubes or they might use something else which we might not know

Not possible with the REL design, simply look at photos of that precooler and at the minimal distance between the tubes. Look also how it is supposed to be installed inside SABRE engine and the direction of air flow.

For 25years RE was a company with just 3 employees, obsessed with solving just one problem.

That can't be correct. They started building that precooler model already 20 years ago.

Theranos did everything inside their company with investor funds and was found to be fraud when they failed customers which were private citizens. The disappointed customers brought in the government regulators. With RE in Colorado the customer is the US government including their internal audit process.

The "customers which were private citizens" (you mean shareholders?) were not disappointed until about 2015. The Theranos stock price went very high and they were very happy, but then an investigative journalist spoiled the party by publicly questioning what Theranos was really doing.
As soon as an investigative journalist publicly starts questioning what REL is really doing that will also be the beginning of the end.

The US gov DARPA sponsored hypersonic research conducted by RE in Colorado is reproducing the flow condition in a cryogenic heat exchanger at high Mach number. It’s frankly absurd to claim that such a purpose built facility conducting such a focused test could switch LN2 with water and the sponsor wouldn’t notice.

There is nothing hypersonic going on by RE in Colorado, no high Mach number and nothing cryogenic.
That test facility is just a big hair dryer blowing low speed hot air over a piece of some inconel alloy of which it's known already for decades that it can withstand that.
That DARPA falls for that is really shocking, hence my suspicion that the people who made that decission know little or nothing about heat transfer but were influenced by FOMO.

Another approach could be switching the direction of the air flow trough the heat exchanger (inside out to outside in and vise versa). The icing will only occure in the downstream section after the air is cooled below 0° C, by changing the direction of the air flow periodically, the ice will always be removed in split seconds.

Not possible with the REL design, look again at photos of that precooler and at the minimal distance between the tubes. Look again how it is supposed to be installed inside SABRE engine and the direction of air flow.

How REL pretended to avoid freezing up the precooler is not a secret. They wrote and talked about it long time ago. In my professional judgement that is a joke.

I said it already several times (but fanboys prefer to ignore it) REL does not talk about -150 oC anymore on their website, or in the brochure that overscan posted in post #487 (see relevant page in attachment), but merely about cooling down to ambient, which is easy.

 

[Nicknick]

Ammonia is easier usable for combustion engines than for turbines

Does that mean "piston engines" as in Super Constellation ? the irony, that would be. Should we bring back the Convair XC-99 or Lockheed Constitution ? Except with ammonia ?

Take a look on this paper (it’s about a Diesel Turbocompound, Turbofan).

AIAA Aerospace Research Central

It’s not as far-fetched as it might seem...

 

[Nicknick]

Is de-icing really impossible, or could it be done e.g., by switching of sections of the heat exchanger periodically? They might also use a device to scrap of the ice from the tubes or they might use something else which we might not know

Not possible with the REL design, simply look at photos of that precooler and at the minimal distance between the tubes. Look also how it is supposed to be installed inside SABRE engine and the direction of air flow.

For 25years RE was a company with just 3 employees, obsessed with solving just one problem.

That can't be correct. They started building that precooler model already 20 years ago.

Theranos did everything inside their company with investor funds and was found to be fraud when they failed customers which were private citizens. The disappointed customers brought in the government regulators. With RE in Colorado the customer is the US government including their internal audit process.

The "customers which were private citizens" (you mean shareholders?) were not disappointed until about 2015. The Theranos stock price went very high and they were very happy, but then an investigative journalist spoiled the party by publicly questioning what Theranos was really doing.
As soon as an investigative journalist publicly starts questioning what REL is really doing that will also be the beginning of the end.

The US gov DARPA sponsored hypersonic research conducted by RE in Colorado is reproducing the flow condition in a cryogenic heat exchanger at high Mach number. It’s frankly absurd to claim that such a purpose built facility conducting such a focused test could switch LN2 with water and the sponsor wouldn’t notice.

There is nothing hypersonic going on by RE in Colorado, no high Mach number and nothing cryogenic.
That test facility is just a big hair dryer blowing low speed hot air over a piece of some inconel alloy of which it's known already for decades that it can withstand that.
That DARPA falls for that is really shocking, hence my suspicion that the people who made that decission know little or nothing about heat transfer but were influenced by FOMO.

Another approach could be switching the direction of the air flow trough the heat exchanger (inside out to outside in and vise versa). The icing will only occure in the downstream section after the air is cooled below 0° C, by changing the direction of the air flow periodically, the ice will always be removed in split seconds.

Not possible with the REL design, look again at photos of that precooler and at the minimal distance between the tubes. Look again how it is supposed to be installed inside SABRE engine and the direction of air flow.

How REL pretended to avoid freezing up the precooler is not a secret. They wrote and talked about it long time ago. In my professional judgement that is a joke.

I said it already several times (but fanboys prefer to ignore it) REL does not talk about -150 oC anymore on their website, or in the brochure that overscan posted in post #487 (see relevant page in attachment), but merely about cooling down to ambient, which is easy.

I just proposed some ways it might have been done or not, not all of their sketches need to show the truth. Anyway, I would be intrested on how they originally intended to deal with the icing problem...

 

[Zoo Tycoon]

For 25years RE was a company with just 3 employees, obsessed with solving just one problem.

That can't be correct. They started building that precooler model already 20 years ago.

Yawn - So how about we look at some independent evidence?

U.K. Companies house filings;- 1989 to present day

REACTION ENGINES LIMITED filing history - Find and update company information - GOV.UK

REACTION ENGINES LIMITED - Free company information from Companies House including registered office address, filing history, accounts, annual return, officers, charges, business activity

find-and-update.company-information.service.gov.uk

There is nothing hypersonic going on by RE in Colorado, no high Mach number and nothing cryogenic.
That test facility is just a big hair dryer blowing low speed hot air over a piece of some inconel alloy of which it's known already for decades that it can withstand that.
That DARPA falls for that is really shocking, hence my suspicion that the people who made that decission know little or nothing about heat transfer but were influenced by FOMO.

Yawn;-

US Air Force partners with Reaction Engines on ‘high-Mach’ engine testing

The UK-based manufacturer specialises in managing the build-up of heat in a variety of aerospace functions, including hypersonic engines.

www.flightglobal.com

Note “USAF FCT manager William Reed. “Reaction Engines technology is world-class and is a great fit for the FCT programme.”and “The US Air Force (USAF) is partnering with the UK’s Reaction Engines to improve the performance of hypersonic and near-hypersonic engines.”

I reckon everyone reading this is aware that Mr W Reed of the USAF knows more about this than we do.

As for TF2, Yes I know there’s no gas traveling at hypersonic speed but that’s not the intent;- it’s reproducing the thermal/pressure/flow conditions within the HTX when the thing would be doing hypersonic speed…. A while ago I watched similar testing on ramjets and gas turbine core stages… it’s how we do things in aerospace… aka “an element test”.

Please feel free to present any independent evidence to support your claims…. Really anything… absolutely anything…. whatever you have… nothing too small….even a shred…make an effort….go on … give it go, eh, .

 

[Dagger]

For 25years RE was a company with just 3 employees, obsessed with solving just one problem.

That can't be correct. They started building that precooler model already 20 years ago.

Yawn - So how about we look at some independent evidence?

U.K. Companies house filings;- 1989 to present day

REACTION ENGINES LIMITED filing history - Find and update company information - GOV.UK

REACTION ENGINES LIMITED - Free company information from Companies House including registered office address, filing history, accounts, annual return, officers, charges, business activity

find-and-update.company-information.service.gov.uk

Do you expect us to dig through some 300 pfds to look for ..... what exactly?
In any case it is irrelevant how many people were REL employees, when they also payed others parties (universities, research centers, companies, whoever) to do work.

In a paper from 2008 Richard Varvill stated that they had been working on the SABRE precooler for 7 years, so that is 21 years ago. Before that they may already have been working on smaller modules for SCIMITAR, not clear to me whether that is included in those 7 years, or whether that started even before 2001.

As for TF2, Yes I know there’s no gas traveling at hypersonic speed but that’s not the intent;- it’s reproducing the thermal/pressure/flow conditions within the HTX when the thing would be doing hypersonic speed…. A while ago I watched similar testing on ramjets and gas turbine core stages… it’s how we do things in aerospace… aka “an element test”.

So you agree that nothing hypersonic is going on by RE in Colorado, no high Mach number and nothing cryogenic.
It’s not "reproducing the thermal/pressure/flow conditions within the HTX when the thing would be doing hypersonic speed" either. It's just blowing some smooth low speed hot air over a bunch of inconel tubes. No sonic shock waves that compress the air and heat it from ambient to 1000 oC, no residual turbulences that can hit the flimsy tubes. Just a perfectly safe show.
Maybe you missed my explanation about how in the process industry an "element test" is done on heat exchangers so I will post it again:

Each year thousands of heat exchangers are designed and built all over the world for use in the process industry.
Are each of them tested to check whether they will perform as intended? No. The design correlations to determine the required size of an exchanger are known and there is no need to check them in a test facility.
Are each of them tested to check whether they can withstand the temperature that they will have to endure during actual operation? No. The materials of each exchanger are selected based on the mechanical design temperature and corrosivity (if applicable). The mechanical properties of each alloy are well known. There are codes and standards that govern the material selection as well as what tensile strength (safety margin included) to be used for wall thickness calculations. There is no need to test them again and again.
Are each of them tested to check whether they can withstand the pressure that they will have to endure during actual operation? Sort of. They are tested at 1.5 to 2 times the mechanical design pressure using cold water. That's all. A simple, cheap test that takes little time. No test of simultaneous occurrence of high temperature and high pressure. That is covered by the factor 1.5 to 2. Following the codes and standards is all a designer and manufacturer needs to do.

A water pressure test, that's all. No "element test" for heat exchangers.
An "element test" may be usefull for ramjets and gas turbine core stages, but those are totally different types of equipment than a simple tubular heat exchanger.
In the process industry an "element test" is also not done for furnace coils (which have to withstand much higher metal temperatures than that precooler), or reactors, or distillation columns, or ....... et cetera. Imagine a huge coal gasifier operating at 1600 oC and 50 bar, or a huge hydrocracker reactor operating at 400 oC and 200 bar. In view of their size those are not even tested with water pressure but instead all welds and brazing is X-rayed to check for leaks.

If REL had felt the need to test their precooler for high temperature and high pressure they could simply have hired a company with a suitable size furnace (that precooler module is only about 1 m by 0.5 m) to bring it up to 677 oC (according to Alan Bond in one of his articles 950 K is the maximum allowable tube metal temperature of the used inconel type) while pressured up to 200 bar. A simple test that takes little time and little cost, but of course that would not have had the same propaganda value as the "hypersonic test facility" they now claim to operate. Low temperature test would also be simple and cheap: just stick the precooler in a bath of liquid nitrogen and pressurize up to 200 bar.

US Air Force partners with Reaction Engines on ‘high-Mach’ engine testing

The UK-based manufacturer specialises in managing the build-up of heat in a variety of aerospace functions, including hypersonic engines.

www.flightglobal.com

Note “USAF FCT manager William Reed. “Reaction Engines technology is world-class and is a great fit for the FCT programme.”and “The US Air Force (USAF) is partnering with the UK’s Reaction Engines to improve the performance of hypersonic and near-hypersonic engines.”

I reckon everyone reading this is aware that Mr W Reed of the USAF knows more about this than we do.

That is typical manager talk and moreover sounds like it was written by REL PR department: “Reaction Engines technology is world-class". What a joke.
If William Reed would only read all my posts in this topic he would seriously start doubting the REL claims, and if I could have a meeting with him he would no longer believe anything that they claim.

 

[Jemiba]

The standpoints about the question "Is REL a fraud or not ?" are clear now, there's absolutely no need
to repeat them again and again !
Further posts about it, please only if they are backed up with some kind of documents, evidences, and so on.

 

[Nicknick]

The cooler in question uses technology developed by a UK company called Reaction Engines, which is working on the development of air breathing rocket motors. These engines have a similar requirement to a turbocharged gasoline engine in that incoming charge air is compressed and needs cooling, but to a much higher degree. The engines are designed to hurtle through the air at five times the speed of sound, with this forward speed helping to ram air into the engine inlet, heating it to around 1000°C in the process. Reaction Engines had to develop what it calls a pre-cooler to drop this temperature back down to ambient levels, and it turns out the technology has lots of uses beyond rockets – including F1.

The rocket tech behind Mercedes’ cutting-edge F1 coolers

A new compact air cooler, using rocket engine technology, could be the key to Mercedes' new slim F1 sidepods. Lawrence Butcher examines how it works

www.motorsportmagazine.com

Rocket technology to thank for Mercedes’ tiny sidepods – Symonds

Formula 1's chief technical officer, Pat Symonds, has provided some insight into how Mercedes has shrunk its sidepods down to

www.motorsportweek.com

How about that. Our own Calum Douglas is surely the man to ask - his day job is Mercedes F1 engine design. I just pinged him, fingers crossed.

Using Water for heat transfer of the charge cooler is nothing new and other Formula 1 teams (e.g. Ferrari) did the same. The cooler is (if not done by Mercedes themself) most likely a product from Mezzo (https://www.mezzotech.com/).

see also:

View: https://www.youtube.com/watch?v=LS47125tUzk
(the corrosponding cooler on the pressure side)

 

[Zoo Tycoon]

In addition to the US Airforce Research Lab, the European Space Agency say Reaction Engines has something really revolutionary;-

ESA said;-

Mark Ford, heading ESA’s Propulsion Engineering section. “It confirms the test version of this revolutionary new class of engine is ready for implementation.”

ESA greenlight for UK's air-breathing rocket engine

The development programme of the world’s first air-breathing rocket engine has taken an additional significant step forward, which will lead to major testing milestones being undertaken within the next 18 months.

www.esa.int

This was after review by eleven of their senior aerospace propulsion experts;-

View: https://m.youtube.com/watch?v=JsvnJNYHjKU

And Boeing used the R word to boot ;-

Boeing announces $26.5mn investment in Reaction Engines Limited

The US-based aircraft manufacturer, Boeing, has announced its £26.5mn (US$37.8mn) investment in Reaction Engines Limited (REL).The UK space technolog...

manufacturingdigital.com

“As Reaction Engines unlocks advanced propulsion that could change the future of air and space travel, we expect to leverage their revolutionary technology to support Boeing’s pursuit of hypersonic flight,” stated Steve Nordlund, Vice President of Boeing HorizonX.

 

[Trident]

So you agree that nothing hypersonic is going on by RE in Colorado, no high Mach number and nothing cryogenic.
It’s not "reproducing the thermal/pressure/flow conditions within the HTX when the thing would be doing hypersonic speed" either. It's just blowing some smooth low speed hot air over a bunch of inconel tubes. No sonic shock waves that compress the air and heat it from ambient to 1000 oC, no residual turbulences that can hit the flimsy tubes. Just a perfectly safe show.

I'm not sure why exactly you think hypersonic flow would be required to reproduce the real operating conditions - it will NOT encounter hypersonic air, ever, in-flight either. As you say yourself, the very reason why the air flow is so hot (and why the HX is even there) is because it has been compressed - that is to say *decelerated* from hypersonic free-stream to subsonic - in the inlet. So long as you can supply enough air at the correct pressure and temperature by other means, there's absolutely no need to include the inlet and free-stream in a test setup concerning the HX only?

EDIT: In fact, if they are using jet engine exhaust as an air supply, the test is significantly more onerous than real operation in a key respect. There will be much higher water vapour content than in stratospheric air, which might in turn explain why they aren't cooling to below ambient.

 

[Nicknick]

To help with cooling perhaps

Cooling in general is not directly SABRE-related and belongs in a different topic. Since you are not reporting on work in the field, The Bar would be the appropriate forum here, thanks.

Cooling is not SABRE related?How does it come, that we talk so much about the pre-cooler???

Ammonia btw. is a valid idea for that, it was allreade choosen for the X-1 plane because of the high heat adsorbtion for boiling and cracking the Ammonia.

 

[F119Doctor]

So you agree that nothing hypersonic is going on by RE in Colorado, no high Mach number and nothing cryogenic.
It’s not "reproducing the thermal/pressure/flow conditions within the HTX when the thing would be doing hypersonic speed" either. It's just blowing some smooth low speed hot air over a bunch of inconel tubes. No sonic shock waves that compress the air and heat it from ambient to 1000 oC, no residual turbulences that can hit the flimsy tubes. Just a perfectly safe show.

I'm not sure why exactly you think hypersonic flow would be required to reproduce the real operating conditions - it will NOT encounter hypersonic air, ever, in-flight either. As you say yourself, the very reason why the air flow is so hot (and why the HX is even there) is because it has been compressed - that is to say *decelerated* from hypersonic free-stream to subsonic - in the inlet. So long as you can supply enough air at the correct pressure and temperature by other means, there's absolutely no need to include the inlet and free-stream in a test setup concerning the HX only?

EDIT: In fact, if they are using jet engine exhaust as an air supply, the test is significantly more onerous than real operation in a key respect. There will be much higher water vapour content than in stratospheric air, which might in turn explain why they aren't cooling to below ambient.

Reminds me of the J58 test stands at P&W Florida plant. They had a J75 engine (minus afterburner) feeding its exhaust into the front of the J58 to simulate the M3 / 80K inlet conditions. While the J58 AB could not operate at full power due to the partial oxygen depletion in the J75, the rest of the engine was seeing the appropriate temperatures and pressures for the test objectives.

 

[Dagger]

That video is 5 years old and still contains the -150 oC lie. The website, the recent above posted brochure and more recent video all mention ambient, not -150 oC.

So you agree that nothing hypersonic is going on by RE in Colorado, no high Mach number and nothing cryogenic.
It’s not "reproducing the thermal/pressure/flow conditions within the HTX when the thing would be doing hypersonic speed" either. It's just blowing some smooth low speed hot air over a bunch of inconel tubes. No sonic shock waves that compress the air and heat it from ambient to 1000 oC, no residual turbulences that can hit the flimsy tubes. Just a perfectly safe show.

I'm not sure why exactly you think hypersonic flow would be required to reproduce the real operating conditions - it will NOT encounter hypersonic air, ever, in-flight either. As you say yourself, the very reason why the air flow is so hot (and why the HX is even there) is because it has been compressed - that is to say *decelerated* from hypersonic free-stream to subsonic - in the inlet. So long as you can supply enough air at the correct pressure and temperature by other means, there's absolutely no need to include the inlet and free-stream in a test setup concerning the HX only?

EDIT: In fact, if they are using jet engine exhaust as an air supply, the test is significantly more onerous than real operation in a key respect. There will be much higher water vapour content than in stratospheric air, which might in turn explain why they aren't cooling to below ambient.

Then they should simply have called it 'High Temperature Test Facility', but that would not have the same propaganda value.
Most process plants that I have designed through the years have at some location a gas temperature of 1000 oC. If I would call that "Hypersonic conditions" or "Mach 5 conditions" and call myself a "hypersonics expert" I would be ridiculed, but that is what REL has been doing for decades and others blindly echo that. It's all over the internet. How can REL be a "hypersonics expert" if they never designed anything that flew hypersonic, not even a simple rocket? How can REL be a "hypersonics expert" if they never designed anything that flew supersonic, or at the speed of a bird, or even at the speed of a butterfly?

They did not cool the air (fluegas) below ambient because that would freeze up the precooler. As I mentioned above multiple times they don't claim anymore that they can cool to -150 oC.
Moreover that TF2 test facility used boiling water as a cooling medium for the circulating helium gas, so the air (fluegas) temperature from the precooler must have been well above 100 oC.

 

[zen]

Water boils at 100 degrees C at 1 BAR (standard atmospheric pressure at average sea level). It boils at lower temperatures if the air pressure is lower and at higher temperatures in higher pressure atmospheres.

Which is why it's hard to get a decent cuppa before the final phase of your ascent of Everest.

 

[Nicknick]

I would like to see the whole idea in reality, but I have to admit I’m not very impressed by that heat exchanger testing. They are using a microtube heat exchanger which are state of the art in several applications since more than a decade and is nothing revolutionary. This type of heat exchanger does work and there is no groundbreaking gain of knowledge when tested under circumstances which are not represantive for the later application (e.g. liquid water instead of Helium, constant flow of hot air).

The whole Helium cycle, the reusable rocket components, the reentry concept, the nose with (or without?) variable intake geometry and at a lot of other stuff is not trivial at all. Why not testing the helium cycle in combination with the heat exchanger?

I could design such an heat exchanger in a couple of weeks (not only me) and it means little when you can proof that the heat exchanger is indeed cooling. There are even more advanced heat exchangers out there:

(https://www.yumpu.com/de/document/v...rausforderungen-bei-der-herstellung-mtu-aero-)

I would like to know more about the other aspects of that thing….

 

[Nik]

As I understand it, the 'trick' was finding a reliable, economic way to securely bond those zillion micro-bore tubes to the rest of the plumbing...

Back then, I showed the report to a BIL who'd had a lot to do with high-pressure capillaries for eg marine diesel lubrication, plus sundry arcane boilers / heat-exchangers etc. To put it politely, he doubted. IIRC, he had to delve his text-books for the math, as the capillary size lay far outside scope of the usual transfer tables. And, IIRC, this was compounded by Helium's 'super-critical' properties under those conditions. You cannot simply extrapolate...

To his surprise, REL seemed to have significantly under-stated the performance...

Filtering his industrial-strength expletives, he described the system as a breakthrough comparable to early steam boiler design improvements that gave enough power/weight and pressure to allow efficient propulsion of trains, ships etc etc.
Naturally, his un-documented comments carry scant authority, and YMMV...

 

[Nicknick]

This trick has already been solved long time ago (as said by Mezzotech), did you watch the video of the Ferrari heat exchanger?

I’m a fan of microtube heat exchanger and I knew them well before I noticed Skylon. If somebody would have asked, what kind of heat exchanger would I use for the job, I would have recommended microtubes.

What makes me suspicious are not potential troubles with the heat exchanger, but why the focus so much on it. You can simply calculate very well the required size and make more feasible tests with smaller test sections instead of a full size prototype. Testing it with completely different medias doesn’t teach you much, if you aready understand basic principles of your heat exchanger design. As you said, the properties of supercritical Helium are critical, so they should do the tests with helium and 200 bar (they don’t, they use water instead).

I have the impression, they do so much publicity on testing the cooler because they are already quite sure, that it will work. This could be a distraction from all the other very demanding tasks. Sealing the helium cycle for example.

 

[steelpillow]

And, IIRC, this was compounded by Helium's 'super-critical' properties under those conditions.

To his surprise, REL seemed to have significantly under-stated the performance...

I would not expect the helium to be cold enough to exhibit superfluid properties (which I assume is what you mean). At 1 atmosphere it is liquid below 4.2 K but does not become superfluid until around half that. No doubt RE's working pressure and temperature are somewhat higher. So a claimed performance significantly below the superfluid's calculated capabilities would be sensible enough.