back to article Brit rocket boffins Reaction Engines notch up first supersonic precooler test

Brit firm Reaction Engines has successfully tested its engine design's precooler heat exchanger – a key step on the path to getting its SABRE donk up and into space. The Synergetic Air Breathing Rocket Engine (SABRE) designed by Reaction is designed to get an attached space vehicle up to Mach 5.4 before switching to liquid …

  1. graeme leggett

    So much potential

    If it works, it'll be amazing.

    Until then...

    1. Mr Catbert

      Re: So much potential

      Until then... It's still amazing!

      1. Doctor Syntax Silver badge

        Re: So much potential

        The really amazing application would be cooling the hot air emanating from politicians.

        1. Mr Catbert
          Joke

          Re: So much potential

          Given what we've seen over the past few weeks, I'm pretty certain that there's not a working fluid that can cool that sort of heat load. That said, dropping them all into the middle of the Atlantic might work!

          1. A.P. Veening Silver badge

            Re: So much potential

            That said, dropping them all into the middle of the Atlantic might work!

            That is an environmentally unsound policy. Besides, you would create an artificial island where they can breed even more of them.

          2. macjules Silver badge

            Re: So much potential

            Unfortunately dumping them into the sea would not work. Sharks or other man-eaters would, out of professional courtesy, not touch them or you would get Greenpeace launching protests at the introduction of criminals into the food chain.

            A far more sensible option would be to tether them in bunches of 10 behind the engine in order to test the minimum distance for those observing the afterburner.

          3. Ian Michael Gumby Silver badge
            Trollface

            Re: So much potential

            That said, dropping them all into the middle of the Atlantic might work!

            That said, you would indeed prove that those who say that climate change is man made because the combined hot air from said politicians would quickly melt the icebergs, causing sea levels to rise dramatically and causing most of the UK to be flooded. (Unless you live in the Mountains of Scotland. )

            So sure. that would be one way to solve Brexit... flooding London along w most of low lying Europe.

            Then on the other side of the pond, most of the US East coast would be under water. Think of all of those yuppies on Wall Street treading literal water.

            1. jake Silver badge

              Re: So much potential

              "Then on the other side of the pond, most of the US East coast would be under water. "

              And those of us on the West side of the Rockies would party.

              1. A.P. Veening Silver badge

                Re: So much potential

                And those of us on the West side of the Rockies would continue to party.

                FTFY ;)

          4. CrazyOldCatMan Silver badge

            Re: So much potential

            not a working fluid that can cool that sort of heat load

            Bose-Einstein condensate? Has the advantage of being very, very, very cold and very, very low pressure. Which means that the heat output of said politician surrounded by BEC would rapidly diminish..

        2. Symon Silver badge
          Coat

          Re: So much potential

          @Dr. S. "You want two lanes or four lanes on that bridge?"

    2. Mr Benny Bronze badge

      Re: So much potential

      So much potential .... to pollute the atmosphere ever more by making launches simpler and cheaper. I guess its not enough to screw up the stratosphere with burnt kerosene from the thousands of jets up there at any one time, lets make sure we mess up every level of the atmosphere and dump even more CO2 into it for .... what purpose exactly? Perhaps it can launch micro satellites which have a lifetime of a few weeks and are essentially space junk the minute they're launched. Or some idiot space tourists to gormlessly stare at the view.

      1. Anonymous Coward
        Anonymous Coward

        Re: So much potential

        Quite right. As i said to my mate Ugg; 'why invent the wheel? all it's going to do is lead to traffic jams and runaway global warming' and history has proven me right.

      2. jake Silver badge

        Re: So much potential

        Mr Benny, do you know how many tons of CO2 you, personally, are going to produce in your lifetime? Perhaps you could do the Earth a favo(u)r and stop?

        1. Mr Benny Bronze badge

          Re: So much potential

          The all or nothing fallacy is not an argument.

          1. jake Silver badge

            Re: So much potential

            I wouldn't dream of making such an argument.

            Just cut back by 50%, then. We'll wait.

      3. Orv Silver badge

        Re: So much potential

        The engine burns liquid hydrogen, which, since it contains no carbon, cannot emit CO2. The exhaust product would be water vapor. (Water vapor is also a greenhouse gas, but since excess water vapor rains out of the atmosphere it's not a major concern.)

        That's not to say it doesn't have a carbon footprint; actually producing, compressing, and chilling the hydrogen is pretty carbon-intensive with current technology. There's nothing precluding doing it with renewable energy, mind, it's just not currently economically feasible when producing it from natural gas is an option.

        1. streaky

          Re: So much potential

          actually producing, compressing, and chilling the hydrogen is pretty carbon-intensive with current technology

          Not really. With *current technology* we can do it for free, the input being water, by-product Oxygen. The fact there hasn't been any investment to scale up isn't the fault of existing technology, it's the fault of governments and people like Elon Musk who are sending the world down the wrong path. We could all be driving HICEVs by now with fairly minimal investment.

          1. Brangdon

            Re: people like Elon Musk who are sending the world down the wrong path

            If by "Musk" you mean SpaceX, they are moving from kerosene to methane, and methane can be made carbon-neutral if anyone actually cares. Which they probably don't as the number of rockets launched is too few to matter.

            1. streaky
              Mushroom

              Re: people like Elon Musk who are sending the world down the wrong path

              You can make methane carbon neutral, burning it carbon neutral not so easy.

              Also I meant Tesla obviously but now you mention it, all that NASA research into liquid hydrogen burning in oxygen rocket engines, pissed away. https://www.youtube.com/watch?v=MjQ0j1a9RcA

      4. Bronek Kozicki Silver badge

        Re: So much potential

        It so happens that the only byproduct of burning hydrogen in oxygen is H2O. Taking the space launch industry in this direction would definitely help reducing the CO2 impact it has on the atmosphere.

        1. Orv Silver badge

          Re: So much potential

          It's already pretty common -- the Delta IV Heavy uses LH2 for all stages, for example. Some other boosters do use RP1 (kerosene), especially in the first stage, because it's both easier to handle and more energy-dense by volume. (LH2 is more energy-dense by weight, but bulky.) It's worth noting that countdown aborts and scrubbed launches due to hydrogen leaks are pretty common on Delta IV missions.

        2. Anonymous Coward
          Anonymous Coward

          Re: So much potential

          burning hydrogen in oxygen does only produce steam - H20. Burning Hydrogen in air will also produce NOx - depending on the actual combustion temperatures.

          1. John Smith 19 Gold badge
            Go

            "Burning Hydrogen in air will also produce NOx "

            As part of the LAPCAT project REL developed a new design of combustion injector that is expected to generate 1% of the NOx of existing combustors.

            The SABRE 4 cycle splits the system into 2 separate combustion chambers this is now much more viable.

            1. DJO Silver badge

              Re: "Burning Hydrogen in air will also produce NOx "

              While burning Hydrogen does only produce water you have to get that Hydrogen from somewhere. There are 2 major way to get the stuff:

              1) Electrolysis of water - hugely inefficient and unless the power is from a renewable source will generate lots of CO2

              2) Catalytic breakdown of hot natural gas with superheated steam - this really produces a lot of CO2 and needs a fair amount of power to get it running hot enough.

              There are less polluting ways to get Hydrogen such as biological methods but they are either very small scale or still in the laboratory stage.

              1. Anonymous Coward
                Anonymous Coward

                Re: "Burning Hydrogen in air will also produce NOx "

                "unless the power is from a renewable source will generate lots of CO2".

                I suspect even powering a large fleet of Sabre-engined Skylons would not make a significant uptick in the global production of H2.

                Is this a case of the perfect is the enemy of the good?

                1. Richocet Bronze badge

                  Re: "Burning Hydrogen in air will also produce NOx "

                  You're point sums up the slippery slope so well.

                  "This small activity won't make a noticeable difference" said 6 billion people.

                  As I look out the window and see the worst wildfires ever burning on the horizon.

          2. Orv Silver badge

            Re: So much potential

            My understanding is that most rocket engines run fuel-rich mixtures for nozzle-cooling reasons, which would limit NOx production somewhat.

        3. Richocet Bronze badge

          Re: So much potential

          Hydrogen and oxygen are not just lying around waiting to be collected and used. Unlike coal, oil, and gas.

          The energy intensity of producing the materials is the most relevant part of the CO2 impact. Yes, if all electricity production was renewable it would be fine, but that is far from the case.

          You might find the energy use of cement and aluminium production interesting.

    3. anothercynic Silver badge

      Re: So much potential

      It's already proven itself... and some applications of it (in a sense) are already in use. I happen to know several RE engineers and yeah, they're stressed but they are proud as punch about this, as am I. That takes some doing.

  2. Doctor Syntax Silver badge

    It's not clear to me how the excess heat gets dumped so efficiently into already hot gas that the helium becomes supercooled again. That seems to me a far more difficult trick than using cold helium to cool hot gas.

    1. TechnicalBen Silver badge

      IIRC you don't.

      Look up current pre-cooler systems on rocket engines.

    2. Andrew Newstead

      The Helium is cooled by the LH2 fuel that is being fed to the engine at that time, effectively pre-warming the cryogenic fuel before combustion and the heat from the heat exchanger being dumped overboard.

      1. Orv Silver badge

        The trick here being you have to pre-warm the fuel anyway, so using it as a heat sink for the helium precooler coolant kills two birds with one stone.

        Some earlier proposed designs used simpler schemes where the liquid hydrogen was used directly as a coolant. The problem is this causes a lot of materials problems. Steel and some other metals become brittle with prolonged exposure to hydrogen.

        1. steelpillow Silver badge
          Boffin

          After preheating the liquid hydrogen fuel, the helium is then passed through a conventional expansion nozzle to liquefy it, just like any other refrigerator coolant. At least, in principle. The full thermodynamic cycle is really rather complicated.

        2. CrazyOldCatMan Silver badge

          metals become brittle with prolonged exposure to hydrogen

          Indeed. And pretty much everything is porous to hydrogen to some extent or other..

          1. A.P. Veening Silver badge

            Metals become brittle at extreme low temperatures, whether caused by liquid hydrogen or liquid helium isn't really important.

            And pretty much everything is porous to hydrogen to some extent or other.

            The same goes to a larger extent for helium, that is mono-atomic.

            1. Orv Silver badge

              It's not just the low temperatures. Hydrogen embrittlement happens because the hydrogen molecules are small enough to get between the grain structures that make up steel. Once in there they combine with carbon to make methane. The methane molecules are then trapped because they're too big to get back out. This creates internal pressure, a lot like how water freezing in a tiny pavement crack will wedge it open.

      2. DJO Silver badge

        The Helium is cooled by the LH2 fuel that is being fed to the engine at that time

        I wonder what they used for that in the static test, I'm pretty certain the J79 engine does not burn hydrogen. Perhaps they vented liquid air to cool the Helium refrigerant?

  3. Chris G Silver badge
    Pint

    Amazing

    If one day we could see RAF roundels on a straight to space craft, a la Jet Ace Logan.

    The sooner Reaction Engines can keep most of their development work in the UK the better.

    See icon for the team.

    1. Persona Silver badge

      Re: Amazing

      Don't hold your breath. It's a fantastic engine concept but its target Skylon space plane sadly stands little chance of taking off from the 5.9km long runway it needs, and putting a payload into orbit. On paper it could put 12.5 tons into LEO with a fuel reserve of 0.5% however like any SSTO spacecraft any additional dry mass that inevitably creeps in during the design and build process directly reduces the payload capacity in a ratio or one to one.

      1. bazza Silver badge

        Re: Amazing

        Exactly how much mass it can launch looks like it won't matter. There's a growing mood for self assembly satellites. Put smaller bits into orbit, have them bolt themselves together. What matters then is speed of repeat launches, where Skylon looks good.

        Doing it this way is attractive, because the cost of an integration facility on earth for an enormous satellite is very expensive. It's much cheaper to have a smaller facility that can handle one sub-sat at a time, you can sub bits of work out more easily, it's appealing because modularity makes design work a hell of a lot easier, etc.

        So, Skylon might not end up being the biggest launcher with the best £/kg, but if customers are saving big time elsewhere and don't need a whole year of SpaceX launches to assemble the spacecraft in orbit (time to operational is also money), it does look quite good.

        1. Persona Silver badge

          Re: Amazing

          The point is that being SSTO (Single Stage To Orbit) if the inevitable dry mass increases during detailed design and build goes up by just 12.5 tons it will not be able to deliver any payload to orbit. SSTO is not a good solution for our planet.

        2. John Smith 19 Gold badge
          Unhappy

          "There's a growing mood for self assembly satellites. "

          Says who?

          The people pitching one of the 18-40 TSTO VTO ELV's that are desperately scrabbling for market?

          The infrastructure to do that does not actually exist. It'll have the compatibility issues of VHS/Betamax/V2000 multiplied by a 1000.

          Now how will they get that tinkertoy satellite to GEO? Or to escape velocity?

          Skylon's T/O buys you a full size GEO comm sat and the stage to get it there (or to escape velocity, or just below, but with a big payload).

      2. MrXavia

        Think about the other options

        There are issues, and if we compare it to current/future rockets, it probably isn't the way forward for space launches, Methane/Hydrogen rockets are probably the future.

        But as an engine, it is amazing tech and could lead to supersonic, environmentally friendly air travel.

        I'm more excited about that than I am about the space launch capabilities in the near term.

      3. Ian Michael Gumby Silver badge
        Boffin

        @Persona Re: Amazing

        Uhm 6km is ~3.6 miles.

        Of course that's not too long when you consider large transport, heavy lift aircraft could need 8-10K feet or ~1.8 miles.

        So I don't think runway length should be an issue.

      4. John Smith 19 Gold badge
        FAIL

        "On paper it could put 12.5 tons into LEO"

        You're about 1 generation behind the D2. That's 15 tonnes.

        What you don't seem to know about Skylon (because you've just cut-and-pasted a generic SSTO idea perhaps) is it is the only SSTO that offers VTO TSTO payload fraction IE 3-4% of GTOW as payload.

        And the 3000 sec Isp (during air breathing mode, but that's enough) buys it a lot of weight growth in a way rocket based VTOL designs just don't have.

        1. Persona Silver badge

          Re: "On paper it could put 12.5 tons into LEO"

          My knowledge on Skylon was from reading the 2003 concept paper (which I still have). The mass budget of 12.5 tons came from there (by adding the payload and fuel reserve numbers) so OK it was a while ago so there must be a latter version and it's now 15 tons.

          The ISP of 3000 air breathing is irrelevant. That great ISP helps put the dry mass of the Skylon plus the payload and the 0.5% fuel reserve into LEO. If the dry mass goes up (it will) the payload will go down by the same amount. If you study the mass budget table in the design paper this should be apparent.

          The good news is that now its 15 tons (or 17 tons according to some sources) they have a lot more to play with . The bad news is that Skylon is still just an idea 15+ years later.

          1. John Smith 19 Gold badge
            Unhappy

            "If you study the mass budget table in the design paper this should be apparent."

            Perhaps you should study the bit labeled "Growth margin."?

            Skylon has one.

            Other SSTO concepts don't.

    2. Steve Davies 3 Silver badge

      Re: Amazing

      I'm worried that El Trumpo will declare this testing (in colorado) to be 'In the US National Interest' and declare it US property.

      1. holmegm Bronze badge

        Re: Amazing

        No you aren't.

    3. steelpillow Silver badge

      Re: Amazing

      More likely, hypersonic atmosphere and sub-orbital vehicles will be the first application. Reaction Engines have taken Skylon off their web site.

    4. John Smith 19 Gold badge
      Unhappy

      "..Reaction Engines can keep most of their development work in the UK the better."

      Actually they do.

      The test facility is in the US.

      The HX was designed and built in the UK.

      Which AFAIK is where the design and mfg operation is planning to stay.

      BTW AFAIK this is the first new high temp,high speed airflow test site in the US for decades. I think they're hoping it will raise some fees testing out other peoples idea for hypersonic flight.

  4. John Brown (no body) Silver badge

    Saw this a earlier this morning on the Beeb site

    ...but then I made the mistake of reading through HYS. OMG there are some luddites out there!!!

    El Reg comments, even Jake, Bob and AMFM1, are sane by comparison! :-)

    Huge thumbs up for all at REL for this next stage. I hope I'm still around to see SABRE power the first Dan Dare style space plane.

    1. I ain't Spartacus Gold badge
      Happy

      Re: Saw this a earlier this morning on the Beeb site

      Well we've lived to see SpaceX give us Flash Gordon style rockets. Now all they need to do is paint the things silver, and perhaps make the landing legs into permanent big fins...

      Why didn't NASA insist on something as basic as that in the COTS contracts?

      1. WonkoTheSane Silver badge
        Headmaster

        Re: Saw this a earlier this morning on the Beeb site

        "Now all they need to do is paint the things silver, and perhaps make the landing legs into permanent big fins..."

        So, you've not been watching SpaceX's "Starhopper" testing then?

        1. Mephistro Silver badge

          Re: Saw this a earlier this morning on the Beeb site

          Starhopper's design would fit in Space: 1999, not in Flash Gordon!

          8^)

    2. werdsmith Silver badge

      Re: Saw this a earlier this morning on the Beeb site

      Ignore BBC comments, it's just a nutter magnet.

      I remember as a kid reading about the amazing HOTOL that was going to bring a travel revolution.

      Here I am decades later reading about sub-components of the engines being tested.

      I am still hopeful to see this fly one day. I bet the NDAs cost as much as the R&D.

  5. Wellyboot Silver badge
    Boffin

    From the BBC - interview

    Excellent progress!

    https://www.bbc.co.uk/news/science-environment-47832920

  6. caffeine addict Silver badge

    I keep meaning to lose an hour to the internet and check an old story my thermodynamics lecturer told me - that Rolls Royce licensed the engine design to a foreign country (Japan springs to mind) who complained that the turbine blades kept melting. His story was that the other company was milling the blades to too great an accuracy and were accidentally removing all the cooling air vortexes across the blade edge.

    I've always assumed this was nothing more than a story. ElReg is sure to have someone who will know. Hell, if it's true, there's probably someone involved in the project here.

    (He also told a story about a beam bender firing an I beam through a factory wall that seemed pretty suspect too...)

    1. Persona Silver badge

      The London Science Museum has some nice turbine blades in its materials display. The top of the range ones being single crystal structures that can withstand the highest temperatures. Being single crystal they are very very smooth and the surface is featureless unlike the lower temperature blades where the crystalline structure of the metal is discernible.

      1. John Smith 19 Gold badge
        Unhappy

        single crysta...are very very smooth..unlike..lower temperature blades

        Actually all turbine blades are very smooth.

        It's just that the usual cast blades are poly crystalline and you can see (when the surface has been suitably prepared) you can see the grain boundaries.

        The trouble with SC blades is they are very slow to cool down, as you have to take them out of the (special) furnace s-l-o-w-l-y.

    2. Jim Mitchell

      Since most walls are built to take vertical loads, it is surprisingly easy to shoot something appropriately skinny but heavy through one that wasn't build for that kind of scenario. You can probably find videos of things like 2x4 lumber being shot right through an unreinforced masonry wall. It is why your tornado shelter is underground.

      1. caffeine addict Silver badge

        This story (as I recall it) was about a system designed to bend I beams ("Eye beams" since there's no serifs here). The MD is showing some investors around and pulls a switch to quieten the machine he's stood next to. The machine's control software thinks "Hmm, more pressure is needed" over and over... until the MD flicks the switch the other way. At which point the system goes all Jeremy Clarkson, shouts "POWEEER" and fires the beam across the workshop, through a wall, and into the bosses car.

        I've always assumed it was an apocryphal story used to convince us students to pay attention to all inputs rather than assume things.

        1. jake Silver badge

          I have seen all kinds of equipment eject all kinds of parts forcibly when used incorrectly (destructive testing has always been one of my favorite games). The "through the wall" bit is likewise quite believable. The boss's car? That's where I call apocryphal and/or wishful thinking.

      2. Ian Michael Gumby Silver badge
        Boffin

        @Jim Mitchell you must not live in the Midwest.

        Not all storm shelters are underground.

        There are reasons for this and there are alternatives where you have re-enforced walls.

        The hollow masonry wall is just that... hollow, but when re-enforced w concrete and rebar, it will withstand the force of a 2x4 being blasted at storm speeds. Homes with no storm shelter or basement can have an inner room be set up as a shelter.

        Part of the issue of going underground... what happens if you have no egress and you get trapped? Or if you have a pipe burst and your shelter gets flooded. (Yes, there is more to the design of a good shelter than just putting it underground.

      3. swm Silver badge

        In Milwaukee, 50 years ago, a company had a problem with a jammed piston. So they got some dynamite to shake it loose. The piston flew a good part of a mile after piercing the roof of the factory.

    3. Anonymous Coward
      Anonymous Coward

      @CaffeineAddict,

      His story was that the other company was milling the blades to too great an accuracy and were accidentally removing all the cooling air vortexes across the blade edge.

      Dunno about that particular story, but engineering is full of subtlety like that.

      The Germans failed to replicate British built magnetrons in WW2. They'd put slight variations in the length of the internal vanes they'd measured on captured devices down to sloppy British engineering. All the ones they made had the vanes the same length. Turns out that was a mistake, and they were unable to effectively jam H2S radar on bombers. Oops.

      1. swm Silver badge

        Then there was the story about the RAF having trouble getting leather seats for their aircraft because of the lack of supply of camel dung. The specs said to rub the leather in camel dung as part of the manufacturing process.

        Well, this part of the process came from making saddles and the camel dung was so the camels wouldn't be afraid of the horse smell. These specs were copied to the airplane seat specs although the reason for this step was lost in the paperwork.

    4. Orv Silver badge

      If this were a VERY early design, I could maybe see it -- some of the WWII-era jets used steel turbine blades and accepted that the engine would need overhauling every 30 hours of operation or so. However, it's hard to imagine the Japanese having trouble with it since they'd already successfully copied Germany's designs, albeit too late in the war to really matter.

    5. timrowledge

      Turbine blades are not milled - at least, not for RR turbines. Hell, I worked on some of the early single crystal blade stuff back in ‘78/9.

    6. anothercynic Silver badge

      RR uses single-crystal turbine blades with micro-channels that blow cool air (relatively speaking) over the surface just to keep the crystal at the right temperature (i.e. run it as hot as possible without melting to milk all the energy possible out of it). Russia licenced an RR design in the early days (I think it was the RR Nene) and struggled because their metals were not quite as pure as RR managed to obtain, so there was a problem with brittleness and bendiness.

      Modern turbofans are extremely closely milled, so much so that Pratt & Whitney has had problems with their PW1000G geared turbofans and bendy shafts that cause rub on the fan cowling. Their solution was to run the engines for 6 minutes to 'cool down' and avoid the shafts from sagging, which was not deemed to be acceptable by Qatar Airways and others. CFM of course hasn't had this problem because a) they don't use geared turbofan machinery, and b) don't use a 3-spool shaft. RR *does* use a 3-spool shaft, but given they've had plenty of experience in this (the RB211 that debuted on the Lockheed L-1011 and still today is on Boeing 767 and 747s was their first 3-spool shaft design), they've resolved the problems sufficiently and consider that a trade secret how they manage to keep things nice and straight.

  7. STOP_FORTH Silver badge
    Flame

    Single stage rockets

    It's amazing how much trouble the Brits will take to avoid having a French stage which blows up/won't ignite/shrugs its shoulders and ruins everything for everybody.

    1. bazza Silver badge

      Re: Single stage rockets

      Nah, basically we want an aircraft that can do it all over again on the same day, home in time for tea and crumpets. Can't do that without SSTO...

      And if we can quoff champagne in a Concorde-esque way whilst we at it, so much the better. Dropping off some satellite during our suborbital hop is just part of the entertainment.

      1. Mephistro Silver badge
        Angel

        Re: Single stage rockets

        Yes, the quaffing would be spectacular, at 0 g.

        1. John Smith 19 Gold badge
          Unhappy

          "Yes, the quaffing would be spectacular, at 0 g."

          Actually it's better than that.

          Skylon was designed to be statically stable in a way that Shuttle (and anything else that's got big point masses at the base, like any rocket stage) is not.

          So it's designed to not need the continuous control surface "fluttering" you see in combat aircraft (that have either relaxed or zero static stability).

          IOW it could be flown by a human without a computer between them and the controls.

          Making Skylon (potentially) the worlds fasted human pilotable aerospace plane.

          Which would be quite exciting so some groups of pilots.

          1. bazza Silver badge

            Re: "Yes, the quaffing would be spectacular, at 0 g."

            IOW it could be flown by a human without a computer between them and the controls.

            Perhaps, but not if it's headed for a sub-orbital hop. I've previously read that they'd envisaged this to be fully automated (perhaps pilots along for the ride), because even a minor course error would see it miss Australia by really quite a long way. It hasn't got the fuel for a pilot to be able to say, "Oh I don't know, just head thataway...".

            If it goes into Orbit, well that's different of course.

            Which would be quite exciting so some groups of pilots.

            I'll make a bid for that to actually include all pilots!

            1. John Smith 19 Gold badge
              Unhappy

              "I've previously read that they'd envisaged this to be fully automated "

              True. The cost of a meatsack in the control loop by default (which NASA Marshall insisted on for Shuttle) makes initial testing very hairy. I'm not sure where you'd get the suborbital hops part.

              REL have looked at what it takes to carry passengers for Skylon. While a design is in a computer you can add and subtract whatever you like so they decided to find out what you should design in (side access doors are not an optional extra for example) and what you can safely leave out.

              Such provisions would still be "Fly By Wire," without a mechanical linkage.

              Which is now SOP for all new large aircraft like the 777 and A380.

      2. Brangdon

        Re: an aircraft that can do it all over again on the same day

        Elon Musk would disagree with you. Reusable two-stage rockets are possible, if you make them really big.

        1. John Smith 19 Gold badge
          Unhappy

          Elon Musk would disagree with you.

          In 2011 Elon Musk though they could do full reusability with the F9.

          In 2014 he took it off the table.

          Now he thinks they can do full reusability with a vehicle about 6x bigger than current LV's and 1.5x bigger than the Saturn V.

          OTOH it's known that a winged vehicle can do re-entry from LEO, as Buran,Shuttle, and the X37b have demonstrated. The latter two multiple times.

  8. l8gravely

    It's not going to work out well....

    First off, LOX in bulk is *cheap*, doing all the testing and development of this sucker is not cheap at all.

    Second, a rocket needs to accelerate, and accelerate alot to get into orbit. Jet engines are, to a large degree, optimized for cruise. You don't cruise on your way to orbit.

    Third, how is this pre-cooler going to do when it sucks in a bird? How benign are the failure modes?

    1. Andy The Hat Silver badge

      Re: It's not going to work out well....

      The pre-stage will immediately freeze the bird ... then an old chicken-based joke rears its head ... :-)

    2. A.P. Veening Silver badge

      Re: It's not going to work out well....

      That third item is worthy of an upvote.

      Lox can be cheap, but getting oxygen from the air you are passing through is cheaper and this way you don't have to lift it either.

      This jet engine isn't optimized for cruise, but for acceleration.

    3. DJO Silver badge

      Re: It's not going to work out well....

      how is this pre-cooler going to do when it sucks in a bird?

      Unless the bird is made of asbestos it will be mainly mixed vapours by the time it hits the cooler.

      1. jake Silver badge

        Re: It's not going to work out well....

        At the temperatures in the OA and the speeds involved, it'll be carbonized feathers over a skinful of room-temperature bird goo when it impacts and clogs the heat exchanger. Given that bird strikes aren't all that common on ordinary aircraft, I rather suspect this won't happen very often ... but when it DOES happen, the plane will simply glide in for a landing.

        1. DJO Silver badge

          Re: It's not going to work out well....

          a skinful of room-temperature bird goo when it impacts

          You're not accounting for the very high air pressure, the bird will be explosively squished flat then the bits will be instantly flash fried, after that the ash and vapours will be cooled right down. Unless it hits something humongous like a fully laden albatross it should be reasonably undamaged.

    4. caffeine addict Silver badge

      Re: It's not going to work out well....

      As with all these things - buying it isn't the issue. It's getting it to the place where it is useful that costs the money.

      If you can use a normal jet concept to get you half the way, you only need a quarter of the LOX at the point where you really need it. That means your system can be lighter, which means your payload can be greater.

      As for a bird strike... I'd guess that the main result is a quantity of very hot chicken soup. Probably with rotor blade croutons.

    5. WonkoTheSane Silver badge

      Re: It's not going to work out well....

      LOX may be *cheap*, but it also has mass, so carrying it cuts into your payload capacity.

    6. Anonymous Coward
      Anonymous Coward

      Re: It's not going to work out well....

      Oh dear. I don't suppose they thought of the cruise argument. There goes the business plan.[ 1) Buy an old jet engine 2) rotate through 90 degrees 3) job's a good'un.]

      But actually, why not cruise to orbit? Instead of all that noisy 'go straight up' malarkey, just cruise in a straight line. As the earth curves away below you you will gradually get higher, and as you get higher you can go faster in the thinner air. I

      1. Flocke Kroes Silver badge

        Re: Why not cruise to orbit?

        For orbit you want a bit of up and about thirty times as much fast. For a normal rocket you start with some up to get out of the worst of the atmosphere then tip over sideways to get some fast when air resistance will not melt your rocket.

        Next imagine a rocket hovering. It is burning through kilo£s of propellant every second without going up or fast. The opposite extreme is taking off from the Moon by burning all the propellant at once. Massive savings in propellant because you do not have to lift any of it up or make it go fast but your rocket has to be a solid lump of steel to survive the explosion. This is why traditional rockets are a compromise between hovering and exploding.

        Aeroplanes are really good at level flight. For the aeroplane not to fall, something else has to. You can either send a small amount down very fast by pointing the engines downward or you can send a large amount down slowly by using a wing. Either way, you want the same mass times velocity going down to get lift, but the energy cost is ½ x mass x (velocity)^2.

        A small amount going down really fast costs too much energy for an aeroplane, but a rocket is much closer to the explosion side than hovering so it works out cheaper to point the engine downwards, and as a bonus you do not have to fiddle around making a wing that works over a huge range of pressures and velocities.

      2. Orv Silver badge

        Re: It's not going to work out well....

        I haven't seen the proposed flight profile for this ship, but one viable scheme for an SSTO works like this:

        - Climb to a high cruising altitude, where there's less air resistance but still enough air to generate lift.

        - Accelerate horizontally to maximum speed in open-cycle mode, conserving your oxidizer by taking advantage of the oxygen in the atmosphere.

        - Pitch up into a zoom climb, converting that horizontal momentum into upward momentum.

        - Switch to closed-cycle mode and burn fuel and oxidizer to get to whatever orbit you need.

        This is both less of a win than you might think (you still need to gain orbital velocity, which is at least five times higher than you'll attain in the atmosphere) but also enough of a win to make gaining orbit in a single stage viable. It's mostly because of not having to lug as much oxidizer around -- a lot of a conventional rocket's fuel is expended just lifting its own fuel and oxidizer.

        Another, more subtle benefit is your engine can be smaller; it doesn't need a thrust-to-weight ratio greater than 1:1 at takeoff.

        1. John Smith 19 Gold badge
          Unhappy

          Another,..subtle benefit is your engine.. smaller; it doesn't need a thrust-to-weight ratio

          greater than 1:1

          True. In fact SABRE's expected to be about 15:1. Rubbish for a pure rocket (but with an Isp of 3000secs in air breathing mode) and pretty phenomenal for a jet engine (SoA is around 10:1).

          Skylon's thrust requirement (depending on what you think is necessary) can be 1/2 to 2/3 of GTOW

          The test engine (which these sections are the precursors to) is expected to be about 20 tonnes thrust, which (at 2/3 GTO) means a (potential) flight test vehicle of 28 tonnes (big fighter aircraft or roughly 60 seat regional jet).

          Now, could you build an orbit capable FTV with that mass? Who can say....

      3. bazza Silver badge

        Re: It's not going to work out well....

        A purely ballistic rocket wastes a lot of fuel just staying up there, when really all it wants to accelerate tangentially. For example, during part of the Shuttle's launch path it's actually losing altitude for the sake of acceleration (the wings add nothing meaningful with all that external gubbins still attached, and I think it would have been upside down at the time too).

        In part this is why the carrier aircraft concept is attractive - the dropped rocket finds itself above a lot of the air already, and can put more effort into tangential acceleration.

        Aircraft with wings benefits from those wings whilst the air is thick enough for them to provide lift. After that they're deadweight, but hey you need somewhere to put wheels and fuel tanks. The wings work for a surprisingly long time; the higher you go, the more speed is needed to generate the required lift for a given wing area, which nicely matches the SSTO's need to accelerate, and the fact that the fuel is being burned off also helps.

        1. Orv Silver badge

          Re: It's not going to work out well....

          Carrier aircraft also have the advantage of being able to take off from a runway. There are currently a lot more runways than there are rocket launchpads.

    7. John Brown (no body) Silver badge

      Re: It's not going to work out well....

      "First off, LOX in bulk is *cheap*,

      True, but how expensive is it to lift it up (and burn) to the altitude where SABRE finally switches from free (and effectively massless since it's not being carried) oxygen to using the much smaller amount of LOX in tanks? How much mass and volume have you wasted getting there?

    8. werdsmith Silver badge

      Re: It's not going to work out well....

      Oh no! It's not going to work out well, somebody better get in touch with REL now and stop them wasting any more time and money.

      I really don't know why they didn't run their idea past the comments sections on The Register before they started. Would have saved so much work!

    9. steelpillow Silver badge
      Boffin

      Re: It's not going to work out well....

      "First off, LOX in bulk is *cheap*, doing all the testing and development of this sucker is not cheap at all."

      The main cost is accelerating that extra tankage and supporting structure to orbital speed. It is ridiculously higher than the speed needed for a sub-orbital hop. Next comes airframe weight and drag.

      "Second, a rocket needs to accelerate, and accelerate a lot to get into orbit. Jet engines are, to a large degree, optimized for cruise. You don't cruise on your way to orbit."

      SABRE is not a conventional jet, it does not obey the rules and nothing about it is optimised for cruise. In low-altitude mode it is an air-breathing rocket, with a supercooler and some extra jet-like bits to deliver the air. "Jet" just helps stop ignorant journos' heads from exploding.

      "Third, how is this pre-cooler going to do when it sucks in a bird? How benign are the failure modes?"

      This is one of the big questions which the test facilities have been built to answer. Essentially, the air has to turn a corner to enter long axially-aligned slots in the pre-cooler from the side, but the bird won't bother. Similar principle to the vortex dust separators used on helicopters for desert operations, but in reverse. So the theory goes....

    10. John Smith 19 Gold badge
      Unhappy

      Third, how is this pre-cooler going to do when it sucks in a bird?

      Firstly I'd like to congratulate you on your amazing grasp of SABRE and Skylon.

      No, really, it's truly quite abnormal.

      In answer to your question the front end of the nacelle housing the SABRE has a spike inlet. The pre-cooler sits behind this so there is no direct path. In the very unlikely event it ricochets round this and does hit part of the pre-cooler the pre-cooler is actually in 4 sections, which I'd guess can all be isolated.

      It's a launch abort, not a loss of vehicle situation. And yes Skylon was designed to take off with one engine failing. Once it's in the air there's time to sort things out. The payload won't go to orbit that day, but nor will it rain down in little pieces.

  9. Richard Scratcher
    Coat

    420°C (~788°F)

    That's gas mark 21.

    1. bazza Silver badge

      Re: 420°C (~788°F)

      And it's just the start. This is about where the cooler starts working. Below that it's unnecessary - existing compressor metalogy will work fine (it did on the SR71).

      It'll have to deal with air a lot hotter than that as it accelerates past M4, M5.

      Excellent start though for REL, go go go! Er, I'm quite excited...

      1. bazza Silver badge

        Re: 420°C (~788°F)

        Er, for metalogy read metallurgy...

  10. The Pi Man

    Matt Morris

    Reaction recently signed up Matt Morris, formerly Chief Engineer for McLaren's F1 team. How about strapping one of these to an F1 car?

    1. John Brown (no body) Silver badge
      Thumb Up

      Re: Matt Morris

      One step at a time, eh? Let's see what Bloodhound does first :-)

      1. steelpillow Silver badge
        Pint

        Re: Matt Morris

        Oh, yes. Bloodhound armed with a SABRE and dangerous! Every commuter will want one.

    2. jake Silver badge

      Re: Matt Morris

      It'd totally fuck up the aerodynamics. On the bright side, cornering would be a non-issue, and tire wear would pretty much disappear :-)

  11. Jellied Eel Silver badge

    Screw the sound barrier, bring the noise!

    So

    The precooler tech on its own is said to have a number of potential uses, including from aerospace to motor sport,

    Oh. Yes please! Mach 5 to Mach 25 faster than a Tesla into a crash barrier!

    Problem with novel precoolers and motorsports is that due to a bunch of luddites (ie politicians and lobbyists), motors that could benefit from pre- or intercooling are being banned.

    1. Mark 85 Silver badge

      Re: Screw the sound barrier, bring the noise!

      Really? Citations please. I can see that possibility in motorsports but only there.

    2. John Smith 19 Gold badge
      Unhappy

      "and motorsports is that due to a bunch of luddites

      True.

      But that still leaves open their use in radiators (and that's basically the reverse of what a pre-cooler is)

      I did not know until recently that F1 engines are built to much narrower tolerances than regular engines. The piston/engine block clearance is roughly 1/2-1/3 that of a regular car and if the block cools down the pistons cease.

      So there are several fluids that need to be kept at the right temperature and REL can certainly help with this.

      However the last time REL looked at this their tech was deemed "Too expensive" for F1.

      Mfg Engineering work has cut REL HX mfg costs to about 1/10 of what they were.

  12. Aladdin Sane Silver badge

    Is anybody else bugged by the direction the engine is facing in the diagrams?

    1. steelpillow Silver badge
  13. amanfromMars 1 Silver badge

    A Sterling Stirling Engine for Advanced IntelAIgent Travellers ......

    ..... aka Virtual Space Pioneers in/on/for/from* Sp00Key AIMissions

    If there is no friction or unbreakable gravitational pulls and/or pushes in the vacuums of space, is speed just a matter of adding more tiny increments of power for delivery of an almighty energy?

    All Patents Pending of course, a priori, whenever such protection is either needed or desired to satisfy and pacify worried souls in terrifying competition and hopeless opposition. There's always the vultures doing IT just for the money honey but having no pollen to give to fertilise growth ...... Start a Creative Flow.

    * That covers pretty much everything and all bases, methinks. We wouldn't be wanting anyone or anything thinking they were being left behind now, would we, although just have far forward they would be is always the killer question most are unable to freely answer, given the seriousness given to any appropriate positive reply revealing an engagingly cogent response?

    1. steelpillow Silver badge
      Boffin

      Re: A Sterling Stirling Engine for Advanced IntelAIgent Travellers ......

      No. You need to deliver more tiny increments of momentum for delivery of an almighty energy. That is something that Stirling engines are unable to do - unless you have a vast hold full of them and catapult a relentless stream of them out the back....

  14. Borg.King
    Pint

    88 mph

    Beeb news states that this test required the transfer of 1.5 MW to transfers the heat energy. Just waiting for the magical 1.21 GW to be mentioned so we can make wisecracks about this engine exceeding 88 mph.

    Good stuff though, well done boffins. Help yourselves to a celebratory beer upon your return to the U.K.

  15. Wolfclaw

    We Can Still Do it !

    Britech at it's best, now watch it go out the window to some US or EU company who will make billions !

    1. Anonymous Coward
      Anonymous Coward

      Re: We Can Still Do it !

      "Britech at it's best, now watch it go out the window to some US or EU company who will make billions !"

      Yeah .... that is my worry !!!

      We have good ideas *but* no stomach for funding things that are not going to work in the next 3 months or other stupid short sighted limits.

      The US is good at taking risks and seeing things through to the end, even if it costs lots of money.

      The only thing we throw money at is Govt projects that should never have seen the light of day.

      i.e. HS2 or any IT project that the 'usual suspects' win then increase the price of by a factor of 5 and the delivery date by 5 years.

      I know procurement is hard for 'big' projects *but* we *never* learn any lessons no matter how many projects fail to be delivered on time or to costs.

      1. werdsmith Silver badge

        Re: We Can Still Do it !

        Everybody know the projects won't hit time or cost. It's part of the SOP to go through a charade of project planning and costing knowing that it will never be realistic.

  16. Will Godfrey Silver badge
    Thumb Up

    All I have to say

    is that it's nice to hear there is still some real engineering going on.

  17. scarper

    Skin heating

    Operating in an atmosphere may save on oxygen tankage, but it really ups the requirement for a tough heat-resistant skin. I have doubts that the ducts, exchangers, turbo whatever, wings PLUS skin adds up to less mass than just enlarging the oxygen tank that you'd have anyway. And the tank won't have wear and tear.

  18. John Smith 19 Gold badge
    Unhappy

    Operating in an atmosphere..really ups the requirement for a tough heat-resistant skin.

    Actually it does not.

    Keeping all the main tankage inside Skylon gives a very "fluffy" vehicle.

    That means it can start to decelerate higher in the atmosphere, that makes it lose speed more gently. That makes the skin temperature requirements relatively relaxed

    As for your "doubts," I'll take the opinions of a group of professional engineers who've continued to be funded over 3 decades (despite none of them having the good sense to have become billionaires first) over some guy on the interwebs.

    1. bazza Silver badge

      Re: Operating in an atmosphere..really ups the requirement for a tough heat-resistant skin.

      Keeping all the main tankage inside Skylon gives a very "fluffy" vehicle.

      That means it can start to decelerate higher in the atmosphere, that makes it lose speed more gently. That makes the skin temperature requirements relatively relaxed

      Ooh, good spot that. Though I doubt that REL would use the term "fluffy" themselves, it's not a common engineering term (no I'm not prepared to bet on that...).

    2. scarper

      Re: Operating in an atmosphere..really ups the requirement for a tough heat-resistant skin.

      >> As for your "doubts," I'll take the opinions of a group of professional engineers who've continued to be funded over 3 decades (despite none of them having the good sense to have become billionaires first) over some guy on the interwebs.

      That's intertubes.

      As for your lack of doubt, I'll take the opinions of the many design teams who, in the last 3 decades, have elected to design rockets instead. Lots of them have flying hardware, and it's noticeable that actually building and flying things tends to cause large and small design changes, and the occasional outright project cancellation.

      As for "fluffy" vehicles: you're changing the subject. Re-entry is the easy part.

  19. ARaybould

    Inlet Air Temperature

    I am pretty sure that, while the inlet ramps on a Concorde's engines did slow down the incoming air, this did not result in cooling, and in fact increased the temperature considerably. One of the purposes of the ramps was pressure recovery, using the kinetic energy of the incoming air to increase its pressure, with a side effect of raising its temperature.

    The inlet cones of the SR-71 served the same purpose, and they increased the temperature at the compressor inlet so much that it was the consequent risk of overheating of the engine, not its thrust, that limited its top speed.

    In fact, this is probably why the SABRE engine has to be able to cool air from 420°C, as the ambient temperature will be much lower. It is probably not a coincidence that I have seen 427°C quoted as the maximum allowable temperature at the SR-71 compressor inlet (limiting its speed to around Mach 3.3, depending on ambient conditions.)

  20. John Smith 19 Gold badge

    BTW

    From the press release.

    This is a preliminary run.

    And it's already got to M3.

    They intend to go much closer to M5 (if not M6). I'd guess by the end of the year.

    Which means we could see a full SABRE test engine on a test stand generating positive thrust by the end of 2020.

    That's a feat that SCramjet fanatics advocates took more than 50 years and North of $10Bn to achieve. IE enough for a good sized pair of SABRE's and an orbital capable test vehicle.

  21. Don The Elder

    Helium is a dead end

    Unless someone develops a way to produce He, current supplies will be exhausted within a decade. No more squeaky voices, dead birds & dolphins, MRIs, SABREs...

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