So much potential
If it works, it'll be amazing.
Until then...
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 …
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Monday 8th April 2019 13:45 GMT macjules
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.
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Monday 8th April 2019 17:05 GMT Ian Michael Gumby
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.
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Monday 8th April 2019 15:52 GMT Mr Benny
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.
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Monday 8th April 2019 16:34 GMT Orv
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.
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Tuesday 9th April 2019 09:20 GMT 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.
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Tuesday 9th April 2019 12:55 GMT 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.
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Wednesday 10th April 2019 02:54 GMT streaky
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
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Monday 8th April 2019 17:23 GMT Orv
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.
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Monday 8th April 2019 20:55 GMT John Smith 19
"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.
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Tuesday 9th April 2019 07:52 GMT DJO
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.
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Tuesday 9th April 2019 11:47 GMT 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?
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Wednesday 13th November 2019 22:20 GMT Richocet
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.
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Monday 8th April 2019 16:36 GMT Orv
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.
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Tuesday 7th May 2019 17:21 GMT Orv
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.
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Monday 8th April 2019 13:09 GMT Persona
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.
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Monday 8th April 2019 15:47 GMT bazza
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.
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Monday 8th April 2019 21:11 GMT John Smith 19
"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).
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Monday 8th April 2019 17:14 GMT 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.
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Monday 8th April 2019 21:06 GMT John Smith 19
"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.
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Tuesday 9th April 2019 13:20 GMT Persona
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.
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Wednesday 10th April 2019 07:24 GMT John Smith 19
"..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.
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Monday 8th April 2019 12:11 GMT John Brown (no body)
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.
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Monday 8th April 2019 12:32 GMT I ain't Spartacus
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?
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Monday 8th April 2019 14:26 GMT WonkoTheSane
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?
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Monday 8th April 2019 12:35 GMT werdsmith
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.
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Monday 8th April 2019 12:49 GMT caffeine addict
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...)
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Monday 8th April 2019 13:22 GMT Persona
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.
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Monday 8th April 2019 21:18 GMT John Smith 19
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.
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Monday 8th April 2019 14:35 GMT 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.
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Monday 8th April 2019 15:01 GMT caffeine addict
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.
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Monday 8th April 2019 17:24 GMT Ian Michael Gumby
@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.
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Monday 8th April 2019 15:19 GMT 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.
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Monday 8th April 2019 22:30 GMT swm
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.
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Monday 8th April 2019 16:42 GMT Orv
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.
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Tuesday 9th April 2019 16:59 GMT anothercynic
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.
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Monday 8th April 2019 15:29 GMT bazza
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.
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Monday 8th April 2019 21:24 GMT John Smith 19
"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.
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Tuesday 9th April 2019 21:15 GMT bazza
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!
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Thursday 11th April 2019 06:18 GMT John Smith 19
"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.
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Tuesday 9th April 2019 20:55 GMT John Smith 19
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.
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Monday 8th April 2019 13:27 GMT 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?
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Monday 8th April 2019 17:30 GMT jake
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.
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Monday 8th April 2019 21:49 GMT DJO
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.
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Monday 8th April 2019 14:24 GMT caffeine addict
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.
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Monday 8th April 2019 15:23 GMT 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
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Monday 8th April 2019 16:06 GMT Flocke Kroes
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.
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Monday 8th April 2019 16:50 GMT Orv
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.
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Monday 8th April 2019 21:40 GMT John Smith 19
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....
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Monday 8th April 2019 18:13 GMT bazza
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.
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Monday 8th April 2019 15:34 GMT John Brown (no body)
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?
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Monday 8th April 2019 17:53 GMT werdsmith
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!
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Monday 8th April 2019 17:58 GMT steelpillow
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....
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Monday 8th April 2019 21:31 GMT John Smith 19
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.
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Monday 8th April 2019 15:25 GMT bazza
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...
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Monday 8th April 2019 15:37 GMT Jellied Eel
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.
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Thursday 11th April 2019 06:27 GMT John Smith 19
"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.
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Monday 8th April 2019 16:30 GMT amanfromMars 1
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?
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Monday 8th April 2019 18:12 GMT steelpillow
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....
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Monday 8th April 2019 16:53 GMT Borg.King
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.
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Monday 8th April 2019 18:22 GMT 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.
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Tuesday 9th April 2019 20:28 GMT 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.
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Tuesday 9th April 2019 21:07 GMT John Smith 19
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.
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Tuesday 9th April 2019 21:24 GMT bazza
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...).
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Thursday 11th April 2019 16:24 GMT 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.
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Wednesday 10th April 2019 03:58 GMT 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.)
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Wednesday 17th April 2019 07:09 GMT John Smith 19
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
fanaticsadvocates 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.
Biting the hand that feeds IT
