back to article Blighty's Skylon spaceplane faces key tech test in June

A British firm seeking to build a radical spaceplane – the Skylon – able to fly to orbit from a runway takeoff without any jettisoning of fuel tanks or boosters says that it will test its main technical special sauce this year. The announcement was made at a spaceplanes conference in California last week. Roger Longstaff, …

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Boffin

@The JonB

Good point. IIRC the design Skylon seems to derive from was developed post area rule.

However not that the area rule is most useful for vehicles that spend *most* of their time in the transonic (c0.9-1.1M ) range which is the worst for drag.

Note that if you're looking at how cross sectional area changes over length you need to take into the engine pods. You might also note that while *all* commercial airliners have to take this into account (since they all spend *most* of their time just below M1). You just don't see the distinctive "Wasp waisting" of earlier aircraft The rule can be met by quite subtle tweaks in detail design.

However Skylon *could* just ignore it and power through the sound barrier. It's a trade off. Launch vehicles *never* cruise. If area ruling the design lost them too much performance over more of the speed range (Orbital velocity is about M23) I'm sure they'd sacrifice it.

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interesting...

The shape looks like its straight out of the 60's, and more than a little reminiscent of the SR-71.

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Happy

@MrGreyZ

"The shape looks like its straight out of the 60's, and more than a little reminiscent of the SR-71."

Actually the planform looks like the AV Roe 730 M3 reconnaissance bomber of the 1950s (wing tip rather than mid wing engine pods and cannards rather than chines)

I'd guess the design team has better access to 730 design data than SR71.

Note they have stated they are planning a design review to "D" standard which might change things.

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Re: interesting...

Out of the 60s yes, SR-71 no. Try the Avro 730 and look very carefully at the distinct similarity between them. The SR-71 has only a passing similarity.

http://prototypes.free.fr/tsr2/images/avro730_03.jpg

http://www.sciencemuseum.org.uk/images/I044/10313130.aspx

http://www.diecastxchange.com/forum1/topic/58397-avro-730-a-planned-british-reconbomber/

http://en.wikipedia.org/wiki/Avro_730

Note; cancelled in 1957, and yes we could do these things if we wanted.

Nostalgia moment:

http://www.wingweb.co.uk/aircraft/The_Avro_Vulcan.html

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meh,

first stage should be a large rail/RAM/mass driver etc gun. Well at least the launch would look cool.

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See above

But it would look cool as the plane vapourised as it left the track. due to atmospheric friction.

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Pint

Awesome

The Skylon should have an Apple logo on it, it just looks so much cooler than the other crap out there, just on this it deserves to be built.

I note the sabre engine also burns hydrogen and so is potentially emission free, not much being said about that but that does have an implication on conventional air travel which is a big polluter (does it not!)

Good on em for keeping trying, and taking a sensible staging approach to testing the technology personally after 30 years of this Reaction engines should work on the assumption there will be no help from UK PLC

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Jobs Horns

Re: Awesome

What????!?!!!! Apple???? Never, not in trillion years. Apple is pretty yes, but that's about it! ;-)

On a more serious note, as far as developmental costs are concerned, this is subject to funding that increases as it jumps through the hoops. It is a very serious project and encouraged to be. I've been crossing my fingers about it for a few years now, and almost dread the interim reports and milestones, such as the one ahead.

This kit is very flexible and will dominate the skies for a while if successful. Imagine having instant rescue kit, or stuff that can flick up there to repair satellites, replace satellites, on demand. The future would begin there.

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Alert

I'm not an aerospace engineer but...

How do those stubby little wings generate enough lift in atmosphere for a 275 tonne plane? I'm guessing high speed compensates in some way?

So does this mean it has super high speed take off & landing speeds and can barely manouvre?

Sounds scary....

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Happy

AC@08:51

2 things.

Those big red things at the start of the animation are the Hydrogen tanks. Its density relative to water is 7-7.7%, depending on how densified it is. It's big but *light*.

You might also check the *real* dimensions on this thing.

IIRC Takeoff and landing speeds are high. Part of their work has been designing a light weight braking system that borrows (of all things) from truck racing technology to use water cooled brake. Note the undercarriage weight is "light" relative to the *common* state of practice, not the state of the art. Landing gear weighing 1.5% of Gross landing mass (for airliners it's more like 4%) were flying in the 1950s and 1960s, specifically on the B58 Hustler.

As for "Barely manouvre" it depends how much you *need*. The tail fin + forward cannards should give aircraft like behavior but throttling the wing tip engines would give significant yaw capability. It might *look* a bit like an SR71 but conceptually its mission is *much* simpler. More or less in a straight line is fine.

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TV21

Fireball XL5

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Ice is the unseen problem that will bring the whole idea to a full stop

Having designed a Freeze Drying Microscope taking samples down to -100C I can tell you from direct experience, the problem they face is ice. It is quite amazing just how much moisture there is in air. Moisture that will, instantly, turn into ice. Remember, when aircraft engines were first created, they had to fit heaters to their engine intakes to melt the ice as it formed..... or the engine would promptly fail.

They make no mention of what they are going to do about the ice that will, inevitably, coat the entire cooler system. Ice is their Achilles heel.

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Title required

You're right and wrong, the secret to the machine's success is frost control.

It is mentioned on their website, but the technical details of this are deliberately kept secret, it is also the apparent breakthrough that they've made and will probably the main success condition of this test.

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Re: Title required

It's possible to glean a little about it:

http://www.theengineer.co.uk/in-depth/analysis/skylon-spaceplane-gathers-momentum/1004713.article

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Thunderbirds.....are....go

did anyone else wonder if Gerry Anderson had anything to do with that promo video?

oh and where are the lateral thrusters to enable it to dock with the ISS etc

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FAB

Yes.

And Strauss's "Blue Danube Waltz" as background music for the orbital rendezvous?

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Happy

Comments on the article.

I've only commented on the bits I disagree with. The rest you can presume I go along with.

"Air is taken in at the front of the SABRE and almost instantly cooled down to the point at which it is almost liquid, using terrifically powerful freezer kit employing a liquid-helium loop."

And driven by a pair of oversize liquid Hydrogen tanks. A very cold thing makes a fairly warm thing substantially colder.

>>The supercold air takes the place of liquid oxygen in the combustion chamber, reacting with liquid-hydrogen fuel to produce thrust in much the same way as the space shuttle main engines. Heat sucked from the intake air is dumped into the fuel.<<

The amazing spaceplane is expected to be able to repay those big investment cheques, as it will be able to deliver payloads – admittedly, at first quite small ones of only 10 tonnes or so compared to its own substantial mass of 275+ tonnes – at low cost.

That's a payload which is c3.6% of GTOW. In the launch biz that's pretty good.

It's better than a Delta IV and on a par with an Atlas V. This counters the traditional whine that SSTO's can't deliver as much payload (as a portion of GTOW) as expendables.

The shuttle manages about 1.25% of GTOW. It has an SSTO payload fraction *without* the actual benefits of SSTO.

REL's engineers have been compelled to shave everything to the limit to produce a design which seems to show that SABREs and the fuel they need to reach orbit can fit into a re-entry-capable airframe along with some cargo.

In a word. No.

The ceramic aeroshell is to be just 0.5mm thick.

Slightly thinner than some part of the SR71 wing structure (which were *also* corrugated BTW).

Skylon's skin is only designed to carry the *thermal* load. Mechanical loads are carried by the geodesic truss framework. The technique was proposed for the X20 DynaSoar.

The undercarriage has had to be lightened too,

Below *common* state of practice, *not* state of the art as far back as the late 1958s (and not a CAD/CAM workstation in sight).

"so that a Skylon won't be able to land on just any runway"

Wrong. This thing might take off like Michelle McManus but it'll land like Britney Spears. Weather or not it'll be *allowed* to use ordinary airports, as it is technically a UAV, is something to be thrashed out.

" – it will need a special reinforced one able to cope with heavily loaded wheels moving rather fast."

On *takeoff* only.

If the craft itself should gain just a few per cent in fueled-up weight during the development process, this would wipe out its entire payload margin.

No. SSTO's are vulnerable to growth in the *dry* weight. In principle the wings make it *less* vulnerable in this area than vertical takeoff designs.

"There are those who would argue that operations using liquid hydrogen fuel will simply never be economical:"

Mostly they argue its a pig to handle. Liquid oxygen freezes out water on top of the insulation if it's not good enough. Hydrogen liquefies *Oxygen* out of the air.Insulation has to be *very* good. It's a PITA.

However *all* alt-space advocates agree the fuel cost is "In the noise".

The *real* cost is the manufacturing and "standing army" of managers, safety inspectors, managers of safety inspectors, document management team etc. Cost is strongly proportional to *complexity* and *weakly* proportional to size.

" the stuff takes up so much room that hydrogen aircraft – including the Skylon – are always made up mainly of fuel tanks."

*All* launch vehicles are mostly fuel tank.

" It is so troublesome, potentially dangerous and expensive to handle that it will infallibly destroy any business model based on it other than that of government-funded military or scientific projects."

No.

Regarding RE's business model it's *strictly* for profit.

They build a vehicle. It's up to *other* people to operate it.

It's like building a taxi. Someone *else* operates it. If they don't make a profit *they* go out of business. Just like a *real* transport systems, not the insane 1 shot ticket-to-ride/govt cost++ system expendables foist on the users.

TBH there were a few moments when I was tempted to flag the article as Troll.

If this is Lewis on a subject I know something about what is he like on subject I don't know anything about?

<sigh> There goes my shot at the Reg spaceplane desk.

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Another key point

Due to the nature in which the engine works:

The second test that they have to endure is using the liquid oxygen to cool the engine.

Due to the inlet being cooled by the liquid hydrogen, the engine and nozzle assemblies need another source of coolant.

This is another reason for the need for cryogenic fuels and also why kerosene is not feasible as a fuel for this engine.

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Boffin

@annodomini2

"Due to the inlet being cooled by the liquid hydrogen, the engine and nozzle assemblies need another source of coolant."

I'm not quite sure why they have mandated using air and Oxygen as the combustion chamber coolants and there is no reference on the simplified flow diagram for SABRE

http://www.reactionengines.co.uk/images/sabre/library/sabre_cycle_l.jpg

However IIRC Oxygen cooled combustion chambers (might include using cooled air) were being investigated as part of the £6m from ESA. It was done by IIRC EADS Astrium in April 2010.

Or they could have asked NASA (unrestricted download) or Doug Jones of Xcor, both of whom have some experience of this. Xcor is probably the US aerospace company closest to RE in their approach to an orbital vehicle.

Sadly that would have enmeshed them with a US aerospace company (albeit not a *big* one) and ITAR. I'd love to know the legal position on designs that incorporate stuff you found out studying *freely* available NASA documents outside the US.

I'm quite sure RE know the best "simulator" when you're testing an engine component is a *working* engine. Build early, test early.

But that's what they can't afford. A test of full size precooler + frost control is presumably the last *core* component that has not been tested. I suspect a successful test will release substantially more funds. This would probably be the first *new* liquid rocket engine in the UK for 40 years.

BTW *most* common rocket engines use the fuel as a coolant *except* hypergolics (use NTO) and Hydrogen Peroxide (usual mass ratio is 6:1 so *plenty* available and it's got an SHC like water). This includes the Russian staged combustion engines like the RD180 powering the Atlas V 1st stage, which have *very* high chamber pressures.

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