How excited should I be about Skylon?

[Nuke]

they could make a fortune in the industrial sector with the heat exchangers alone. if i were them id try to bring those to market asap, this would provide the neccisary funds to build the engine/spaceplane.

[shynung]

It does: and that also is new, untried tech. They envisage using two counter-rotating compressor fans with no stators. Nobody has tried anything like it for a supersonic engine, and they have yet to prove it will work as well as they hope.

True, but contra-rotating single-shaft helicopter rotors have been around for some time. Theoretically, it should work, but the margin of safety is very thin. What would happen if the blades on adjacent differently-rotating turbines flex and slap against each other?

[magnemoe]

True, but contra-rotating single-shaft helicopter rotors have been around for some time. Theoretically, it should work, but the margin of safety is very thin. What would happen if the blades on adjacent differently-rotating turbines flex and slap against each other?

Think the gearing is the main issue, stators can also provide structural support.

Not sure how much the earn from it, counter rotating rotors is mostly to reduce rotor diameter and eliminate the tail rotor not to increase efficiency.

[Nibb31]

they could make a fortune in the industrial sector with the heat exchangers alone. if i were them id try to bring those to market asap, this would provide the neccisary funds to build the engine/spaceplane.

Even that would be a stretch. The only organisations with the infrastructure, workforce, and supply chain to build airframes the size of the A350 in Europe are Airbus or BAe. Airbus employs thousands of people and hundreds of subcontractors. To build an industrial base like that takes billions of dollars over decades. Regardless of what REL says, you can't build a Skylon in your back garden shed, or even in a rented workshop on an industrial estate.

Skylon will only happen if the big aerospace companies get involved, and that will only happen if they have secure orders for a minimum number of spacecraft. Companies like Boeing or Airbus only start designing a new aircraft when customers have preordered a certain number. Customers preorder because they know that those companies will deliver. They have an accurate idea of the operating cost before they commit.

Given that there is no market for several orbital launches per day, there is no business model for operating a fleet of reusable fast-turnaround spaceplanes, it's impossible to calculate a positive return on investment on Skylon operations, there are no customers ready to buy Skylon. Therefore nobody wants to commit resources into building it.

Edited December 1, 2014 by Nibb31

[magnemoe]

Even that would be a stretch. The only organisations with the infrastructure, workforce, and supply chain to build airframes the size of the A350 in Europe are Airbus or BAe. Airbus employs thousands of people and hundreds of subcontractors. To build an industrial base like that takes billions of dollars over decades. Regardless of what REL says, you can't build a Skylon in your back garden shed, or even in a rented workshop on an industrial estate.

Skylon will only happen if the big aerospace companies get involved, and that will only happen if they have secure orders for a minimum number of spacecraft. Companies like Boeing or Airbus only start designing a new aircraft when customers have preordered a certain number. Customers preorder because they know that those companies will deliver. They have an accurate idea of the operating cost before they commit.

Given that there is no market for several orbital launches per day, there is no business model for operating a fleet of reusable fast-turnaround spaceplanes, it's impossible to calculate a positive return on investment on Skylon operations, there are no customers ready to buy Skylon. Therefore nobody wants to commit resources into building it.

Yes, most technologies are incremental.

Smartest would be to do it in steps, perhaps a hypersonic cruise missile first, the US has shown interest here regarding scramjets, simple compared with an SSTO, engine don't need to be large or live long and you start moving and up in the atmosphere.

next would be something who was not designed to reach orbit, but only halfway, this way you would only need an second stage, this would be relevant for lots of missions, gps and lower orbit communication satellites perhaps even small satellites to GEO. Skylon would not reach this orbits anyway so you would need an upper stage anyway.

Platform would also be usable as an fast recon or bomber.

Now you have an plane who is useful. You could even make an upgrade who goes faster or have more payload, both enable larger payloads.

Last make something who can reach orbit.

[Nibb31]

Sadly, the size and fragmentation of military budgets in Europe doesn't allow envelope-pushing aerospace research programs any more. We can't even agree on a common jet fighter or a drone program, and we barely got a new turboprop cargo plane, so fundamental research in hypersonic cruise missiles is simply not going to happen.

As for the halfway thing, hypersonic airlaunch is a whole other can of worms that is probably more complex than SSTO. Skylon doesn't make sense economically as an SSTO launcher. It will make even less sense as carrier aircraft with an expendable second stage.

But yes, one of the problem's with REL's approach is that they are not doing incremental improvements on state of the art aerospace engineering. Skylon implements not one, but a dozen new unproven technologies: airframe structure, engine, TPS, propellant operations, business model, construction techniques, materials, etc... Nothing in Skylon is off-the-shelf or even a conventional design. To be successful, these theoretical technologies ALL have to work exactly as planned on paper. If any of these technologies underperforms in one way or another (cost, weight, schedule, reliability, supply-chain, performance...), then the whole project falls through and the entire effort is wasted.

[Iskierka]

Skylon doesn't make sense economically as an SSTO launcher. It will make even less sense as carrier aircraft with an expendable second stage.

Not according to multiple independent economic studies - the very worst cases, where they made sure to make it as expensive as reasonable and fly as little as reasonable, it worked out as competitive with Falcon 9.

Additionally, they have a lot more resources than you're imagining now, as they've entered into research agreements with USAF development labs, and have multiple clients interested in helping with engine and airframe.

They also have much larger margins on the design than you seem to assume - just because they're not publicly quoting it often, doesn't mean they've pushed theory to its limit. Many of the features are specified as significantly heavier than they could be, and the SABRE engine is currently quoted as lower performance than they think they can get. The fuel tanks are specified only as standard aerospace aluminium, whereas they know there are a few likely alternatives that could improve performance - but they know that alloy will work. Yes, the project will fall through if parts underperform - but they've already assumed that -everything- -will- underperform, giving them margins for improvement rather than loss.

And they've stated that they did consider an incremental approach, but the trouble is incremental approaches die off. The technology can very definitely get orbital - sub-orbital simply cannot provide enough of a business case to get the funding required to make the final vehicle, and would actually be more expensive as it would require scaling down the full-performance engine. They're aiming straight for orbital because they're confident they can do it, and they know it 100% -will- fail if they try smaller first.

Edited December 1, 2014 by Iskierka

[Kryten]

Not according to multiple independent economic studies - the very worst cases, where they made sure to make it as expensive as reasonable and fly as little as reasonable, it worked out as competitive with Falcon 9.

Falcon 9 can put reasonably sized payloads to GTO, Skylon cannot; it wouldn't be competitive if it could go up for free. A study that ignores that payloads are real objects with minimum sizes made for specific purposes is worthless, and that's the state of a lot of the studies in the sector.

[Iskierka]

Falcon 9 can put reasonably sized payloads to GTO, Skylon cannot; it wouldn't be competitive if it could go up for free. A study that ignores that payloads are real objects with minimum sizes made for specific purposes is worthless, and that's the state of a lot of the studies in the sector.

Skylon is fully intended to have a second stage that can put up to 6.39 tonnes into GTO and return for reuse. Its development cost will be near-nil as it uses the same OMS engines as Skylon and simply needs a couple fuel tanks and some light structure attached. If allowed to reenter destructively (estimated every ten launches, as it's quoted that it will have 10x reusability) it can carry up to 8.08 tonnes. Is that competitive enough?

[Kryten]

If they really are assuming structure and avionics only=near nil dev. cost, then no, that's not going to be competitive with anybody.

[Iskierka]

Comparative to the billions for the Skylon itself and the engine the upper stage requires, yes, that's pretty minimal dev cost.

[*Aqua*]

They think the complete Skylon project (includes development and I guess a working prototype plus different payload container) will cost 12 billion US$.

Looking at the numbers I'm sure they already included an upper stage.

The estimated cost for bringing a kg of payload into orbit is 1100 US$. A Falcon 9 is at 4100 US$ per kg.

Btw they successfuly tested a smaller scale precooler. At the moment they a building a facility for testing a SABRE engine in jet and rocket mode.

[Frozen_Heart]

Btw they successfuly tested a smaller scale precooler. At the moment they a building a facility for testing a SABRE engine in jet and rocket mode.

Are there no pre-existing places in Europe for testing rockets?

[NERVAfan]

Yeah, everything I've read suggests the Skylon project has quite significant margins.

The money remains the big question... as in pretty much all big technological projects.

[*Aqua*]

Are there no pre-existing places in Europe for testing rockets?

I think there are. But which of them can test a hybrid engine? In rocket engine tests you don't need hypersonic air. In jet engine tests you don't need a vacuum. They need a special facility which can provide both to simulate going to space and back again.

[Iskierka]

I think there are. But which of them can test a hybrid engine? In rocket engine tests you don't need hypersonic air. In jet engine tests you don't need a vacuum. They need a special facility which can provide both to simulate going to space and back again.

Basically this. They don't yet have a facility for it, but their intention is to build one while performing individual mode tests at the separate facilities, then move onto testing transition once the new facility is ready.

[magnemoe]

Sadly, the size and fragmentation of military budgets in Europe doesn't allow envelope-pushing aerospace research programs any more. We can't even agree on a common jet fighter or a drone program, and we barely got a new turboprop cargo plane, so fundamental research in hypersonic cruise missiles is simply not going to happen.

As for the halfway thing, hypersonic airlaunch is a whole other can of worms that is probably more complex than SSTO. Skylon doesn't make sense economically as an SSTO launcher. It will make even less sense as carrier aircraft with an expendable second stage.

But yes, one of the problem's with REL's approach is that they are not doing incremental improvements on state of the art aerospace engineering. Skylon implements not one, but a dozen new unproven technologies: airframe structure, engine, TPS, propellant operations, business model, construction techniques, materials, etc... Nothing in Skylon is off-the-shelf or even a conventional design. To be successful, these theoretical technologies ALL have to work exactly as planned on paper. If any of these technologies underperforms in one way or another (cost, weight, schedule, reliability, supply-chain, performance...), then the whole project falls through and the entire effort is wasted.

It will not be an hypersonic launch if they drop payload in space, limitation is that you are not able to reach orbital speed but you would still be suborbital.

Has been designs for this using conversational engines, Jets to mach 3 then rocket engine, release upper stage and return.

Main issue is the design of airframe, you need an huge hypersonic plane who are expensive to design and build.

[Nibb31]

They think the complete Skylon project (includes development and I guess a working prototype plus different payload container) will cost 12 billion US$.

Looking at the numbers I'm sure they already included an upper stage.

The estimated cost for bringing a kg of payload into orbit is 1100 US$. A Falcon 9 is at 4100 US$ per kg..

Those figures are bogus, and everyone in the industry knows it.

Skylon is bigger than an Airbus A380. Just to build a conventional heavy airliner requires a major airport with a reinforced runway, a production facility the size of a small city, and a supply chain involving hundreds of subcontractors. It took Boeing $32 billion and 10 years to develop the 787, which is just an airliner with fairly mature and well-understood technology, except for the carbon-fiber body. EADS spent $25 billion dollars to develop the A400M, which is just a conventional turboprop cargo plane.

Airliners and military aircraft projects have a market, with firm orders years before the first test flight and minimal risk. There currently simply isn't a mass market for hundreds of Skylons with daily or weekly orbital launches, even at the cost of an airline ticket. Which is why EADS, BAE Systems, Rolls Royce or Boeing and Lockheed Martin are not lining up to buy their idea.

But Skylon doesn't just have to design an aircraft. They have to invent new technologies, test them, train people to use them, develop manufacturing techniques for them, fund contractors to invest in new tooling and processes, etc... Those conventional aircraft development programs usually reuse tooling, facilities, and construction techniques that are well proven. When they don't (look at the 787), they get cost overruns, delays, sometimes unsurmountable structural problems.

Yet REL estimates that Skylon will only cost $12 billion, and that each unit will be cheaper than a good old Airbus A330, although just about everything in Skylon is new, unproven, and unconventional.

Now, an A330 costs somewhere around $100 million. If half of that price is development, then to recoup a development cost of $12 billion, they need to sell at least 240 units, which is rubbish.

1100$/kg for a 6 ton payload puts the cost of a flight at $6.6 million. That means that each Skylon will have to fly 15 launches over a period of say 10 years, which means that the market has to absorb over 360 orbital launches per year, at $6.6 million per launch. Sorry, that's not going to happen.

The cost estimates are simply not realistic, and therefore neither is their business model.

[Nibb31]

I think there are. But which of them can test a hybrid engine? In rocket engine tests you don't need hypersonic air. In jet engine tests you don't need a vacuum. They need a special facility which can provide both to simulate going to space and back again.

There are engine test facilities in France, UK, Germany, and Sweden at least. They would need government support (ESA at least) to use them though.

What they are also going to need is flight experience with the engine. For the subsonic flight regimes, they could test it by mounting it on an old A330 or something similar. For hypersonic, they are going to need a hypersonic wind tunnel or actual flight experience.

My doubts are mainly with the actual airframe more than with the engine. Nobody builds ogival fuselages any more. Nobody builds ogival structural tanks, and nobody builds entire airframes out of composite carbon structures with wierd shapes. Nobody knows how much these things are going to cost. Nobody knows how these materials resist to hypersonic airflow, to UV exposure, to thermal cycles, vacuum, and refueling, how much maintenance it needs, how it can be repaired... There is a long way between "this works on paper" and real-world operations.

Without knowing this, there is no way to know how much it will cost to operate Skylon. So without such basic information, again, their business model is bogus.

[lincourtl]

Nobody builds ogival fuselages any more...

Pardon my ignorance, but that assertion caught my eye. Really? How are supersonic aircraft fuselages designed these days? I thought ogives were essential to supersonic flight. Obviously, I'm not a member of the aerospace industry, just a curious observer.

[Nibb31]

Who builds SuperSonics airframes the size of an A380 these days?

[Iskierka]

Which is why EADS, BAE Systems, Rolls Royce or Boeing and Lockheed Martin are not lining up to buy their idea.

Or so you assume, with precisely zero knowledge of current negotiations REL may be in.

Yet REL estimates that Skylon will only cost $12 billion, and that each unit will be cheaper than a good old Airbus A330, although just about everything in Skylon is new, unproven, and unconventional.

Now, an A330 costs somewhere around $100 million. If half of that price is development, then to recoup a development cost of $12 billion, they need to sell at least 240 units, which is rubbish.

Cost estimate is based on them using much more conventional materials than the 787. (only the TPS uses a material new to airframes, but it's not new to high-temperature structural applications. It's already used in F1 engines and exhaust systems.) $12 bn was the development cost of the A380, and the Skylon does not require man-rating in its initial development. Aside from the engines, Skylon is more conventional than most modern airliners - it's certainly a LOT simpler, even if its task is more complex.

Also, where on Earth are you getting $100 mn? The quoted unit price for Skylon is £190 mn, or $320 mn at the time that estimate was published. Into $12 bn, that means only 37.5 units are required - market estimates performed expect at least 30 units demand, more likely 60+.

1100$/kg for a 6 ton payload puts the cost of a flight at $6.6 million. That means that each Skylon will have to fly 15 launches over a period of say 10 years, which means that the market has to absorb over 360 orbital launches per year, at $6.6 million per launch. Sorry, that's not going to happen.

The cost estimates are simply not realistic, and therefore neither is their business model.

$1100/kg is the maximum all-inclusive price for LEO insertion of about 15+ tonnes, so make that $16.5 million. (This is initial launch costs while amortising purchase.) That means each vehicle has to absorb 20 launches individually to pay for itself, when the launcher is expected to last at least 200 launches, likely expandable to 500 after the first vehicles are retired and can be destructively examined for lifetime estimate. With a mere 40 vehicles, that's only 800 launches - so even if this was only over the next ten years, they would only have to take 80/yr, less than current launch rates at less than half the cost of the cheapest launch vehicle we have, the Pegasus, capable of a mere 450 kg to LEO.

Try using real numbers and you find they have a hell of a good business case.

[PakledHostage]

Try using real numbers and you find they have a hell of a good business case.

One might suggest that you do the same... Your "business case" has some significant oversights. Things like the cost of materials, facilities, staff, fuel, etc. Some of those are rolled into the development cost but you haven't accounted for them in your operating and production costs. You can't make a "hell of a good business case" if you ignore those costs.

[MBobrik]

Yet REL estimates that Skylon will only cost $12 billion, and that each unit will be cheaper than a good old Airbus A330, although just about everything in Skylon is new, unproven, and unconventional.

Is this even a disadvantage ? How much of the development costs is just the bureaucracy around building a passenger plane with all those certificates, tests and re tests, safety measures, supervision of production and stuff ?

I believe that if someone started building an A330 minus all the stuff that is there to assure that something moving 5-6 times faster than a car, and 10 km above ground is actually safer than cars, he would end up with an order of magnitude less cost.

[PakledHostage]

Is this even a disadvantage ? How much of the development costs is just the bureaucracy around building a passenger plane with all those certificates, tests and re tests, safety measures, supervision of production and stuff ?

That's something of a straw-man argument. While Skylon doesn't need to meet the strict standards of airworthiness that transport category aircraft have to meet (especially if it isn't man rated), it does need to work at speeds and altitudes over 30 times higher than a typical transport category aircraft. The cost of developing Skylon won't be that of certification. It will be the cost of developing the technology required so that it can work at all.