Will Skylon Actually Fly?

[Hasegawa]

Do I think Skylon will fly? Probably not, too many systems are only in paper with far too much room to under-perform or be over-weight.

And that's assuming that their economics work out and aren't stomped by the tyranny of trivial flight rates...

And the reason nobody tries to launch things twice a day is because nobody has the ability to launch stuff twice a day.

Soyuz does have a demonstrated ability to launch once a day from the same pad, as was demonstrated multiple times in the 60s for various rendezvous and docking tests. As there is now an identical pad of the same design, it could very well be launched twice a day.

Or what about the Gemini missions with the Agena Target Vehicle? The Gemini could be launched about 90 minutes after the ATV.

Separate pads and differing launch vehicles, admittedly, but it shows that it could be done.

I suspect lack of payloads are more of a limiting factor than anything else.

When airplanes were first mass produced I bet you never had hundreds of people trying to get from point A to point B consistently every day, now look at the world. As supply increases, cost decreases to increase demand, and when you have enough demand cost will increase and whoever has supply gets rich.

That assumes the market is elastic enough to make it work. Have you seen any data to back this up?

Also:

Flying a rocket to space and back is the equivalent of buying a new car to drive to work every day simply because it became expended during the trip. Rockets are cool, I'll admit. Rockets are awesome. But they are also dirty, inefficient, and money eaters.

Lovely analogy. How well does it stack up though?

Your car finishes it's journey on the ground and stationary, as part of it's mission requirements. Does a rocket?

Edited October 13, 2015 by Hasegawa
Clarifying a statement

[fredinno]

Do I think Skylon will fly? Probably not, too many systems are only in paper with far too much room to under-perform or be over-weight.

And that's assuming that their economics work out and aren't stomped by the tyranny of trivial flight rates...

Or what about the Gemini missions with the Agena Target Vehicle? The Gemini could be launched about 90 minutes after the ATV.

Separate pads and differing launch vehicles, admittedly, but it shows that it could be done.

I suspect lack of payloads are more of a limiting factor than anything else.

That assumes the market is elastic enough to make it work. Have you seen any data to back this up?

Also:

Lovely analogy. How well does it stack up though?

Your car finishes it's journey on the ground and stationary, as part of it's mission requirements. Does a rocket?

Hmm. Generally modern rockets launch every 1 month to 3 weeks from the same pad, from looking at launch statistics. Though I'm not an expert on foreign (non-american) launches, SpaceX would not have bought LC-39A if it could launch from its existing pads every day. Probably has to do with modern safety requirements/

[Kryten]

SpaceX needs LC-39A for crewed dragon and falcon heavy, so that doesn't mean too much on it's own.

[fredinno]

SpaceX needs LC-39A for crewed dragon and falcon heavy, so that doesn't mean too much on it's own.

No. The existing LC-40 pad is capable of hosting Falcon Heavy (it is going to host Heavy, just like LC-39A) and it would not be worth it to buy and modify LC-39A just to be able to use a crew access tower that needs to be modified to support crewed Dragon. SpaceX was originally going to launch crews from LC-40.

SpaceX most likely needed the extra pad to relieve some of the pressure on LC-40, and to clear its 3-year launch backlog.

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By being cheap and reliable enough to get the ENTIRE low mass market to itself?

If it can reenter with a payload, that another market that right now only Dragon fills.

Only thing is, reentry with a payload to repair is probably not that economical- even if the Skylon ends up being very cheap- as the satellites will generally be in many differing orbits. It might be a competitor to repair stations in Orbit though- but with only very slightly more flexibility.

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Ok, I'm a layman, but how much different is that to a combat aircraft firing large (say, cruise) missiles?

The Concorde, however, was retired and no aircraft has appeared to compete with it. There is a lot of difference in the time it takes to cross the Atlantic by ship than by subsonic aircraft. But how many people would be willing to pay the price difference of a few hours in first class at match 0.9 and a super-fast, less than an hour, but vastly more expensive suborbital hop?

I don't think it will work for regular transportation. Where it can work, is for tourism.

Keep in mind there is also the cost of making/buying the satellite itself and tracking it later. A cheaper launch vehicle doesn't help with that.

More satellite launches allows for more standardisation and mass production to become economical.

[Nibb31]

And the reason nobody tries to launch things twice a day is because nobody has the ability to launch stuff twice a day. When airplanes were first mass produced I bet you never had hundreds of people trying to get from point A to point B consistently every day, now look at the world. As supply increases, cost decreases to increase demand, and when you have enough demand cost will increase and whoever has supply gets rich.

Actually, the reason that air travel (or any of the other transportation industries) developed was because there was already a huge demand for fast transportation. The demand to go from point A to point B existed before there were cars, trains, and airplanes. The need for transportation has existed ever since civilization started spreading around the Mediterrean, and the innovations making it faster and safer have never stopped, because the demand was always there.

The problem is that LEO is not a point B that is in high demand. It's a destination that doesn't exist, and an SSTO with frequent launch rates is simply another bridge to nowhere.

"Build it and they will come" doesn't work when it's a bridge to nowhere, because creating supply doesn't automatically generate demand. History is full of great ideas that were industrial failures because they didn't have a market. You could make orbital launches 10 times cheaper, it won't make the market 10 times larger, simply because there isn't that much to do in space.

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More satellite launches allows for more standardisation and mass production to become economical.

Standardization of what? Mass production for what purpose?

The GEO comsat market is already saturated, and being replaced by low-latency ground networks (fiber, 4G) and a couple of constellation projects. How many more comsat constellations can the market really support? Earth observation is typically an institutional market. Maybe there is a market for a private sector, but realistically, how many satellites would they need? Do you think it would support 100 launches per year?

And then there are the other red herrings that have never attracted any real attention from the industry: semiconductor production, space tourism, and maybe in a distant future, asteroid mining. But none of these activities have any real business case. Nobody has actually run the numbers or done any realistic studies that have proved that they are actually sustainable.

Edited October 13, 2015 by Nibb31

[prophet_01]

Judging from the pre-orders that virgin galactic claims to have, there seems to be some interest in tourism if it's somewhat affordable. On the other end, the very few realized ISS-tourust trips show that there definitely is an upper limit of how much people are willing to spend.

So price seems to be a factor here. But I don't think that skylon could offer ticket prices low enough to atract enough tourists to break even on that alone. Mass tourism however isn't realistic at all. At best, it might be an additional source of income next to sattelite deployment and repairs.

Is that enough to realize one flight per week or to make a significant profit? Probably not. I'd be surprised if they could break even without significant support from the britishand european goverments. Aside from finishing the project at all, if it ever flies like once a month, it would be a huge success for REL.

[Nibb31]

Is that enough to realize one flight per week or to make a significant profit? Probably not. I'd be surprised if they could break even without significant support from the britishand european goverments. Aside from finishing the project at all, if it ever flies like once a month, it would be a huge success for REL.

Not really. 12 flights per year isn't enough to justify a 7 billion dollar reusable launcher program.

[prophet_01]

I wasn't rly refering to the finacial side with that last bit. I totally agree that the huge development costs won't ever break even with that amount of launches. But I also think that even 12 launches per year is fairly optimistic, assuming that skylon won't be sold a lot to other nations and organisations as the market isn't that big. Also, space is also a critical part of many nation's defense interests and they are more likely to keep and fund their own programs instead of buying skylons.

12 launches per year for, let's say 2 skylons wouldn't be that bad compared to how often the shuttles flew in reality (even before the challenger disaster). And since there isn't a single (not even partly) reusable space craft that has been launched nearly as frequently, I say that once per month would be quite remarkable.

On that matter, Space shuttle missions weren't exactly the routine trips to orbit that NASA tried to realize. And although I highly doubt that skylon will ever be a comercial success or get even close to the level routine that airplanes have, it might realize some of the shuttle's original goals (not the financial fantasies of course) like a less complex access to space. It might be well worth the expense with all the new technologies in development for this program. It could become a fairly meaningful proof of concept for cheaper and more practical reusable designs in the future.

Edited October 14, 2015 by prophet_01

[Korizan]

I say go for it and even if it has limited success and the design needs to be change it is worth it.

Something like this all the space agencies in the world should bee handing over some cash (or support) to keep this in motion.

Especially considering the eventual payoff.

Nationalism is good to a point but sometimes it just gets in the way.

[KerikBalm]

I'd still prefer a 2 stage design, with the Sabre engine on the recoverable lower stage.

Maybe you could have sabres on both stages if its als oa decent vacuum engine... that way you've also got a turbine engine for powered flight before landing the upper stage

[Nibb31]

I say go for it and even if it has limited success and the design needs to be change it is worth it.

Something like this all the space agencies in the world should bee handing over some cash (or support) to keep this in motion.

Especially considering the eventual payoff.

Nationalism is good to a point but sometimes it just gets in the way.

The whole point of a national space program is to fund and subsidize a domestic space industry. The main purpose of that is to create highly qualified jobs and to stimulate the economy. National space agencies don't typically buy from other countries, because that goes against the whole point of having a space agency.

Skylon is British, so its only chance to get government funding is if the UK government all of a sudden acquires an interest in space. Historically, that's unlikely at this point.

The UK is part of ESA, but ESA splits its own funding proportionally to the countries that fund ESA. Therefore, it can only increase funding of a British program if the British government allocates more funds to ESA (which is also very unlikely). The only other option would be to spread Skylon development over several ESA member states by getting Alenia-Thales and Airbus DS involved in the project, but it doesn't seem that REL or any of the potential partners are interested in that either.

[Kryten]

The UK government does have a big interest in space, hence UK outfits like Avanti and O3B; it just doesn't have much interest in launchers.

[Nibb31]

The UK government does have a big interest in space, hence UK outfits like Avanti and O3B; it just doesn't have much interest in launchers.

Agreed, but the budgets allocated to space in general are symbolic compared to other nations.

[Hasegawa]

Hmm. Generally modern rockets launch every 1 month to 3 weeks from the same pad, from looking at launch statistics. Though I'm not an expert on foreign (non-american) launches, SpaceX would not have bought LC-39A if it could launch from its existing pads every day. Probably has to do with modern safety requirements/

As I said, 2 different launch vehicles, two different pads . The Atlas Agena Target Vehicle launched from Cape Canaveral Airforce Station's Launch Complex 14, the Titan 2 GLV/Gemini from CCAS LC 19. They must have processed them in parrallel, and had them both stacked and fueled at the same time. But the crews managed two launches in one day, which puts a hole in kStrout's claim that no-one tries to launch twice a day because they can't.

You're probably right about the usual launch rate for re-using a pad. And that's undoubtedly because it takes time to ensure all the ground side stuff is working correctly after a launch. Indeed, the shortest time between launches from the same pad I know of is Gemini 7 -> Gemini 6A at ~11 days, which is probably not a sustainable rate. Too much overtime and too much deferred maintenance, I guess.

[Kryten]

You're probably right about the usual launch rate for re-using a pad. And that's undoubtedly because it takes time to ensure all the ground side stuff is working correctly after a launch. Indeed, the shortest time between launches from the same pad I know of is Gemini 7 -> Gemini 6A at ~11 days, which is probably not a sustainable rate. Too much overtime and too much deferred maintenance, I guess.

Soyuz 6 and Soyuz both launched from Baikonur 31/6 almost exactly two days apart.

[Hasegawa]

Soyuz 6 and Soyuz [8] both launched from Baikonur 31/6 almost exactly two days apart.

Huh, well I've learnt something today

And two parts of a triple launch mission too. Very neat. Pity they had the issues with the rendezvous gear on all 3 Soyuz.

(Addition to quote in square brackets mine, adding omitted number)

[fredinno]

I'd still prefer a 2 stage design, with the Sabre engine on the recoverable lower stage.

Maybe you could have sabres on both stages if its als oa decent vacuum engine... that way you've also got a turbine engine for powered flight before landing the upper stage

Maybe this could allow a more commercially viable ~10T to LEO stratolaunch-style rocket design.

[Sanic]

Or methane fuel!

[fredinno]

Or methane fuel!

Hydrogen is needed to cool the engines.

[KerikBalm]

Liquid methane is still pretty cold, and you could cool it further.... granted, it won't maintain a low temperature on its own due to boiling at the phase transistion.... but

If its 60k instead of 20K, cooling something at > a thousand degrees... the temperature difference isn't that much. I imagine that due to its higher density, its got better heat transfer properties anyway?

[Nothalogh]

Hydrogen is needed to cool the engines.

I was under the impression that liquid helium was used as the precooler coolant, and that the hydrogen was used for regenerative engine cooling only, something methane could easily do

[magnemoe]

Liquid methane is still pretty cold, and you could cool it further.... granted, it won't maintain a low temperature on its own due to boiling at the phase transistion.... but

If its 60k instead of 20K, cooling something at > a thousand degrees... the temperature difference isn't that much. I imagine that due to its higher density, its got better heat transfer properties anyway?

Hydrogen has an benefit in an hypersonic engine, scramjet designs also use hydrogen.

Not sure about how much one kg of methane cools compared to one kg of hydrogen. You might also undercool the hydrogen a bit, as I understand the cooling need more hydrogen than the engine can burn so some are burned in an small ramjet.

The closed loop used helium, but the hydrogen cools the helium.

[SargeRho]

And Hydrogen cools that Helium. Methane is apparently not cold enough.

[Lukaszenko]

Hydrogen has a very high specific heat capacity, which is useful for obvious reasons when you're using it as a cryogenic coolant. In a launch vehicle.

[Slam_Jones]

Sorry to be off-topic, but every time I see this thread, I can't help but think of how great the name "Will Skylon" would be for a sci-fi character