Author Topic: The Reaction Engines Skylon/SABRE Master Thread (6)  (Read 437846 times)

Offline Robotbeat

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #320 on: 11/18/2016 08:17 pm »
Also, I have to say the idea of a civil hypersonic transport is super exciting to me, too. And it'd use hydrogen, so technically this can be done pretty easily with zero carbon emissions! Very neat. :)
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Offline oddbodd

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #321 on: 11/19/2016 03:38 am »
The issue as I see it is that the original Skylon SSTO concept had a narrow(-ish) window of opportunity. It made sense while rockets were expendable, but we now have Space X pushing the envelope on reusability, and if they reduce costs enough (not necessarily down to theoretical Skylon levels) then the business case for progressing to create Skylon (or similar) will not be attractive enough to pull in the needed investment. This new site seems to push SSTO Skylon further and further out, giving the likes of Space X more and more time to consolidate and lock down the market. So SSTO Skylon is at risk of withering on the vine, and without it (or something similar) it's not clear that we will ever reach SSTO and airliner style operations. Without those two things space access is never going to progress much beyond what we already have. Here's an illustration https://en.wikipedia.org/wiki/Timeline_of_spaceflight
The annual launch rate is not increasing even with commercial competition, not even breaking a hundred since 1990, and the failure rate is not being significantly reduced.
In comparison Heathrow handles 1400 takeoffs and landings in one day, with an almost non-existent failure rate. And that's why airline ops and SSTO are needed. Yes, yes, I know the whole mantra that space is hard, but unless we do something better than rockets which have been the modus operandi since the 60's, we as a species are likely to be permanently stuck on this rock until whatever ELE comes along to wipe us out.

Oddbodd; Even with Skylon and SSTO launch will not be anything like 'airline' operations. The analogies break down very quickly beyond a very basic application. Space launch is very different than any other form of transportation used on Earth, it has to be as it has almost no way to 'tap' into the pre-existing nodes and networks of Earth based transportation and has strictly limited destinations and current uses.

Launching something into space, even assuming an 'operational' (Skylon for example) SSTO is not only difficult it requires deliver of the 'payload' to a specific orbit when all is said and done and unlike any Earthly transportation the main vehicle has to provide all aspects of that delivery since in most cases the payload can not. Our notional vehicle requires something to the size of, but far more complex and expensive to build and maintain, a 747 which then 'delivers' a payload equivalent of a DC3. (Not the whole aircraft, JUST its cargo and/or passenger equivalent)

Heathrow didn't exist 100 years ago but London did and it 'handled' quite a lot more cargo and passengers than Heathrow does on a daily basis back then. And anyone looking to compare the rickety, wobbly 'aeroplane' to what ships could accomplish was laughed at. But the aeroplane could in fact eventually interface with the same destinations that the ships did and while they could not carry MORE cargo/passengers per trip they did so faster and therefore could make more trips over the same amount of time.

Space launch has no destinations already in place and only a very limited economic 'niche' to service so even if they WERE capable of being operated at 'aircraft' rates and utility they would not have the market to do so. Having relatively 'cheaper' and more ready access will increase that market... Somewhat but in truth the overall 'current' market will quickly become saturated. The hope is that increased access will generate new markets and forces but in truth that's not how it's ever worked before as there always been pre-existing destinations and markets which new and more 'efficient' transportation systems tapped into to expand and grow.

There are no destinations, no pre-existing markets or service sectors to expand into other than the few that exist today and very little likelihood of those markets expanding significantly due to greater access and lower cost. (There is or course SOME elasticity in the pre-existing markets but there are regulatory and governmental/international pressures that will be applied to keep those from expanding too rapidly)

In summery, (too late I know :) ) the question has always been less about capability and access but economics, market and requirements. Space travel has always been significantly harder than air travel and it may be reduced some with coming technology and operations but it will not ever be as easy as air travel, or ships, trains, or cars, trucks, etc unless there is a VERY radical change in the fundamental aspects of space travel. SSTO, air-breathing or not, is not that radical of a change despite what many people think.

Randy

I understand what you're saying, and agree with much. What I'm trying to say (in a cack-handed way) is that the current methods are too slow, inflexible and prone to exploding to ever end up with a significant human space presence. Even Space X with a partially reusable rocket will take weeks (if not months) to reintegrate for a second launch.

It's a vicious circle: no destinations, no market; no market, no demand; no demand, no destinations. Until someone/something comes along to break that, it feels like we will be forever stuck in LEO for manned missions, GEO for communications, and the occasional splurge for scientific robotic observation BEO. So those of us dreaming of Moon/Mars colonies, orbital space stations, or research bases on Europa, will just keep on dreaming.

The only way we get space based destinations (and thus markets and demand) is if we make them, and they aren't realistically going to be created using expendable rockets. Look at the ISS; constructed over 16 years from payloads launched on EELV's and the partially reusable jigsaw puzzle that was the STS. It is totally dependent on a steady stream of additional launched supplies from earth (excl. energy), holds a handful of people in non-ideal conditions, cost $150 billion, and can't (or doesn't as far as I know) act as a staging point for beyond earth orbit missions.

I'm not saying we need to reach airline levels of ops or flight rate. That would be insane. But till the turnaround can be brought down to say sub-week and not tying up the launchpad/runway, we will never go beyond the current levels of activity. I just don't think you can push out further with any vehicle that you have to reassemble/replace every time you use it. Are there any other fully reusable SSTO's in active development right now? Skylon was the only one I'm aware of, and is now firmly on the back burner in favour of military and industrial applications, hypersonic planes, and if we're lucky a small satellite launcher. With all those diversions it would likely be the 30's before serious attention/finances would be brought to bear on a Skylon scale SSTO if it ever happens. By this time will the reduced benefits still justify the investment? To quote Hudson: "Game over, man. Game over!"

Offline oddbodd

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #322 on: 11/19/2016 03:52 am »
Also, I have to say the idea of a civil hypersonic transport is super exciting to me, too. And it'd use hydrogen, so technically this can be done pretty easily with zero carbon emissions! Very neat. :)

You do realize that the vast majority (~95%) of hydrogen comes from the processing of fossil fuels? Electrolysis (i.e. using wind, hydro or solar PV) is highly inefficient. There are laboratory scale experiments that may eventually bear fruit (i.e. algae), but I certainly wouldn't say that currently hydrogen can be done pretty easily with zero carbon emissions.

Offline t43562

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #323 on: 11/19/2016 05:21 am »
I'm not saying we need to reach airline levels of ops or flight rate. That would be insane. But till the turnaround can be brought down to say sub-week and not tying up the launchpad/runway, we will never go beyond the current levels of activity. I just don't think you can push out further with any vehicle that you have to reassemble/replace every time you use it. Are there any other fully reusable SSTO's in active development right now? Skylon was the only one I'm aware of, and is now firmly on the back burner in favour of military and industrial applications, hypersonic planes, and if we're lucky a small satellite launcher. With all those diversions it would likely be the 30's before serious attention/finances would be brought to bear on a Skylon scale SSTO if it ever happens. By this time will the reduced benefits still justify the investment? To quote Hudson: "Game over, man. Game over!"

The investment will also be greatly reduced as a consequence of all the diversions. Meanwhile we should be looking for new applications which are going to make investment flow in. We probably only need so much global-positioning and internet-from-space so what's going to be next that will unlock all the piggy banks?   No point burping out a Skylon in one great effort and then watching the company go bust while it waits for the ideas to catch up.

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #324 on: 11/19/2016 09:41 am »
The investment will also be greatly reduced as a consequence of all the diversions.
That's certainly the hope but the fact remains that Skylon is very large. The question is how much of that cost is down to it's novelty and how much is down to it's size. Remember these are the cost models that said SX's spend on the F1 up to the first F9 launch could not be less than $2Bn, which was simply not the case. On that basis, the SABRESkylon programme, run as efficiently as SX's development, would actually be about $2Bn.  [EDIT IRL there are enough "unknown unknowns" to make that doubtful. But how doubtful is a question you can only really answer after you'd run the project  :( . I'd bet REL's internal estimates, based on what's actually been done and how much it's actually cost are rather different, but you can't take those to a bank. ]
Quote
Meanwhile we should be looking for new applications which are going to make investment flow in. We probably only need so much global-positioning and internet-from-space so what's going to be next that will unlock all the piggy banks?   No point burping out a Skylon in one great effort and then watching the company go bust while it waits for the ideas to catch up.
Skylon, rather than SABRE also changes the business model from a sole builder /sole operator model to a sole builder multiple operators model. As Skylon should be able to self-ferry it also means it can stay in one country and only fly to an equatorial launch site for full load missions. Depending on latitude it could spend most of its career being launched from its home country.

That level of flexibility is simply impossible for any kind of rocket that's wedded to a unique launch pad configuration.  The closest this has been approached is the Soyuz and that's still months between launches.
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Offline knowles2

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #325 on: 11/19/2016 08:28 pm »
Sabre is conceived as a zero to ~Mach 5 air breathing engine, then transitioning to rocket mode.  Why would the test vehicle need to be launched at speed/altitude?
Limited onboard fuel.

Offline Jim

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #326 on: 11/19/2016 08:36 pm »

Skylon, rather than SABRE also changes the business model from a sole builder /sole operator model to a sole builder multiple operators model.configuration.  The closest this has been approached is the Soyuz and that's still months between launches.

More likely not.  It still could be too complex to be run by anybody other than the developer/manufacturer.

Offline knowles2

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #327 on: 11/19/2016 08:40 pm »
Sabre is conceived as a zero to ~Mach 5 air breathing engine, then transitioning to rocket mode.  Why would the test vehicle need to be launched at speed/altitude?
Limited onboard fuel.
[url]
http://www.orbital-access.com/projects.html[url]

I think these guys are gunning to be the ones that build Skylon. I wouldn't be surprise if we seem some of the technologies needed for the construction Skylon fuselage and control systems and other technologies needed for the vehicle.

Offline oddbodd

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #328 on: 11/19/2016 10:53 pm »

http://www.orbital-access.com/projects.html


I think these guys are gunning to be the ones that build Skylon. I wouldn't be surprise if we seem some of the technologies needed for the construction Skylon fuselage and control systems and other technologies needed for the vehicle.

From the link you provided:
Quote
The project’s specific targets include an initial horizontal small payload launch system
in service by 2020, as well as a fully reusable system in service by 2030.
The technical and operational discoveries made during the development
of these systems will also lay the foundation for the creation of Skylon in the long-term.

So yeah, it looks like any likely implementation would begin in the 2030's. I was making a bit of a prediction in my previous message, but it looks like I probably nailed it. So best case 2035 - 2040 for a prototype Skylon class SSTO fully-reusable vehicle (assuming available funding) to be available for testing. At this point SpaceX would have had two decades of launches incorporating some level of reusability and making improvements / refinements (i.e. Merlin 1 @~850kN, Raptor @~3000kN, Merlin 2 @~7000kN) and driving down costs. Can Skylon attract the investment in that environment? It's a tough sell now with current launch costs... I understand the proposed program would "retire a lot of risk" as JS19 likes to say, but it will still need many wheelbarrows of £50 notes to create the Skylon class vehicle.

And here's some sad thoughts for you. While it is not impossible, it becomes ever more unlikely that Alan Bond (~72) will be around to see Skylon fly. John Scott-Scott has unfortunately already passed away, never knowing if Skylon will even be built or not. Richard Varvill (~55) has a fighting chance, although if he were to retire at 65 he'd not have any involvement with the Skylon program.

Offline oddbodd

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #329 on: 11/19/2016 11:13 pm »
http://www.orbital-access.com/projects.html

I think these guys are gunning to be the ones that build Skylon. I wouldn't be surprise if we seem some of the technologies needed for the construction Skylon fuselage and control systems and other technologies needed for the vehicle.

Actually having read a bit around them, I don't think these are likely to be the ones building Skylon. It seems they are very young (<18 months) and have a handful of staff. Or can someone point me toward some resource that shows they are more than just a PowerPoint company.

Offline ChrisWilson68

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #330 on: 11/20/2016 01:19 am »
The issue as I see it is that the original Skylon SSTO concept had a narrow(-ish) window of opportunity. It made sense while rockets were expendable, but we now have Space X pushing the envelope on reusability, and if they reduce costs enough (not necessarily down to theoretical Skylon levels) then the business case for progressing to create Skylon (or similar) will not be attractive enough to pull in the needed investment. This new site seems to push SSTO Skylon further and further out, giving the likes of Space X more and more time to consolidate and lock down the market. So SSTO Skylon is at risk of withering on the vine, and without it (or something similar) it's not clear that we will ever reach SSTO and airliner style operations. Without those two things space access is never going to progress much beyond what we already have.

It's too bad you're so hung up on SSTO that you can't see that both SpaceX and Blue Origin are well on their way to providing what you're really looking for, which is low cost made possible by full reusability.

Reusability is the key, not SSTO.  The people who are actually having success with reusuability have done the analysis and realized that SSTO actually makes things more expensive than staging for fully-reusable systems.

A Skylon SSTO depends on lots of expensive techniques, such as using hydrogen, very high mass ratios, and thermal protection with properties beyond anything ever successfully used before.  Staging is the cheaper technique for fully-reusable, low-cost space launch.

Even Space X with a partially reusable rocket will take weeks (if not months) to reintegrate for a second launch.

Not according to Elon Musk.

It baffles me why you would believe REL's optimistic predictions about Skylon, when REL hasn't flown anything but not believe SpaceX's predictions, when SpaceX is trying something much more conservative and has a lot of real-world experience and a track record of success.

Offline knowles2

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #331 on: 11/20/2016 01:23 am »
http://www.orbital-access.com/projects.html

I think these guys are gunning to be the ones that build Skylon. I wouldn't be surprise if we seem some of the technologies needed for the construction Skylon fuselage and control systems and other technologies needed for the vehicle.

Actually having read a bit around them, I don't think these are likely to be the ones building Skylon. It seems they are very young (<18 months) and have a handful of staff. Or can someone point me toward some resource that shows they are more than just a PowerPoint company.

The age of the company means nothing, a lot of the facilities needed for Skylon would have to built from scratch anyway no matter who took on the project and their orbital 500 presuming it becomes operational should give plenty of experience as a airframe manufacture and experience of putting stuff into space an give some of the facilities needed for Skylon. More concerning is that so far they only have 2 million euros and a bit of money from UK Space Agency. Somedays I wish I had a idea that would make me billions so I could fund this properly.

Reaction engines spent years being a powerpoint company.

Quote
And here's some sad thoughts for you. While it is not impossible, it becomes ever more unlikely that Alan Bond (~72) will be around to see Skylon fly. John Scott-Scott has unfortunately already passed away, never knowing if Skylon will even be built or not. Richard Varvill (~55) has a fighting chance, although if he were to retire at 65 he'd not have any involvement with the Skylon program.
Hopefully they will see the prototype vehicle flying.

I hope we will see quicker process that 2035-2040. I think the earliest is 2030 for Sky launch.
« Last Edit: 11/20/2016 01:30 am by knowles2 »

Offline oddbodd

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #332 on: 11/20/2016 02:57 am »
The issue as I see it is that the original Skylon SSTO concept had a narrow(-ish) window of opportunity. It made sense while rockets were expendable, but we now have Space X pushing the envelope on reusability, and if they reduce costs enough (not necessarily down to theoretical Skylon levels) then the business case for progressing to create Skylon (or similar) will not be attractive enough to pull in the needed investment. This new site seems to push SSTO Skylon further and further out, giving the likes of Space X more and more time to consolidate and lock down the market. So SSTO Skylon is at risk of withering on the vine, and without it (or something similar) it's not clear that we will ever reach SSTO and airliner style operations. Without those two things space access is never going to progress much beyond what we already have.

It's too bad you're so hung up on SSTO that you can't see that both SpaceX and Blue Origin are well on their way to providing what you're really looking for, which is low cost made possible by full reusability.
I'll agree that SpaceX are well on the way to partial reusability, albeit without having actually reflown a used first stage yet. I don't think second stage reusability is a given yet. Future development/testing will determine if it's something SpaceX can justify offering to customers, or if the trade-offs are too high, and the second stage remains expendable.

I'd argue about Blue Origin being well on the way, as we're (or at least I'm :) ) talking about LEO and up. BO have gone up, and come back down in a relatively small rocket. Maybe the tech will translate to a larger rocket easily, allowing LEO, and making it closer to SpaceX, but they are a ways-away at the moment.

Reusability is the key, not SSTO.  The people who are actually having success with reusuability have done the analysis and realized that SSTO actually makes things more expensive than staging for fully-reusable systems.
As no one has done SSTO yet, the only people "having success" are the ones doing staging. Does this not risk a degree of confirmation bias?

A Skylon SSTO depends on lots of expensive techniques, such as using hydrogen, very high mass ratios, and thermal protection with properties beyond anything ever successfully used before.  Staging is the cheaper technique for fully-reusable, low-cost space launch.
I'll concede that hydrogen is a pain to deal with compared to other rocket fuels, incurring more cost. On the other hand it's a lot less toxic than some of the stuff used. And at a real stretch it could be carbon neutral by the time Skylon would be ready.

I'll pass on the mass ratio. IANARS (I am not a rocket scientist) and I don't follow how high mass ratio = expensive technique.

On the TPS, I was under the impression that DLR concluded that the reentry conditions were not too bad. Or is it the mass vs. performance that is the "beyond anything ever successfully used before" bit?

Even Space X with a partially reusable rocket will take weeks (if not months) to reintegrate for a second launch.

Not according to Elon Musk.

It baffles me why you would believe REL's optimistic predictions about Skylon, when REL hasn't flown anything but not believe SpaceX's predictions, when SpaceX is trying something much more conservative and has a lot of real-world experience and a track record of success.

Assuming this report is accurate: http://www.theverge.com/2016/4/8/11395606/elon-musk-spacex-landing-falcon-9-relaunch-schedule-date

"Ultimately, SpaceX hopes to reduce the turnaround time for its rockets to a couple of weeks."

If the launch of the reused first stage goes ahead in January, it will have been around nine months. I'm sure they'll keep cutting that down, but I also read that a single launchpad can only launch once every few weeks, as the pads need attention too. Of course SpaceX could start building new launch pads I suppose.

And just to point out that I don't believe REL's predictions, because belief is for religions. I do think that so far all the external studies, audits and checks have come back saying that it is not impossible. Technical challenges sure, but not beyond the realm of the possible. So I do hope they can deliver (although I'm increasingly pessimistic as stated elsewhere) because if they do, I think it will move space transport into a new phase. Think PC's, boring utilitarian grey boxes that got the job done for years... then along came the Macs which dragged PC's out of the dark ages. Right now it feels like space needs a Mac moment if it is to be much more to human race than it is now. Whether that's Skylon or some other thing I can't predict.

Offline oddbodd

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #333 on: 11/20/2016 03:29 am »
http://www.orbital-access.com/projects.html

I think these guys are gunning to be the ones that build Skylon. I wouldn't be surprise if we seem some of the technologies needed for the construction Skylon fuselage and control systems and other technologies needed for the vehicle.

Actually having read a bit around them, I don't think these are likely to be the ones building Skylon. It seems they are very young (<18 months) and have a handful of staff. Or can someone point me toward some resource that shows they are more than just a PowerPoint company.

The age of the company means nothing, a lot of the facilities needed for Skylon would have to built from scratch anyway no matter who took on the project and their orbital 500 presuming it becomes operational should give plenty of experience as a airframe manufacture and experience of putting stuff into space an give some of the facilities needed for Skylon. More concerning is that so far they only have 2 million euros and a bit of money from UK Space Agency. Somedays I wish I had a idea that would make me billions so I could fund this properly.
The image for the Orbital 500 looks more like a rocket with winglets than an airframe to me so I'm not sure how useful that bestowed experience would be. Agreed that the lack of money is a worry. I suspect that right now they don't have the required engineers and depth of experience to pull this off. That 2 million won't go far (I think rocket scientists are well paid ;) ) so they'll need investment. I think that might be hard to drum up, at least from what info is available publicly.

Never mind "Somedays", every time I read this forum :)

Reaction engines spent years being a powerpoint company.
I kinda think that's a mis-characterization. REL was founded by three engineers, who I'm pretty sure were working on the engineering problems pretty much immediately after being founded if not before. By contrast Orbital Access seems to be a company whose only apparent staff are CEO's, Market and Business Development and similar board level positions. Granted the CEO is an engineer, but the news, history and feeds are very uninformative. There's no sense of engineering going on, at least from the website, and a presentation by the CEO I found on YouTube.

Quote
And here's some sad thoughts for you. While it is not impossible, it becomes ever more unlikely that Alan Bond (~72) will be around to see Skylon fly. John Scott-Scott has unfortunately already passed away, never knowing if Skylon will even be built or not. Richard Varvill (~55) has a fighting chance, although if he were to retire at 65 he'd not have any involvement with the Skylon program.
Hopefully they will see the prototype vehicle flying.

I hope we will see quicker process that 2035-2040. I think the earliest is 2030 for Sky launch.

According to the blurb 2030 was for the small payload launch system. Skylon was after that, building on the experience. I was being optimistic that the SPLS would allow them to create Skylon quicker, but 5 years is not long for something like Skylon I think, even with that previous experience. Unless someone else comes along with a bulging sack of cash and a fire in their belly I think it's unlikely we'll see Skylon by 2030.

Offline Paul451

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #334 on: 11/20/2016 05:42 am »
I'll pass on the mass ratio. IANARS (I am not a rocket scientist) and I don't follow how high mass ratio = expensive technique.

There's an engineering rule-of-thumb that I was given years ago: for every 10% reduction in mass or thickness of a part, the life-span halves. (Or every 10% increase/double.) In practice, you end up substituting complexity for mass. The greater engineering complexity then increases cost-of-development.

Offline ChrisWilson68

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #335 on: 11/20/2016 08:40 am »
I'll agree that SpaceX are well on the way to partial reusability, albeit without having actually reflown a used first stage yet. I don't think second stage reusability is a given yet. Future development/testing will determine if it's something SpaceX can justify offering to customers, or if the trade-offs are too high, and the second stage remains expendable.

The point is that SpaceX is a lot closer to second-stage reusability than Skylon is to SSTO.

I'd argue about Blue Origin being well on the way, as we're (or at least I'm :) ) talking about LEO and up. BO have gone up, and come back down in a relatively small rocket. Maybe the tech will translate to a larger rocket easily, allowing LEO, and making it closer to SpaceX, but they are a ways-away at the moment.

Again, the comparison is with Skylon.  Blue Origin is far closer to fully-reusable orbital launch than Skylon is.

Reusability is the key, not SSTO.  The people who are actually having success with reusuability have done the analysis and realized that SSTO actually makes things more expensive than staging for fully-reusable systems.
As no one has done SSTO yet, the only people "having success" are the ones doing staging. Does this not risk a degree of confirmation bias?

Both Musk and Bezos came to the space world as complete outsiders, without any bias.  The considered the options and both chose two-stage reusable systems with horizontal take-off and landing.  No confirmation bias there.

I'll concede that hydrogen is a pain to deal with compared to other rocket fuels, incurring more cost. On the other hand it's a lot less toxic than some of the stuff used.

Neither methane nor RP-1 is particularly toxic -- not toxic enough to be more expensive to deal with safely than hydrogen.  And what we're talking about here is what's less expensive.

And at a real stretch it could be carbon neutral by the time Skylon would be ready.

So could methane.  Anyway, again, it doesn't affect the cost, which is what we're talking about here.

On the TPS, I was under the impression that DLR concluded that the reentry conditions were not too bad. Or is it the mass vs. performance that is the "beyond anything ever successfully used before" bit?

It depends on what you consider "not too bad".  The projections are something like 830 Celsius.  It will require active cooling.  Skylon is supposed to have a ceramic skin on a huge scale to handle that.  The only other operational vehicle to ever try ceramic TPS was shuttle, and we all know how many surprise issues it had that weren't anticipated, and how much that drove costs through the roof and resulted in a dead crew.

Not according to Elon Musk.

It baffles me why you would believe REL's optimistic predictions about Skylon, when REL hasn't flown anything but not believe SpaceX's predictions, when SpaceX is trying something much more conservative and has a lot of real-world experience and a track record of success.

Assuming this report is accurate: http://www.theverge.com/2016/4/8/11395606/elon-musk-spacex-landing-falcon-9-relaunch-schedule-date

"Ultimately, SpaceX hopes to reduce the turnaround time for its rockets to a couple of weeks."

That is not correct.  Musk has said on various occasions that the long-term target is a turn-around time of hours for the first stage and 24 hours for the upper stage.

They may or may not achieve that target, but the target is just as aggressive as that for Skylon.  And, since Skylon has lower margins available because it needs such high performance to make up for the lack of staging that it's far more likely SpaceX will meet its targets than that Skylon will.

If the launch of the reused first stage goes ahead in January, it will have been around nine months.

And that's completely irrelevant, because it's during the development program.

I'm sure they'll keep cutting that down, but I also read that a single launchpad can only launch once every few weeks, as the pads need attention too. Of course SpaceX could start building new launch pads I suppose.

SpaceX has already done launches off the same pad just two weeks apart and they have plans to automate the whole process and have the pad ready for multiple launches the same day.

Pad procedures historically have required a few weeks between launches just because there's no point in designing them for faster turn-around for expensive expendable vehicles.  Once vehicles can be reused and the launch rates can go up, procedures will change to allow the quick turn-around time needed.

And just to point out that I don't believe REL's predictions, because belief is for religions. I do think that so far all the external studies, audits and checks have come back saying that it is not impossible. Technical challenges sure, but not beyond the realm of the possible.

And the same is true for SpaceX and Blue Origin too.

And yet you stated sadness that Skylon seems unlikely to happen because it meant we'll never get cheap spaceflight.

iIf you're going to give REL the benefit of the doubt, give SpaceX and Blue Origin at least as much.

So I do hope they can deliver (although I'm increasingly pessimistic as stated elsewhere) because if they do, I think it will move space transport into a new phase. Think PC's, boring utilitarian grey boxes that got the job done for years... then along came the Macs which dragged PC's out of the dark ages. Right now it feels like space needs a Mac moment if it is to be much more to human race than it is now. Whether that's Skylon or some other thing I can't predict.

The thing is, you are predicting.  You're predicting it won't be SpaceX or Blue Origin.  Why not?  Because their solutions aren't as aesthetically pleasing?  Aesthetically pleasing doesn't give us cheap access to space.  Good engineering choices will do that.

Offline t43562

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #336 on: 11/20/2016 11:39 am »
The thing is, you are predicting.  You're predicting it won't be SpaceX or Blue Origin.  Why not?  Because their solutions aren't as aesthetically pleasing?  Aesthetically pleasing doesn't give us cheap access to space.  Good engineering choices will do that.

This is the Skylon thread, we don't come here to talk about how it isn't any good and how we should all give up now and pray at other altars.  That would make the thread pointless.  In any case, as industries get bigger they get more cut-throat and even small improvements make a great difference.   

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #337 on: 11/20/2016 11:42 am »
I'll agree that SpaceX are well on the way to partial reusability, albeit without having actually reflown a used first stage yet. I don't think second stage reusability is a given yet. Future development/testing will determine if it's something SpaceX can justify offering to customers, or if the trade-offs are too high, and the second stage remains expendable.

The point is that SpaceX is a lot closer to second-stage reusability than Skylon is to SSTO.

I'd argue about Blue Origin being well on the way, as we're (or at least I'm :) ) talking about LEO and up. BO have gone up, and come back down in a relatively small rocket. Maybe the tech will translate to a larger rocket easily, allowing LEO, and making it closer to SpaceX, but they are a ways-away at the moment.

Again, the comparison is with Skylon.  Blue Origin is far closer to fully-reusable orbital launch than Skylon is.

Reusability is the key, not SSTO.  The people who are actually having success with reusuability have done the analysis and realized that SSTO actually makes things more expensive than staging for fully-reusable systems.
As no one has done SSTO yet, the only people "having success" are the ones doing staging. Does this not risk a degree of confirmation bias?

Both Musk and Bezos came to the space world as complete outsiders, without any bias.  The considered the options and both chose two-stage reusable systems with horizontal take-off and landing.  No confirmation bias there.

I'll concede that hydrogen is a pain to deal with compared to other rocket fuels, incurring more cost. On the other hand it's a lot less toxic than some of the stuff used.

Neither methane nor RP-1 is particularly toxic -- not toxic enough to be more expensive to deal with safely than hydrogen.  And what we're talking about here is what's less expensive.

And at a real stretch it could be carbon neutral by the time Skylon would be ready.

So could methane.  Anyway, again, it doesn't affect the cost, which is what we're talking about here.

On the TPS, I was under the impression that DLR concluded that the reentry conditions were not too bad. Or is it the mass vs. performance that is the "beyond anything ever successfully used before" bit?

It depends on what you consider "not too bad".  The projections are something like 830 Celsius.  It will require active cooling.  Skylon is supposed to have a ceramic skin on a huge scale to handle that.  The only other operational vehicle to ever try ceramic TPS was shuttle, and we all know how many surprise issues it had that weren't anticipated, and how much that drove costs through the roof and resulted in a dead crew.

Not according to Elon Musk.

It baffles me why you would believe REL's optimistic predictions about Skylon, when REL hasn't flown anything but not believe SpaceX's predictions, when SpaceX is trying something much more conservative and has a lot of real-world experience and a track record of success.

Assuming this report is accurate: http://www.theverge.com/2016/4/8/11395606/elon-musk-spacex-landing-falcon-9-relaunch-schedule-date

"Ultimately, SpaceX hopes to reduce the turnaround time for its rockets to a couple of weeks."

That is not correct.  Musk has said on various occasions that the long-term target is a turn-around time of hours for the first stage and 24 hours for the upper stage.

They may or may not achieve that target, but the target is just as aggressive as that for Skylon.  And, since Skylon has lower margins available because it needs such high performance to make up for the lack of staging that it's far more likely SpaceX will meet its targets than that Skylon will.

If the launch of the reused first stage goes ahead in January, it will have been around nine months.

And that's completely irrelevant, because it's during the development program.

I'm sure they'll keep cutting that down, but I also read that a single launchpad can only launch once every few weeks, as the pads need attention too. Of course SpaceX could start building new launch pads I suppose.

SpaceX has already done launches off the same pad just two weeks apart and they have plans to automate the whole process and have the pad ready for multiple launches the same day.

Pad procedures historically have required a few weeks between launches just because there's no point in designing them for faster turn-around for expensive expendable vehicles.  Once vehicles can be reused and the launch rates can go up, procedures will change to allow the quick turn-around time needed.

And just to point out that I don't believe REL's predictions, because belief is for religions. I do think that so far all the external studies, audits and checks have come back saying that it is not impossible. Technical challenges sure, but not beyond the realm of the possible.

And the same is true for SpaceX and Blue Origin too.

And yet you stated sadness that Skylon seems unlikely to happen because it meant we'll never get cheap spaceflight.

iIf you're going to give REL the benefit of the doubt, give SpaceX and Blue Origin at least as much.

So I do hope they can deliver (although I'm increasingly pessimistic as stated elsewhere) because if they do, I think it will move space transport into a new phase. Think PC's, boring utilitarian grey boxes that got the job done for years... then along came the Macs which dragged PC's out of the dark ages. Right now it feels like space needs a Mac moment if it is to be much more to human race than it is now. Whether that's Skylon or some other thing I can't predict.

The thing is, you are predicting.  You're predicting it won't be SpaceX or Blue Origin.  Why not?  Because their solutions aren't as aesthetically pleasing?  Aesthetically pleasing doesn't give us cheap access to space.  Good engineering choices will do that.

Except, accurate or not, all of that is irrelevant.
Skylon, should it ever be built in the manner described, won't be competing with SpaceX or Blue Orgin because neither of them intend to be selling launch vehicles to other launch companies in 2030 and there are dozens of other launch providers who intend to still be in business in 2030 and also thousands of payloads that can't launch on American launch vehicles to fly with them.
 So the actual question is what is everybody other than SpaceX and Blue Orign launching, because that is Skylon's
market. Skylon doesn't have to be better than falcon or new Glenn, just better than any other option to compete with them. Or alternatively Skylon doesn't need to be faster than the bear, just faster than anybody else running from it.
The only situation in which Skylon and falcon would directly compete in the manner you've described  would be if SpaceX were to consider switching to a Skylon fleet so that it internally could focus on Mars and infrastructure.

Offline Robotbeat

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #338 on: 11/20/2016 01:55 pm »
Also, I have to say the idea of a civil hypersonic transport is super exciting to me, too. And it'd use hydrogen, so technically this can be done pretty easily with zero carbon emissions! Very neat. :)

You do realize that the vast majority (~95%) of hydrogen comes from the processing of fossil fuels? Electrolysis (i.e. using wind, hydro or solar PV) is highly inefficient. There are laboratory scale experiments that may eventually bear fruit (i.e. algae), but I certainly wouldn't say that currently hydrogen can be done pretty easily with zero carbon emissions.
Yes I am. And untrue it's inefficient. 65-70% efficient electrolysis isn't unheard of for large plants. It's completely inaccurate to label that as mere lab-scale. And it can easily be done with zero emissions, it's just that natural gas is super duper cheap right now.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

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Re: The Reaction Engines Skylon Master Thread (6)
« Reply #339 on: 11/20/2016 03:56 pm »
[Except, accurate or not, all of that is irrelevant.
Skylon, should it ever be built in the manner described, won't be competing with SpaceX or Blue Orgin because neither of them intend to be selling launch vehicles to other launch companies in 2030 and there are dozens of other launch providers who intend to still be in business in 2030 and also thousands of payloads that can't launch on American launch vehicles to fly with them.
 So the actual question is what is everybody other than SpaceX and Blue Orign launching, because that is Skylon's market.

It doesn't matter if Skylon intends to be a vehicle builder or a service provider, since the market that they are addressing is moving mass to space - which is the same market that Blue Origin and SpaceX are addressing.  The only difference is who owns the vehicles, which is really immaterial when discussing supply and demand.

For instance, if the cost of buying and operating a Skylon does not result in the ability of a service provider to offer a competitive $/kg to orbit price, then no one will buy a Skylon.

Quote
Skylon doesn't have to be better than falcon or new Glenn, just better than any other option to compete with them. Or alternatively Skylon doesn't need to be faster than the bear, just faster than anybody else running from it.

To a degree that is true, but only to a degree.  For instance, "the payload market" does want competition, and is willing to buy services from companies that are not the lowest bidders in order to ensure that there are enough choices to support competition and redundancy.

However, that may mean that there is only a market opportunity for (as an example) five launch service providers.  So the situation ends up being like the musical chairs game, where those that are the least competitive are trying to out maneuver each other in order to continue being one of the chosen competitors - which if you don't have deep pockets, can create a fiscal death spiral.

So no matter what, if Skylon wants to be a big success, they have to be one of the least expensive options for moving mass to space.  Anything less means their potential growth won't happen the way they need it to happen.

Quote
The only situation in which Skylon and falcon would directly compete in the manner you've described  would be if SpaceX were to consider switching to a Skylon fleet so that it internally could focus on Mars and infrastructure.

Assuming reusability is perfected, SpaceX will have the advantage of being able to iterate their existing Falcon 9 design to make it more and more reliable and to drive down costs.

Because of that, the Skylon cost advantage over the Falcon 9 would have to be not only obvious, but significantly better than the Falcon 9 in order for SpaceX to consider abandoning the Falcon 9.  Again, this gets back to the supply and demand issue, and being in the top group of service providers.

But at the pace Skylon is currently going at, SpaceX won't have to worry about their marketshare for at least another decade - at which point their successor to the Falcon 9 (whatever that will be) may already be getting ready for it's own launch.  Skylon needs to go faster...
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

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