Whoop-dee-derp, looks like they aren't trying to make the Skylon an SSTO anymore

[DDE]

http://www.bbc.com/news/science-environment-36773074

Many knew that it probably won't play out from the start, but this is a confirmation: apparently SABRE tech is now being pegged for an air-launch system.

Which has its own unsolved challenges.

 

[lrd.Helmet]

ehm, that's not what that article says. 

They're going to use test flights as possible launch platforms for payloads. Earning some money while still being in the atmospheric test phase.

[HebaruSan]

In fact, this article affirms the long term ambition to make the Skylon an SSTO:

Quote

The approach should save weight and allow Sabre to impel a space vehicle straight to orbit without the need for the multiple propellant stages seen in today's throw-away rockets.

 

[Nuke]

idk i always figured the skylon is way to big to be a first step. rel should get the engines working and see who buys them. you can save a lot of money using an existing aircraft as a test bed, they mentioned a dc-10 in the article, figure replace its center engine with a sabre and your tankage in the fusalage. that would be something to see. however that configuration isnt going to do anything to test supersonic operation, let alone hypersonic. its probibly enough to test airbreating mode in the subsonic regeme, and cycle switching. you would need to send a few engines to nasa to have them test it on an sr71, which is probibly the only aircraft that can get into sabre's full air breathing flight regime, nasa has used them in tests before. thats ignoring the fact that its a lot of engine for a not very big bird.

[kerbiloid]

2 hours ago, Nuke said:

should get the engines working and see who buys them. you can save a lot of money using an existing aircraft as a test bed, they mentioned a dc-10 in the article, figure replace its center engine with a sabre and your tankage in the fusalage

Unlikely a cryoplane would become really popular in a civil aviation. Such attempts already had been undertaken but cryoproblems look disgusting for commercial use,
Probably, their intention is just to interest some more investors for this engine development itself, not to really put the engine on something rather than Skylon..

[PB666]

3 hours ago, Nuke said:

idk i always figured the skylon is way to big to be a first step. rel should get the engines working and see who buys them. you can save a lot of money using an existing aircraft as a test bed, they mentioned a dc-10 in the article, figure replace its center engine with a sabre and your tankage in the fusalage. that would be something to see. however that configuration isnt going to do anything to test supersonic operation, let alone hypersonic. its probibly enough to test airbreating mode in the subsonic regeme, and cycle switching. you would need to send a few engines to nasa to have them test it on an sr71, which is probibly the only aircraft that can get into sabre's full air breathing flight regime, nasa has used them in tests before. thats ignoring the fact that its a lot of engine for a not very big bird.

Well at least get a modest scale test. 

http://www.bbc.com/news/science-environment-36773074

I give them thirty years they might have something, bunch of guys syanding around in suits with hands in their pockets. . . . . . . . . . . SR71 is a diiferent kind o bird, they used a buick v8 to start it, the gear was not rated for a full fuel load, and there were more than a few accidents.

Sabre is for civilian use. 

[Nuke]

3 hours ago, PB666 said:

Well at least get a modest scale test. 

http://www.bbc.com/news/science-environment-36773074

I give them thirty years they might have something, bunch of guys syanding around in suits with hands in their pockets. . . . . . . . . . . SR71 is a diiferent kind o bird, they used a buick v8 to start it, the gear was not rated for a full fuel load, and there were more than a few accidents.

Sabre is for civilian use. 

sr-71 has been used several times for science (tm), with tail featuring the nasa logo (not usaf).

https://www.reddit.com/r/SR71/comments/4j5acm/q_what_is_this_on_the_back_of_the_aircraft/?st=iqkipimo&sh=3d933870

its kind of unique in its flight regeme. good for testing hypersonic components. not a whole lot of aircraft that can do that. so its no wonder that nasa is still flying them. i dont think we would hand one over to rel for testing, but we probibly wouldnt be against letting them bring the engines over here to run the tests under nasa/usaf supervision. actually i think rel has negotiated with the usaf in the past. renting the blackbird is likely a lot cheaper than building a new airframe from scratch.

 

 

[Nibb31]

NASA retired the last airworthy SR-71 in 1999. All USAF/NASA/CIA airframes have been retired to museums. There might be a couple left mothballed in a USAF hangar somewhere, but it would cost a lot to return them to flightworthiness. Certainly not worth expense.

Edited July 13, 2016 by Nibb31

[p1t1o]

I think it is clear now that the "Skylon" spaceplane is/was a concept only, intended simply to give credence to the idea of their new engine - "We think we can build an engine that can do such-and-such. If we can, look at the type of aircraft we could build!". This is pretty normal IMO. If any spaceplane does emerge from REL it will likely have major similarities to Skylon (given the same general design goal) but will almost certainly be a fresh project from the ground up.

It seems more likely that someone else (eg: BAE) will design a spaceplane/other hypersonic airbreather, and then source the engines from REL. Much like Rolls-Royce don't build airliners, but their engines power most of them. I fully expect the military to be the first people using these engines.

[PB666]

1 hour ago, p1t1o said:

I think it is clear now that the "Skylon" spaceplane is/was a concept only, intended simply to give credence to the idea of their new engine - "We think we can build an engine that can do such-and-such. If we can, look at the type of aircraft we could build!". This is pretty normal IMO. If any spaceplane does emerge from REL it will likely have major similarities to Skylon (given the same general design goal) but will almost certainly be a fresh project from the ground up.

It seems more likely that someone else (eg: BAE) will design a spaceplane/other hypersonic airbreather, and then source the engines from REL. Much like Rolls-Royce don't build airliners, but their engines power most of them. I fully expect the military to be the first people using these engines.

If you are counting BAE or RR to do this, they don't have the financial backing or a business model that would garner the investment needed to complete. 

[p1t1o]

31 minutes ago, PB666 said:

If you are counting BAE or RR to do this, they don't have the financial backing or a business model that would garner the investment needed to complete. 

I wouldn't expect RR to suddenly be in the business of designing planes, but BAE have a huge history of such involvement. Plus they already own 20% of Reaction Engines. Its almost a certainty that BAE are at some point going to produce a design incorporating SABRE (or SABRE-derived) engines, whether it is an airliner, a missile, a military aircraft or indeed, an SSTO, with the latter being the furthest in the future, if at all.

[PB666]

2 hours ago, p1t1o said:

I wouldn't expect RR to suddenly be in the business of designing planes, but BAE have a huge history of such involvement. Plus they already own 20% of Reaction Engines. Its almost a certainty that BAE are at some point going to produce a design incorporating SABRE (or SABRE-derived) engines, whether it is an airliner, a missile, a military aircraft or indeed, an SSTO, with the latter being the furthest in the future, if at all.

But the banks look for a profit making motive, after the novelty of the concorde wore off it could not survive bad financial time, the banks would expect them to come up with demonstrative commercial viability before they funded such a project, and I don't think its there. If the concorde were truely profitable it would have been redesigned for increased safety, takeoff and landing performance, and efficiency, but with essentially 4 flights, there is not enough demand to justify that. 737 which preceded the concorde is still being produced, even DC3 are still in operation. That is the perspective that I am looking at the SABRE from, is it going to produce something like that, I think not.

 

[p1t1o]

@PB666 perhaps not, though the allure of Concorde-like travel lingers still. But SABRE will power something eventually, like I said, the military will be interested. And once oil runs out... 

[wumpus]

22 hours ago, DDE said:

http://www.bbc.com/news/science-environment-36773074

Many knew that it probably won't play out from the start, but this is a confirmation: apparently SABRE tech is now being pegged for an air-launch system.

Which has its own unsolved challenges.

 

Hardly unsolved, and nothing like the challenges of SSTO.

Solution one: air launch.  See Orbital's Pegasus.  Additional problem air launching at mach 6 might be a bigger issue.

Solution two: space launch.  See shuttle dropping the boosters and fuel tank.  Additional problem: losing a bunch of delta-v when moving from air-breathing flight ceiling to sufficient vacuum to launch.  Personally, I'd eat the delta-v and avoid having to design a SABRE that can use a stored oxidizer (even though I love the idea of increasing an air-breather's speed by using an oxidizer to maximize the speed and then the amount of air available, thus increasing the speed).  Hopefully the whole thing is unmanned so you can easily add COTS SRBs to get you from mach 6 to vacuum (ok, that last bit is just too kerbal.  But I still think you should launch in vacuum and avoid using oxidizer in the SABRE).

Solution three: Maximum kerbal.  Light an [well, presumably multiple] X-43 engine at mach five and go all the way to mach 10 or more.  Pull up and launch a rocket with an incredible mass ratio into orbit.  Problem: never will happen.

Edited July 13, 2016 by wumpus
strikethrough bug strikes again.

[PB666]

1 hour ago, p1t1o said:

@PB666 perhaps not, though the allure of Concorde-like travel lingers still. But SABRE will power something eventually, like I said, the military will be interested. And once oil runs out... 

Jet aircraft have a bigger problem without oil than rockets. In fact the cuurect policies regarding liquid fossil fuels are ludicrous if you want a passnger jet aircraft industry 50 or 60 years out. I dont see a military intested other than a payload delivery system, they can have their choice of several.. With brexit i think that the UK is goin to tie itself closer to canada and the us, which means they can share delivery systems. If they want to develope an X type sustem with the US as a major backer, thats plausible, go it alone i dont see it happening. 

BTW, this is exactly the type of development systen the UK and other EU sould have been working on from 7 years ago, with an acceleerated developemnt plan, its cost to benefit ratio would have been trivial then, now the ratio is ratcheting now. There are alot of competitors now in commercial space and this will spill over into defense contracts. Had they stimulated these economies properly . . . . . .

 

[DDE]

26 minutes ago, wumpus said:

Solution one: air launch.  See Orbital's Pegasus.  Additional problem air launching at mach 6 might be a bigger issue.

Which is exactly what I was talking about.

[p1t1o]

37 minutes ago, PB666 said:

Jet aircraft have a bigger problem without oil than rockets. In fact the cuurect policies regarding liquid fossil fuels are ludicrous if you want a passnger jet aircraft industry 50 or 60 years out. I dont see a military intested other than a payload delivery system, they can have their choice of several.. With brexit i think that the UK is goin to tie itself closer to canada and the us, which means they can share delivery systems. If they want to develope an X type sustem with the US as a major backer, thats plausible, go it alone i dont see it happening. 

BTW, this is exactly the type of development systen the UK and other EU sould have been working on from 7 years ago, with an acceleerated developemnt plan, its cost to benefit ratio would have been trivial then, now the ratio is ratcheting now. There are alot of competitors now in commercial space and this will spill over into defense contracts. Had they stimulated these economies properly . . . . . .

 

What I was getting at was that the higher oil prices go, the better the hydrogen fuelled SABRE starts to look. Civil air travel and air-breathing space delivery are but two of many possibilities.

[wumpus]

Just now, p1t1o said:

What I was getting at was that the higher oil prices go, the better the hydrogen fuelled SABRE starts to look. Civil air travel and air-breathing space delivery are but two of many possibilities.

The only benefit higher oil prices on hydrogen would be the chance to lower weight on long haul flights.  Best guess is that the problems with using a cryofuel is so high that they would still leave the methane uncracked even for flights for England/Australia (note that much of this is that you would pretty much need to redesign the entire aircraft to use hydrogen, those tanks would be huge.  Designing a plane for such limited use isn't going to happen).

The obvious lack of long haul aircraft (who could lose 30-40% of their takeoff weight by using hydrogen) is an obvious strike against using such a silly fuel in much less weight conscious areas such as cars.

[PB666]

Hydrogen would not lower weight, even though its lighter than air, its not lighter than air when pressurized to densities required for storage.

You wouldn't use a cryofuel you would use compressed gas and cut the transport distance by a fraction. Imagine a jet plane sitting on a tarmack during bad weather waiting for clearance, and the hydrogen just boiling off.

 

[wumpus]

1 hour ago, PB666 said:

Hydrogen would not lower weight, even though its lighter than air, its not lighter than air when pressurized to densities required for storage.

You wouldn't use a cryofuel you would use compressed gas and cut the transport distance by a fraction. Imagine a jet plane sitting on a tarmack during bad weather waiting for clearance, and the hydrogen just boiling off.

 

The point is that it is lighter than kerosene/jet fuel*, even with a larger tank (well, only if stored as a liquid.  The size of the tanks might get extreme if stored as a compressed gas.  I wouldn't be surprised if those are some of the many reasons hydrogen isn't used.  If it can't handle the boiloff on the runway, it can't handle the boiloff over 20+ hours in flight (normal subsonic flight).  If it can't handle that, it probably can't handle the weight and drag of the supersized compressed air tank either).

* pretty much the same stuff as RP1, but without quite as much extra cost.

[p1t1o]

13 hours ago, wumpus said:

The only benefit higher oil prices on hydrogen would be the chance to lower weight on long haul flights.

I think there would also be the benefit that flight would actually be possible. I wasn't thinking, "ooh the price of oil is quite high!", i was thinking "In breaking news: Touring one of the last remaining oil refineries, Donald Trump and Bill Gates clubbed together to fully fuel this jet."

[DDE]

12 hours ago, PB666 said:

Hydrogen would not lower weight, even though its lighter than air, its not lighter than air when pressurized to densities required for storage.

You wouldn't use a cryofuel you would use compressed gas and cut the transport distance by a fraction. Imagine a jet plane sitting on a tarmack during bad weather waiting for clearance, and the hydrogen just boiling off.

 

Unfortunately, that's precisely how a hydrogen-fuelled plane would work.

Compressed tanks wouldn't just get insanely big, they'd also get insanely heavy because, unlike cryo tanks, they have to handle a lot more pressure. Add to this the need for complicated mechanics of wing mechanization to operate right to the stuff, and you have a massive issue on your hands.

Synthetic kerosene, biofuel or methane are way easier.

[magnemoe]

5 minutes ago, DDE said:

Unfortunately, that's precisely how a hydrogen-fuelled plane would work.

Compressed tanks wouldn't just get insanely big, they'd also get insanely heavy because, unlike cryo tanks, they have to handle a lot more pressure. Add to this the need for complicated mechanics of wing mechanization to operate right to the stuff, and you have a massive issue on your hands.

Synthetic kerosene, biofuel or methane are way easier.

This, you don't use hydrogen if you don't have very good reasons. Its nice for upper stage or deep space stages because of the good ISP, its also nice for high hypersonic planes because it burn fast, Skylon uses it for it precooler, other stay away unless you need it as lifting gass 

[DDE]

At this point, I'm tempted to drop H2 and bring up H, which is implied to have been one of innovations of Project SUNTAN. Sure, it requires supercooled tungsten matrices to store, but it should be a lot more compact.

[p1t1o]

I forgot about synthetic hydrocarbons, but I still have high hopes for hydrogen. Not any time soon mind.