Author Topic: The Reaction Engines Skylon Master Thread (2)  (Read 814478 times)

Offline Turbomotive

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #20 on: 12/13/2012 07:18 am »
I'm interested in the economic and operational aspects of launching big payloads with multiple Skylon missions. Surely cost/ kg maintains in units of 15,000 kg? How feasible would it be to construct, say a 10 tonne comsat in two or more parts and mate them in LEO, and propel said comsat to its desired orbit? Would the Skylon launch missions have to be close to each other?
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Offline MP99

Re: The Reaction Engines Skylon Master Thread (2)
« Reply #21 on: 12/13/2012 07:42 am »
I'm interested in the economic and operational aspects of launching big payloads with multiple Skylon missions. Surely cost/ kg maintains in units of 15,000 kg? How feasible would it be to construct, say a 10 tonne comsat in two or more parts and mate them in LEO, and propel said comsat to its desired orbit? Would the Skylon launch missions have to be close to each other?

Would dual almost-simultaneous launches be more feasible with two Skylons than with two conventional launchers?

While two planes would need to duplicate all the ground support equipment, could the second use the runway once the first is clear and no abort is required (ie minutes apart)?

It also seems to me that the airplane-mode phase of the launch might offer a more "relaxed" environment for two Skylons to align themselves in preparation for LEO rendezvous.

cheers, Martin

Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #22 on: 12/13/2012 01:36 pm »
I'm interested in the economic and operational aspects of launching big payloads with multiple Skylon missions. Surely cost/ kg maintains in units of 15,000 kg? How feasible would it be to construct, say a 10 tonne comsat in two or more parts and mate them in LEO, and propel said comsat to its desired orbit? Would the Skylon launch missions have to be close to each other?

This is actually an "Operational" question which REL tends to avoid as it would be "customer" question rather than one for the builder :)

Off-hand I'd say this is pretty much the way Skylon would have to work within an overall "system" of transportation. If the required payload won't fit into a single Skylon launch then the "idea" is that satellite makers would find it more 'economical' to change the way satellites are made to fit into the available payload margins. This is based on the assumption that Skylon will be cheaper and more reliable to operate than any other LV and therefor will pretty much dominate the market.

(This is needed to generate the high flight rate that helps make the Skylon economical)

If all the above is 'true' then some form of on-orbit assembly will be required at some point to allow larger payloads to be launched. And of course if THAT is 'true' then eventually all this will be facilitated by having a "destination" station in LEO where all the payloads end up which does all assembly, check-out, and transfer operations to higher orbits or other destinations.

On the "way" to that outcome though there very well could be multiple Skylon missions with orbital rendevous to deploy, assemble, and launch larger payloads.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #23 on: 12/13/2012 01:54 pm »
I'm interested in the economic and operational aspects of launching big payloads with multiple Skylon missions. Surely cost/ kg maintains in units of 15,000 kg? How feasible would it be to construct, say a 10 tonne comsat in two or more parts and mate them in LEO, and propel said comsat to its desired orbit? Would the Skylon launch missions have to be close to each other?

Would dual almost-simultaneous launches be more feasible with two Skylons than with two conventional launchers?

While two planes would need to duplicate all the ground support equipment, could the second use the runway once the first is clear and no abort is required (ie minutes apart)?

It also seems to me that the airplane-mode phase of the launch might offer a more "relaxed" environment for two Skylons to align themselves in preparation for LEO rendezvous.

cheers, Martin
I think that's one of the points that REL has been "pushing" about the Skylon is its closer to "aircraft" than "spacecraft" operations :)

Multiple launches from the same "port" shouldn't be a huge problems as long as such a fight rate was supportable with the on-site equipment. Being able to have some "flying" manuever margin/room means that they would be much easier to "organize" to arrive at the same point in LEO, which would allow Skylons from different launch sites to reach the same destination in a short time frame from multiple launch sites within that margin.

The ability to adjust orbital "phasing" using in-atmosphere powered flight would be a real advantage and if multiple launch sites are use any single "abort" is far less critical.

Of course as I noted above at some point, pretty quickly too I'm guessing, it will become operationally "easier" to provide a transportation-waypoint-transfer station in LEO where the majority of your payloads pass through.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline BobCarver

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #24 on: 12/13/2012 02:01 pm »
The Project Troy document from 2007 (REL's Project Troy, A Strategy for a Mission to Mars) discusses this kind of mission:

Quote
The total mass at departure from Earth is 1357 tonnes. Of this, 1083 tonnes is propellant. The ship is assembled in Earth orbit, and a total mass of 1541 tonnes must be placed in orbit for the first mission, including construction platforms which can be re-used for subsequent missions. A total of 25 main assembly launches planned for each Mars mission. Two or three more are required to deliver the crew and top up the propellant tanks. At a rate of one launch every two months, the construction phase is expected to take 4.6 years.

Offline Jim

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #25 on: 12/13/2012 02:03 pm »


Off-hand I'd say this is pretty much the way Skylon would have to work within an overall "system" of transportation. If the required payload won't fit into a single Skylon launch then the "idea" is that satellite makers would find it more 'economical' to change the way satellites are made to fit into the available payload margins. This is based on the assumption that Skylon will be cheaper and more reliable to operate than any other LV and therefor will pretty much dominate the market.


There are also external influences such as limited GSO orbital slots, which is driving to fewer spacecraft with more transponders.  But then again, there are the "electric" spacecraft, which reducing spacecraft mass by use of electric propulsion.

Offline Turbomotive

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #26 on: 12/14/2012 08:46 am »
Thanks - it's my understanding of comsat trends that while coverage will extend to most sparseley populated areas (where a satellite is more cost effective than cables), there will be certain in-demand footprints for which satellites will probably continue to become ever bigger. From all your replies, I read that Skylon will be continue to be economic for large payloads split into pieces.
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Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #27 on: 12/14/2012 02:41 pm »
Thanks - it's my understanding of comsat trends that while coverage will extend to most sparseley populated areas (where a satellite is more cost effective than cables), there will be certain in-demand footprints for which satellites will probably continue to become ever bigger. From all your replies, I read that Skylon will be continue to be economic for large payloads split into pieces.
Before you go TOO far with that "read" please keep in mind this all depends on Skylon being "economical" itself :)

I have listened to some pretty elaborate and detailed "anaylisis" that question quite a few of the Skylon's underlying assumptions. They have compared several different engine cycles, propellant combinations, and vehicle concepts that "show" to be easier and cheaper to build than the Skylon. Many that have much higher TRLs, (Technological Readyness Level) than the SABRE, and are much "closer" to operational readyness.

Of course the "cavaet" to this is that currently you don't find anyone actually WORKING on these system and for the most part major development (actually bending metal and testing "full-up" system in at least the lab) pretty much stopped in the early 1970s. :)

Note: NONE of these "systems" either used or required "scramjet" engines and for the most part none of the engines systems used air-breathing past Mach-8 which can be "handled" by ramjet/ram-rocket systems. I make this point to make it clear that the past, but especially the "current" obsession with scramjet propulsion was NOT a factor in the lack of development progress.

THE main "sticking" point for the majority of engines was a lack of hypersonic flight platforms and interest in their development as well as a general lack of funding activites. The other major issue was a focused interest in AIRCRAFT applications with the assumption that high-supersonic/hypersonic aircraft were going to be the "next" step in aviation. There was some effort to attach these cycles to space launch but the majority proposals in such cases added scramjet development as a "requirement" for that application.

IMHO, the majority of the "major" aerospace companies seem to be focused more on tech-development rather than actual capability. This is probably makes a "sense" given the general lack of interest, (and money) in high speed and hypersonic aircraft in general. I consider practical scramjet applications, (note I said "practical" that's an important point :) ) a "future" technology due to the difficulty in USING a scramjet for any "practical" purpose beyond weapons technology at this point.

An interesting "aside" here is that given that focuse by the larger companies it seems that the ARE a number of smaller, (more "hungry" I suppose would be applicable as well) companies, organizations, and individuals who are attempting to pick up where those larger groups left off in the past. REL can be classified as one of these and there are others pursuing different cycles as well.

"I" consider this a good thing of course, and whish there were more actually, but as usual YMMV :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline simonbp

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #28 on: 12/16/2012 06:07 am »
IMHO, the majority of the "major" aerospace companies seem to be focused more on tech-development rather than actual capability. This is probably makes a "sense" given the general lack of interest, (and money) in high speed and hypersonic aircraft in general. I consider practical scramjet applications, (note I said "practical" that's an important point :) ) a "future" technology due to the difficulty in USING a scramjet for any "practical" purpose beyond weapons technology at this point.

Yeah, that's the real point. The aerospace majors aren't going to spend money to develop combined-cycle engines (like SABRE) unless a government give them money to do so. Until or unless a major government wants a hypersonic airplane, they won't bother.

REL was founded precisely to avoid all this. They are personally accepting the technical risk and are developing the engine themselves. If it fails, no government or corporation gets burned. If they succeed, then the barrier to entry for hypersonics and SSTOs is drastically lower than now.

Offline Archibald

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #29 on: 12/16/2012 07:52 am »
Quote
Yeah, that's the real point. The aerospace majors aren't going to spend money to develop combined-cycle engines (like SABRE) unless a government give them money to do so. Until or unless a major government wants a hypersonic airplane, they won't bother.

REL was founded precisely to avoid all this. They are personally accepting the technical risk and are developing the engine themselves. If it fails, no government or corporation gets burned. If they succeed, then the barrier to entry for hypersonics and SSTOs is drastically lower than now.

I call this pragmatism, and from what I know of HOTOL history, Alan Bond and his team learned it the hard way. In the 80's they were somewhat mauled by governments (British and others).
Let's see
- Thatcher funded them in 1985, only to stop without a warning in 1988
- the government (more exactly, the British military) classified RB-545, forcing REL to start again from zero
- when battling for ESA funding, they faced the French (Hermes, Ariane 5) and German (Sanger) governments. It was certainly not pretty nor a happy experience.

I think all three historical elements explain why REL doesn't wanted / want government funding for Skylon research and development. They took the whole issue by the other end: build something interesting and groundbreakring (see, the heat exchanger tests) then (and only then)  have a government interested enough that it may fund it further.
Han shot first and Gwynne Shotwell !

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #30 on: 12/16/2012 09:35 am »
Let's see
- Thatcher funded them in 1985, only to stop without a warning in 1988
- the government (more exactly, the British military) classified RB-545, forcing REL to start again from zero
- when battling for ESA funding, they faced the French (Hermes, Ariane 5) and German (Sanger) governments. It was certainly not pretty nor a happy experience.

I think all three historical elements explain why REL doesn't wanted / want government funding for Skylon research and development. They took the whole issue by the other end: build something interesting and groundbreakring (see, the heat exchanger tests) then (and only then)  have a government interested enough that it may fund it further.
Going back further there is the Concorde experience as well. Some REL staff were involved and it left some unhappy memories not just with them but also the British civil servants they had to deal with. The CS were terrified of another giant money sink that HMG would be stuck with the bill for (Concorde was cost plus all the way). My impression is it has literally taken the demise of that generation of senior officials (and the final establishment of the separately funded BSA) to get the ball rolling for UK government support.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Turbomotive

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #31 on: 01/08/2013 07:26 am »
Everything gone quiet - problem finding money?
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Offline Dalhousie

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #32 on: 01/08/2013 07:36 am »
Everything gone quiet - problem finding money?

Christmas-New Year holiday!
Apologies in advance for any lack of civility - it's unintended

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #33 on: 01/08/2013 02:48 pm »
Christmas-New Year holiday!

You also need to factor in UK tech companies for doing stuff rather than talking about it.

I think REL's approach falls somewhere between Blue Origins ("A few months ago we did some stuff. It was cool. Here's a video") and say Xcorp. a bit more informative but still quite "discrete")

Their game plan for the £250m they were looking to raise was to design a sub scale ground test SABRE for full up testing of the engine system and the Nacelle Test Vehicle, a very sub scale Skylon shaped vehicle to refine the nacelle design, along with the full drawings of the full size SABRE4.

A lot of this stuff is not very "showy" until hardware gets completed. The upside is that a full SABRE will pull the airflow through the pre-cooler much better than the jet engine they have been using.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline grondilu

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #34 on: 01/08/2013 03:27 pm »
Everything gone quiet - problem finding money?

It's not like they should report on their progress everyday, you know.   To follow this kind of stuff, one needs patience because it is a very long process.  It is a bit frustrating though, because Skylon is certainly one of the most exiting launcher projects at the moment, imho.

Offline Rugoz

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #35 on: 01/14/2013 04:27 pm »
REL should use a biplane design for LAPCAT, would eliminate the sonic boom.

http://news.discovery.com/tech/biplane-could-go-supersonic-120320.htm

Also it seems JAXA has a precooled engine program and an experimental vehicle is in development.

http://arc.aiaa.org/doi/abs/10.2514/6.2012-5839

If JAXA is serious about this we can expect ESA to be interested to fund further research in that field.
« Last Edit: 01/14/2013 04:30 pm by Rugoz »

Offline guckyfan

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #36 on: 01/14/2013 04:47 pm »
REL should use a biplane design for LAPCAT, would eliminate the sonic boom.

http://news.discovery.com/tech/biplane-could-go-supersonic-120320.htm

Great idea. Add another level of complexity to an already enormously complex project.


Offline Rugoz

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #37 on: 01/14/2013 05:28 pm »
^

Without sonic boom a mach 5+ airliner has huge potential which alone could easily legitimize 10bn+ dev. cost.

Offline BobCarver

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #38 on: 01/14/2013 05:39 pm »
The last thing I read was that LAPCAT was a dormant project. ESA paid for the study and it ended.

Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (2)
« Reply #39 on: 01/14/2013 06:36 pm »

REL should use a biplane design for LAPCAT, would eliminate the sonic boom.

http://news.discovery.com/tech/biplane-could-go-supersonic-120320.htm


Great idea. Add another level of complexity to an already enormously complex project.
Quote
Without sonic boom a mach 5+ airliner has huge potential which alone could easily legitimize 10bn+ dev. cost.
Rugoz, I'd suggest you do some more reading on the idea of the "Bussman-Biplane" supersonic design which the above is a version of. Number one it does not totally eleminate the sonic boom, number two it is most efficent at only a SINGLE Mach speed and therefore would not work well as a "accelleration" design which is what Skylon is and has to be to make it into orbit. Number three the design won't work for HYPERSONIC speeds (aka speeds at or above Mach-5, not the Skylon needs to reach at least speeds of around Mach-5.5 to work) Number four the Sabre engine is NOT an efficent supersonic engine, it is in fact not a really efficent engine at all but for the problem of Single-Stage-To-Orbit using air-breathing propuslion it has enough advantages in being a single engine to offset its various shortcomings at any one stage of flight.

In REL's case the engine is THE most important part of the program and the airframe is more a secondary consideration at this point. Designing and building a "supersonic" aircraft is not going to do they any good they need at LEAST hypersonic performance and it HAS to use a Sabre or derived engine to be of any value to them. In the case of LAPCAT and the Scimitar engine it would have been "derived" from but still possesing the major components of the Sabre engine with much more ephisis on the air-breathing cycle, to attempt to increase efficiency for that purpose. It would still be dependent on the Sabre engine process working which is still an unknown.

Quote
Also it seems JAXA has a precooled engine program and an experimental vehicle is in development.

http://arc.aiaa.org/doi/abs/10.2514/6.2012-5839

If JAXA is serious about this we can expect ESA to be interested to fund further research in that field.
This is continued work on the Japanes "ATREX" Turbo-Ramjet (with Expander Cycle) aircraft engine.
This is a hypersonic deep-cooled Liquid Hydrogen powered/cooled engine that they have been working on since the early '90s
http://www.tfd.chalmers.se/~valeri/Ajax/IAF-97-S.5.01.pdf

Unlike the Sabre/Scimitar engine is does not use a rocket-cycle anywhere in it so it is actually an easier engine to design and develop. Note that there are no flying examples as of yet, but they have actually tested scale size full-up engines in wind tunnels which REL has yet to do with the Sabre/Scimitar.

Yes the ESA was interested in seeing what REL could come up with in regards to a hypersonic airliner and engine. They paid for the LAPCAT study and that was it. There is little real interest in developing a hypersonic aircraft engine or airframe at this point in time and it is doubtful that there will be any funding forthcoming for more advanced work without substantial development by REL.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

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