Author Topic: The Reaction Engines Skylon Master Thread (5)  (Read 441426 times)

Online QuantumG

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1320 on: 03/15/2016 10:19 PM »
A first stage that gets to Mach 5 in the atmosphere, pops over the top of the atmosphere for second stage separation, turns around to return to the launch site, and does a powered landing on a runway. Sounds pretty awesome to me.

Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline Radical_Ignorant

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1321 on: 03/15/2016 10:22 PM »
A first stage that gets to Mach 5 in the atmosphere, pops over the top of the atmosphere for second stage separation, turns around to return to the launch site, and does a powered landing on a runway. Sounds pretty awesome to me.

Virgin is pursuing such a concept. Maybe if White Knight could do Mach5... But then look at the shape of White Knight. Anything like that can't do anything near Mach5.

Offline Radical_Ignorant

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1322 on: 03/15/2016 10:53 PM »
Unfair treatment of REL.
As few people before I also feel that many here have hostile attitude toward REL.
 They don't have working stuff? That's the very nature of advanced concepts that they are nothing until they are build, because they are not, they do not exist, they are not part of reality. Just what's the reason for looking at advanced concepts If everything is doomed, because you have seen so many failures in the past?
And please keep in mind that in Europe there are nor Elons with 100s millions to throw at their dream (even Branson is building VG, not anything here), nor NASA (ESA is so tiny in comparison), nor DARPA, nor USAF. We even hardly have any VC - so the fact that anything is happening is a miracle in itself :-)

Offline ChrisWilson68

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1323 on: 03/16/2016 12:02 AM »
Unfair treatment of REL.
As few people before I also feel that many here have hostile attitude toward REL.
 They don't have working stuff? That's the very nature of advanced concepts that they are nothing until they are build, because they are not, they do not exist, they are not part of reality. Just what's the reason for looking at advanced concepts If everything is doomed, because you have seen so many failures in the past?

Or, you could try reading what people are actually saying here.

Nobody is saying everything is doomed.  People are saying it's risky.  People are saying it's riskier to put all the eggs in the single-stage basket and maybe it would be less risky to try a two-stage system first.

I'm not sure how you think people are saying "everything is doomed" from that unless you aren't really interested in what people are actually saying.

Offline Radical_Ignorant

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1324 on: 03/16/2016 07:53 AM »
  People are saying it's risky.  People are saying it's riskier to put all the eggs in the single-stage basket and maybe it would be less risky to try a two-stage system first.


That is not what I've seen. Of course - I haven't read all the comments, but on last few pages and somewhere on start of this thread5 you were saying making it TS will improve the margins, not that it'll be less risky.

But still - How one vehicle can be more risky than two? Where is more potential points of failure?
What you save in TSTO if first stage fails? How much reputation and value for client you save if only second stage fails?

All I can agree is that it would be more probable if it was smaller and required smaller upfront dev cost. But as few people pointed out, this technology doesn't scale well. Except if they somehow could make it single engine vehicle... Hmm... But then this small vehicle could be like Falcon 1 - rather proof of concept and tech demonstrator than commercial vehicle. Don't know, but I suspect it wouldn't save much development.

Offline Hankelow8

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1325 on: 03/16/2016 08:14 AM »
  People are saying it's risky.  People are saying it's riskier to put all the eggs in the single-stage basket and maybe it would be less risky to try a two-stage system first.


That is not what I've seen. Of course - I haven't read all the comments, but on last few pages and somewhere on start of this thread5 you were saying making it TS will improve the margins, not that it'll be less risky.

But still - How one vehicle can be more risky than two? Where is more potential points of failure?
What you save in TSTO if first stage fails? How much reputation and value for client you save if only second stage fails?

All I can agree is that it would be more probable if it was smaller and required smaller upfront dev cost. But as few people pointed out, this technology doesn't scale well. Except if they somehow could make it single engine vehicle... Hmm... But then this small vehicle could be like Falcon 1 - rather proof of concept and tech demonstrator than commercial vehicle. Don't know, but I suspect it wouldn't save much development.

Could the fact adding a sub scale demonstrator would increase the  already large development costs on their decision to go straight to a full size prototype?.

Offline t43562

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1326 on: 03/16/2016 08:19 AM »
The talk  at the University of Nottingham by Mark Thomas should have happened yesterday (15 March) did anyone go or find any materials about it?


Tonight there seems to be this one in Gloucester:

Quote
The RAeS Gloucester & Cheltenham Branch invite you to explore the history of the aviation industry and learn about the future of space launcher SKYLON with Dr Robin Davies, Senior Control and System Engineer of Reaction Engines Ltd.
A Joint Event with the IMechE.


The space launcher industry is still using rocket technology from the 1950s to place things in orbit; it's expensive and involves a new rocket for every launch. SKYLON is an unpiloted, reusable Spaceplane intended to provide reliable, responsive and cost effective access to space. The advanced combined cycle air-breathing SABRE rocket engine enables the vehicle to take off from a runway, fly direct to earth orbit and return for a runway landing, just like an aircraft. This is a game-changing engine technology that could make conventional rockets obsolete overnight!

18:00 visit to Jet Age Museum and networking
19:30 Lecture starts

ALL WELCOME, but please book as spaces are limited.

To book, please email:
Guillermo Durango
guillermo.durango@safranmbd.com

For enquiries about the event:
Kerissa Khan
kerissa.khan1@safranmbd.com


Event address:

Jet Age Museum
Meteor Business Park
Cheltenham Road East
Gloucester
GL2 9QL

Offline ChrisWilson68

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1327 on: 03/16/2016 08:33 AM »
  People are saying it's risky.  People are saying it's riskier to put all the eggs in the single-stage basket and maybe it would be less risky to try a two-stage system first.


That is not what I've seen. Of course - I haven't read all the comments, but on last few pages and somewhere on start of this thread5 you were saying making it TS will improve the margins, not that it'll be less risky.

Better margins means less risky.

But still - How one vehicle can be more risky than two? Where is more potential points of failure?
What you save in TSTO if first stage fails? How much reputation and value for client you save if only second stage fails?

I'm talking about design risk here, not the risk of a particular mission -- that is, the risk that the design doesn't pan out and can't carry the intended payload to orbit and/or is too costly.  But, even though it's not what I was talking about, you absolutely can have one vehicle be more risky than two if the one vehicle is pushing the envelope too far.  Instead of spending the margin on getting to orbit in a single stage, you can spend it on making each of the stages simpler and more reliable.

Offline Radical_Ignorant

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1328 on: 03/16/2016 08:41 AM »

[...] But as few people pointed out, this technology doesn't scale well. Except if they somehow could make it single engine vehicle... Hmm... But then this small vehicle could be like Falcon 1 - rather proof of concept and tech demonstrator than commercial vehicle. Don't know, but I suspect it wouldn't save much development.

Could the fact adding a sub scale demonstrator would increase the  already large development costs on their decision to go straight to a full size prototype?.

Not sure. IMHO Skylon is "power-point vehicle" at the moment. Sabre is an engine in development which will allow something Skylonish to happen, and maybe as well something very unskylonish as well. Diesel engine happened for cars but allowed big changes in maritime/rails.
Single engine vehicle would not change a bit in next few years of development. And having more possibilities, like vision for small 5humans to orbit cheaper vehicle would maybe help to find founds.
However that's far from their focus - they want to develop engine, not vehicle, so it's very little chance they will take resources from engine development to investigate such a case. But it doesn't make it stupid/wrong/impossible.

Offline Star One

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1329 on: 03/16/2016 08:45 AM »
I suppose it's a vain hope that there will be anything in today's budget for REL.

Offline Radical_Ignorant

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1330 on: 03/16/2016 09:01 AM »
  People are saying it's risky.  People are saying it's riskier to put all the eggs in the single-stage basket and maybe it would be less risky to try a two-stage system first.


That is not what I've seen. Of course - I haven't read all the comments, but on last few pages and somewhere on start of this thread5 you were saying making it TS will improve the margins, not that it'll be less risky.

Better margins means less risky.


Payload margins is wasted opportunity and means lost income.
Better financial margins means ULA against Space X way, not sure if that's always better.
It's all about trade offs.

Finally as far as I understand whole concept, making it two stage is just over complication which does not help as far as LEO is considered. Then they are talking about thugs for GEO, rockets for BEO - so you have your second stage.

All benefits of Sabre disappear if you have to carry engine which is not used for bigger part of the way. I think you are still reasoning by analogy. First leg of the journey is not as hard as in VTOL rocket in any way. You don't need so powerful engines, you don't need so much fuel. So stage separation becomes much less attractive. That's the very core of Sabre/Skylon concept. Like not having a sail on steam boat.

Offline Radical_Ignorant

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1331 on: 03/16/2016 09:18 AM »

But still - How one vehicle can be more risky than two? Where is more potential points of failure?
What you save in TSTO if first stage fails? How much reputation and value for client you save if only second stage fails?

I'm talking about design risk here, not the risk of a particular mission -- that is, the risk that the design doesn't pan out and can't carry the intended payload to orbit and/or is too costly.  But, even though it's not what I was talking about, you absolutely can have one vehicle be more risky than two if the one vehicle is pushing the envelope too far.  Instead of spending the margin on getting to orbit in a single stage, you can spend it on making each of the stages simpler and more reliable.

That is a point. How far and how do we want envelope to be pushed. If you push it to little you have nothing new and your efforts are not providing any benefit.
If you push to far into unknown territory all becomes just research. But then to quote them "we have all research done, what's left is development not research" - so they aren't pushing envelope into unknown territory.
Maybe I'm dumb but it seems simple. If Sabre works, then there is nothing very risky in Skylon. If Sabre does not work, then no matter number the stages or scale it makes no sense. And unfortunately Sabre is not very scalable. Nor down (engine reasons) nor up (infrastructure reasons) except single engine possibility.
But I got off. In short if you don't push envelope you don't have benefits. You much prefer Space X way of pushing it in small steps. But then we have Space X and they won't stop doing it, so duplicating their way is doing what other does and makes no sense if you are not established player on the market.
 Can you go to investors and tell them: hey I need few hundred millions and I'll do things like Space X is doing except I'm much late into the game and don't have experience and hmmm, here in Europe I can't count on NASA, DOD, USAF contracts?

Offline t43562

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1332 on: 03/16/2016 09:38 AM »
I have found some tweets from the talk at the University of Nottingham:

https://twitter.com/search?q=sabre%20reactionengines&src=typd

Some samples (Most from a gentleman called Jon Knight):
Quote
#sabre engine flight demonstration aimed for 2023-2025, with production in following decade. Are @ReactionEngines going to be too late?

Question asked about @ReactionEngines finances. They see #sabre and heat exchange tech as they income generators.

Mark Thomas: Since @BAESystemsInc investment @ReactionEngines has scaled up and improved manufacturing processes further #SABRE

There is a schools competition between @ReactionEngines and iMechE to design a #Sabre powered transport aircraft for RAF.

Offline SICA Design

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1333 on: 03/16/2016 10:49 AM »
...And unfortunately Sabre is not very scalable. Nor down (engine reasons) nor up (infrastructure reasons) except single engine possibility.

You have mentioned "single engine possibility" more than once now.

It should be pointed out that it was the rear-heavy design failure of HOTOL - which became a "means for lifting hydraulics into orbit" (huge canards to compensate CoM issues) - which principally drove the twin-engined Skylon design.

Offline Jim

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1334 on: 03/16/2016 12:29 PM »

Payload margins is wasted opportunity and means lost income.


Wrong.  They are not talking about payload margins for a specific launch, but development margins.  You design for X + 20% capability, so that as issues and things like weight creep and ISP/thrust losses come around, you can still hit your target X capability.   TS means better development margins.

Shuttle has a problem because of margins.  Mass to orbit was not just the payload at 50klb (round numbers) but the 250klb orbiter.  So if the orbiter came in too heavy at 5%, that means the payload loses 12.5klb mass.  that is why they had to increase the performance of the system.  For SSTO, it is worse.

Also, most payload use the whole capability of current vehicles.
« Last Edit: 03/16/2016 12:38 PM by Jim »

Offline TrevorMonty

Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1335 on: 03/16/2016 03:24 PM »
A strapon booster for existing/future LV is one possibility.

Does anybody know what type performance increase 2 1xsabre boosters would give Vulcan assuming they separate at Mach5.

Offline Paul451

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1336 on: 03/16/2016 04:07 PM »
People are saying it's riskier to put all the eggs in the single-stage basket and maybe it would be less risky to try a two-stage system first.
you were saying making it TS will improve the margins, not that it'll be less risky.
Better margins means less risky.
Payload margins is wasted opportunity and means lost income.

Engineering margins.

That might be the difference between designing for 700 degrees, versus 1200 degrees. Between using machine stamped aluminium, versus hand-made carbon-composite. Between a component lasting a hundred hours, versus just ten hours. Between a modular assembly that can be quickly swapped out, versus deeply integrated components that require thousands of hours of disassembly to change one part. Between being able to use lower cost mass-produced off-the-shelf components for mundane elements, versus having to design and customise every single part in low-volume production.

There's an old engineering rule-of-thumb that each 10% increase in material, doubles the life of the part. Probably the same with cost. Things don't scale linearly, there's an exponent in the curve.

And that feeds back into every other assumption in your business case. Cost of development, cost of operations, lifespan of vehicles, turn-around time of vehicles.

But still - How one vehicle can be more risky than two?

Because the one and the two are not the same types of vehicles.

Two trucks are clearly easier to develop than one jet. The engineering challenge of developing an SSTO is so astoundingly far beyond the engineering challenge of TSTO. Not just twice as hard, but orders of magnitude.

proof of concept and tech demonstrator [...] but I suspect it wouldn't save much development.

This is, IMO, one of the most destructive myths in aerospace. The belief that developing directly to the end goal is going to be cheaper than passing through three or four operational stepping-stones.

Reality is the opposite. Unless what you are developing is completely mundane and your designers, engineers, technicians and ops people are all experienced in that technology, it will always cost less to pass through multiple iterative stages before even attempting the final design. (Indeed, before attempting to design the final design.)

(It's the same "one is less than two" mentality.)

REL is at least doing one form of iterative development: subscale component testing. It also seems like they are happy to have other players use their technology on lower risk iterations, ironically unlike many of their defenders here.

In short if you don't push envelope you don't have benefits. You much prefer Space X way of pushing it in small steps. But then we have Space X and they won't stop doing it, so duplicating their way is doing what other does and makes no sense if you are not established player on the market.

That's silly. It's their method you'd be copying, iterative development, not the product.

Can you go to investors and tell them: hey I need few hundred millions and I'll do things like Space X is doing except I'm much late into the game

Versus going to investors and saying: hey I need a ten billion (probably) and I'll (try to) develop something that no-one (including me) has ever done before, and without doing any risk-reducing steps? Oh, and because I'm developing directly to the end-goal, you won't see any return for twenty years. Oh, and it involves sustained high-mach flight, which has been traditionally horribly expensive. Oh, and it involves a hybrid engine, which has traditionally been horribly expensive. Oh, and we're not airframe designers, so we'll need to outsource that anyway, but don't worry, this computer model says my design is perfect.

[edit: typos]
« Last Edit: 03/16/2016 05:59 PM by Paul451 »

Offline Paul451

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1337 on: 03/16/2016 04:21 PM »
A strapon booster for existing/future LV is one possibility.
Does anybody know what type performance increase 2 1xsabre boosters would give Vulcan assuming they separate at Mach5.

SABRE has a projected thrust-to-weight ratio of around 14. That's double the F119 engine, for example, which itself it higher than most commercial engines.

But rocket engines are up around 80-100. (The record is either Merlin 1D (180:1) or one of the Russian engines.)

[edit2: to clarify that. It means that if your SABRE-booster and fuel masses 14 times the mass of the engine, the booster will only be able to hover, it won't add any lift. If it masses more than 14 times the engine, the boosters will actually be hanging off the core stage, merely adding to the weight.]

SABRE's Isp is massively better than any rocket during its air-breathing mode, but for a vertical launch that precisely when you are most willing to sacrifice Isp for thrust. (The amount of fuel you burn in your first three minutes is much less important than the amount consumed in the last three minutes, because the fuel burnt in the last three minutes has to be carried during the rest of the flight.)

Skylon can cope with low thrust/weight because it gets lift from aerodynamic surfaces to compensate for gravity losses. And that long horizontal climb is where you need high-Isp.

[edit1: added the parenthesised comments]
« Last Edit: 03/16/2016 04:31 PM by Paul451 »

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1338 on: 03/16/2016 07:11 PM »
You have mentioned "single engine possibility" more than once now.

It should be pointed out that it was the rear-heavy design failure of HOTOL - which became a "means for lifting hydraulics into orbit" (huge canards to compensate CoM issues) - which principally drove the twin-engined Skylon design.
True.

For a demonstration vehicle what is essentially a winged nacelle would be possible.

To preserve the CoG protecting features you'd need to put it on top of the payload bay, like a sort of V1 cruise missile.

But that would leave the issue of how  you open the bay to get the payload out. 

The latter is a slightly closer to Skylon so might shorten the test programme of the real Skylon, while the former is likely to be cheaper.

Both would probably make the test programme more expensive overall.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1339 on: 03/16/2016 07:21 PM »
A strapon booster for existing/future LV is one possibility.
No it's not. This was a running theme of WIlliam Escher.  It's a bad notion given the poor T/W of airbreathers (although SABRE's is excellent by turbofan standards).

"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

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