Author Topic: The Reaction Engines Skylon Master Thread (5)  (Read 420862 times)

Offline RanulfC

  • Senior Member
  • *****
  • Posts: 4416
  • Heus tu Omnis! Vigilate Hoc!
  • Liked: 765
  • Likes Given: 32
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #60 on: 02/21/2015 04:33 AM »

The two biggest hurdles technology wise were the heat exchanger and the rocket motor both of which have been demonstrated.

The rest of your post was reasonable, but this I must inquire about:
When was the rocket motor demonstrated? Did I miss that?

LOX apparently not air. So that's still a bit of question I suppose though to be honest the "Low-NOx" engine test would seem to indicate air use.
http://www.reactionengines.co.uk/sabre_techdevel.html

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 ChrisWilson68

  • Senior Member
  • *****
  • Posts: 3519
  • Sunnyvale, CA
  • Liked: 2076
  • Likes Given: 2412
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #61 on: 02/21/2015 04:38 AM »

The two biggest hurdles technology wise were the heat exchanger and the rocket motor both of which have been demonstrated.

The rest of your post was reasonable, but this I must inquire about:
When was the rocket motor demonstrated? Did I miss that?

LOX apparently not air. So that's still a bit of question I suppose though to be honest the "Low-NOx" engine test would seem to indicate air use.
http://www.reactionengines.co.uk/sabre_techdevel.html

On the page you link to, REL says this about the Low Nox test: "REL has designed and tested a new rocket combustion chamber".  A combustion chamber is an important part of a rocket motor, but it is only a part, not a complete motor.

It's also not clear whether this combustion chamber is full size or a small-scale test.

Offline RanulfC

  • Senior Member
  • *****
  • Posts: 4416
  • Heus tu Omnis! Vigilate Hoc!
  • Liked: 765
  • Likes Given: 32
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #62 on: 02/21/2015 06:29 AM »
When are you proposing to stage this notional TSTO? Inside the atmosphere so you can use a simpler non rocket mode SABRE losing LOX tanks from the first stage or outside still using SABRE?
Are you carrying the second stage internally or externally? If externally how are managing the damage that does to the aerodynamics and thermal protection? If internal how are making the vehicle trimable given the damage that does?   
What engine is powering the second stage?
How does any of that make the development of SABRE cheaper? Either you're proposing using the SABRE design as is, or you're suggesting development of a second engine, on top of SABRE, without a pure rocket mode neither of which can be cheaper for REL as an engine developer than just building SABRE.
Indeed. It's one of those ideas that sounds very sensible, until you look at it a bit more closely.

lkm: Good questions because it IS a "good-idea" depending on the answers. REL has already determined it is NOT a good answer for their purposes and having read their reasoning I'd have to agree. Since I'm currently arguing the "viability" of sub-orbital rendezvous and re-fueling I can't very well say I don't think it's possible :)
Quote

Quote
I can't help feel that rocketry (successfully putting things in orbit since 1957)  is somewhat better understood that Scramjets ( someday soon we'll reach ten minutes cumulative flight time). Who is seriously researching scramjets for anything other than hypersonic cruise? Also please name these other people who think that the development challenges of NASP in 1984 are of comparable difficulty to the challenges of Skylon in 2015.
That would be an interesting list.

lkm: A WHOLE lot better but really "beside-the-point" as the whole attraction of SCramjets is how fast they can go in theory rather than fact in the first place :) The answer to the second is no one as that's about its only use being considered. And lastly I blame confusion between what was "required" of NASP with many of the supposed issues with Skylon. Well that and confusion with issues with the X-33, DC-Y, Roton, etc, etc, etc :)
Quote
Quote
Many people believe that VentureStar wasn't viable, but I don't think anybody believes the X-33 couldn't have flown and gathered useful data. The X-33 wasn't VentureStar, VentureStar was a powerpoint, X-33 was an active x-plane project with a similar budget and goals to the X-15. The X-15 wasn't a failure because it had no follow on project so why  should the X-33? When the X-15 first flew it didn't have it's intended engine yet because it wasn't ready, so why should the X-33 not have been given the same leeway? Like I said, there was a change in administration, a desire to cancel and repudiate the projects of the previous one, people obliged.
Actually the view amongst some people was that the X33 was extremely complex and risky for its stated purpose. I'd suggest VTOHL SSTO is the most difficult way to do it. It calls for both a T/W of at least 1.1:1 and a strong structure in two axes.

lkm: I'd be one of the ones who would argue that no, the X-33 would in fact NOT have been useful since it could not in fact met its flight related goals. That was in fact a major issue with the program as LM kept dropping the "goals" because the design was incapable of meeting the original series. Couple that with the development issues and cost over-runs it was pretty inevitable IMHO. Even if there had been no change in the political landscape the problems with the X-33 program overall would have ended up the same. Similarly I was never convinced that the VentureStar was going to happen even IF the X-33 was able to fly. LM had to constantly "update" the design to take into account problems they were running into with the X-33 AND there were inherent issues with the design that LM really should have known about given their background. (Come on, the design could not in fact "fly" because it was too tail heavy and no one in an aircraft company figured this out till AFTER? :) )

Comparison of the X-33 to the X-15 isn't really applicable. The "X-33" was an "X" vehicle only due to it supposedly being a technology demonstrator/development program which in fact it didn't do. The X-15 on the other hand was a test aircraft along the line of progression to higher speeds and altitudes. I don't actually consider the X-33, (or X-34, X-37, etc) to be actual "X-Planes" but this is pretty much OT for this thread.

JS19: While technically accurate (VTHL design) we HAVE done this before and its a pretty straight forward engineering problem. Has issue but then again so will designing and building what amounts to a hypersonic zeppelin :)

Its always a plus if you can design a vehicle to only handle the "exact" loads it needs and not a bit more. (Henry Ford logic/economics at work :) However that "logic/economics" leads to surviving a crash only to be killed when the "minimum" roof of the car collapse on you :) ) And since every ounce counts/costs going into space...

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 Dalhousie

  • Senior Member
  • *****
  • Posts: 2057
  • Liked: 251
  • Likes Given: 306
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #63 on: 02/21/2015 06:33 AM »

The two biggest hurdles technology wise were the heat exchanger and the rocket motor both of which have been demonstrated.

The rest of your post was reasonable, but this I must inquire about:
When was the rocket motor demonstrated? Did I miss that?

LOX apparently not air. So that's still a bit of question I suppose though to be honest the "Low-NOx" engine test would seem to indicate air use.
http://www.reactionengines.co.uk/sabre_techdevel.html

Randy

That page list contra-rotating turbines, Sabre combustion chamber, Sabre nozzles, low NOx engines, and Sabre intakes, so REL have a lot more than "just" a "cooler".
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline Paul451

  • Full Member
  • ****
  • Posts: 1238
  • Australia
  • Liked: 607
  • Likes Given: 520
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #64 on: 02/21/2015 08:32 AM »
The X-33 wasn't VentureStar, VentureStar was a powerpoint, X-33 was an active x-plane project

But when someone makes a comment like that about the Skylon vehicle vs REL's actual development, they get their heads bitten off.

Aside: One of the reasons the X-33 failed was the belief by some senior people that saying "there's no showstoppers" meant that you could treat development as a fait accompli. Therefore... Well, I recall (no refs, sorry, it was awhile ago) a program manager testifying before Congress that the program would be "worthless" (I think he even used that word) if it didn't launch with every piece of technology on his wish-list (mainly the composite hydrogen tank). So when the development of key pieces of technology stalled, what outcome would you expect?

I similarly worry that REL's people are so fixed on their end goal that they can't see alternative approaches. A TSTO is dismissed because it isn't as "economical" as their SSTO... which they expect will cost $10b to develop...

(I worry the same thing about Musk. But his development philosophy results in useful, low cost vehicles at each stage, even if his end goal fails.)

Offline Paul451

  • Full Member
  • ****
  • Posts: 1238
  • Australia
  • Liked: 607
  • Likes Given: 520
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #65 on: 02/21/2015 08:41 AM »
What would people think of separating this thread into two threads: Skylon Updates and Skylon Discussion?  There's been a lot of discussion in the Skylon threads, and not everyone who is interested in hearing about news from Skylon has the time or inclination to follow all the discussion.

Agreed. But I'd suggest three.

- REL development news. Info only (Plus the usual RFI questions. "Does anyone know if..." "Are they going to...")

[edit: Ah, what the hell, Reaction Engines Ltd (REL) news and information )

- Skylon general discussion. Everything else... except...

- Alternative uses of REL tech. A2/Scimitar discussion. General application to aviation. Alternative applications to spacecraft. Alternative paths to Skylon. (The discussion you were trying to start, which got bogged down in... {waves hand} ...this.)


when the space shuttle idea was proffered, did people say 'what's wrong with normal rockets?, we know how to do normal rockets'  were there naysayers arguing for incremental steps?

I would suspect there were a lot of "naysayers" and "skeptics" arguing for a more incremental development path. Not because they hated the idea, or wished ill upon it, but because the Shuttle required too many new technologies all to work exactly as predicted. Any problems would turn the Shuttle into a fragile expensive system which would fail in its goal of making access to space affordable and routine...

And I know in the '80s a lot of us space advocates used the lack of incremental development in the Shuttle program in the '70s as an example of "what not to do". And we despaired as program after program (Freedom, NASP, VentureStar, even Delta Clipper to a degree(*), and almost all of the big science missions) repeated the same mistake with the same or similar results. And now, of course, SLS and Orion doing the same thing. "They say the definition of madness is doing the same thing over and over and expecting a different result."

It's this pattern that we see being repeated in Skylon, and this outcome that I fear for REL.

(* While DC-X was a lovely cheap research program, next "step" was meant to be a full sized SSTO demonstrator, DC-Y. Ick.)

Do I then assume that you deride the various "Fully-reusable TSTO is a done deal" SpaceX fans the same way?

Yes. Often.

I also deride those who build a strawman out of a handful of the most naive enthusiasts into some general behaviour of "SpaceX Fans".

Quote
And yes Skylon is the latest in a long line of "promising" SSTO vehicle but I'd point out that it in fact is much close to, and much easier to implement than most where and does not (at this point) really need as significant technologies as most of the previous concepts did.

Out of curiosity, can you think of a single one of those previous designs whose advocates didn't say exactly the same thing about their design?
« Last Edit: 02/21/2015 09:23 AM by Paul451 »

Offline banjo

  • Member
  • Posts: 37
  • Liked: 17
  • Likes Given: 5
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #66 on: 02/21/2015 09:42 AM »


And from what I saw over the last 25 years, that's part of the reason it's taken so long for Bond's ideas to receive backing. If you're an investor (or administrator) in aerospace/aviation and this comes across your desk; a report that's actually about some guy who thinks he's solved the pre-cooler icing problem, but if you saw a picture of Skylon and pages of detail on the vehicle, payloads and missions, would you even read the report? Would you wade through the rest to even get to the two paragraphs on Bond's actual pre-cooler design? Because Skylon hit the quadrella of aerospace "alarm bells": a tiny unknown company proposing a radical vehicle design, plus it's an SSTO, plus it uses air-breathing jet/rocket hybrid engines, plus it's all based (with no margins) around their own new unproven technology proposal.

OTOH, you're in aerospace and a report crosses your desk about a small start-up that thinks it has solved the pre-cooler icing program. They point out that if their idea works, it could make high-speed turbojet engines more efficient and effective. Oh sure, they speculate - just as an aside, making it clear that they are just speculating - that the idea could even be useful for future space vehicles. And that's it, the report is about their pre-cooler idea, nothing else.

that's some back to front thinking you have going on there Paul451.   REL need heavy investment.  Investors need to be wooed.  showing them what the ultimate goal of their investment is is logical.   telling them that you have done no work on plausible applications of the pre-cooler breakthrough and then asking for investment is nuts.   REL did exactly the right thing in commissioning business case reviews and framing end use scenarios.  if you're after investment, this is what you do.

about wooing investors with the promise of making high-speed turbojet engines more efficient and effective.  why would they?   REL's goal is not to make high-speed turbojet engines more efficient and effective.   we know what their ultimate goal is and they are entitled have it. 
« Last Edit: 02/21/2015 07:03 PM by banjo »

Offline 93143

  • Senior Member
  • *****
  • Posts: 3039
  • Liked: 292
  • Likes Given: 1
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #67 on: 02/21/2015 09:56 AM »
Out of curiosity, can you think of a single one of those previous designs whose advocates didn't say exactly the same thing about their design?

SSTO was always about making up negative margins with handwavy breakthroughs.  X-33 was actually sold on that basis.  Before Skylon, what SSTO concept had double-digit mass margins after decades of iterative design and component fabrication/testing? What SSTO concept could have absorbed a 10% Isp hit (and used up its structural margins) without failing to make orbit?  REL has been busy making sure nothing on the vehicle is below TRL 4 before committing to so much as an engine development program, and while the resulting design is unconventional it does not seem to require any breakthroughs.

Paul451, I understand you haven't really been around for the technical discussions, but it gets really old having newcomers assume proponents of the idea are handwaving in a vacuum.  Skylon is nothing like X-30.

Lars_J, you have been around long enough and should know better.
« Last Edit: 02/21/2015 10:22 AM by 93143 »

Offline Paul451

  • Full Member
  • ****
  • Posts: 1238
  • Australia
  • Liked: 607
  • Likes Given: 520
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #68 on: 02/21/2015 10:27 AM »
that's some back to front thinking you have going on there Paul451.   REL need heavy investment.  Investors need to be wooed.  showing them what the ultimate goal of their investment is is logical.

And yet for over 20 years it didn't work. Only now are they picking up some actual revenue, and not for Skylon but for a hypersonic passenger plane study.

"Step 1: Get 10 billion investment..."

Umm, no.

Quote from: banjo
about wooing investors with the promise of making high-speed turbojet engines more efficient and effective.  why would they?

Because high speed military aircraft are a lucrative market. And a company that develops the next big thing in aircraft engines will end up with much spare cash for their more speculative R&D.

And I suspect they'll end up somewhere like that anyway. Only it will take a demonstration of the full SABRE engine to get potential customers to ignore Skylon long enough to say, "Oh hey, that's actually useful technology". Something REL may have achieved 15-20 years sooner had they not publicly fixated on Skylon.

Paul451, I understand you haven't really been around

I've just started posting here, but I've been watching REL since they started, and HOTOL before it. And I've been "around" these discussions long before NSF existed. Your patronising is unnecessary.

Offline t43562

  • Full Member
  • *
  • Posts: 172
  • UK
  • Liked: 72
  • Likes Given: 37
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #69 on: 02/21/2015 10:41 AM »
that's some back to front thinking you have going on there Paul451.   REL need heavy investment.  Investors need to be wooed.  showing them what the ultimate goal of their investment is is logical.

And yet for over 20 years it didn't work. Only now are they picking up some actual revenue, and not for Skylon but for a hypersonic passenger plane study.

I thought their money is from a 60 million pound government investment for developing SABRE and private capital.  I mean I know they were part of LAPCAT but that seems like a minor part of what funding they managed to get.  Why are you leaving out the major sources?

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 5871
  • Everyplaceelse
  • Liked: 744
  • Likes Given: 4507
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #70 on: 02/21/2015 10:44 AM »
What your calling Science I would simply call 'real man's engineering' and looking something up from a book is 'engineering for dummies'.  Iteration in engineering doesn't in my opinion
make it a science because science is the creation and testing of theories, engineering is the creation and testing of devices.
Then you'll be pleased to know that SpaceX have been doing plenty of 'real man's engineering'   :)
 
Quote
make it a science because science is the creation and testing of theories,
SpaceX's failure to deliver a fully reusable F9 strongly suggest that the current theories, and the models derived from them have flaws in them that mean going from their very public video to actual hardware was impossible.

That's when  you start doing Science.

BTW if you look at the book cases of successful real engineers in any field you'll find an extensive back catalogue of stuff they can dip into when a new problem arrives and say "Ah, this looks like something in <textbook name/journal article/web page I copied> " The skill is knowing how to "flex" what's there into what's wanted.

They are called "inspection" or "cookbook" methods but a lot of the time they get the job done.

Trouble is what SpaceX want to do is not in any "cookbook"  :(

That's when you start getting into Applied Physics and hacking the source code on your CFD systems.

Unfortunately that's when development schedules go out the window and you may have to scrap all your previous work. You think you can get away with something (turning an ELV into an RLV at a certain size while still having a large payload say) and you can't.

To make this more Skylon centric look at what Skylon does not do.  It does not
1) Take off vertically. So it's engine T/W  ratio can be worse and T/O Thrust much lower than GTOW. That's not the whole story of course. It's that it then turns the atmosphere around it into IIRC about 100 tonnes of extra propellant (80% of it is more strictly "reaction mass" but it all helps).

2) No main engine re ignition in an oncoming (albeit tenuous) hypersonic airstream.

3) No engines forward re-entry. I can't imagine the CFD days (weeks?)  SpaceX took for them to be comfortable doing that. In particular the heat load on the most forward bell of the most forward engine (it'll be slightly below the horizon of local airflow) That's a combined aero/thermo/chemical load simulation problem. It's like the little patch on the Apollo heat shield. The temperature fall off outside it is huge but that's because that patch will run hot

4) No direct exposure of main propellant tanks to airflow. This side steps heating and bending forces which will try the F9 1st stage to a "face on" directly into the flow have to be resisted. It also side steps questions about wheather the LOX vaporises and the Merlins need to run on GO2/RP1 instead.

5) No large lumps of propellants sloshing round in the main tanks, which are vented.  Keeping in mind an F9 stage is not "end on" to the stream so the deceleration forces smear the propellants onto the wall facing the airflow at an angle. Hard enough  (like a guy charging a door) to make the stage flips over? What's the safe loading range to avoid that? Is it enough to land on? Who knows.

6) No ablatives (of unknown erosion rates) to replace.

Some of these are Science problems with no existing methods to solve them and some of them are situations that have no precedence, so no one has got constants for them for others to use.

And those are the obvious ones from a layman's PoV.  :(

Those forces interact in lots of interesting ways to give new force vectors (which will of course change over the course of the flight).

SABRE/Skylon "solves" these problems by not having to deal with them. However it has a set of problems of its own to solve, which would be on topic for this thread. The difference is REL don't need flights to collect the basic data to start to build the models (not the vehicle, the models) in the first place.

So if you're a CFD programmer or an Applied Physicist this makes SpaceX possibly the most exciting place on the planet for you to work right now.  :)

And you will work.
« Last Edit: 02/21/2015 11:48 AM by john smith 19 »
"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 Paul451

  • Full Member
  • ****
  • Posts: 1238
  • Australia
  • Liked: 607
  • Likes Given: 520
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #71 on: 02/21/2015 11:53 AM »
I thought their money is from a 60 million pound government investment [...] Why are you leaving out the major sources?

Nothing sinister about it. It was an arbitrary decision to draw a distinction between the UK Govt giving them bare-minimum funding to keep REL viable, to keep from losing technology to someone else (even if they didn't believe in the technology enough to properly fund it), and someone completely independently saying "hey, you guys have mad skills, care to do some work for us?" The latter struck me as more significant, even if it garners fewer dollars pounds euros.

Offline t43562

  • Full Member
  • *
  • Posts: 172
  • UK
  • Liked: 72
  • Likes Given: 37
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #72 on: 02/21/2015 02:48 PM »
that's some back to front thinking you have going on there Paul451.   REL need heavy investment.  Investors need to be wooed.  showing them what the ultimate goal of their investment is is logical.

And yet for over 20 years it didn't work. Only now are they picking up some actual revenue, and not for Skylon but for a hypersonic passenger plane study.

I thought their money is from a 60 million pound government investment [...] Why are you leaving out the major sources?

Nothing sinister about it. It was an arbitrary decision to draw a distinction between the UK Govt giving them bare-minimum funding to keep REL viable, to keep from losing technology to someone else (even if they didn't believe in the technology enough to properly fund it), and someone completely independently saying "hey, you guys have mad skills, care to do some work for us?" The latter struck me as more significant, even if it garners fewer dollars pounds euros.

I'm sorry but I read it as "they have no money other than for a hypersonic study" and I don't see how anyone could possibly read it otherwise.  Now it twists into another comment which is also wrong because they always have had private support and 60m pounds is the lesser part of it from what we know of their plans for developing the engine i.e. what they said they'd need versus what we know for sure they have.

Are we expected to have detailed information about their private funding? I didn't think private companies usually handed that kind of thing out to everyone.

It is obvious, however, that to get this far they certainly have impressed people who certainly have put a very large amount of money in.
« Last Edit: 02/21/2015 03:36 PM by t43562 »

Offline Impaler

  • Full Member
  • ****
  • Posts: 1283
  • South Hill, Virgina
  • Liked: 362
  • Likes Given: 0
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #73 on: 02/21/2015 06:35 PM »

SpaceX's failure to deliver a fully reusable F9 strongly suggest that the current theories, and the models derived from them have flaws in them that mean going from their very public video to actual hardware was impossible.

That's when  you start doing Science.

THIS is the kind of comment that destroys your credibility.   As Lars-J said earlier is smacks of "Denigrating the hard work by done by people trying for the same goal but by different means." 

It has been pointed out repeatedly to you that SpaceX is not PURSUING full reusability for F9 because they have decided to focus on the followup vehicle which they DO intend to make fully-reusable.  They have said this is a decision driven by market volume and development resource, NOT one forced on them by hitting technological barriers.

But you have been repeatedly portraying this a technical failure on SpaceX's part and further more that this failure invalidates the vertical take-off, vertical landing paradigm, leaving your preferred Horizontal arrangement the 'only' viable solution.  And you blatantly ignore that they are STILL WORKING on the goal, which puts them in the same race as REL, but miles ahead, while you try to treat them as if they have dropped out.

And no this is not Science, it is ALL engineering.  Science is creating the rocket-equation, Bernoulli's principle and all the other THEORIES that let us know how the world behaves.  SpaceX nor any other Airo-space company dose science, they engineer vehicles using well established theories.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 26876
  • Minnesota
  • Liked: 6779
  • Likes Given: 4808
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #74 on: 02/21/2015 06:48 PM »
Thank you again, Impaler! Can I subscribe to your newsletter?
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

Offline Star One

  • Senior Member
  • *****
  • Posts: 8008
  • UK
  • Liked: 1278
  • Likes Given: 168
The Reaction Engines Skylon Master Thread (5)
« Reply #75 on: 02/21/2015 08:39 PM »

SpaceX's failure to deliver a fully reusable F9 strongly suggest that the current theories, and the models derived from them have flaws in them that mean going from their very public video to actual hardware was impossible.

That's when  you start doing Science.

THIS is the kind of comment that destroys your credibility.   As Lars-J said earlier is smacks of "Denigrating the hard work by done by people trying for the same goal but by different means." 

It has been pointed out repeatedly to you that SpaceX is not PURSUING full reusability for F9 because they have decided to focus on the followup vehicle which they DO intend to make fully-reusable.  They have said this is a decision driven by market volume and development resource, NOT one forced on them by hitting technological barriers.

But you have been repeatedly portraying this a technical failure on SpaceX's part and further more that this failure invalidates the vertical take-off, vertical landing paradigm, leaving your preferred Horizontal arrangement the 'only' viable solution.  And you blatantly ignore that they are STILL WORKING on the goal, which puts them in the same race as REL, but miles ahead, while you try to treat them as if they have dropped out.

And no this is not Science, it is ALL engineering.  Science is creating the rocket-equation, Bernoulli's principle and all the other THEORIES that let us know how the world behaves.  SpaceX nor any other Airo-space company dose science, they engineer vehicles using well established theories.

I kind of agree with what you said other than please do not just dismiss what REL has achieved so far by the glib sentence of saying that Space X is miles ahead. Especially as this is not some kind of race as I don't even regard Space X & REL as being in the same business.
« Last Edit: 02/21/2015 08:41 PM by Star One »

Offline ChrisWilson68

  • Senior Member
  • *****
  • Posts: 3519
  • Sunnyvale, CA
  • Liked: 2076
  • Likes Given: 2412
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #76 on: 02/21/2015 08:43 PM »
I kind of agree with what you said other than please do not just dismiss what REL has achieved so far by the glib sentence of saying that Space X is miles ahead.

To me, saying SpaceX is miles ahead doesn't dismiss what REL has achieved.  SpaceX was once far behind ULA, but held promise.  Being behind doesn't mean they won't eventually end up in front.  It just means they have a longer journey ahead and there is more uncertainty because of that.

Offline knowles2

  • Full Member
  • *
  • Posts: 115
  • Liked: 20
  • Likes Given: 50
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #77 on: 02/21/2015 09:16 PM »
That's fine, but this engine company is making projections about the performance and economic viability of the complete system, including engines and airframe.

Don't they have to? Is it not necessary at all times to make such projections and keep updating them as new information is learned?

There'd be no shame in their saying "we don't know yet".

There no shame in that but say "we don't know yet", tend to put off investors and especially investors who will put money into such early projects, they want to be sold a dream a visions, they don't want ifs and buts.


Quote
Personally I think the greatest threat to Skylon development will be a failure of an airframer to commit to it. I think REL may find that despite developing an engine that works well and engenders a lot of interest in the end there may be a general reticence to throw in with another companies grand scheme and disrupt their own planning among the likely consortium partners. I could see REL being bought by RR as a part of an attempt at forming a successful consortium only to end being used to get some lucrative US hypersonics research money.
This is my biggest fear as well, that REL squash under a barrage internal politics from any consortium.
« Last Edit: 02/21/2015 09:20 PM by knowles2 »

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2057
  • Liked: 251
  • Likes Given: 306
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #78 on: 02/21/2015 09:54 PM »

SpaceX's failure to deliver a fully reusable F9 strongly suggest that the current theories, and the models derived from them have flaws in them that mean going from their very public video to actual hardware was impossible.

That's when  you start doing Science.

THIS is the kind of comment that destroys your credibility.   As Lars-J said earlier is smacks of "Denigrating the hard work by done by people trying for the same goal but by different means." 

It has been pointed out repeatedly to you that SpaceX is not PURSUING full reusability for F9 because they have decided to focus on the followup vehicle which they DO intend to make fully-reusable.  They have said this is a decision driven by market volume and development resource, NOT one forced on them by hitting technological barriers.

But you have been repeatedly portraying this a technical failure on SpaceX's part and further more that this failure invalidates the vertical take-off, vertical landing paradigm, leaving your preferred Horizontal arrangement the 'only' viable solution.  And you blatantly ignore that they are STILL WORKING on the goal, which puts them in the same race as REL, but miles ahead, while you try to treat them as if they have dropped out.

And no this is not Science, it is ALL engineering.  Science is creating the rocket-equation, Bernoulli's principle and all the other THEORIES that let us know how the world behaves.  SpaceX nor any other Airo-space company dose science, they engineer vehicles using well established theories.

I think you are completing misreading John Smith 19's points.  As I read it, he is pointing out that there is a difference between applying well known existing engineering principles to a particular problem (engineering), and developing new processes that require new and deeper understand of fundamental processes (science). The distinction isn't clear cut, but it is there.

Nor is it correct to say that John Smith 19 has consistently denigrated SpaceX.  He has not as far as I can see. He has merely pointed out that SpaceX and REL are approaching things differently and have different goals.  As others have said, it isn't a race.


« Last Edit: 02/21/2015 09:57 PM by Dalhousie »
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Online adrianwyard

  • Full Member
  • ****
  • Posts: 947
  • Liked: 160
  • Likes Given: 209
Re: The Reaction Engines Skylon Master Thread (5)
« Reply #79 on: 02/21/2015 10:43 PM »
Question: Do we think we know enough about SABRE to state categorically that it only works when integrated with a Skylon type of airframe? Are there no other possibilities? Like, say, fitting it to a smaller vehicle that has aerodynamics/wing area suited for landing, but that's air-launched from the StratoLaunch carrier aircraft?

This is just a (probably crazy) example. If it could be useful in other configurations, what are they?

Tags: