Talk:Skylon (spacecraft)

Science fiction ?
So, there is still not a single working prototype, no technology developed and tested, - actually nothing, just some concept drawings + some speculations from REL about how they believe "it could possibly work", somewhere in the future. A proper material for a serious encyclopedia, indeed. But then again, when you have nothing to show well into half a century of the space age, you'll at least be glad you have some sketches. —Preceding unsigned comment added by 83.176.154.9 (talk) 19:57, 23 September 2010 (UTC)
 * You who? UK Black Arrow--Kitchen Knife (talk) 20:33, 23 September 2010 (UTC)
 * Why bother building real-world craft that really works? it's so old-school, when merely a pdf presentation is all you need these days —Preceding unsigned comment added by 83.176.153.214 (talk) 20:09, 24 September 2010 (UTC)
 * Is that a bit of bitterness from a German because the ELDO stage 3 which failed and but the European Space program back years, was designed by Germany.--Kitchen Knife (talk) 21:06, 24 September 2010 (UTC)
 * Dear Mr. Alan Bond, sir, please log in under your real name. Thank you. —Preceding unsigned comment added by 83.176.152.212 (talk) 08:53, 25 September 2010 (UTC)
 * Ah didums.--Kitchen Knife (talk) 12:44, 25 September 2010 (UTC)
 * This sounds like a highly national program—Go UK! So the theoretical HOTOL was proven to be unworkable… and was replaced by the theoretical Skylon, right?  I’m guessing  Skylon has little chance of seeing flight (why? oh, just a hunch ; ).  What will replace Skylon?  If you ask me, you're going to waste a perfectly good name.  —Preceding unsigned comment added by 143.115.159.54 (talk) 17:25, 10 March 2011 (UTC)
 * They are working toward this goal with all the funding available.. which is not alot. Think that they got a grant from the ESA for the sabre engines which is the key to the whole design (using the atmosphere as reaction mass at low altitude). —Preceding unsigned comment added by 2.102.47.176 (talk) 02:18, 4 April 2011 (UTC)

Yes first poster is from Germany IP checked.

March 2005 discussion on "burns 5x less propellent"
"burns about 5x less propellent there; and so can take off with less"

Has just been incorrectly replaced with for the second time.

"only needs 20% propellant there; and so takes off with much less"

I have several issues with this. I actually wrote the orginal text; so I actually know what it refers to. The 5x less propellent refers to the fuel efficiency i.e. [Specific Impulse], inside the atmosphere with the SABRE engine you burn fuel 5x slower than you would if this was a hydrogen/oxygen rocket. The ISP within the atmosphere ranges from 2000-2800 seconds, whereas the exatmospheric value is about 450 seconds. Hence the factor of about 5. A phrase such as "20% propellent" is meaningless. 20% of what? 20% of the takeoff mass? Nope, sorry, it ain't. The replacement sentence is meaningless. Please stop vandalising this page in this way. If you want to actually *clarify* it or add quantitative information go ahead. WolfKeeper


 * The changes are correct. You are the one who is confused.  If you had been paying attention, you would also know that two different people have made this change; originally Bobblewik, then my reversion.  It's your phraseology that's wrong.
 * It might take "5 times more" fuel in the atmosphere. That means it takes "0.8 times less" in the exoatmosphere.  Or 80% less.  Or 20% as much.  The multiplier is applied to what you start with.  And when it is less, it is never greater than one.
 * If you want to talk about "fuel efficiency" or "specific impulse", then do so. It doesn't matter if the fuel efficiency is 5 times as good; it still isn't "5 times less fuel".  What do you multiply by five?  So throw out some proposed rewordings here on the talk page if you'd like.  Just realize that throwing it back in the way it was is likely to get reverted again by somebody.  Gene Nygaard 03:13, 20 Mar 2005 (UTC)


 * Ok, fair enough. But your correction 'only needs 20% propellant there' wasn't grammatically or logically correct *either*.


 * It was not Gene that made that edit. It was me. My english and maths understanding does not extend to parsing phrases of the form 'x times less'. My best guess was that it meant '1/x'. If it did not, then I am at a loss as to what it meant. I am grateful that you have sufficient knowledge in this field to write the article and I was interested in what you had to say. I just didn't understand that bit. I might not be the only one that has difficulty with such phrases. Feel free to change my edits that I made. But rather than using that type of phrase, would you mind trying to explain it in another way? Thanks Bobblewik (talk) 21:24, 20 Mar 2005 (UTC)

The ISP numbers should be in the article, with sources that aren't blank makebelief. Otherwise it's just fantasy-based claims about performance, projected into the future fantasy like a wunderwaffle.Gendalv (talk) 17:07, 29 November 2021 (UTC)


 * I checked the source, the numbers are unusually high for the airbreathing portion but are not unprecedented. But it's because they're employing hydrogen fuel. Hydrogen has twice the energy/weight ratio, so twice the Isp. Allowing for that, the Isp figures aren't out of the ordinary for an airbreathing engine. Outside the atmosphere they're only claiming 450 seconds. GliderMaven (talk) 20:28, 29 November 2021 (UTC)

Thrust-to-weight ratio
Since Bobblewik has already started this discussion on Talk:SABRE I will continue it there. In my edit comment, I don't mean that nobody uses it as if it were dimensionless--but more on that page. Gene Nygaard 06:42, 21 Mar 2005 (UTC)

when?
The project has a projected R&D cost of under $10 billion and an estimated program length of 7-10 years.

But when did it begun?


 * It hasn't exactly, it's not funded yet. Alan Bond has a company that is working towards building an engine.WolfKeeper

Aren't brakes supposed to be for landing?
The article says Skylon uses water-cooled brakes, but the water is jettisoned on takeoff. So how will it land?


 * Frankie 16:59, 2005 August 11 (UTC)

The worse-case for the brakes are when the vehicle loses thrust *just* before takeoff. Then the vehicle is full of fuel, and has to stop before the end of the runway and needs to dissipate all the energy that represents.

Landing after reentry, the thing is light as a feather, and you don't need the extra cooling tricks (or atleast not nearly as much).WolfKeeper

I do not like the sound of this. If the flight has to be aborted near the start, say due to a bird strike, after the water has been dumped how does the aircraft land? Dumping liquid hydrogen is not safe. Andrew Swallow (talk) 20:24, 17 July 2008 (UTC)


 * FWIW dumping liquid hydrogen is perfectly safe. It will mix with the air and evapoarate and dissipate. Obviously you would really, really want there to not be an ignition source around, although Skylon's reentry-proof skin would probably handle this better than an awful lot of things if it did ignite.- (User) Wolfkeeper (Talk) 01:57, 24 February 2009 (UTC)


 * The hydrogen is near the ground it will land on people, animals, plants, machines and buildings. At liquid hydrogen temperatures it can produce cold burns.

Andrew Swallow (talk) 20:45, 9 November 2009 (UTC)


 * No, it wouldn't the aircraft flies quite fast even to take off so the hydrogen would have evaporated by the time it reaches the ground because it would be diluted down, and the aircraft wouldn't fly over anyone like that anyway. In any case talk pages are not places to discuss technical issues related to the article's topic.- Wolfkeeper  00:31, 10 November 2009 (UTC)


 * The spread of the fuel would mean it would very rapidly heat to tolerable temperatures - and further, the liquid hydrogen likely wouldn't be dumped. The liquid oxygen is much warmer, so less dangerous to dump, much denser, so it can be dumped more rapidly for emergency weight reduction, and there's four to five times as much of it to get rid of. Note that the water is specifically dumped after takeoff - hence at a point where the aircraft would have to loop around, giving it time to lose the fuel required to meet landing requirements. 31.205.21.4 (talk) 15:35, 11 February 2013 (UTC)

Takeoff Weight to Payload
In the article you said

...the proportion of takeoff weight to payload is more than twice that of normal rockets and it should be fully reusable. That means that each flight makes twice as much money...

From what I understand about rocketry, most of the takeoff weight is fuel. If maintenance costs can be controlled better than the US Shuttle, the cost of that fuel should consume most of the operational budget.


 * Um. No. Cost per kg of hydrogen based propellant is about $5. Even on Skylon it wouldn't be the highest cost, by a very long way.WolfKeeper

So if the ratio of takeoff weight to payload is twice that of normal rockets then the ratio of fuel to payload is twice that of normal rockets. This says that for a given payload it would be twice as expensive to use the Skylon as a normal rocket. Is the Skylon getting its savings from some economization other than takeoff weight to payload or was this improperly worded.


 * Actually, the most important metric is probably payload to unladen weight; and Skylon scores well on that too. The fact that you get the unladen back again after the mission is pretty important though.WolfKeeper
 * Then state that. The existing statement does not make sense and contradicts the claims in the SABRE article. This is an excerpt "the vehicle reaching orbit with more payload mass per take-off mass than just about any non-nuclear launch vehicle ever proposed." your article specificly states that the take off mass per unit payload is twice as high as any conventional rocket which is the opposite.Commdweeb

The next problem is "it should be fully reusable" implies that the entire take off weight including the fuel can be fully be reused. This doesn't make sense. Shouldn't this passage have been worded


 * I'm not sure if you're being serious, but strictly speaking, the fuel weight can be reused. Admittedly you have to wait for the water produced in the exhaust to rain out of the atmosphere, but 100% reuse is conceivable, since none of the exhaust reaches escape velocity.WolfKeeper
 * Hmmm, I am being serious.


 * You poor thingWolfKeeper


 * Are you??? The fuel is no more reusable than the external tank on the Shuttle. Both are burned and dispersed through the atmosphere on launch. Or am I missing something here. Are you arguing that the US Space Shuttle is a fully reusable launch system since none of it's componnents reach escape velocity? Commdweeb

...the proportion of takeoff weight to payload is less than half that of normal rockets and the vehicle should be fully reusable. That means that each flight costs less than half as much money...

or perhaps

...the proportion of payload to takeoff weight is more than twice that of normal rockets and the vehicle should be fully reusable. That means that each flight makes twice as much money...

I prefer the first version because, if you are running on a 10% profit margin and you reduce your costs by 50%, this increases the profit margin to 55% or more than five and a half times the original profit margin. On the other hand if you are running on a 60% profit margin halving your costs yields an 80% profit margin, or an increase in profit of only 30%. So I contend that the second proposed version and the original versions are ambiguous at best.

Center of mass
"The weight of the rear-mounted engine tended to make the HOTOL vehicle fly backwards"... shouldn't this be tip backwards?


 * Not exactly, it's sort of like a shuttlecock thrown feathers first; it tends to spin around in the air .WolfKeeper 14:07, 20 June 2006 (UTC)

couldn't they apply relaxed stabillity techneques using fly by wire to impose artifichial stability on the aircraft, or are there problems with control in a thin atmosphere at high altitude? also don't space planes have problems with getting the major axis of inertia in the right direction to avoid cartwhealing. i belive some erly space capsuals tended to tumbel in flight due to improper weight distribution with the craft rotating around the incorect axis, resulting in some very sick ocupents, also i think some space satalight recently had a simmilar problem where it was using too much power to keep it solar panels correctly orientated, resulting in the eventual loss of power, and loss of the satalite

don't mix up stability with equilibrium,(trim) all forces and moments in balance, regardless of how stable it is. it is likely that if the aircraft's CG is too far back it will be impossible to keep the aircraft in trim, let alone stable. its like trying to keep a pencil balanced at the tip but lying horizontally, never going to happen as its not in equilibrium. however a pencil balancing on its tip, vertically, is in equilibrium, but is not stable, this is what artificial stability on the aircraft is about. RichardMathieRichardMathie (talk) 22:33, 11 April 2008 (UTC)


 * Alan Bond addresses this in one of his lectures - to paraphrase closely, to simply make it relaxed stability, HOTOL became "a system for transporting flaperons to orbit". They had to be so large to counter the pitching moment that they consumed a very large portion of the would-be payload capacity. It is far better to simply make an aircraft that is naturally in trim throughout the flight profile. Also note that relaxed stability does not mean unstable, only a very large reduction in static margin. 31.205.21.4 (talk) 15:43, 11 February 2013 (UTC)

Removed oringinal research
I rfemoved the following statement from the article, as it seemed to violate WP:OR:


 * The overall shape of the fuselage of Skylon bears a resemblance to the similarly named futuristic structure, the Skylon at the Festival of Britain.

Anxietycello (talk) 03:57, 22 December 2009 (UTC)

Removing the statement is fair enough. However, the resemblance is striking and I would be very surprised if it were a co-incidence. If anyone could find a source to back up any connection with the structure from the Festival of Britain that would be very useful.81.101.123.171 (talk) 20:06, 6 June 2012 (UTC)


 * Alan Bond said he named it after this structure in a lecture he gave. Reference to the structure is 21 minutes in. http://www.youtube.com/watch?v=2G-HPHNrrLQ#t=1260s 98.203.242.147 (talk) 10:48, 16 July 2012 (UTC)Nydoc


 * He gave the same information at a recent lecture at the European Astrofest 2013. Björn Sandberg (talk) 11:33, 10 February 2013 (UTC)

"standard payload container"
The article states, as of 26 March 2010, "The payload would be carried in a standard payload container." What is a "standard payload container" in this context? Is there some kind of "industry standard" payload container defined by some industry or government organization? Is that standard widely adopted? Is that the standard that is meant here? If so, let's specify what the standard is.

On the other hand, I suspect that, to date in the space industry, there have been few standards since government programs have been the major efforts in space programs and launch payload specifications have tended to be rather proprietary and launch-vehicle specific. In any case, I think we need to clarify the "standard payload container" claim in this article. Cheers. N2e (talk) 18:15, 26 March 2010 (UTC)


 * There aren't any standards for space vehicles at the moment, but Skylon would have a standard payload container, the linked reference talks about it somewhere or other.- Wolfkeeper  18:39, 26 March 2010 (UTC)


 * To explain in short, I believe the articles describing their standardised container concept say it would be based on standard airline freight containers, meaning they're already compatible with other transport, but specially lightened and provided with the required opening door for deployment in space. It it not specified how close the resemblance would be, but the implication is mainly that they would fit readily in cargo aircraft for ease of delivery. The plan would be for payloads to be built to fit the containers, for simplicity and cost reduction, then the container can easily be fitted to skylon for rapid launch. 31.205.21.4 (talk) 15:53, 11 February 2013 (UTC)

SERIOUS NEUTRALITY ISSUES HERE
Right, like I said, serious neutrality issues. YUK! 108.7.9.7 (talk) 21:07, 23 April 2010 (UTC)


 * Probably not. REL have published in reputable journals, and have delivered public lectures on the idea, there's no known howlers, although there is the odd tricky bit, and they've come from a background of conventional rocketry, and are well respected individuals. They've also been awarded funding from various government and non governmental organizations, those guys are not that easy to pull the wool over their eyes.- Wolfkeeper  21:41, 23 April 2010 (UTC)

I wasn't saying that the project itself was flakey, just that the article is not neutral. It is obviously written from the POV of the designers and promoters. Still YUK!! :-)

108.7.9.106 (talk) 06:37, 12 July 2010 (UTC) (same guy)


 * Neutrality in the wikipedia is about trying to match the overall written analysis on the subject. There isn't that much criticism written about skylon that I'm aware of.- Wolfkeeper 15:40, 12 July 2010 (UTC)


 * I think Wolfkeeper is largely correct: there has not been much written analysis by other sources that would make for WP:V-compliant criticism.  That being said, I think there is some copyediting we could do to make the article less WP:POV-ish.  I made a first-pass attempt to do so with a few paragraphs in the lede:  clarifying that this is a design concept/proposal/paper-studies-not-prototyped-fact/etc., and that most of the [{WP:V]] info on which the article comes from is from the development team, even if some of it is peer-reviewed-published.  I think more of this sort of thing would probably be appropriate.  And if this were done more thoroughly, I suspect it would partially ameliorate the sort of neutrality criticism by 108.7.9.106.  N2e (talk) 19:26, 18 July 2010 (UTC)

The Sabre Engine
Is it possible to get consensus as to the nature of the SABRE engine, not just for this article but also for the engine itself? The current version of this article states;

"The proposed engine for the vehicle is not a scramjet, but a jet engine running combined cycles of a precooled jet engine, rocket engine and ramjet."

My first element of concern is the level one can describe that the ramjets are running in combined cycle with any of the other components. The air they use comes direct from the intake, it is air not cooled by the precooler or passed through any of the other components. Similarly the hydrogen drawn is only the heat sink for the helium based Brayton cycle. Secondly as they are simply a bypass system and not the driving principle of the engine is it not confusing to mention them except in the details of the engine's article?

Further, although a rocket engine is technically a form of jet engine is it not confusing to call this a jet engine + a rocket engine? Reaction Engines make clear that SABRE is a single rocket engine, in the "Skylon User Manual" it states, "SKYLON is powered by a combined cycle rocket engine which has two operational modes.". Furthermore, in the "A Comparison of Propulsion Concepts for SSTO Reusable Launchers" document engines of SABRE's type are referred to as, "Precooled Hybrid Airbreathing Rocket Engines". The SABRE article on their website also states, "The SABRE engine is essentially a closed cycle rocket engine with an additional pre-cooled turbo-compressor to provide a high pressure air supply to the combustion chamber."

Calling it a (separate) jet engine + rocket engine, when a principle element of the design has been the creation of a high pressure system so that it can use as many rocket components as possible, seems unwieldy. The term that Reaction Engines themselves use seems more appropriate as a description of the system. It is also the least likely term to cause confusion. Frodz (talk) 22:20, 12 August 2010 (UTC)


 * I think that its whatever we agree it is here, using the information we have from the sources. I'm not entirely sure that they describe it very well, we need to use the words that will give the most accurate impression to the reader of how it works, and we have no requirement to use the same words as REL uses. We're trying to summarise it for our readers.- Wolfkeeper 22:58, 12 August 2010 (UTC)


 * Given that they are the experts on modern LACE-like engines I think it’s safer to defer to their opinion of what this engine is!


 * Yes I understand we need to summarise for the readers, but at the same time the terminology must be accurate. As I said I don’t think it is accurate to call it anything running in “combined cycles” with particular types of engines and in this case certainly not ramjets. “Combined cycles” refers to combinations of thermodynamic cycles, not to combinations of engines.  The phrasing at present implies that this is more than one engine which isn't right.


 * It must also be clear as to the function, not to potentially imply things it clearly is not. The engine is closer to a turbo-compressor-fed rocket engine than to a pure jet engine, in fact the turbo-compressor is the only real component familiar from jet engines.  At best it would be accurate to say the rocket engine works in a similar fashion to a conventional jet engine within the atmosphere, essentially it is an engine designed to mimic a conventional jet engine, but that doesn’t make it one.


 * This is why I think sticking to what the experts refer to this engine as is the safest for encyclopaedic use.


 * Is a football/soccer ball square because we say so on here? Frodz (talk) 23:35, 12 August 2010 (UTC)


 * No, never. But if they were playing some game with a square ball, and the professionals described it as other than that then we would still be at liberty to use the word 'square' if we agreed to do so based on a diagram of the shape of the balls or something.- Wolfkeeper 03:51, 13 August 2010 (UTC)


 * It's not a rocket in the atmosphere, it's an airbeathing jet engine. It might be combined cycle rocket/airbreathing jet engine if they're squirting in LOX as well from tanks.- Wolfkeeper 03:51, 13 August 2010 (UTC)


 * The rocket, turbocompressor and ramjetty burners do seem to be running different overlapping cycles. The ramjets don't have any compressors- just the inlet compression, the rockets use turbopumps and the turbocompressors use gas compressors.- Wolfkeeper 03:54, 13 August 2010 (UTC)


 * You are assuming that they are incorrect, but that requires evidence, and even then according to Wiki’s guidelines we would still have to include the expert’s opinion and provide a sourced counter-argument.


 * Reading the sources and providing a novel conclusion not presented in those or any other reliable sources is original research. I suggest that unless this assertion is backed by sources stating in so many words that the interpretation in the article is a correct one then it comes under WP:V and WP:OR, it’s sources that are important, not truth.


 * We cannot state any substantial ideas that are not referred to elsewhere by reliable sources, which would constitute original research, and especially not on issues within the article likely to be questioned which comes under verifiability. The nature of the SABRE engine is clearly a part of the article likely to be questioned.


 * Unless there is a source stating this interpretation of the facts as to what the SABRE engine is (which lets face it are more complex than a diagram of a ball), the only well-sourced description of the engine comes from Reaction Engines themselves.


 * This issue is notoriously confused, these articles until recently claimed without evidence that the engine is a turboramjet/turborocket/ramjet (take your pick!) which it categorically isn’t (and cannot be) and there’s now a reliable source on SABRE’s page explaining why. Frodz (talk) 11:28, 13 August 2010 (UTC)


 * For a start a turbopump is part of a Staged-combustion cycle! The turbo-compressers are run off the same Brayton cycle as the precooler is.  This is the meaning of combined cycle as the engine combines the Brayton cycle with Staged combustion.  It does not mean it is two (or more) different engines.  The ramjets take their air direct, and the rejected hydrogen is a heat sink for the Brayton cycle, there is no combined cycle here.  Again, even if there were given that the ramjets are just bypass burners and not designed to produce significant thrust, invoking them in the description on this page is clearly going to cause confusion with other engine concepts unnecessarily.  But either way this is irrelevant as whatever is written must be backed by evidence the interpretation is correct. Frodz (talk) 11:29, 13 August 2010 (UTC)


 * Look, they describe it as:

''The SABRE engine is essentially a closed cycle rocket engine with an additional pre-cooled turbo-compressor to provide a high pressure air supply to the combustion chamber. This allows operation from zero forward speed on the runway and up to Mach 5.5 in air-breathing mode during ascent. As the air density falls with altitude the engine eventually switches to a pure rocket propelling SKYLON to orbital velocity (around Mach 25).''

''Air collection is via a simple conical two shock inlet with a translating centrebody to maintain shock-on-lip conditions. The centrebody moves forward to close the inlet for re-entry. A bypass system is used to match the variable captured air flow to the engine demand. This bypass flow is reheated in order to recover the momentum lost through the capture shock system.''


 * The bit where it says 'a bypass system is used.... bypass flow is reheated' is clearly talking about a type of ramjet. That's what a ramjet is, it's a pipe with reheat (ironically reheat is a bit of a misnomer in this case since it's not heated in the first place...)- Wolfkeeper 18:16, 13 August 2010 (UTC)


 * I can summarise those two paragraphs as saying that the engine is a combined cycle airbreathing jet engine/ramjet/rocket without any concern whatsoever.- Wolfkeeper 18:16, 13 August 2010 (UTC)


 * As can be seen from my passages above I know there are ramjets in the system, I was the one that edited SABRE’s page expanding on that and supplying a video reference of a lecture Alan Bond gave where among other things he explains their function as bypass burners to increase efficiency. For example it explains that the Brayton cycle running the precooler currently requires much more hydrogen as a heat sink than the engine's combustion chambers can burn (the level of hydrogen drawn is well above stoich.) so the surplus is dumped into the burners before ever reaching the Staged Combustion cycle and that this is mixed with the air that bypasses the engine, I recommend watching it. But they do not exist for the purpose of providing significant thrust for the engine at any point. Quoting them as anything more than a detail in SABRE's article as if they are a significant part of the engines function is liable to cause confusion between this engine and actual ramjets/turboramjets, which rely on ramjets for primary propulsion, as has already happened!  Indeed the function of the ramjets in this system is somewhat analogous to the fan in a Turbofan, they are both designed to control bypassed airflow to increase efficiency, one of the main differences is a lightweight fan wouldn’t be of much use at mach 3….You don’t refer to a Turbofan as a "jet engine + fan" do you? It’s simply a type of jet engine.  In fact when SABRE was described as a turboramjet on here it was never at any point called a turbojet + ramjet despite it being far more sensible to say that if this were the case than in the case of what the engine actually is, an air breathing rocket.  Why is it acceptable to call a turboramjet a single engine and not this one?  Just because this engine has components familiar from other concepts does not make it sensible to call it multiple different engines and REL agree with that.


 * But that wasn’t the only issue with the line at present. That was that I believe describing it as a jet engine "running in combined cycles” with any other types of engine, and especially here with the ramjets, fundamentally does not make any sense.  Combined cycle refers to combining thermodynamic cycles (Brayton, Staged Combustion etc), not combining “engines” like "jet engine + rocket engine".  Please explain the combination of thermodynamic cycles that are present in the operation of the ramjets for example. The problem isn’t that ramjets are involved in the engine, it’s the description of them and the rest of the engine that is seemingly incorrect as well as liable to cause confusion, which is removed if you use REL's description of the system as a precooled hybrid air breathing rocket engine.  REL explain it in the way they do because this is the way that makes most sense when you get what is going on, as opposed to just looking at individual components and assuming their function. Frodz (talk) 23:32, 13 August 2010 (UTC)


 * Sorry, but I'm certain that the term combined cycle in aeronautics doesn't only refer to combining thermodynamic cycles it can also be used to refer to combinations of engine types. For example combining ramjet/turbojet/scramjet is referred to as combined cycle. That's simply how it's used; but that's not what you'll get at combined cycle and the reason for that is that the Wikipedia isn't a dictionary, it only covers one meaning per article. In addition, the SABRE engine is actually running multiple cycles, there's cycles of the helium and hydrogen through the engine as well as those of the air and the rocket cycles.- Wolfkeeper 00:20, 14 August 2010 (UTC)


 * No, because none of that is supported by that passage. In fact the passage directly contradicts your summary.  Everywhere in REL’s literature it is made clear that SABRE is a single air breathing rocket engine, albeit one with components familiar from other systems. To say anything else without a reference is original research and not encyclopaedic. Frodz (talk) 23:32, 13 August 2010 (UTC)


 * I'm sure that there's nothing I've written that is directly contradicted.- Wolfkeeper 00:20, 14 August 2010 (UTC)

Yes I’m aware of that, that’s because the standard “types” of engine tend to be based on a particular type of thermodynamic cycle, jets engines usually being versions of Brayton cycles for example. The problem however is that some engines do not run on a simple (or single) cycle so it’s not necessarily like for like. I wasn’t saying there wasn’t more than one cycle present, obviously there are in a combined cycle engine! The rocket engine and the precooler/turbo-compressor Brayton are working in combined cycle during air breathing for example. I am questioning how this is represented to be most accurate, to not cause confusion with other principles, and to stick as close as possible to references. For example a turboramjet is a combined cycle engine and yet we didn’t feel the need to break it down into component engine cycles and instead refer to it as a single engine.

Having said that, I’ve somewhat changed my mind re the ramjets. I overlooked the nature of the hydrogen in the rocket’s cycle. The problem would not be so much the ramjets as those could rather simply be described in combined cycle fashion, but can the precooler Brayton cycle be called a full jet engine cycle? It’s not a full cycle like the turbojet in a turboramjet for example. I'd be interested to know.

I still think referring to this engine by breaking it down into cycles is unnecessarily obfuscating. But given that the rocket cycle remains in both modes, if we must refer to all the cycles it would probably be better to use “combined cycle rocket engine” as the basis and then refer to cycles present in precooled turbojets and ramjets. Is something like this an acceptable compromise?

“The proposed engine for the vehicle is not a scramjet, but a rocket engine running combined cycles of a precooled jet engine and ramjets.”

Frodz (talk) 01:37, 14 August 2010 (UTC)


 * Well, we could just refer to it as simply as not being a scramjet, but being a precooled jet engine in the summary and then go into more details about the cycles further down.- Wolfkeeper 16:41, 14 August 2010 (UTC)


 * "“The proposed engine for the vehicle is not a scramjet, but a precooled jet engine.”- Wolfkeeper 16:41, 14 August 2010 (UTC)


 * And then just move the bit about combined cycles further down.- Wolfkeeper 16:41, 14 August 2010 (UTC)

There's probably too much information here about the SABRE engines, given there is a wikipedia article dedicated to them. Stgpcm (talk) 00:54, 23 August 2017 (UTC)

Specially strengthened runway ?
So this aircraft needs a specially strengthened runway ?? It says so, twice. But if the aircraft has a takeoff mass only one tenth of a loaded Boeing 747, then why does it need a special runway ?Eregli bob (talk) 09:08, 21 September 2010 (UTC)


 * Simple...Momentum is the product of mass times velocity, and the runway has to deal with that momentum. Though this craft is far lighter than a 747, its takeoff speed will be massive (Half the speed of sound), and will subject the runway to a proportionate amount of stress.-- Novus Orator  09:08, 26 September 2010 (UTC)


 * Well the 747 takes off at 290 km/hour.  So "half the speed of sound" is double that.   So if the skylon is one tenth of the mass,  and double the speed,  of the 747,   then its momentum is only one fifth of that of the 747.    So your rationale doesn't make sense at all.Eregli bob (talk) 13:16, 28 September 2010 (UTC)


 * 747 442 tonnes Skylon 275 tonnes. Half speed of sound 615 km//hour. SO Skylon had 1.32 * the momentum, and 2.8 * the energy.--Kitchen Knife (talk) 14:34, 28 September 2010 (UTC)


 * I'm not convinced this explanation is sound. Momentum, like velocity, is a vector quantity, and its largest component by far is parallel to the runway. So increasing a plane's takeoff or landing speed (i.e. its groundspeed) doesn't seem relevant to me. As I see it, what's relevant re the necessary strength of the runway is only the momentum that's normal (perpendicular) to the runway, i.e. whether a plane makes a "hard landing" or a "soft" one, and how heavy it is. The vertical component of the velocity at which the plane touches down should be about the same as that of a 747. It would correspond to a vertical airspeed of just a few feet per second, one would hope: anything more and you have a crash landing, anything less and you overshoot and don't leave enough runway for braking after you touch down. The aircraft's groundspeed shouldn't matter at all except as it affects takeoff and landing/braking distance. It's been a long time since college physics, though, so perhaps I've neglected some factor that y'all are aware of? –  OhioStandard  (talk) 02:36, 2 October 2010 (UTC)


 * Yes, you are correct, my explanation was not clear. As far as I understand it, velocity and acceleration are vector quantities, and the acceleration vector of the landing aircraft is diagonal to the runway, e.g. it has a x-component and a y-component. The Force of Kinetic Friction is equal to the Normal Force (Weight) and the mu k (frictional constant), which contribute the additional stress that I am referring to.  The y-component is smaller than the x-component, but the Normal Force caused by the aircraft/(in this case spaceplane)'s mass is a part of the frictional force equation (which is the friction the runway exerts on the spaceplane's wheels). The combination of the y-component of the acceleration vector (working down) and the Fk (working horizontally against the wheels) together is what puts the stress on the runway.


 * To solve for the total linear force the runway must exert on the spaceplane (neglecting air resistance) is:


 * (in x) (1.0) Frictional Force in x-dimension=(mu k)×(Normal Force)
 * (in y) (1.1) Normal Force=mass × acceleration


 * If you wanted to find the Momentum of the Spaceplane once on the runway, you would then take the x-component of the resulting Force in the following equation:


 * (1.3) Momentum=[(Force of Thrust in x dimension)-(Frictional Force in x-dimension)]×(change in time)


 * Which you could then relate to the horizontal velocity in the Momentum equation:


 * (1.4) Momentum=mass×velocity


 * Though this is a very interesting topic, I am reminded of the policy WP:NOTAFORUM and therefore I must end this discussion. It's great knowing that there are editors out there who love Physics as much as I do.. -- Novus Orator 03:12, 2 October 2010 (UTC)


 * I'm sorry, Terra Novus, but that won't do. I've reverted your deletion of the preceding, of this entire section, despite your having copy-pasted it to your talk page. This topic is germane to the improvement of the article, so wp:forum doesn't apply. I don't imagine you're bothered by your initial mistake, but if you are, please don't be. Every single editor here, myself included, has made many mistakes before, and we all will again. Heck, I've made some really remarkable ones, and then even continued to argue my point in the past when my mistake was pointed out to me because I didn't understand another editor's correction. Nothing to worry about in the least, it's a very normal part of the process, is all. Best, –  OhioStandard  (talk) 05:37, 2 October 2010 (UTC)


 * The reason specially-strengthened runways would be desirable is explained on page 29 of The SKYLON Spaceplane, the Varvill & Bond article in JBIS, which is cited as a ref in our article. The designers wanted to keep the undercarriage and related components (i.e. the wheels, and all that support them) to no more than 1.5% of the plane's Gross Takeoff Weight. As I read page 29, they plan to do that by giving the plane a "highly loaded tightly spaced wheel assembly". They plan to give the plane less wheel surface to land on, in other words, to conserve both the weight and also the size of the wheels-up compartment inside the plane's hull or body. ( Remember it's really expensive to carry additional weight into orbit, so they want to minimize it. )


 * Think of it this way: fewer wheels (or, more exactly, less overall contact area between wheels and runway) means a higher load factor on the runway. It's just like the way a woman's spike heel shoe will put "dents" in a wood floor where the same woman in a more reasonable shoe won't. Her whole weight is concentrated over a much smaller area in the heels, and thus makes far greater demands re deformation on the floor. Same thing with decreasing tire-runway contact area for a plane of a given weight.


 * I don't have time right now to put this explanation into the article. But if we're going to mention the strengthened runways, we should explain why they need to be strengthened. So anyone who wants to, please go ahead and add the appropriate explanation to the article. Otherwise I'll try to get back to this within the next few days and do so myself. Best, –  OhioStandard  (talk) 05:44, 2 October 2010 (UTC) (I had the time after all, see below. revised by Ohiostandard at 06:19, 2 October 2010 (UTC)

Thank you for pasting it back in. You are correct that it can be applied to improve the article...-- Novus Orator 05:58, 2 October 2010 (UTC)

Thanks, Terra Novus. I did go ahead and change the article, too. See if you approve, or work it around any way you like. I have no particular attachment to my edits on this article, so feel free if you can phrase it better or want to expand on that at all. Best, –  OhioStandard  (talk) 06:19, 2 October 2010 (UTC)


 * Needs more - and with an accessible source. (the pdf above has moved to The SKYLON Spaceplane. JBIS 2004) - Rod57 (talk) 13:59, 14 December 2015 (UTC)

Citations and sources
Hi User:Terra Novus. Looks like you have made a lot of useful edits, and added a number of helpful inline citations to the article recently. I am happy to see that as this article needed that. I have a thought to offer on the use of refnames, especially as used for citing primary sources from the company website. My thought is that a refname is somewhat more useful—and importantly, a bit less likely to be misused in the future by other editors who may try to reuse the refname when looking at the source at a later date—if it contains an embedded date within the refname.

For example, if the article is a reliable secondary source, I generally embed the date of the source (e.g., for an Aviation Week article, something like ). However, for primary sources, my sense is that it is important to embed the date I looked at the source into the refname (e.g., if I looked at the Reaction Engines company website on 25 Jan 2011, I would do something like ) which of course would then match the "accessdate=2011-01-25" in the citation metadata.

Many of your recent citations are to the company website, and have generic refnames such as  or. While totally correct today (where you have noted the correct date accessed in the citation metadata), I would anticipate many future editors may look at those company websites, on future dates, and simply reuse the userskylon or skylonfaq cites, only now their new cites will be looking at a website that may be quite different from the website you looked at on 2011-01-25.

What do you think? Too much ado about nothing? Or useful input? If you are interested, I would be happy to help make some changes to existing refnames—but don't want to offend you recent good faith and diligent work. Cheers. N2e (talk) 18:33, 25 January 2011 (UTC)
 * That is an excellent idea. Go for it. I will be happy to help.--  Novus    Orator     04:10, 26 January 2011 (UTC)
 * I followed your suggestions on all the related references. Please feel free to help improve this article.--  Novus    Orator     04:48, 26 January 2011 (UTC)


 * Great work Novus! I think that will be helpful to the future quality of the article.  And thanks very much for your kindness in taking the suggestion so well.  N2e (talk) 14:14, 26 January 2011 (UTC)

Minor copyedit of the lede
I made what I hope is a fairly minor, and also accurate, copyedit of the part of the lede that summarizes funding on the project. My intent was to write at a lead-worthy level of abstraction (summary level) and ensure that the detail is adequately explicated in the body of the article.

On whether or not citations are required for each sentence or major assertion in the lede, I'm sort of agnostic. As long as the details are articulated, and fully sourced, in the body of the article, I'm okay with the citations not being repeated on the summary claims in the lede. I think this practice helps the lede stay at a high-level-summary level of abstraction. And it can oftentimes assist with the claims and cites not getting out of synch so quickly (when they are summarized differently but still redundantly cited in two parts of the article). Therefore, on the edits I just did, I did not duplicate the citations in the final lede paragraph (which is the only part of the lede I edited). Other editors preferences may vary. So if someone wants that paragraph sourced in the lede, as many other paras in the lede currently are, I'm okay if someone adds them back in. N2e (talk) 17:07, 27 January 2011 (UTC)


 * Yes the funding sourcing wasn't the best. I'm not so sure about some changes though, particularly that reference to the novelty of SABRE has been removed!  This is the main feature of the spaceplane, the design of Skylon is built around its engines, they are fundamental to the subject.  The only reason the Skylon proposal exists is because of the airbreathing engines, as such I think the lede now doesn't adequately get across what makes Skylon different to other concepts. ChiZeroOne (talk) 17:25, 27 January 2011 (UTC)


 * I have no problem with more about the engine uniqueness being in the lede. The lede should be about four paragraphs, which is currently is.  So if more about the engine is to go in (which is, as you say, probably quite appropriate) it might be necessary to copyedit the several paras of the lede that I did not just copyedit with my recent edits.  Cheers.  N2e (talk) 17:39, 27 January 2011 (UTC)

GA pass
Congratulations to all the editors who contributed to getting this article to Good Article status.--  Novus    Orator     07:28, 9 March 2011 (UTC)

Sourcing
Quite a bit of the article is sourced with primary sources. While a lot of this is unavoidable—we must use Reaction Engines as a source for many claims where the information exists nowhere else—it is the case that we really ought to get more secondary sources supporting the major claims of the article. I will add below one recent source I just read, from CNN, in the mainstream press. Others please add secondary sources you run into as well. Cheers. N2e (talk) 17:01, 10 March 2011 (UTC)


 * 'Skylon' space plane aims to fill void left by Discovery -- CNN -- 10 Mar 2011


 * This is a conclusion that I agree with; it would be helpeful to increase Secondary Sources, and it would look more professional to do so. I've brought in a good document from Parliament, now inserted in the Bibliography, which I recommend a good reading of for further referencing to. If wanted, I can fish around for more sources from good Secondaries as well. Kyteto (talk) 00:19, 11 March 2011 (UTC)

"...as it required a heat exchanger that was ten times lighter than the state of the art..."
 * I can't see that factoid quoted anywhere in the sources. —Preceding unsigned comment added by 213.208.114.181 (talk) 16:33, 24 May 2011 (UTC)

Rename?
As per this discussion there appears to be consensus that company names as disambiguators are not favoured for spacecraft. The actual name of the vehicle here is officially Skylon, not Reaction Engines Skylon. I suggest it would be consistent to rename the article "Skylon" or, given that there are other common uses, "Skylon (spacecraft)". This would be in line with the advice developed at the Spaceflight Wikiproject, WP:SPACENAME. ChiZeroOne (talk) 18:54, 23 April 2011 (UTC)
 * Support: Seems reasonable enough to me. --Xession (talk) 18:57, 23 April 2011 (UTC)
 * Support: Good. If this thing is successful it will most likely be referred to as just Skylon anyways...--  Novus    Orator     07:56, 25 April 2011 (UTC)


 * Support - per nom. - BilCat (talk) 08:07, 25 April 2011 (UTC)
 * Support - per nom also. Rememberway (talk) 02:20, 27 April 2011 (UTC)

Ok, support seems unanimous for the change, but the question is is this vehicle considered the primary topic? Although it does receive the most traffic i'm not sure it's necessarily enough to be considered the primary topic over Skylon (tower). If that's the case then it would make sense if "Skylon" redirected to the disambiguation page and this article be renamed "Skylon (spacecraft)". ChiZeroOne (talk) 19:08, 24 May 2011 (UTC)
 * I have gone ahead and made the changes. ChiZeroOne (talk) 17:14, 1 June 2011 (UTC)

Consistency
There appears to be a mismatch in a number of the figures given throughout this article because they are using values assigned to different iterations of the Skylon design. The figures given at the bottom of the page mostly use the latest C2 specification (which is effectively baselined with similar capabilities to the final D1 specification, which is part way through its design) given in an update of the manual. However the payload (12 tonne max, around 10 tonnes more likely though) comes from the "classic" C1 version, not C2's or D1's 15 tonnes.

The problem is because D1 isn't complete REL still often talk about Skylon based on the "current" C1 specs so mostly do not refer to the increased capablilities in media interviews, while their publicity does discuss these.

So what do we propose to do? The most detailed document, the user manual, is now written for C2/D1 but for the time being media reports for example will still report based on C1. ChiZeroOne (talk) 02:28, 24 April 2011 (UTC)


 * We follow WP:RS. We use the most reliable sources, which (in this case) would be the user manual, at least until more media coverage surfaces.--  Novus    Orator     07:53, 25 April 2011 (UTC)


 * In that case, the article should be proofed to consistently read for C2 specs. Part of the issue is likely that many sources were written when C1 was the current spec, as recently as 2008, so there are conflicting numbers from sources that appear current. Anywhere possible numbers should be drawn from the manual, which specs C2, or sources which can be confirmed to be on the same spec. As a future note D1 will not have the same payload capacity as C2 - Alan Bond claims in recent interviews the target is "25% greater" - around 18 tonnes, so the article will need updating and/or clarifying the distinction when that specification is complete and public. 31.205.21.4 (talk) 16:05, 11 February 2013 (UTC)

WP:FA drive
WikiProject Spaceflight would like to see more articles of Featured quality. Please post below if you are interested in helping raise this article to the next level.--  Novus    Orator     06:33, 25 May 2011 (UTC)
 * Will do--  Novus    Orator     06:33, 25 May 2011 (UTC)

Rename to Skylon (spaceplane)
The title term spacecraft seems to imply that it's only a spacecraft, whereas actually it's a launch vehicle or spaceplane.

So I propose to rename it to Skylon (spaceplane). -Rememberway (talk) 11:46, 4 June 2011 (UTC)
 * Support--  Novus    Orator     08:29, 5 June 2011 (UTC)


 * Oppose Disambiguators are not supposed to be specific. Skylon (tower) was not "just" a tower but a "Tensegrity tower", but that isn't required to disambiguate.  It is not implying it is "only" a spacecraft but that is what it is and there are no other spacecraft/launch vehicles called Skylon with which it could be confused.  We don't want a whole range of different disambiguators, we had that before and it was terrible, just a small set to keep things simple.  That's part of why the WikiProject set up  Wikipedia:SPACENAME. ChiZeroOne (talk) 11:38, 5 June 2011 (UTC)


 * But the problem is that it's too specific, it unreasonably seems to imply that it's not a launch vehicle. When the title implies that it might be something other than it is (like just a spacecraft), then, sorry it's the wrong title. It's not primarily built as a spacecraft, although it does that as well. Space Shuttle isn't at Space shuttle (spacecraft), neither is Space Shuttle Orbiter (spacecraft) even linked. -Rememberway (talk) 15:11, 5 June 2011 (UTC)


 * The page isn't at Space shuttle (spacecraft) because the article Space Shuttle does not need disambiguation as there are no other objects of the same name! On the other hand Skylon is originally the name of a tower, as well as also being the name of a more recent one. ChiZeroOne (talk) 17:45, 5 June 2011 (UTC)


 * Titles are supposed to help confirm to the user that they're at the right place, but (spacecraft) doesn't do that very well. -Rememberway (talk) 15:11, 5 June 2011 (UTC)


 * Skylon IS a spacecraft, and calling it that does not imply it isn't anything else too. How many other spacecraft are there with the name Skylon? It does the job perfectly well. ChiZeroOne (talk) 17:45, 5 June 2011 (UTC)


 * The user doesn't necessarily know that there aren't other spacecraft called skylon, and the spacecraft bit kinda implies that they're at the wrong place. So it doesn't seem to be the best title. -Rememberway (talk) 01:45, 6 June 2011 (UTC)


 * Actually, calling it a spacecraft does kind of imply that is not an aircraft. A spaceplane is both an aircraft and a spacecraft; which it is at any given time is a function of where it is at that time.  Disambiguating it as a spacecraft if overspecific to the point of being misleading to people who are looking for a spaceplane.  Readers should not have to read an article that they think is the wrong one in order to find out that it is fact they one they are after.  The diambig was supposed to have already sorted that out for them.  LowKey (talk) 01:02, 11 July 2011 (UTC)


 * Rockets are all disambiguated as, ex. "Atlas (rocket family)", not "Atlas (spacecraft family)", when these vehicles also (partially) reach space and if anything are more designed for that environment than Skylon is. Also, while they are not disambiguated, articles on all other spaceplanes, such as the X-30, X-33, and Dynasoar, all specifially use the term spaceplane, not spacecraft, for this class of vehicle. "Spacecraft" is the term for something like the ISS or the lunar landers - Skylon is a spaceplane. 31.205.21.4 (talk) 16:18, 11 February 2013 (UTC)


 * Support LowKey (talk) 06:56, 8 June 2011 (UTC)
 * Oppose overly specific, runs counter to the guideline WP:NCDAB "use the same disambiguating phrase already commonly used for other topics within the same class and context" which in this case is spacecraft. GraemeLeggett (talk) 09:40, 8 June 2011 (UTC)


 * That's an WP:OTHERSTUFF exists argument, which are never very good arguments. -Rememberway (talk) 09:50, 8 June 2011 (UTC)


 * And how is it overspecific if it's been mainly designed to have to fly through the air, something which a spacecraft isn't designed to do? Maybe if it was (spaceship), you would have a point, but spacecraft to me says it's primarily designed for space, which it isn't, it's designed to reach space. And it seems to me that all of the spaceplanes (like Hermes (spacecraft)) should actually be tagged with (spaceplane). -Rememberway (talk) 09:50, 8 June 2011 (UTC)
 * No its not an OtherStuffExists argument - its an argument supported by a direct quote from a long established guideline on how to edit Wikipedia.
 * If the flight part of the mission profile is what marks it out as different from rocket launched vehicles, then perhaps it comes under WP:AVIATION's scope and we can go back to Reaction Engines Skylon under their naming convention. GraemeLeggett (talk) 10:24, 8 June 2011 (UTC)


 * I don't think that it's well known as Reaction Engines Skylon- not even REL call it that, so I don't agree that that's a reasonable name; the general naming guidelines don't support that name.


 * And on the otherstuff issue, even if it's in the guideline, it's still an Other stuff exists argument because it presupposes that the other articles are well named; but in a significant number of cases they seem to be badly named also. And this isn't a question of overspecificity; if it really was overspecific, none of the other articles would be able to take that suffix. So I put it to you that this is just the best name we are likely to find for the articles of this group of launch vehicles, if we use that, nobody will have any reason to change it again. -Rememberway (talk) 13:46, 8 June 2011 (UTC)

Tailless?
There is an illustration in the "Technology and Innovations" section with a caption stating that the Skylon is to be "tailless", but in the illustration itself - and in fact in all the illustrations of the Skylon in the article - there is a tail visible. What gives? LowKey (talk) 01:36, 11 July 2011 (UTC)


 * See Tailless aircraft, the "Tail" on aircraft usually refers to just the horizontal surfaces which Skylon lacks at the rear, it only has the vertical. Though it does have canards so technically it isn't tailless, but not for the reason you mean! ChiZeroOne (talk) 20:44, 11 July 2011 (UTC)

surely the pictures are just an avro 730 with amended canards at the front, the wing mived forward & down and a funky black paintjob anyway. — Preceding unsigned comment added by 90.195.66.127 (talk) 10:07, 16 July 2011 (UTC)

Cost
"The complete Skylon project has a projected R&D cost of over $10 billion and will continue for another 7–10 years.[2]" The source is the FAQ page on Skylon's website, but all the page says right now is coming soon. The BBC news article from 2012 quotes 250m pounds to take the project into the final phase. 98.203.242.147 (talk) 10:49, 16 July 2012 (UTC)Nydoc
 * In accordance with this dispute, the content has been removed. Kyteto (talk) 00:06, 24 July 2012 (UTC)

Shouldn't all financial information be converted into British Pound Sterling? They are based in the UK and they will be basing their cost projections on what was costed for a British company at that time, currency fluctuations can mean the U.S. dollar valuations are meaningless even if that is how they originally published it. Example, U.S. Dollars against the Pound is not the same today as it was back then but ultimately the Pound Sterling was the currency they ultimately based their figures upon. — Preceding unsigned comment added by Feathersk (talk • contribs) 19:24, 3 July 2015 (UTC)

Technical details
A technical lecture by Alan Bond reveals this about Skylon : http://www.youtube.com/watch?v=2G-HPHNrrLQ (as shown above) The video has unclear origins, and therefore cannot be used as a reference. TGCP (talk) 20:48, 8 December 2012 (UTC)
 * fuselage inspired by airships with Warren girder frame rather than stressed skin 21min
 * glass ceramic aeroshell 23min
 * insurance cost is the major part of launch cost 48min

Well you can clearly see Alan Bond there. What type of wikipedia guidelines are there for this types of sources? Quantanew (talk) 03:12, 9 December 2012 (UTC)


 * This is just a cut down version of the reference I added to the SABRE article over two years ago, Travelling at the edge of space: Reaction Engines and Skylon in the next 20 years, that was given at the University of Strathclyde. ChiZeroOne (talk) 11:01, 9 December 2012 (UTC)

Citations and sources, part 2
I noticed that some of the references had red missing title parameter errors in the article display. I have corrected these by using instead of the previous definitions. This provides a link from the reference to the bibliography citation and removes the necessity for maintaining extra ref name attributes. Unless someone objects, I will make a similar change for the Hempsell and Longstaff (2009) refs: this will make all the references to items in the bibliography uniform. --Mirokado (talk) 14:39, 21 July 2013 (UTC)

Valkyrie and VDSR?
Valkyrie and VDSR are suborbitals rockets designed for various tests of the Skylon and SABRE components. I see no mention of them in the article, which is unfortunate, imho. Informations can be found on forum.nasaspaceflight.com, and on the RE website I guess. Of course it would require third party sources, but if those can be found, it'd be interesting to add them in the article, I think.

link to the forum.nasaspaceflight.com about valkyrie and VDSR

--Grondilu (talk) 10:55, 11 January 2014 (UTC)

Skylon Competition - from vertical recovery eg SpaceX - 2016
With the recent successful launch and vertical recovery of the first stage by American companies Blue Origin and SpaceX, the prospect for any further development of Skylon has dimmed significantly. One of Skylon's financial suppliers, the ESA, is under cost pressure from upstart launch provider SpaceX. There is a dawning realization throughout the industry that the vertical launch/recovery design is the most economically efficient and achievable method for the future. To complete the highly speculative and unproven design of Skylon, billions would have to be spent to even construct a prototype composed of cutting edge technologies--some of which have yet to be built. Note that we are discussing the prototype, not the final production design capable of lifting 15 tons, which will be several magnitudes more complex--not to mention the staggering financial resources that will be required to build and test it. Maybe it could be built by the Americans (possibly the Russians or Chinese), if they wanted to pour in the necessary funds, but certainly not the UK (who weren't able to overcome the technical challenges in building the Nimrod AEW Surveillance aircraft). Contrast that to the methods employed by Blue Origin (New Shepard) and SpaceX (Falcon 9): proven, reliable technologies, albeit with the addition of a fabulous twist (vertical landing). Surely the desire by the UK and the ESA to provide precious funds for Skylon is vanishing quickly. — Preceding unsigned comment added by 143.115.159.58 (talk) 18:19, 22 March 2016 (UTC)

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Need for a stronger runway
(see also section above ~2010) Article says "it would require a specially designed runway which is strengthened more than usual" with a now dead reference. This seems very important (possibly a major hindrance) so can we have some more details on what the runway requirements are (length and strength) (maybe compare to existing strong runways) and likely cost to build/upgrade ? - Rod57 (talk) 13:55, 14 December 2015 (UTC)
 * ref name=JBIS2004 states that it can use conventional runways. I deleted the opposite comment and its dead link. Thx. BatteryIncluded (talk) 18:13, 14 December 2015 (UTC)
 * PS: Some Boeing 747 weigh 450 tons and use regular runways. BatteryIncluded (talk) 18:17, 14 December 2015 (UTC)
 * It's a dead link, but the article exists, which I trivially googled and found, and can be downloaded, as well as a new version you can also download. Neither version states it can take off from a conventional runway. Indeed, it indicates it would have it own, extended runway.GliderMaven (talk) 00:22, 15 December 2015 (UTC)
 * The 2014 Reaction Engines web site states it will require a reinforced runway. Having edited that, you have to learn that in Wikipedia, your edit is as good as your reference. If the link is dead, so is your edit and your argument. If you have a live link, then WTF, use it! Last, the "offending" 2004 reference (JBIS vol. 57 2004) states: The vehicle is capable of taking off and landing from conventional runways on its own undercarriage. BatteryIncluded (talk) 03:14, 15 December 2015 (UTC)
 * Stop deleting the weight of the spaceplane and the live reference to the reinforced runway. If you want a pissing contest, Wikipedia is not the place. Thank you. BatteryIncluded (talk) 03:27, 15 December 2015 (UTC)
 * I believe, particularly in earlier earlier cases, REL use "conventional runway" as opposed to unconventional horizontal take off methods, such as rocket sleds or ski-jumps &mdash; i.e. something that someone looking at would say "that's a runway" — Preceding unsigned comment added by 82.22.197.128 (talk) 17:31, 19 October 2017 (UTC)

50/60m funding
"The second grant of £10 million was approved by the European Space Agency in July 2016" I understand the 10 million was paid to the ESA to have them oversea the development (to lend credibility?) 213.205.194.179 (talk) 23:28, 22 July 2016 (UTC)

External links modified - 2017
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University of Bristol
"since 2000, the firm has been working with the University of Bristol to develop a suitable engine design, which has been deemed to be vital to the success of Skylon.

This seems to suggest a great deal of involvement from Brisol, STRICT/STERN were 2007-2010 and were about validating nozzle designs, rather than "developing a suitable engine design". A number of other features are vital to the success of Skylon, e.g the precoolers, TPS, undercarriage...

Please could more information about the start and finish dates, and work undertaken be provided? Stgpcm (talk) 01:07, 23 August 2017 (UTC)

Need for a longer landing strip (erroneous?)
Kyteto in https://en.wikipedia.org/w/index.php?title=Skylon_(spacecraft)&oldid=797526756 has added a reference from The Verge claiming Sklon needs a long runway to land on - which appears to be confusion on the authors part as it is the orbital launch runway length that is quoted (needed to reach the 155m/s speed, and then decelerate in a pre-rotation abort). a high quality reference to a normal runway for landing, (and non-rocket mission launch) would be appreciated so the information can be removed. Stgpcm (talk) 20:38, 1 September 2017 (UTC)
 * As the SELSO study claims the Skylon could land on the 3.2km runway provided for cargo planes, I've removed the long landing strip claim. However this doesn't answer how short a runway need be for Skylon to land.

Comparison to ATV
I'm increasingly uncomfortable with comparing Skylon with ATV for payloads to ISS - it's very much an apples to oranges situation. Skylon would need a payload container, and it would need engines to provide the reboost cabability (the fuel for which was two thirds of the ATV payload). Using the SPLM would reduce the amount of cargo delivered to ISS to 3.2 tonnes, but that's overkill for just payload, containing life support and control facilities. Stgpcm (talk) 15:30, 22 September 2017 (UTC)

Mistake in current cost peg kg.
The following claim is not in agreement with the linked reference... "...  In paper studies, the cost per kilogram of payload carried to LEO in this way is hoped to be reduced from the current £1,108/kg (as of December 2015) ..." The linked reference shows a couple figures around 5 mT cargo around 60+ million pounds, which computes to an order of magnitude higher cost than provided in this article in thw quote above. BGriffin (talk) 03:47, 18 December 2017 (UTC)BGriffin
 * I think I used the Falcon Heavy reusable price with the expendable payload, the expendable price would have been around 1500 GBP/kilo. The heavy was used to prevent accusations of cherry-picking as it gave lower per kilo prices - Stgpcm (talk) 14:41, 18 January 2018 (UTC)

A Commons file used on this page has been nominated for deletion
The following Wikimedia Commons file used on this page has been nominated for deletion: Participate in the deletion discussion at the. —Community Tech bot (talk) 03:06, 6 February 2019 (UTC)
 * ILA 2018, Schönefeld (1X7A5246) (cropped).jpg

Update needed
As far as I can see, the last update in this article is from 2018. I appreciate this is to some extent a confidential project, but is there any information on any further development since then? The article currently includes: 'if all goes to plan, the first ground-based engine tests could happen in 2020'. It's 2020 now, did all go to plan? It seems like an update is needed. Robofish (talk) 20:46, 24 March 2020 (UTC)
 * No, construction of TF1 was terminated implying the supplier unfulfilled promises. Too depressed (lockdown) to continue editing. Stgpcm (talk) 23:53, 26 February 2022 (UTC)

Technology and Design : Overview : Important omission?
((1) Sentences are too long.)

(2) Nevertheless, the third and final sentence has an omission. It currently includes : "... attain a peak altitude of roughly 28 kilometres (92,000 ft), where payloads would typically be launched prior to the vehicle's re-entry into the atmosphere, ...". For SSTO, the rocket part must not be forgotten. Re-entry cannot start below the Karman line. --94.30.84.71 (talk) 12:46, 9 February 2022 (UTC)
 * (2) is very wrong.Stgpcm (talk) 00:00, 27 February 2022 (UTC)
 * we were lucky to receive one of Kyteto's overhauls, which I believe accounts for both of these issues (and possibly others.) Stgpcm (talk) 10:22, 27 February 2022 (UTC)

Payload to GTO - Use of recoverable Upper Stage
The intro says "7.3 tonnes (16,000 lb) to Geosynchronous Transfer Orbit (GTO)," without a citation. The Skylon operations videos (on vimeo & YouTube eg Skylon operations show a recoverable "Upper Stage" used to put payloads into GTO. I'll just add for now. - Rod57 (talk) 20:02, 12 February 2024 (UTC)


 * Skylon User Manual says 6.68 tonnes deployable to GTO on a reusable Skylon Upper Stage (SUS). - Rod57 (talk) 20:50, 12 February 2024 (UTC)

"Skylon (spacecraft" listed at Redirects for discussion
The redirect [//en.wikipedia.org/w/index.php?title=Skylon_(spacecraft&redirect=no Skylon (spacecraft] has been listed at redirects for discussion to determine whether its use and function meets the redirect guidelines. Readers of this page are welcome to comment on this redirect at  until a consensus is reached. Utopes (talk / cont) 18:15, 3 March 2024 (UTC)