Skylon Update

[mark_d_s]

Looking interesting...

http://www.bbc.co.uk/blogs/thereporters ... hose.shtml

 

[flyer456654]

So these people are much much smarter than I am and know a lot more about this than I do but i do see an issue with this. First, doesn't the engine require high speeds to operate effeciently? If so, doesn't that mean that the whole plane needs to be brought up to that speed so that the Sabre Engine will work properly? Also, how do you shut off the intake valves of the engine to create a rocket? I guess they could just hit a switch, but wouldn't the phenominal speeds cause some issues with any closing mechinism (have you ever tried to open a door underwater when the inside of what you are opening has air instead of water?) Basically, this still seems solidly in the science fiction realm to me so if someone could explain this a little more clearly, that would be great.

 

[Boris_Badenov]

Are they actually bending metal? I really couldn't tell from this article.

 

[docm]

Sounds like they plan on testing the pre-cooler in the middle of next year, and that's a big part of the SABRE engines supersonic air-breathing flight mode.

Also: the UK govt has been supporting them, both the previous Labour govt and the new Conservative/Liberal-Democrat coalition.

>
The breakthrough for Reaction Engines has been in the development of its pre-cooler system. At Mach 5, SABRE will need to cope with gases entering at temperatures reaching 1,000 degrees celcius. The pre-cooler uses thousands of small-bore thin-wall tubes, each around the width of a human hair, to drop the air temperature to -150degrees celcius in just 30ms. Back when Skylon was still a concept, the required heat exchangers for this type of pre-cooled jet engine were impossible to make, but with improvements in materials and manufacturing techniques, Varvill believes the technology has turned a corner.
>

SABRE cycle -

Pre-coolers are on the center-left in light gray -

 

[EarthlingX]

For the reference and starting points for digging :
Wiki :

• Reaction Engines Skylon
• Reaction Engines SABRE
• Reaction Engines A2
• Reaction Engines Limited

Some of the Wiki references might have a bit dated links.

Reaction Engines :

• Skylon
• The SABRE Engine

 

[EarthlingX]

www.ukspaceagency.bis.gov.uk : Skylon System Requirements Review

Page last updated: 21 September 2010

by the UK Space Agency

On September 20-21st, the UK Space Agency hosted a meeting at the International Space Innovation Centre at Harwell, England to look at the feasibility of a proposal by the privately-held Reaction Engines Ltd. (link opens in a new window) for the design of a single-stage to orbit launch vehicle (Skylon) and its novel propulsion concept (SABRE). The meeting brought together nearly a hundred invited experts from the UK, Europe, Russia, the US, South Korea and Japan to examine the technical and economic prospects for the technology.

The SABRE (Synergistic Air-Breathing Rocket Engine) is a variable-cycle engine which can use air taken in through intakes like a turbojet when operating in the atmosphere before converting to pure rocket mode as it enters space. In the Skylon vehicle concept, it would allow 10-15 tonnes of satellite payload to be injected into Low Earth Orbit before the vehicle returned under automatic control to its spaceport close to the equator.

Both SABRE and Skylon would represent major advances in aerospace technology and could change the economics of access to space. Supported by funding from the private sector and the UK Space Agency, the European Space Agency (ESA) is managing a technology contract to demonstrate key parts of the SABRE engine. So the workshop was an important step in allowing the wider space community to understand progress towards the ultimate goal building a vehicle like Skylon.

The workshop was one of a series of space innovation events at the International Space Innovation Centre, the new hub of space projects in the UK.

 

[alpha_centauri]

So these people are much much smarter than I am and know a lot more about this than I do but i do see an issue with this. First, doesn't the engine require high speeds to operate effeciently? If so, doesn't that mean that the whole plane needs to be brought up to that speed so that the Sabre Engine will work properly?

No, the engine works from static which is why it can take-off from a runway. In fact up until the rocket phase begins it operates much like a conventional turbojet you'll see in many military aircraft, albeit burning hydrogen instead of kerosene with the air and having rocket-like combustion chambers for commonality between flight phases. Once the engine has finished air-breathing, it converts to conventional closed-cycle propulsion using on-board liquid oxygen with the hydrogen.

I think a lot of people confuse this with a scramjet/ramjet (which are the commonly touted SSTO engines) which it most certainly is not and doesn't suffer from the problems these have, like having to have high ram pressure (read: high speed) to work. The SABRE uses a turbocompressor like conventional jet engines for the air-breathing mode which removes the need for this. The problem historically using this for SSTO is that the high temperatures of the inlet air would damage a lightweight engine, hence the major innovation with this design being the new lightweight pre-cooler. Having the air supercooled is also what allows the same rocket machinery to be used in both modes. The pre-cooler is the major question-mark which is why the ESA funding is going towards demonstrating this, everything else is fairly conventional or at least well understood.

Also, how do you shut off the intake valves of the engine to create a rocket? I guess they could just hit a switch, but wouldn't the phenominal speeds cause some issues with any closing mechinism (have you ever tried to open a door underwater when the inside of what you are opening has air instead of water?).

New more detailed specs are about to be released so this may be redundant anyway. From what I have seen I'm not entirely sure if they will shut off the intake on ascent, that is not clear. They will for re-entry but that is obviously not a problem.

Anyway they are using an axially-moved inlet cone/forebody, in some ways like the SR-71 Blackbird. From the calculations I've seen the inlet cone does not experience too high pressures that would not allow this to be done on ascent. As I said, I have a feeling they might be changing this slightly though based on the updated SABRE images they've begun to put up on their website.

Basically, this still seems solidly in the science fiction realm to me so if someone could explain this a little more clearly, that would be great.

This is certainly not science fiction, in fact I'd go as far to say it is probably the most feasible of all SSTO concepts, and that includes the much-vaunted scramjets.

 

[James_Bull]

Thanks for clearing that up alpha c. This has the potential to completely revolutionise the space industry in a nearly incomprehendable way. I can imagine hundreds of these spaceplanes one day. The big test is next year with the pre-cooler evaluation, which they are very confident they have perfected. They'll get all the finance they need if that is sucessful. Very excited about this technology.

 

[alpha_centauri]

I should probably explain why it is often confused with a ramjet engine for completeness, that's because it does actually have ramjets in it! If you notice they are above and below (forming a ring) the main rocket nozzles in the image above. But these are not the engine's main form of propulsion which is why REL don't normally refer to them. You see at low speeds the volume of air going through the intake is much larger than at high speeds so in an engine that works over a variety of speeds any excess air is "wasted" and in fact causes drag losses. The main engine core can only compress and pump a certain volume of air. To compensate, the ramjet burners burn off this excess air at low speeds adding a little extra thrust to recoup some of the losses. This is known as a bypass system, and is the same reason why commercial airliners use high efficiency Turbofans (the fan does a similar thing) rather than Turbojets. The ramjets are just a high-speed solution where a fan would be impractical.

Unfortunately some people are not reading the documents that REL provide on their website, I've seen a number of claims that Skylon is a "spaceplane with ramjets", and in part I think that's why there's a lot of unfounded suspicion about the engine.

 

[alpha_centauri]

As to explaining the UKSA announcement, here is REL's submission to the UK Parliament Commons Select Committee about the UKSA a few months ago which stated,

http://www.parliament.uk/ : Memorandum submitted by Reaction Engines Limited (UKSA 09)

Since the Agency was formed the main interaction with Reaction Engines has related to the organising of a major international review of the SKYLON spaceplane to be held on 20th to 21st September. This review will host over 100 experts from around the world to assess the economic and technical aspects of the SKYLON concept. The outcome of this Review, supported by an evaluation from the European Space Agency will give the UK Government confidence that, should further support to project be given, it will be on the basis of a thorough assessment.

And here's REL's update on the review,

http://www.reactionengines.co.uk/ : News Update - September 2010

On 20th and 21st September, the UK Space Agency held a System Requirements Review on the commercial and technical capabilities of SKYLON at the International Space Innovation Centre at Harwell, England. Approximately ninety invited experts attended the event venturing from various European and global nations including the USA, Russia, India, Japan and South Korea. In the months leading up to the Review, three engineers from the European Space Agency (ESA) were seconded to REL in order to investigate our technology, methods and analysis. ESA will provide the UK Space Agency with an official report on the Workshop within in[sic] the next month.

The preliminary results of the event are indicative that the majority of the attendees consider SKYLON to be a viable concept. Responses to questions on the project provided a clear and honest overview of the programme. Dr Constantinos Stavrinidis, Head of Mechanical Engineering at ESA, gave the closing address and commended the competence of REL and its SKYLON concept.

REL hopes that the feasibility of the SKYLON programme is no longer in doubt and that the commercial and technical aspects of the project are well understood and recognised. Over the coming months, discussions with government, industry and private investment are due to take place and REL looks forward to further progressing SKYLON.

The UK Space Agency’s press release for the event is available at http://www.ukspaceagency.bis.gov.uk/19661.aspx?pf=1

Recently, one of the recurring questions has been the degree of government involvement in the SKYLON development. To date, the public contribution stands at 15% with the remaining 85% provided by private investment. REL intends SKYLON to remain as commercial a programme as possible.

I wonder whether that report, or at least the final review, will be made public? Would be nice to see their take, but sounds positive so far.

Also, according to the latest update they're currently in the process of building the full production pre-cooler.

 

[mr_mark]

This smells of the Concorde. One crash and it will all be over. The Europeans don't have what it takes for space travel funding and how long are British citizens, who are tight to begin with, going to shell out for this. The Europeans are already squaking about just having return capability for the cargo transport and you expect them to pay for this? No BEO capability? At least Orion, Dragon and CST-100 could be adapted for BEO. Both Dreamchaser and Skylon are money pits. Both will never happen.

 

[neutrino78x]

No BEO capability? At least Orion, Dragon and CST-100 could be adapted for BEO.

Those are just capsules, not launch systems. From I understand, these rocket planes are for transporting men to LEO. From there they would go inside of an Orion or similar craft, which had been launched previously with a different technology, to go to Mars.

--Brian

 

[vulture4]

A wonderful and ingenious design, but in reality a space launch vehicle spends so little time in the sensible atmosphere that airbreathing launch is probably not practical.

 

[aaron38]

This smells of the Concorde. One crash and it will all be over. The Europeans don't have what it takes for space travel funding...

So? If it crashes, that means the engine actually got off the ground, which is a pretty big freakin' deal. Let them build the engine, and if they don't want to actually fly it, someone will take that engine off their hands for them.

The Concorde comparison is a bit unfair. The Concorde speed difference wasn't enough to compete with a 747 on price. Skylon, if it flies, WILL compete on price. Have you seen the passenger compartment models? There's no other system in development that can boost 40 people to a commmercial space hotel or transfer station. That's how Skylon will make money, and why the engine is worth developing.

And if it can't be done, that's useful knowledge as well. Right now all I want is a working air breathing rocket engine.

 

[vulture4]

Skylon should be built and tested; it is ingenious and may be a practical alternative for orbital launch. Whether or not it is practical is difficult to determine without testing at the prototype level. Some aspects of the design push the limits of feasibility and it isn't possible to say from any paper study whether they would really work. But realistically Skylon cannot compete for commercial point-to-point transportation; the time spent getting to, from and through the airport is already so long that making the flight segment faster does not help much.

 

[aaron38]

Has anyone proposed using the Skylon for Earth surface transport? It would probably be capable of the coveted 2 hour London-Tokyo run, and if a market for that developed it'd be gravy. But I meant it would compete on price for access to LEO only.

 

[EarthlingX]

That would be (also above)
Wiki :
Reaction Engines A2
LAPCAT

Reaction Engines : LAPCAT

Configuration A2 Mach 5 Civil Transport

Reaction Engines is presently engaged on an EU 50% funded project as part of Framework 6. This study is to examine the propulsion concepts and technologies required

“...to reduce long-distance flights, e.g. From Brussels to Sydney, to less than 2 to 4 hours. Achieving this goal intrinsically requires a new flight regime for commercial transport with Mach numbers ranging from 4 to 8.”

To fulfill this mission, a hypersonic aircraft with near antipodal range (20,000 km) is required. To achieve the range requirement liquid hydrogen fuel is mandatory since the specific calorific energy of hydrocarbon fuels is too low. Reaction Engines have conceived the Scimitar pre-cooled engine concept which exploits the unique thermodynamic properties of liquid hydrogen. This engine is capable of sustained Mach 5 flight whilst achieving an effective exhaust velocity of order 40,900 m/s. In addition the engine has a second operating mode that features a high bypass airflow permitting efficient subsonic flight and moderate take-off noise.

...

 

[alpha_centauri]

This smells of the Concorde. One crash and it will all be over. The Europeans don't have what it takes for space travel funding and how long are British citizens, who are tight to begin with, going to shell out for this.

Odd comparison, Concorde wasn't ditched because it crashed but because it simply wasn't cost effective to continue maintaining them. Due to flight restrictions imposed by its sonic boom the speed advantage was greatly reduced, and then to top it all off the approx. 100 passenger capacity simply wasn't good enough to produce profits. The crash was simply the final nail in the coffin of a system that didn't live up to its promises.

Skylon wouldn't be cancelled if it crashed, airbuses have had accidents but they haven't been pulled, especially given in most situations it would be unmanned anyway!

The Europeans are already squaking about just having return capability for the cargo transport and you expect them to pay for this?

REL aren't looking for government funding to build Skylons, just to develop the technologies. They are keen that the actual development is funded by private firms and investors,

http://www.hobbyspace.com/nucleus/index ... emid=15674

And off-topic, but that squaking will dissappear in a month anyway once the EU gets involved in European spaceflight.

No BEO capability? At least Orion, Dragon and CST-100 could be adapted for BEO. Both Dreamchaser and Skylon are money pits. Both will never happen.

Eh? Skylon is a launch vehicle, designed to launch payloads into orbit. It's the "Ares 1", not the "Orion"; the "Falcon 9", not the "Dragon". It's designed to orbit a wide range of payloads, like satellites or people, rapidly and cheaply as a "shuttle" between the earth and orbit and allowing this to be done on a commercial basis. It has never claimed to be an exploration vehicle.

 

[aaron38]

"Our work shows that it is possible technically; now it's up to the world to decide if it wants it. ”
— Alan Bond, managing director of Reaction Engines Limited

So it sounds like the LAPCAT A2 design is the natural next step for technology development. As Mr. Bond says, it may or may not be commercially developed, but I bet it could be prototyped. The military would love it. And while the Scimitar Engine is not a rocket engine, the same precooler and airframe design would be used as with the SSTO. It splits the risk up, so that when it comes time to test the SSTO rocket burn to orbit, the 0-5 Mach airbreathing flight envelope is already mapped out and optimized.