The Reaction Engines Skylon/SABRE Master Thread (6)

[t43562]

From the side it's obviously a separate fairing. It's possible it could be housing an auxiliary engine for return to base when it finishes its test flight but this is not as sensible as it seems. If this will be a sub scale SABRE presumably it will have close to SABRE 4 T/W IE 14:1. No jet is that good. It would make more sense to glide back with the main intake closed (to limit LH2 use) to a low enough speed then restart the SABRE briefly. Remember SABRE in air breathing has the Isp of a jet, not a rocket.  The features that made this a good idea for Shuttle don't really apply.

Could it be . . . .da da da daaaaaa . . . a scramjet? :-D

[Star One]

This is the 3rd generation of the REL website. It's certainly the most polished and about the least informative, if you're aware of the previous versions in terms of what their background work has been.  All the PDF's are gone AFAIK.

Pulled up the SABRE page, tried to scroll down.Needed to allow "typekit" before it would let me. I'm wondering if the site was tested by someone on the laptop they wrote it on instead from another browser outside their network. 

I think the most interesting thing about this page is their plan to test the precooler, engine core and rocket system in 2017/18/19 at flight scale, with the goal of a flight vehicle in 2020.

Note they did not say full trajectory, IE to LEO, so I doubt this will be an SSTO, but even a few seconds past the rocket transition (in a flight vehicle) would retire a lot of risk.

Possibly the most interesting stuff was a couple of press releases. In July this year they were part of a consortium headed by "Orbital Access Ltd" looking at small space launchers for the UK. Interestingly this was specifically in regard to HTO and included SSTL and both Strathclyde and Glasgow universities. They are based at Prestwick airport.

That said their website shows something quite a lot like an Orbital-ATK Pegasus.

Another item dates from 2015 when REL announced they had been working with the Defense Science Technology Laboratory of the MoD since 2013 on military applications of SABRE.

IIRC that pre dates their work with the USAFRL.

The new website is a bit more outward looking and REL looking to be trying to capitalize on the skills and IP they've generated over the last thirty years to be more self funding in pursuing their goals.

It worked fine on my mobile which I imagine was what it was first and foremost designed to work on judging by the overall design.

[adrianwyard]

From the side it's obviously a separate fairing. It's possible it could be housing an auxiliary engine for return to base when it finishes its test flight but this is not as sensible as it seems. If this will be a sub scale SABRE presumably it will have close to SABRE 4 T/W IE 14:1. No jet is that good. It would make more sense to glide back with the main intake closed (to limit LH2 use) to a low enough speed then restart the SABRE briefly. Remember SABRE in air breathing has the Isp of a jet, not a rocket.  The features that made this a good idea for Shuttle don't really apply.

Could it be . . . .da da da daaaaaa . . . a scramjet? :-D

How ironic would that be! And yet, it's as good a theory as any yet floated. Assuming the vehicle hits the intended Mach numbers it would be an excellent test bed for scramjet testing - and one that returns them safely rather than ditching them X-43 style.

If this turns out to be correct, then the logic behind it will have been something like this:

Location: somewhere in the USAF.

"So you're saying this REL project can be used to test our scramjets?"
"Yes, sir."
"And your confident it will actually fly at the hypersonic speeds we wish to test at?"
"Yes, sir. It checks out."
"Then that's all I need to know: here's your check. I really hope this test bed will finally allow us to prove the value of scramjets at that flight speed. I hear rumors of a competing technology from the UK that we need to beat to the punch, so get to it!"

I'm mostly joking of course as there are cases where scramjet technology would be more suitable than SABRE.

Another slim possibility is the features on top are there to test the bypass ramjets intended for the full size SABRE?

[Ravenger]

You can view the entire vehicle background image, which has a full view of the proposed UAV:

https://www.reactionengines.co.uk/wpcms/wp-content/uploads/2016/11/Skylon_LApcat_UAV_Side-1.jpg

It really looks like there's some form of secondary engine mounted on top of the airframe.

As adrianwyard says it could be a bypass burner test feature.

[Alpha_Centauri]

Might sound mad but honestly it looks a bit like a pulsejet.  These are fuel hungry and comparatively simple/lightweight, so actually makes some sense as a bypass alternative.  But they are not generally supersonic.

[john smith 19]

I'm mostly joking of course as there are cases where scramjet technology would be more suitable than SABRE.

That's certainly an imaginative idea. It would depend on the design of the airframe since it's already known that SCramjets can run up to M9 and have very poor T/W ratios. IOW that "backup" or supplementary system would be 1/2 the GTOW of the vehicle.

SCRamjets only make sense if you need long duration + high altitude + high speed (>M5 as conventional ramjets have operated to that speed already) and you're OK with high airframe heating and very poor T/W since you'll still need another system to get it up operating speed. About the only potential benefit they have is they can run with room temperature storable fuels. Basically unless you can find a way to make them accelerate from a standing start and improve the abysmal T/W ratio this is only ever going to be a missile technology.

Another slim possibility is the features on top are there to test the bypass ramjets intended for the full size SABRE?

If the test vehicle is a complete SABRE it will have a spill ramjet of some kind on it already.

[Star One]

Perhaps they are going to use it to test the proposed hybrid propulsion system for the SR-72.

[Robotbeat]

This new plan is way better. May actually happen!

[Alpha_Centauri]

Post in commercial about REL/BAE partner operator Orbital Access raising funds;

http://forum.nasaspaceflight.com/index.php?topic=41650.msg1610740#new


Also don't suppose there's a remote chance anyone here has access to this full paper by Orbital Access' CEO? It's essentially talking about the next steps using a SABRE-derived small launcher/testbed.

The abstract gives some hints;

http://eprints.gla.ac.uk/130443/

[topsphere]

Post in commercial about REL/BAE partner operator Orbital Access raising funds;

http://forum.nasaspaceflight.com/index.php?topic=41650.msg1610740#new


Also don't suppose there's a remote chance anyone here has access to this full paper by Orbital Access' CEO? It's essentially talking about the next steps using a SABRE-derived small launcher/testbed.

The abstract gives some hints;

http://eprints.gla.ac.uk/130443/

Attached

[oddbodd]

Looks like the new website is live... and it's... underwhelming.

A fairly generic site with pretty pictures, and most of the older interesting info gone so far as I can tell. More a brochure than an information site.

Also seems to me that focus has shifted toward hypersonic flight, with space access almost feeling like an "oh yeah, that too". It gets mentioned, but always secondary to hypersonic flight or mentions of how quickly you could fly from X to Y.

Is it just me, or is this picture (from the careers page) a little telling:
https://www.reactionengines.co.uk/wpcms/wp-content/uploads/2016/05/1607-REL-FIA2016-012_B-1-e1471338140911.jpg

Varville seemingly being pushed into the background, and no sign of Alan Bond. It's such a shame that we don't have a Brit version of Elon Musk. A bit of vision, some balls, and a honking big bag of cash. I'd love to be proved wrong, but it looks like the original vision is as dead as the proverbial parrot. Splattered over the windscreen by the relentless drive to justify ones existence on a per-quarterly clock.

Or you empathise what you have at least a half realistic chance of getting financed and built in the short to medium term. Rather than complaining about the loss of something that probably didn't have a chance of becoming reality until at least the technology had actually proved itself in practical use.

There is also nothing in the new site that says that they've abandoned their longer term goals. Especially given on the vehicles page the first thing that's mentioned is space access, which hardly tallies with a downgrading of the importance of space.

I personally think the new site looks far more presentable and modern.

The issue as I see it is that the original Skylon SSTO concept had a narrow(-ish) window of opportunity. It made sense while rockets were expendable, but we now have Space X pushing the envelope on reusability, and if they reduce costs enough (not necessarily down to theoretical Skylon levels) then the business case for progressing to create Skylon (or similar) will not be attractive enough to pull in the needed investment. This new site seems to push SSTO Skylon further and further out, giving the likes of Space X more and more time to consolidate and lock down the market. So SSTO Skylon is at risk of withering on the vine, and without it (or something similar) it's not clear that we will ever reach SSTO and airliner style operations. Without those two things space access is never going to progress much beyond what we already have. Here's an illustration https://en.wikipedia.org/wiki/Timeline_of_spaceflight
The annual launch rate is not increasing even with commercial competition, not even breaking a hundred since 1990, and the failure rate is not being significantly reduced.
In comparison Heathrow handles 1400 takeoffs and landings in one day, with an almost non-existent failure rate. And that's why airline ops and SSTO are needed. Yes, yes, I know the whole mantra that space is hard, but unless we do something better than rockets which have been the modus operandi since the 60's, we as a species are likely to be permanently stuck on this rock until whatever ELE comes along to wipe us out.

[Hanelyp]

Skylon SSTO vs. rocket 2STO seems to me to depend on how much attention the Sabre engine needs between flights vs. stage re-mating.

[TrevorMonty]

Not very clear but this is how I interpret it.

The plan is to develop an RP1/LOX powered air launched booster similar to XS1. Payload to SSO would be 500kg, with upper stage stored in payload bay. A modified version of booster airframe would also be used to test SABRE.

All going well with SABRE tests, they would build commercial TSTO version powered by SABRE, still going after same payload range ie smallsats to SSO.

If SABRE engine doesn't work out they still have RP1/LOX RLV.

[Hanelyp]

Sabre is conceived as a zero to ~Mach 5 air breathing engine, then transitioning to rocket mode.  Why would the test vehicle need to be launched at speed/altitude?

[Alpha_Centauri]

Sabre is conceived as a zero to ~Mach 5 air breathing engine, then transitioning to rocket mode.  Why would the test vehicle need to be launched at speed/altitude?

Look at the test vehicle, does it look like it has much room for LH2 fuel tanks?

The most crucial parts of the launch phase they will need to test in-flight are the hypersonic phase and the cycle transition from airbreathing to rocket mode. Air-launching allows you to build a far simpler test vehicle to reach these regimes.

[john smith 19]

Post in commercial about REL/BAE partner operator Orbital Access raising funds;

http://forum.nasaspaceflight.com/index.php?topic=41650.msg1610740#new


Also don't suppose there's a remote chance anyone here has access to this full paper by Orbital Access' CEO? It's essentially talking about the next steps using a SABRE-derived small launcher/testbed.

The abstract gives some hints;

http://eprints.gla.ac.uk/130443/

Attached

Thanks for that. It's made interesting reading.

Looking over the plan it's basically a semi reusable Pegasus XL. In fact I think if you convert the price to $/lb it's also about the same price. IE the most expensive LV on the planet.

That said it is reusable and being LOX/RP1 should have substantially higher performance, giving a smaller package. IIRC OSC launch price doubled when their core supplier (who IIRC was also one of their owners) doubled their solid rocket prices. Going with conformal IE wet wings should give a narrower fuselage and potentially better aerodynamics.

For real cost savings you'd want to make the upper stage as "dumb" as possible. I'm wondering if you could do it all in hard wired logic in a FPLA or similar. A return to the Black Arrow approach?

The real question is where it fits in with REL's plans?

The last graphic shows a progression from the D21 like single engine UAV to something else then (presumably) a full size Skylon.

I'm vague where exactly the OA vehicle sits in this. Do they plan to upgrade it to wing mounted engines? Put a sub scale SABRE in the payload bay? If so what is it testing? The "D21" should have tested past the AB/rocket transition already. Is it big enough to demonstrate LH2 rocket to orbit? Will it return?

It would at least appear that a UK smallsat launcher is possible. The question is how much of the market can it capture and how much will it cost to develop.

[Alpha_Centauri]

Attached

Thanks, not quite as much detail on the vehicle as i'd hoped but it does give a good idea of what is going on in the  background and show the evolution from this to the flight test vehicle cgi.

Not very clear but this is how I interpret it.

The plan is to develop an RP1/LOX powered air launched booster similar to XS1. Payload to SSO would be 500kg, with upper stage stored in payload bay. A modified version of booster airframe would also be used to test SABRE.

All going well with SABRE tests, they would build commercial TSTO version powered by SABRE, still going after same payload range ie smallsats to SSO.

If SABRE engine doesn't work out they still have RP1/LOX RLV.

Yes that's how I see it.  The reality is flight-testing SABRE is going to cost a lot.  BAE are already working with Orbital Access to study modifiying the carrier aircraft for its Orbital 500 plan.  It makes sense to synergise their efforts and allow the test vehicle to provide a return, making it easier to sell to investors.

[Alpha_Centauri]

The "D21" should have tested past the AB/rocket transition already. Is it big enough to demonstrate LH2 rocket to orbit? Will it return?

The configuration 3B-1 in figure 5 is the D21 vehicle. 3A-2 is an earlier configuration. The concept design work was done by BAE...

[RanulfC]

The issue as I see it is that the original Skylon SSTO concept had a narrow(-ish) window of opportunity. It made sense while rockets were expendable, but we now have Space X pushing the envelope on reusability, and if they reduce costs enough (not necessarily down to theoretical Skylon levels) then the business case for progressing to create Skylon (or similar) will not be attractive enough to pull in the needed investment. This new site seems to push SSTO Skylon further and further out, giving the likes of Space X more and more time to consolidate and lock down the market. So SSTO Skylon is at risk of withering on the vine, and without it (or something similar) it's not clear that we will ever reach SSTO and airliner style operations. Without those two things space access is never going to progress much beyond what we already have. Here's an illustration https://en.wikipedia.org/wiki/Timeline_of_spaceflight
The annual launch rate is not increasing even with commercial competition, not even breaking a hundred since 1990, and the failure rate is not being significantly reduced.
In comparison Heathrow handles 1400 takeoffs and landings in one day, with an almost non-existent failure rate. And that's why airline ops and SSTO are needed. Yes, yes, I know the whole mantra that space is hard, but unless we do something better than rockets which have been the modus operandi since the 60's, we as a species are likely to be permanently stuck on this rock until whatever ELE comes along to wipe us out.

Oddbodd; Even with Skylon and SSTO launch will not be anything like 'airline' operations. The analogies break down very quickly beyond a very basic application. Space launch is very different than any other form of transportation used on Earth, it has to be as it has almost no way to 'tap' into the pre-existing nodes and networks of Earth based transportation and has strictly limited destinations and current uses.

Launching something into space, even assuming an 'operational' (Skylon for example) SSTO is not only difficult it requires deliver of the 'payload' to a specific orbit when all is said and done and unlike any Earthly transportation the main vehicle has to provide all aspects of that delivery since in most cases the payload can not. Our notional vehicle requires something to the size of, but far more complex and expensive to build and maintain, a 747 which then 'delivers' a payload equivalent of a DC3. (Not the whole aircraft, JUST its cargo and/or passenger equivalent)

Heathrow didn't exist 100 years ago but London did and it 'handled' quite a lot more cargo and passengers than Heathrow does on a daily basis back then. And anyone looking to compare the rickety, wobbly 'aeroplane' to what ships could accomplish was laughed at. But the aeroplane could in fact eventually interface with the same destinations that the ships did and while they could not carry MORE cargo/passengers per trip they did so faster and therefore could make more trips over the same amount of time.

Space launch has no destinations already in place and only a very limited economic 'niche' to service so even if they WERE capable of being operated at 'aircraft' rates and utility they would not have the market to do so. Having relatively 'cheaper' and more ready access will increase that market... Somewhat but in truth the overall 'current' market will quickly become saturated. The hope is that increased access will generate new markets and forces but in truth that's not how it's ever worked before as there always been pre-existing destinations and markets which new and more 'efficient' transportation systems tapped into to expand and grow.

There are no destinations, no pre-existing markets or service sectors to expand into other than the few that exist today and very little likelihood of those markets expanding significantly due to greater access and lower cost. (There is or course SOME elasticity in the pre-existing markets but there are regulatory and governmental/international pressures that will be applied to keep those from expanding too rapidly)

In summery, (too late I know ) the question has always been less about capability and access but economics, market and requirements. Space travel has always been significantly harder than air travel and it may be reduced some with coming technology and operations but it will not ever be as easy as air travel, or ships, trains, or cars, trucks, etc unless there is a VERY radical change in the fundamental aspects of space travel. SSTO, air-breathing or not, is not that radical of a change despite what many people think.

Randy

[Paul Howard]

I like how they've improved their website. Says they are serious about keeping up to date.