The Reaction Engines Skylon/SABRE Master Thread (6)

[nec207]

what thread are you replying to? This one http://forum.nasaspaceflight.com/index.php?topic=43514.0

[Pete]

Ok, its a while since I've been here..
Last I heard, REL had a working subscale heat-exchanger/pre-cooler for their proposed Sabre engine, and big plans but short funding for turning this into an SSTO Skylon spaceplane.
.
What has changed in this picture, in the last 5 years since then?

[t43562]

Ok, its a while since I've been here..
Last I heard, REL had a working subscale heat-exchanger/pre-cooler for their proposed Sabre engine, and big plans but short funding for turning this into an SSTO Skylon spaceplane.
.
What has changed in this picture, in the last 5 years since then?

They got some money at last (but peanuts compared to e.g what Jeff Bezos apparently spends on Blue Origin for example), plus an investment from BAE Systems. There is a new CEO, Mark Thomas, formerly at a snazzy position in Rolls Royce. They have broken ground on a testing centre at Westcott for their demonstrator engine which will be smaller than that needed by a Skylon but about right for a TSTO configuration.  Skylon is too expensive to be a first step, so they're looking for smaller steps which may end up being military. 

They are busy doing the detailed design of all sorts of difficult stuff like the turbopump for the helium loop  and the engine inlets and so on.   They will be doing some testing of the pre-cooler in the US with hot high speed incoming air courtesy of the AFRL.
Some engine nozzles have been designed and tested for them on a small scale by Airborne Engineering.

They have their own vacuum furnace for making the precoolers and seem to be able to make some spare change by hiring that out to various agencies and companies for space-related testing or manufacturing.

There is a talk coming up but my general impression is that they rehash and explain from scratch and give out interesting tidbits but really truly they are not telling their story (and this is understandable for various reasons from the defence aspect to just general commercial secrecy).   So we are twiddling our thumbs and waiting for the next thing they think they can tell us.

They have an office in the US and apparently its job is to handle all the issues and details that people in the UK are not allowed to know about.

In 2017 they're supposed to do the hot precooler tests.
In 2020 the engine core.

[CrewtaiL]

Pre-cooler going to America end of this year/early next; core testing planned for 2019, iirc

[JCRM]

The USAF produced a couple of TSTO concepts which match some of their requirements.

Orbital Access's reusable FSPL^UK concept, uses conventional rockets in a horizontally landing air-launched first stage which carries the upper stage and payload in an internal bay. It is however designed so the airframe can be used as a hypersonic test vehicle for a SABRE development engine (replacing the payload bay and engines) Presumably they applied for further funding for this concept, the result should be announced 'soon'
Orbital Access also have a TSTO concept using SABRE in the first stage.

As Crewtai mentioned, precoolers are going for full range testing (previous testing was from ambient to -150), as part of a contract with AFRL

REL are working on a helium loop test platform for 2019 , followed by a test engine for 2020

[adrianwyard]

Very interesting - I had not heard that the air-launched vehicle could potentially be used to test SABRE. Was that announced officially somewhere? I couldn't find much online beyond this sort of overview:
http://www.satellitetoday.com/launch/2017/07/06/esa-awards-200000-euro-contract-orbital-access/ and http://www.satellitetoday.com/launch/2016/08/11/uk-startup-plans-domestic-launchers-future-spaceport/

From the description on their site, it sounds like the 1st stage is more than powerpoint: http://www.orbital-access.com/the-orbital-500/

The small sat launch market is going to be very crowded!

[JCRM]

Very interesting - I had not heard that the air-launched vehicle could potentially be used to test SABRE. Was that announced officially somewhere?

that was the "debate over whether the test vehicle should also be useful for small payloads"

Link to pdf

 This design concept continues to be sized to permit internal configurations for the fitment of development SABRE propulsion for the purposes of air testing. This enables the attractive prospect of a commercially productive reusable small payload first stage vehicle that can be fully flight proven ahead of application for SABRE air test duties. This ensures that SABRE air test can be carried out with a proven vehicle, and, importantly a vehicle whose principal development cost is amortised through its own commercial productivity under conventional rocket power.[/quote]
Simon Feast of Reaction Engines Limited and Michael West of Bae were listed as authors. (other Strathclde papers from the 2016 UKSA funded research)

but I doubt this will be the official plan unless and until funding is secured for it. This round is for up to £10 million.

From the description on their site, it sounds like the 1st stage is more than powerpoint: http://www.orbital-access.com/the-orbital-500/

The small sat launch market is going to be very crowded

I don't think its much beyond spreadsheets yet, but the UK government do rather seem to want a 2020 UK  launch of some sort.

[ringsider]

I don't think its much beyond spreadsheets yet, but the UK government do rather seem to want a 2020 UK  launch of some sort.

They are trying to raise hundreds of millions but from what they show so far (renderings) I think they don't have much cash. Also not sure it is still SABRE-based. They recently announced moving to Malta because of Brexit/to try to raise money:

https://www.timesofmalta.com/articles/view/20170730/local/satellites-to-be-launched-from-malta.654403

In the UK these guys seem to be further along with hardware, which implies some money:-

https://forum.nasaspaceflight.com/index.php?topic=43334.0

Also some info on Twitter:

https://twitter.com/orbexspace

[adrianwyard]

Interesting. If there's much more discussion on the Orbital Access air-launched first stage it might warrant it's own thread as it only becomes related to SABRE/REL down the road.

The docs from March 2017 say they're thinking LOX-RP1 and Yuzhnoye RD-8 class engine(s).

You have to wonder if they've considered asking Richard Branson if they can borrow his LauncherOne 747 on weekends rather than buy and modify their own MD-11... :-)

[ringsider]

Interesting. If there's much more discussion on the Orbital Access air-launched first stage it might warrant it's own thread as it only becomes related to SABRE/REL down the road.

They were initially very tight with REL but the timeline on SABRE and Skylon is so far away they have to find a more direct route - REL is only planning engine tests in the next 5 years and they have been working on it for literally decades, so it's not a concept you can build a secondary business on any time soon.

The docs from March 2017 say they're thinking LOX-RP1 and Yuzhnoye RD-8 class engine(s).

There you go. I didn't know that explicitly but it makes sense in the context of what I said above.

To me that looks like a hot mess.

[gongora]

Trimmed some posts and moved some posts to the Orbital Access Thread

[Archibald]

Lots of interesting ideas. Albeit I wonder how does the airliner taxis and land - that rocketplane looks pretty big. Will they modify the MD-11 undercarriage and give it longer "legs" ?

[john smith 19]

Interesting. If there's much more discussion on the Orbital Access air-launched first stage it might warrant it's own thread as it only becomes related to SABRE/REL down the road.

The docs from March 2017 say they're thinking LOX-RP1 and Yuzhnoye RD-8 class engine(s).

You have to wonder if they've considered asking Richard Branson if they can borrow his LauncherOne 747 on weekends rather than buy and modify their own MD-11... :-)

You might like to factor in that they are also talking about make the wings ct as fuel tanks. Also note that the Pegasus 1st stage does not use TVC of the nozzles. It relies on aerodynamic control surfaces. This should lighten the engine considerably.

[john smith 19]

I finally found something accessible on the USAFRL plan for a SABRE based TSTO

http://www.w54.biz/showthread.php?1083-Space-Warfare&p=66950

They looked at 2 vehicles with payloads of 5Klb and 20Klb.

Orbits 100nm/28.5 deg IE CCAFS SSO at 378nm from VDB AFB and the porposed spaceport at Newquay, England.

they're looking at staging at M8, 260Kft, 0.8psf dynamic pressure IE 0.04% of SL pressure with the expendable US dropping from it

And then we get this
"“We assumed we would have conformal hydrogen tanks and that would be another technology challenge that would have to be solved to make this design work,” said Barry Hellman, of the USAF's High Speed Systems division.

Because apparently building a LH2 fueled M8 aircraft with a big door in its TPS is not difficult enough for them. 

I'd love to find out who (and when) that requirement was added to the spec. AFAIK it's completely unnecessary.

So the full size vehicle is 190ft long and will deliver 20Klb to orbit with a fully reusable rocket powered US.
the whole system weighing 1.3 million lbs or 591 tonnes.

And OMG they managed to not "need" a SCramjet.   

[john smith 19]

A follow up note on the SEI report.

The report describes 2 versions of the USAFRL vehicle. The baseline 5Klb payload and the full (and fully reusable) 20Klb payload. The line items of the second are simply scaled up from the first.

The baseline has a landing gear mass for the booster of 12630lb, with a GTOW of 317100lb carrying an upper stage of 35330 lb. IOW 3.58% of the total TOW is landing gear.

There is no indication of how much of the US mass is landing as it is "derived from previous internal studies at AFRL"

That's important because landing gear is a key issue in determining the feasibility of HTO SSTO, and was one REL played special attention to. It has been noted that the B58 had a landing of about 1.8%
but that only went to barely M2.

However listed on the Boeing site for the XB70
http://www.boeing.com/history/products/xb-70-valkyrie.page
 (which they inherited from the takeover of NAA) gives us

With a maximum takeoff weight of 542,000 pounds (245,847 kilograms), the XB-70 remains the largest and heaviest airplane ever to fly at Mach 3. A rugged landing gear, weighing more than 6 tons (5.4 tonnes) and consisting of 2 tons (1.8 tonnes) of wheels, tires and brakes supported the XB-70 on the ground. E

Note that 542Klb is actually about 246 364 Kb, not the figure listed. Assuming the landing is 6 US tons that's about 5455 Kg, meaning the actual landing gear mass for a very big M3 aircraft, designed using early 1960's technology was in fact 2.22% of GTOW, nearly 38% lower than the model figure SEI came up with.

[JCRM]

A new(ish?) animation of the revised/test engine, a "naming of the parts" if you will, showing the "core engine" and an up-skirt shot blurredly showing the split bell acting as a pintle and nozzle


(from https://www.reactionengines.co.uk/sabre-engine/)

[CameronD]

A new(ish?) animation of the revised/test engine, a "naming of the parts" if you will, showing the "core engine" and an up-skirt shot blurredly showing the split bell acting as a pintle and nozzle

Nice find!  One issue though:  At 0.43 they say "Air Pre-cooler: Keeping engine components cool at high speed". I thought the pre-cooler was for combustion air compression and had nothing to do with "keeping engine components cool".   Have I missed something?? 

[JCRM]

 At 0.43 they say "Air Pre-cooler: Keeping engine components cool at high speed". I thought the pre-cooler was for combustion air compression and had nothing to do with "keeping engine components cool". 

from 0:40 it says
AIR PRE-COOLER: Cools the hot incoming air  --  Keeping engine components cool at high speed  --   1,000 K temperature drop in 1/20th of a second --  Unlocking new capabilities in hypersonic flight

The need for pre-cooling was not so much to densify the air, but (as gasses heat as they are compressed) to keep the turbine outlet temperature cool enough not to melt the turbine blades. In addition (for reasons I'm not entirely convinced about) the engine bell is cooled by oxidiser.  So the pre-cooled air is used to keep the compressor and the nozzle cool (and the injector and the plumbing as well I'd guess).

They've dropped the -150 C, which combined with the split bell makes it look as though it's a variant of the SABRE 4 engine they are testing

[JCRM]

I've copied bits of a conversation from the Orbital Access thread about technologies the Orbital 500R could investigate that would be beneficial to SABRE/Skylon.

Having the payload fuelled as part of Skylon's launch sequence is a REL design goal. This would allow some experience of that.

True. But if the first stage is LOX/RP1 how many extra lines will you plumb in for the US? And of course if you solid they are redundant. OTOH if this is to partly support REL that would mean LH2, which normally requires "Vacuum jacketed" line 

for testing the operational aspects of supplying fuel to a payload through a published interface with minimal integration work paraffin/lox/helium (or nitrogen) would be good enough. while Lh2 is efficient weight wise, it isn't in terms of volume, so it might not be a good option for this application - but that's up to the detailed design phase.


To support test flying a SABRE engine LH2 would indeed be needed too - although it's relatively light so it could possibly be loaded before takeoff - which would also give them the opportunity to test whether hydrogen could be kept in insulated flight tanks at 18K without the need for venting.

Using a space frame isn't common practice, but that's the approach they're taking.

True, but it may have inherent benefits as well. While stressed skins are SOP for transport vehicles few have such a demanding temperature environment. High temperature strength quickly drops off but the structure REL plan to use (which IIRC originated from the X20 programme) lets you have a cold structure separate from a hot skin

Dyna-Soar had a chassis and skin construction, but not a spaceframe chassis - but it demonstrates some prior art even if it never flew.

Like fuel nozzle expansion ratio is one of those (relatively) cheap ways designers have to increase Isp. It would be interesting if part of REL's contribution was their E/D nozzle work. This would allow a much bigger ratio without flow separation or very high chamber pressures, but again that's a development risk.

as the Orbital 500 burns from around 10K to 70K (as opposed to Skylon's 28K to 70K) altitude compensation is more important to it for efficiency reasons whereas Skylon needs it to reduce plume impingement.
I would rather the concentrated on the drop down nozzle aspect of the SABRE 4 design, and how it influences plume shape and flow separation rather than the E/D portion which is only used for the airbreathing phase in the SABRE 4 design.

[CrewtaiL]

Alan Bond interview

http://www2.warwick.ac.uk/newsandevents/pressreleases/rocket_scientist_reveals/