Looks like the official description of sabre using "jet engine" technology for the airbreathing cycle has been misleading me. :( I just took a closer look at the engineering design. It doesn't work at all like a jet engine, beyond a general ability to compress air as it enters. The important bit for me is that there's a pre-burner combustor which [feeds a heat exchanger which heats helium which] drives the air turbo-compressor. This means that the combustor which powers the compressor is a different combustor from the one which generates thrust. Hooray! No need to build high-performance mega-valves! That removes one of my concerns about the viability of SABRE. :)
 
First update from Reaction Engines Limited in sometime & it's a major one.

Reaction Engines Ltd announces company growth and completion of first SABRE development milestone.

This year, the Reaction Engines team are expanding in staff and activities to complete the SABRE demonstrator programme, with delivery on track for 2019. The company has relocated to larger premises on Culham Science Centre" post= consolidated its two manufacturing subsidiaries to a single new location in Didcot; and is recruiting across the company, ready for the design, manufacture and testing of the full SABRE engine cycle. This growth phase has also included the purchase of new, bespoke equipment which will enable Reaction Engines to manufacture its proprietary SABRE pre- coolers in-house, at full scale.

Rest of the press release on the link below.

http://www.reactionengines.co.uk/press_release.html
 
A new press release from REL and some positive news in their relationship with the AFRL. Be interesting to see where this leads.

AFRL Analysis Confirms Feasibility of the SABRE Engine Concept
Wednesday 15th April 2015
Reaction Engines Ltd. is pleased to announce that analysis undertaken by the United States’ Air Force Research Laboratory (‘AFRL’) has confirmed the feasibility of the Synergetic Air-Breathing Rocket Engine (‘SABRE’) engine cycle concept.
The analysis was undertaken by AFRL as part of a Cooperative Research and Development Agreement (‘CRADA’) with the Air Force Research Laboratory’s Aerospace Systems Directorate (AFRL/RQ). These investigations examined the thermodynamic cycle of the SABRE concept and found no significant barrier to its theoretical viability provided the engine component and integration challenges are met.
Reaction Engines Ltd. and AFRL are now formulating plans for continued collaboration on the SABRE engine; the proposed work will include investigation of vehicle concepts based on a SABRE derived propulsion system, testing of SABRE engine components and exploration of defence applications for Reaction Engines’ heat exchanger technologies.
AFRL/RQ program manager Barry Hellman stated - "The activities under the CRADA have allowed AFRL to understand the SABRE engine concept, its pre-cooler heat exchanger technology, and its cycle in more detail. Our analysis has confirmed the feasibility and potential performance of the SABRE engine cycle. While development of the SABRE represents a substantial engineering challenge, the engine cycle is a very innovative approach and warrants further investigation. The question to answer next is what benefit the SABRE could bring to high speed aerospace vehicles compared to other propulsion systems. Although application of the SABRE for single stage to orbit space access remains technically very risky as a first application, the SABRE may provide some unique advantages in more manageable two stage to orbit configurations. Furthermore, the heat exchanger technology also warrants further investigation for applications across the aerospace domain."
Sam Hutchison, Director of Corporate Development at Reaction Engines Ltd commented - “The confirmation by AFRL of the feasibility of the SABRE engine cycle has further validated our team’s own assessment and conviction that the SABRE engine represents a potential breakthrough in propulsion that could lead to game changing space access and high speed flight capability. We look forward to continued collaboration with AFRL”.
SABRE is an innovative class of aerospace propulsion that has the potential to provide efficient air- breathing thrust from standstill on the runway to speeds above Mach 5 (4,500mph) in the atmosphere – twice as fast as jet engines. The SABRE engine can then transition to a rocket mode of operation for flight at higher Mach numbers and space flight. Through its ability to ‘breathe’ air from the atmosphere, SABRE offers a significant reduction in propellant consumption compared to conventional rocket engines which have to carry their own oxygen – which is heavy. The weight saved by carrying less oxygen can be used to increase the capability of launch vehicles including options for high performance reusable launch vehicles with increased operational flexibility, such as horizontal take-off and landing. Additionally, the SABRE engine concept could potentially be configured to efficiently power aircraft flying at high supersonic and hypersonic speeds.

http://www.reactionengines.co.uk/press_release.html
 
Some more details Sabre/AFRL

http://nextbigfuture.com/2015/04/us-air-force-confirms-hypersonic-sabre.html
 
Flyaway said:
A new press release from REL...
Although application of the SABRE for single stage to orbit space access remains technically very risky as a first application, the SABRE may provide some unique advantages in more manageable two stage to orbit configurations.

Yes indeed. Stage separation in sub-orbital space looks sensible: SABRE gets you up there but has nothing new to offer once you are in space. Why accelerate all that thermodynamic wizardry, air ducting and empty fuel tankage on the long haul to orbital velocity, it's just dead weight. Long periods of extreme hot/cold cycles followed by hypersonic re-entry won't help its reliability engineering either.
 
TBH I'd thought the Air Force would be more interested in the Scimitar engine rather than Sabre.
 
"SABRE engine concept passes US Air Force feasibilty test"
b David Szondy

April 26, 2015

Source:
http://www.gizmag.com/sabre-engine-afrl-feasibility-study/37092/

Reaction Engines' Skylon reusable spaceplane project has been given a boost, with analysis by the United States Air Force Research Laboratory (AFRL) confirming the feasibility of the SABRE engine cycle concept that lies at its heart.

The feasibility study conducted as part of a Cooperative Research and Development Agreement (CRADA) with the AFRL’s Aerospace Systems Directorate (AFRL/RQ) looked at the thermodynamic cycle of the SABRE concept. That is, whether the engine is able to do what Reaction Engine claims it can do. According to AFRL, there's no theoretical problem with the concept if the engine is properly built and integrated.

The SABRE (Synergetic Air-Breathing Rocket Engine) is a scramjet. That is, it reduces the propellant load because it acts as a jet while in the atmosphere and a rocket in space, so it doesn't have to carry as much oxygen to burn the liquid hydrogen fuel. It does so at velocities above Mach 5 (4,500 mph, 7,200 km/h) before flying into space, when it switches to rocket mode to achieve the even faster speeds needed to reach orbit.

The limit of the engine is how hot it gets. Above a certain point, even the best metal alloys soften and melt. At hypersonic speeds, the air is coming into the engine at 25 times more force than that of a Category 5 hurricane and the heat is like something blasting out of a cutting torch.

Paradoxically, before it can be burned, the air needs to be cooled dramatically, so as it enters the SABRE it passes over a series of heat exchangers that use the cryogenic hydrogen fuel to cool it down from 1,000° C (1,832° F) to minus 150° C (minus 302° F) in 1/100th of a second. Previously, this sort of heat exchanger was the size of a factory, but the SABRE uses one that's small and light enough to be installed inside the scramjet.

Reaction Engines and AFRL are currently collaborating on vehicle concepts that can use the SABRE engine. These not only include space launch vehicles, but also hypersonic aircraft and military applications of the Reaction Engines heat exchanger technologies.

"The activities under the CRADA have allowed AFRL to understand the SABRE engine concept, its pre-cooler heat exchanger technology, and its cycle in more detail," says AFRL/RQ program manager Barry Hellman. "Our analysis has confirmed the feasibility and potential performance of the SABRE engine cycle. While development of the SABRE represents a substantial engineering challenge, the engine cycle is a very innovative approach and warrants further investigation. The question to answer next is what benefit the SABRE could bring to high speed aerospace vehicles compared to other propulsion systems. Although application of the SABRE for single stage to orbit space access remains technically very risky as a first application, the SABRE may provide some unique advantages in more manageable two stage to orbit configurations. Furthermore, the heat exchanger technology also warrants further investigation for applications across the aerospace domain."
 
http://nextbigfuture.com/2015/06/reaction-engines-uk-will-have-new-tests.html
 
http://aviationweek.com/technology/reaction-engines-reveals-inner-secret-sabre-propulsion-technology?NL=AW-19&Issue=AW-19_20150713_AW-19_859&sfvc4enews=42&cl=article_1&utm_rid=CPEN1000000230026&utm_campaign=3138&utm_medium=email&elq2=d0dfe7ba023e4ad1bc8c0f0e4164f5f7

The development of a single-stage-to-orbit launch capability has been the Holy Grail to many since the dawn of the space age.

Yet achieving orbit in one stage with conventional rocket power is completely impractical and, despite decades of research into alternate concepts, no workable solutions have been found. It is no surprise, then, that for years the space community has been highly skeptical of claims from a British-based developer, Reaction Engines, that it had discovered an answer with a hybrid air-breathing rocket system.

But after endorsements of the basic technology from the European Space Agency and, more recently, the U.S. Air Force’s Research Laboratory, the company’s synergetic air-breathing rocket engine (Sabre) concept is being taken far more seriously. Designed to power a vehicle from a standing start to Mach 5.5 in air-breathing mode, and from the edge of the atmosphere to low earth orbit in pure rocket mode, the Sabre engine and heat exchanger at the heart of the design is attracting widespread interest for potential application on a range of atmospheric and space vehicles.
 
http://aviationweek.com/technology/air-breathing-sabre-concept-gains-credibility
 
bobbymike said:
http://aviationweek.com/technology/air-breathing-sabre-concept-gains-credibility

SUBSCRIBE TO ACCESS THIS PREMIUM CONTENT

:(
 
:eek:

That's going to be a date with Destiny. Lordy - hope the US don't stiff them ala RB 545.
 
It's free membership. You register - just like you did for this site - then you get access to extra stuff. Subscribe, and you get access to even more.

<edit> Ah. The piece on Sabre *is* subscribers-only.
 
Aviation Week is a business, after all, while this forum doesn't have to make money.
 
steelpillow said:
bobbymike said:
http://aviationweek.com/technology/air-breathing-sabre-concept-gains-credibility

SUBSCRIBE TO ACCESS THIS PREMIUM CONTENT

:(
No longer subscribers-only.
 
PaulMM (Overscan) said:
Aviation Week is a business, after all, while this forum doesn't have to make money.

And a hundred bucks for what you get is chump change. (Unlike Janes Defense Weekly. Major disappointment there.)
 
Arjen said:
No longer subscribers-only.
Ah, thank you. However, "I acknowledge and agree to Penton's Terms of Service and to Penton's use of my contact information to communicate with me about Penton's or its third-party partners' products, services, events and research opportunities. Penton's use of the information I provide will be consistent with Penton's Privacy Policy." Said small print confirms that I will be well spammed with the above-mentioned cruft by them and every "partner" who buys my details off Aviation Week. Does that happen a lot?
 
I've been a subscriber for a while and I don't recall seeing a whole lot of spam that obviously came from there. Of course, I have my email on aservice with good spam filters.
 
Thanks, that's encouraging. I'll try and pluck the courage to register.
 
NASA just did some research on the Skylon...
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150015818.pdf
 
antiquark said:
NASA just did some research on the Skylon...
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150015818.pdf
Wow, if ever there was a lesson in keeping well clear of the rocket exhaust!
"If the aft fuselage heating at M∞ > 8.5 is an issue that cannot be addressed with appropriate structures and materials, then the overall design of Skylon D1.5a needs to be changed."
Let's hope they can do one or the other.
 
New update from REL.

Reaction Engines Ltd Announces Collaboration with Defence Science and Technology Laboratory
Monday 17 August 2015
Reaction Engines Ltd. is pleased to announce its collaboration with the United Kingdom Defence Science and Technology Laboratory (‘Dstl’).

The collaboration commenced in December 2013 and provides a framework for Dstl to assess the military utility of Reaction Engines’ Synergetic Air-Breathing Rocket Engine (‘SABRE’) and its enabling technologies. In particular, the collaboration aims to explore and evaluate the potential defence applications of REL’s heat exchanger technology.
Varunjay Ahluwalia, Technical Lead for the collaboration at Dstl, stated - “The technological advances being made by Reaction Engines could open up exciting new opportunities for defence. As part of MOD’s wider investment in disruptive technology, our collaboration with REL will enable us to explore the impact that SABRE technologies could have to current or future defence systems.”
Ben Gallagher, Business Development Lead at Reaction Engines Ltd, commented - “We are pleased to be working with Dstl to analyse and explore potential applications for our SABRE engine and heat exchanger technologies. This collaboration is a welcome addition to the portfolio of technology partnerships that Reaction Engines is participating in and we look forward to growing the relationship into the future.”

http://www.reactionengines.co.uk/news_17aug2015_rel_dstl.html
 
Must be for the military applications after the AFRL interest as BAE are primarily a defence company these days.
 
Hopefully BAE Systems are interested in the whole Skylon concept which is to deliver a self contained payload (commercial or military) into orbit. I wonder if Rolls Royce are interested and whether Reaction Engines would be open to investment from them too? Hopefully it won't turn out like HOTOL.

SKYLON D1 paper - http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=30702.0;attach=492037
 
SteveO said:
Hopefully BAE Systems are interested in the whole Skylon concept which is to deliver a self contained payload (commercial or military) into orbit. I wonder if Rolls Royce are interested and whether Reaction Engines would be open to investment from them too? Hopefully it won't turn out like HOTOL.

SKYLON D1 paper - http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=30702.0;attach=492037

Too right SteveO, I am old enough to remember when HOTOL got canceled. After the Space Shuttle Challenger accident I was an early supporter of the whole Space Plane concept.
 
SteveO said:
Hopefully BAE Systems are interested in the whole Skylon concept which is to deliver a self contained payload (commercial or military) into orbit. I wonder if Rolls Royce are interested and whether Reaction Engines would be open to investment from them too? Hopefully it won't turn out like HOTOL.

SKYLON D1 paper - http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=30702.0;attach=492037

That might be the longer term plan, but a defence contract for the engine technology would probably represent a quicker return.
 
HOTOL foundered because Rolls-Royce didn't believe the heat exchangers could happen and refused to invest. (B.Ae as it then was were all gung-ho and got government permission to team up with Tupolev for a piggyback-launched mini-HOTOL). Now that the key technology has been developed and proven, I'll bet Reaction Engines' buy-in price has risen. :)

Interesting that BAE Systems are still ahead of the engine men.
 
steelpillow said:
HOTOL foundered because Rolls-Royce didn't believe the heat exchangers could happen and refused to invest. (B.Ae as it then was were all gung-ho and got government permission to team up with Tupolev for a piggyback-launched mini-HOTOL).

I think that was Antonov (8-engined An-225), not Tupolev.
 
Hobbes said:
steelpillow said:
HOTOL foundered because Rolls-Royce didn't believe the heat exchangers could happen and refused to invest. (B.Ae as it then was were all gung-ho and got government permission to team up with Tupolev for a piggyback-launched mini-HOTOL).

I think that was Antonov (8-engined An-225), not Tupolev.

D'oh! I knew that!

That explains why the name "Tupolev" didn't feel quite right - but, being me, I couldn't quite place why.

Thanks for the corrections.
 
US Military Set to Unveil Concepts Based on Skylon Space Plane Tech


Within the next year, the U.S. Air Force plans to unveil novel spacecraft concepts that would be powered by a potentially revolutionary reusable engine designed for a private space plane.

Since January 2014, the Air Force Research Laboratory (AFRL) has been developing hypersonic vehicle concepts that use the Synergetic Air-Breathing Rocket Engine (SABRE), which was invented by England-based Reaction Engines Ltd. and would propel the company's Skylon space plane.

http://www.space.com/32115-skylon-space-plane-engines-air-force-vehicle.html?cmpid=514648
 
Flyaway said:
US Military Set to Unveil Concepts Based on Skylon Space Plane Tech


Within the next year, the U.S. Air Force plans to unveil novel spacecraft concepts that would be powered by a potentially revolutionary reusable engine designed for a private space plane.

Since January 2014, the Air Force Research Laboratory (AFRL) has been developing hypersonic vehicle concepts that use the Synergetic Air-Breathing Rocket Engine (SABRE), which was invented by England-based Reaction Engines Ltd. and would propel the company's Skylon space plane.

http://www.space.com/32115-skylon-space-plane-engines-air-force-vehicle.html?cmpid=514648
Ohhh interesting B)
 
http://nextbigfuture.com/2016/06/us-air-force-research-will-develop.html

The lab will reveal two-stage-to-orbit SABRE-based concepts either this September, at the American Institute of Aeronautics and Astronautics' (AIAA) SPACE 2016 conference in Long Beach, California, or in March 2017, at the 21st AIAA International Space Planes and Hypersonic Systems and Technologies Conference in China, said AFRL Aerospace Systems Directorate Aerospace Engineer Barry Hellman
 
Will SABRE power the first or second stage?

My guess is the first stage, as it seems a bit mental first time round to accelerate all that precooler/intercooler/compressor hardware to orbital speed in the first place, never mind hardening its intake against the destructive rigours of orbital re-entry.

OTOH you could argue that if you drop the need to fly below 400 knots or 20,000 ft or to cruise to the Equator, then that makes a SABRE orbital re-entry cycle more feasible.

Personally, first time round I would carry a sub-orbital SABRE spaceplane, with a modest internal payload bay, on top of a Jumbo jet and get that working before I got more ambitious.
 
I missed it, what is the heat-transfer medium in the AF pre-cooler? And what kind of cycle? Hydrogen-Helium ... what?

Seems all they want to do is keep the otherwise typical GT compressor section from melting.

David
 
merriman said:
I missed it, what is the heat-transfer medium in the AF pre-cooler? And what kind of cycle? Hydrogen-Helium ... what?

Seems all they want to do is keep the otherwise typical GT compressor section from melting.

David

The heat transfer fluid in the pre-cooler heat exchanger is liquid helium, which is then used to pre-heat the liquid hydrogen fuel. And yes, the main function of the pre-cooler is to stop the turbocompressor from melting, exactly that. It also provides a first stage of compaction through cooling and even partial liquefaction, making the compressor's life doubly easy. Of course, the compressor's thermal problems do not disappear, the breakthrough is to shift them onto a precooler which can at least be purpose-designed to deal with them.

There is also some innovation in the way the thermodynamic cycle is integrated with the pumping mechanisms to provide both airbreathing and pure rocket modes. For example doubling up the helium cooler / fuel preheater as a gas generator to drive the fuel turbopump, creating what is essentially a jet engine within the main engine, is pretty neat. Note the otherwise perpetual-motion way in which helium flowing through HX4 is used to drive the fuel pump while the resulting fuel flow is used to drive the helium circulator.

From their web site at http://reactionengines.co.uk/sabre_howworks.html :

"The diagram shows in simplified form the complete SABRE cycle. The air from the intake (blue) is shown going though the Pre-cooler and into the compressor. The cooling is achieved with helium (green) that has been itself cooled by HX4 using the liquid hydrogen fuel (purple). Once it has left the Pre-cooler the helium is further heated in HX3 by the products of the Pre-burner to give it enough energy to drive the turbine and the liquid hydrogen (LH2) pump."

sabre_cycle_1024.jpg
 
BAE Systems Hypersonic Response Aircraft concept using a Sabre type engine
Armed forces of the future could be using rapid response aircraft equipped with engines capable of propelling those aircraft to hypersonic speeds - similar to the Synergetic Air-Breathing Rocket Engine (SABRE) which is currently being developed by Reaction Engines Limited, a small British company in which BAE Systems has invested £20.6 million.
https://youtu.be/cInXWApcbew
 
They used a Mach 5 spaceplane to deliver 2 UAVs and a crate of supplies? Seems a bit of a waste.
 

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