Reaction Engines Ltd
Discussion
Flibble said:
DoubleSix said:
Why have others (with deeper pockets) not adopted a version of this technology? is it already protected IP?
Is been tried. It's hard to make it work across the full range of conditions. The main issue is getting both low speed thrust and not melting at high speed.The key part of Sabre is the heat exchanger which is patented.
To date they haven't actually made a flight weight heat exchanger.
The whole concept is still pretty far from a slam dunk, issues.
1: Given TSTO designs are on the cusp of full reusability having a SSTO design is not necessarily giving you very much.
2: The Sabre weighs a lot and hydrogen is very bulky. It may be that you can achieve comparable performance with much less complication by using rockets particularly if you use a tri-propellant mixture where you initially burn hydrogen-kerosene and oxygen and switch to hydrogen and oxygen at higher altitudes.
3: The idea of having to build a special long high spec runway sounds expensive and difficult for widespread adoption. I would actually suggest their best option would be to team up with Strato-launch, it simplifies the design considerably.
4: The cost of developing the vehicle is likely to be much greater than developing a rocket and you won't be able to expend the early prototypes and have someone pay for it like SpaceX did.
In practice Reaction Engines are following the money, the Sabre concept is much more likely to be used in hypersonic military aircraft than getting people to orbit anytime soon.
I imagine the military utility of being able to sling some SPACE MARINES YO! or a secret squirrel satellite into an SSTO and lob them into orbit at <24hrs notice would be quite high; rockets are unlikely to ever get their turnaround time down to what could potentially be offered by Skylon. It does seem likely to this armchair technologist that the 'early adopter' will be the Pentagon simply because they have a massive budget and like being able to do stuff no-one else can.
The ability to launch quickly and for one orbit only was part of the spec of the original Space Shuttle. However, this capability was way beyond the technology of the 1970s when the Shuttle was designed so it was never able to fulfill that role. Skylon, in theory, would be able to perform such missions - but it is still right at the edge of what will be possible over the next ten to twenty years.
Some good news on the heat exchanger tests:
https://www.bbc.co.uk/news/science-environment-478...
This is a really tantalising process, is it true we're not expected to see anything flying till 2025?
https://www.bbc.co.uk/news/science-environment-478...
This is a really tantalising process, is it true we're not expected to see anything flying till 2025?
hidetheelephants said:
Strapping the thing to the underside of a mule 747 or whatever could be pretty quick once there is a functioning prototype, building a Skylon or proto-SSTO would indeed be protracted.
That did cross my mind - as it was common practice in years gone by.Obviously, a 747 could only provide data for limited aspects of the Sabre's potential performance capability.
The progress of Skylon and the Sabre makes the SLS team look like they are rushing recklessly.
Rivenink said:
Just a random thought on what happens if this reaches passenger carrying production...
What would the flight path for such a plane leaving Heathrow headed for Sydney look like? What would the date/time implications be for the passengers?
How about in reverse - Sydney to London?
Their website cites Brussels to Sydney in just over 4 hours, cruising at Mach 5.What would the flight path for such a plane leaving Heathrow headed for Sydney look like? What would the date/time implications be for the passengers?
How about in reverse - Sydney to London?
Eric Mc said:
That did cross my mind - as it was common practice in years gone by.
Obviously, a 747 could only provide data for limited aspects of the Sabre's potential performance capability.
The progress of Skylon and the Sabre makes the SLS team look like they are rushing recklessly.
If Reaction Engines had NASA's stationery budget they'd have an engine by now. Obviously, a 747 could only provide data for limited aspects of the Sabre's potential performance capability.
The progress of Skylon and the Sabre makes the SLS team look like they are rushing recklessly.
Rivenink said:
Just a random thought on what happens if this reaches passenger carrying production...
What would the flight path for such a plane leaving Heathrow headed for Sydney look like? What would the date/time implications be for the passengers?
How about in reverse - Sydney to London?
I'm not sure what you mean by the date/time implications, they will be exactly the same as for existing airliner passengers; the flight path is likely to be quite similar to conventional airliners, a climb to the altitude that offers economic flight(for SABRE-powered hypersonic aircraft that is perhaps 40 miles up) optimised for fuel burn while not making the SLF vomit.What would the flight path for such a plane leaving Heathrow headed for Sydney look like? What would the date/time implications be for the passengers?
How about in reverse - Sydney to London?
In recent years they have been promoting the Skylon as an unmanned single stage to low earth orbit vehicle rather than a super fast airliner.
I have not heard or read anything about what type of heat shielding they will use on re-entry from orbit. If I bump into the team again at Farnborough I'll try to remember to ask them that.
I still think it has years and years of development work ahead of it.
I have not heard or read anything about what type of heat shielding they will use on re-entry from orbit. If I bump into the team again at Farnborough I'll try to remember to ask them that.
I still think it has years and years of development work ahead of it.
Eric Mc said:
In recent years they have been promoting the Skylon as an unmanned single stage to low earth orbit vehicle rather than a super fast airliner.
I have not heard or read anything about what type of heat shielding they will use on re-entry from orbit. If I bump into the team again at Farnborough I'll try to remember to ask them that.
I still think it has years and years of development work ahead of it.
I don't think they have done much work on the heat shielding.I have not heard or read anything about what type of heat shielding they will use on re-entry from orbit. If I bump into the team again at Farnborough I'll try to remember to ask them that.
I still think it has years and years of development work ahead of it.
The original proposal was to use a Silicon carbide composite reinforced with glass fibres with active cooling on leading edge. They can get away with this because Skylon's ballistic coefficient is so low that reentry heat is not that high.
The main structure is a truss made from Titanium reinforced with silicon fibre, the tanks are aluminium and non structural.
Personally I suspect that the stainless steel tank and structure proposed by SpaceX for the Starship might be equally applicable to the Skylon and also be much cheaper to develop.
Eric Mc said:
I am pretty sure that no matter what material you manufacture the hull and wings from, if coming back from earth orbit, it will have to withstand temperatures in some areas in excess of 2,000 degrees C.
Indeed, at some point you're going to be doing c. Mach 20 through the atmosphere which is a lot of heat even with mega streamlining. Not to mention you have to shed that speed somehow, and short of using rockets that generally means dumping kinetic energy as heat. Regarding the skin, the mention of "ceramic composite" is all I have seen. I would guess that a long distance airliner wouldn't need the high kinetic energies (lower altitude and velocity) compared to ISS access flights or full orbital altitudes, so it would make sense to have different skins for different applications. SpaceX are working on various alloys of stainless steel for use on StarHopper, and venting fuel through pores in the skin to cool it, which may be an interesting option, and more robust than ceramics.
SpaceX are going with "301 Stainless Steel" which is also pretty damn cheap compared to exotic materials like carbon fibre and ceramics.
https://www.smithmetal.com/301-stainless.htm
https://www.smithmetal.com/301-stainless.htm
Beati Dogu said:
They believe reentry temperatures will get no higher than 830 degrees Celsius.
It will re enter higher and with a much higher ballistic coefficient than the likes of the Shuttle, which had the aerodynamics of a brick.
How do they kill the orbital velocity without using the atmosphere to aerobrake? Do they plan to start re-entry much higher than every other re-entering spacecraft so that by the time they enter denser air they have lost a lot of the velocity. They would need to start the re-entry about 2/3 around the globe from their eventual landing spot.It will re enter higher and with a much higher ballistic coefficient than the likes of the Shuttle, which had the aerodynamics of a brick.
No other spacecraft has kept skin temperatures to under 830 degrees.
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