The Reaction Engines Skylon/SABRE Master Thread (7)

[Soundbite]

There is another air breathing rocket engine concept further ahead in development than Fenris.... It's Space Engine Systems https://www.spaceenginesystems.com/.  It is also setting up an office in the UK https://www.cornwallti.com/2020/06/03/spaceport-cornwall-and-space-engine-systems-agree-future-partnership/.

I tried to search for it in advanced concepts but the search turned up empty... honest!

[oddbodd]

There is another air breathing rocket engine concept further ahead in development than Fenris.... It's Space Engine Systems https://www.spaceenginesystems.com/.  It is also setting up an office in the UK https://www.cornwallti.com/2020/06/03/spaceport-cornwall-and-space-engine-systems-agree-future-partnership/.

I tried to search for it in advanced concepts but the search turned up empty... honest!

Don't think I'd seen them before. I'm no expert, but I think they are exposed patent wise. There are quite a lot of similarities with REL, however REL already have patents granted. SES state on the website images that patents are pending, but I couldn't find anything in the google patent search tool. Difficult to say if they actually have anything significant developed, as there is not much public information, and they seem like a small operation based on what I could find in my cursory search.

Supposedly they use Boron Carbide nanoparticles injected into the airflow at the inlet to improve thermal performance. I know they are small (duh... nano) but isn't that still going to be an abrasive in the engine? Boron Carbide is one of the hardest known materials. Hell, Wikipedia literally lists it as an "engine sabotage powder"
I'm also curious what the exhaust product would be. I found a comment saying it would produce Boron Oxide as a liquid glass, that builds up on the exhaust nozzle. If correct Yuk.

My last critique would be that their engine requires multiple fuels (hydrocarbon, hydrogen, plus the boron carbide), 2 oxidisers (air and pure LOX) and up to four modes of operation, including that old chestnut, the ramjet. That sounds awfully complicated.

Also, their rendering of a spaceplane is ridiculously small, and like the original HOTOL, has the engines at the rear. I'd assume it will suffer the same extreme pitching forces that plagued the HOTOL design.

[oddbodd]

SES state on the website images that patents are pending, but I couldn't find anything in the google patent search tool. Difficult to say if they actually have anything significant developed, as there is not much public information, and they seem like a small operation based on what I could find in my cursory search.

Correcting myself, I did find a couple. They are in the CEO's name:
https://patents.google.com/patent/WO2017075718A1/en?inventor=Pradeep+Dass&oq=Pradeep+Dass&sort=new
https://patents.google.com/patent/WO2017075717A1/en?inventor=Pradeep+Dass&oq=Pradeep+Dass&sort=new

They were filed after REL's and are still not listed as granted as far as I can see.

[john smith 19]

Supposedly they use Boron Carbide nanoparticles injected into the airflow at the inlet to improve thermal performance. I know they are small (duh... nano) but isn't that still going to be an abrasive in the engine? Boron Carbide is one of the hardest known materials. Hell, Wikipedia literally lists it as an "engine sabotage powder"
I'm also curious what the exhaust product would be. I found a comment saying it would produce Boron Oxide as a liquid glass, that builds up on the exhaust nozzle. If correct Yuk.

My last critique would be that their engine requires multiple fuels (hydrocarbon, hydrogen, plus the boron carbide), 2 oxidisers (air and pure LOX) and up to four modes of operation, including that old chestnut, the ramjet. That sounds awfully complicated.

Also, their rendering of a spaceplane is ridiculously small, and like the original HOTOL, has the engines at the rear. I'd assume it will suffer the same extreme pitching forces that plagued the HOTOL design.

Looking at the patents the boron carbide has 2 uses.
1) Boundary layer separation control, where apparently the injection of the right sized particles can substantially reduce this phenomenon
2) Acting as a fuel.

Boron based (cycloborane and pentaborane IIRC) were the big hope for high speed, long range jets in the 1950's. The USN bankrolled a plant to make them. The thermodynamics were excellent, but they have massive problems.  They are staggeringly toxic and when they burn in jet engines they have two further problems. As you noted they can burn to give highly abrasive powders that effectively shot blast the turbines or they can forma  "gummy" layer that coated the blades.

This was going to be the fuel for the B70, then they thought they coculd make it work in the afterburners, but that proved impossible.

So they seem to be using a mix of LH2 to cool the flow and some of powers a fan to blow boron carbide dust into the flow to suppress  flow separation. The design is quite  like the J85 powering the SR71, but instead of lots of holes in the entry aerospike and duct (to remove the boundary layer) they inject the dust into to flow to do the same thing.

Now injecting boride into the flow should cool it a bit (cold particles, hot flow) but if they are combustible that would seem to be the last place you want to add heat. 

You're right the cycle  is complex and it does indeed look like a 2 Oxidizer/3 fuel engine.  Could it be efficient enough that despite that complexity it still delivers enough benefits to enable an SSTO, or at least a mostly SSTO?

Which is another way of saying that it the SABRE design is very clever and it's only when you try to copy it (without infringing patents) you discover how subtle it is.

[Asteroza]

They're not thinking of using the nanoparticles in a pumpable LH2 slurry in the precooler to absorb heat, then flush through combustor/bypass burner are they?

[oddbodd]

They're not thinking of using the nanoparticles in a pumpable LH2 slurry in the precooler to absorb heat, then flush through combustor/bypass burner are they?

From what I saw in the patents (and confirmed by john smith 19) is that the nano particles are pushed out through the inlet cone to prevent boundary layer separation, mixing with the incoming hot air. I think this requires the particles be suspended in LH2, but it seems counterintuitive to also inject H2 into the hot airflow before the HX. It seems to be what is show in Fig 2 of the patent application however. Hydrogen has an auto-ignition temperature of just 536 °C, and based on SABRE details, they were expecting inlet temperatures over 1000. If the H2 is pumped, are we also pushing these particles through this (very) high speed pump too? Either way, that means that the nano-particles then pass back through the HX, through all the turbine blades, into the combustion chamber, and finally spat out the back, but in a form that will possibly coat and foul the inside of the nozzle. I don't like to think of how much this will reduce the working life of all those components.

[RON_P]

Sry for the off the topic question ( i don't know if it's worth opening a new thread )  . But are there any news or an interview with Alan Bond on his new advanced propulsion company Mirror Quark Ltd  ?

[john smith 19]

They're not thinking of using the nanoparticles in a pumpable LH2 slurry in the precooler to absorb heat, then flush through combustor/bypass burner are they?

From what I saw in the patents (and confirmed by john smith 19) is that the nano particles are pushed out through the inlet cone to prevent boundary layer separation, mixing with the incoming hot air. I think this requires the particles be suspended in LH2, but it seems counterintuitive to also inject H2 into the hot airflow before the HX. It seems to be what is show in Fig 2 of the patent application however. Hydrogen has an auto-ignition temperature of just 536 °C, and based on SABRE details, they were expecting inlet temperatures over 1000. If the H2 is pumped, are we also pushing these particles through this (very) high speed pump too? Either way, that means that the nano-particles then pass back through the HX, through all the turbine blades, into the combustion chamber, and finally spat out the back, but in a form that will possibly coat and foul the inside of the nozzle. I don't like to think of how much this will reduce the working life of all those components.

That's pretty much how I read it.  The symbols on the figure suggest a GH2 driven fan blowing the powder out.

It's always entertaining when people say "The SABRE cycle is so complex." Then someone tries to beat it and comes up with something more complex.

SABRE is as simple as it can be to do the job it was designed to do. Which is very tough.

Now might be the time to move further discussion of this engine to a new thread in Advanced Projects, which is what it is right now.

[john smith 19]

Sry for the off the topic question ( i don't know if it's worth opening a new thread )  . But are there any news or an interview with Alan Bond on his new advanced propulsion company Mirror Quark Ltd  ?

I know of nothing apart from the end segment of a podcast he did for a youtube channel and a presentation from about 2018.

Any new thread would definitely be in the "Advanced Projects" section.

[john smith 19]

They're not thinking of using the nanoparticles in a pumpable LH2 slurry in the precooler to absorb heat, then flush through combustor/bypass burner are they?

No.

[t43562]

This talk might have some interesting bits in it - one thing is that it's the spiral heat exchangers that are being tried out in motorsports.

[john smith 19]

This talk might have some interesting bits in it - one thing is that it's the spiral heat exchangers that are being tried out in motorsports.

Quite interesting on the Demo-A stuff.

Over the years I've followed various proposals for high temperature gas cooled reactors, usually with helium cooling.

IRL the biggest He turbine ever built has been for the German pebble bed test reactor, which was for 5MW. AFAIK REL is the only company in the world doing actual development work on He turbines in the 100s of MW range.

Everyone else is just Powerpoints. 

[EDIT IOW REL is accumulating a significant chunk of IP on the detail design and mfg of very large He turbines which could speed up deployment of various HTGR designs by years for companies that wanted to do so, and were prepared to put money on the table. ]

[t43562]

Mark Thomas  is on here.

ADS Space Industry Roundtable


He starts at about 12m 15s with platitudes. then 26m 40s with a comment, 45m 36s.

On the whole I don't think we have much to learn here except that various interest groups are trying to big themselves up and get government interest and money.

It is nice though, just to see any appearance at all by REL.

[john smith 19]

Mark Thomas  is on here.

ADS Space Industry Roundtable

He starts at about 12m 15s with platitudes. then 26m 40s with a comment, 45m 36s.

On the whole I don't think we have much to learn here except that various interest groups are trying to big themselves up and get government interest and money.

It is nice though, just to see any appearance at all by REL.

Thanks for the markers The sound was awful for a professionally produced event (which I presume this was). 

[t43562]

https://www.virgingalactic.com/articles/virgin-galactic-unveils-mach-3-aircraft-design-for-high-speed-travel-and-signs-memorandum-of-understanding-with-rolls-royce/

So, Rolls Royce and a Mach 3 aircraft - no mention of SABRE.........I wonder? Rolls is big enough that it can do multiple things in hypersonics, including things that that are not related to SABRE but it is tempting to wonder if there might be some degree of connection?

I feel that it may have already been debated but I don't understand the nasaspacefight search mechanism and cannot find out. If so I will delete this and my apologies in advance if it turns out to have been discussed before.

[Robotbeat]

Mach 3 doesn't require SABRE. See: Valkyrie, SR-71, Archangel, etc.

[t43562]

Mach 3 doesn't require SABRE. See: Valkyrie, SR-71, Archangel, etc.

Without wishing to be mean that is a fairly obvious point, but are we sure that a Mach 3 engine cannot benefit from a SABRE cycle or at least some of the SABRE technologies?

[ChrisWilson68]

Mach 3 doesn't require SABRE. See: Valkyrie, SR-71, Archangel, etc.

Without wishing to be mean that is a fairly obvious point, but are we sure that a Mach 3 engine cannot benefit from a SABRE cycle or at least some of the SABRE technologies?

I don't remember ever hearing REL or anyone associated with them saying SABRE technology is applicable to an engine that doesn't go past Mach 3.  Is there something I missed where they said that?

[john smith 19]

Mach 3 doesn't require SABRE. See: Valkyrie, SR-71, Archangel, etc.

Depends what you're talking about.

In some ways the SABRE cycle is quite a bit like the cycle P&W developed to power the Suntan M3 aircraft, but using an HX in the exhaust to heat LH2 to drive the compressor (sound familar?)

Moving away for the cycle itself and moving to precoolers all of the LACE concepts from the 60's to the 80's would have benefited from better pre coolers.

All jet engine performance suffers as the inlet temperature rises and the inlet pressure falls.

But a pre cooler at the front of an engine above increases the density of the air, hence raises the mass flow. The lowered inlet temperature means turbine materials retain more of their properties as t hey are running cooler, or can run at higher speeds without failure.

So yes there are significant benefits to the sort of technology that REL can supply.

[john smith 19]

I don't remember ever hearing REL or anyone associated with them saying SABRE technology is applicable to an engine that doesn't go past Mach 3.  Is there something I missed where they said that?

Yes.

Where you confuse not having with not wanting.