what's the sabre engine's secret sauce?

[tater]

25 minutes ago, SpaceFace545 said:

Reaction engines is deeply rooted in BAE so I bet their is a lot of progress that just isn’t being shared with the public.

They've been working on this for what, 30 years?

Maybe they need BO to buy them to speed them up some

 

[DDE]

1 hour ago, magnemoe said:

As I understand the engine is relevant for very high speed cruise missiles or an strike platform.

Cryogens make it relevant exclusively as a vehicle rather than a munition. Besides, Western high-speed airbreathing cruise missile projects seem to have an almost inexplicable tendency to be stillborn.

RATTLRS - Wikipedia

Besides, at suborbital velocities we're likely to start seeing mini-Rods from God, shifting emphasis (and the costs center) from the munition back to the platform.

28 minutes ago, SpaceFace545 said:

Reaction engines is deeply rooted in BAE so I bet their is a lot of progress that just isn’t being shared with the public.

Few arguments I despise as much as this one. Certainly, arms manufacturers seek to keep things under wraps, but between them needing to advertise with the worlds' militaries, and the military needing to advertise with the politicians and the taxpayers, few things are going to truly stay under wraps.

[mikegarrison]

14 hours ago, wumpus said:

Officially, the secret sauce is the air/air cooling system for the intake air.

That's the bit that people are interested in. One limit to the efficiency of a jet engine is that the temperature rise across the combustor is limited by what the turbine can survive and how cool the compressor can deliver air at the required pressure. If they could cool down the intake air, that would let them go to higher pressures, and higher pressures are more efficient. So people are interested in heat exchanger technology that can work in the full flow of a jet engine.

[magnemoe]

1 hour ago, DDE said:

Cryogens make it relevant exclusively as a vehicle rather than a munition. Besides, Western high-speed airbreathing cruise missile projects seem to have an almost inexplicable tendency to be stillborn.

RATTLRS - Wikipedia

Besides, at suborbital velocities we're likely to start seeing mini-Rods from God, shifting emphasis (and the costs center) from the munition back to the platform.

Good point, and yes an starship bomber version let you remove the mini part from rods. 
 

[Nuke]

20 hours ago, Xd the great said:

"You see good sir, when you put money in this end, you get cool-looking spaceships fro the other end!"

I remembered they use some new techniques to create channels that are about 0.1mm wide. That should allow heat to be rapidly exchanged, cooling the air and heating up the fuel.

thats how the heat exchangers worked. back in the hotol days they did some tests and their heat exchangers would freeze up pretty fast due to water vapor in the atmosphere. apparently they have solved this problem, but are hush hush about it, which is the reason i created this thread.

[wumpus]

4 hours ago, mikegarrison said:

That's the bit that people are interested in. One limit to the efficiency of a jet engine is that the temperature rise across the combustor is limited by what the turbine can survive and how cool the compressor can deliver air at the required pressure. If they could cool down the intake air, that would let them go to higher pressures, and higher pressures are more efficient. So people are interested in heat exchanger technology that can work in the full flow of a jet engine.

If it could work in a subsonic "jet" I'd expect them to have plenty of funding long before now.  Mach 6 is pretty much only good for suborbital flight, either for transportation or as the first stage to orbit.

Granted,  mach 6 is plenty for orbital rockets.  This certainly surprised me after learning some wrong lessons from KSP (sure, in theory you want to stage at roughly half the delta-v to orbit, but the engines for lift off are heavy, and there's little point in giving them more delta-v than you have to.  And real propellant tanks are nowhere near as heavy as they are in KSP).

[Nuke]

19 hours ago, wumpus said:

Even with Sabre, that would be difficult.  The problem with SSTO is that approximately for every ton your SSTO can lift to orbit, a TSTO can be designed to do the same thing, and deliver the same tonnage to orbit.  And by tonnage, I mean the SSTO payload, plus the mass of the SABRE engines, plus the mass of whatever fuel tank is needed for all that extra delta-v (note that while SABRE 'first stage' might have extreme Isp, it is hydrolox, and that means a fuel tank with volume issues).

Officially, the secret sauce is the air/air cooling system for the intake air.

Really, the "secret sauce" is the magic of the promise of a "spaceplane".  That gets a lot of attention, but not enough money to really build anything but powerpoint.

i think a more practical application of the engine is to launch a sub orbital space plane as kind of a first stage for a second stage disposable rocket. you can seriously upgrade the payload capacity if you dont have to take the whole plane to orbital velocity.  essentially its another carrier aircraft, but one capable of getting out of the atmosphere and with more velocity than something like stratolaunch. you still get most the benefits skylon would give you, and some of the advantages of a 2 stage rocket. 

Edited May 9, 2021 by Nuke

[mikegarrison]

20 minutes ago, wumpus said:

If it could work in a subsonic "jet" I'd expect them to have plenty of funding long before now.  Mach 6 is pretty much only good for suborbital flight, either for transportation or as the first stage to orbit.

I know for a fact that Rolls-Royce paid money to buy into the technology developed for the Skylon engine. And I've just explained why. Adding an intercooler stage is one of the acknowledged potential paths to increasing jet engine efficiency (along with geared turbofans, open rotors, and hybrid-electric engines).

https://www.aerospacetestinginternational.com/news/rolls-royce-increases-involvement-in-hypersonic-air-breathing-engine-development-project.html

Rolls did not buy a stake in Skylon or a share of the SABRE -- they are paying for the heat exchanger technology. Boeing also has bought a smaller stake.

Quote

Mark Thompson, director of global strategy and business development at Rolls-Royce said, “We have been working closely with Reaction Engines for the past two years, including exploring the potential of high-Mach systems for defence applications, and I am delighted that we are able to strengthen that relationship. This partnership follows our recent announcements with Boom Supersonic and Virgin Galactic.

“Reaction Engines’ thermal management skills, added to our suite of existing technologies and capabilities, will further assist us as we explore opportunities in supersonic and hypersonic aviation.

“Building on our many decades of innovation, we will also explore the use of Reaction Engines’ technology within our aerospace gas turbines and its potential application in future hybrid-electric propulsion systems, as we look to make flying ever more efficient and sustainable.”

Rolls-Royce initially invested in Reaction Engines in 2018 alongside Boeing, and will make a further investment in Reaction Engines as part of a current wider funding round. BAE Systems also has a 20% stake in Reaction Engines.

 

Edited May 9, 2021 by mikegarrison

[tater]

1 hour ago, mikegarrison said:

Boeing also has bought a smaller stake.

An article I saw said that they were testing something in Colorado. Is that related to the Boeing interest?

[Single stage to ocean]

Powerful dryers as well as an intake shape that won’t easily be clogged by ice and maybe compressed air jets in the intake to push out ice, or hydrophobic coated materials.

[mikegarrison]

7 hours ago, tater said:

An article I saw said that they were testing something in Colorado. Is that related to the Boeing interest?

I have no idea.

[Nuke]

9 hours ago, Single stage to ocean said:

Powerful dryers as well as an intake shape that won’t easily be clogged by ice and maybe compressed air jets in the intake to push out ice, or hydrophobic coated materials.

more of this. 

wonder if the spiral arrangement of the tubes has something to do with it, maybe create a vortex to spin out the water/ice crystals. 

some kind of antifreeze injection system? 

 

[Single stage to ocean]

They use methanol for that, but haven’t told much else other than an uploaded 3D model of it.

[Single stage to ocean]

or i got it, a centrifugal thing that spins ice to the sides where it is pushed out by ramps, and air stays in the center and goes to the engine.

[KSK]

I’m going to be terribly boring and suggest looking up Reaction Engines’ patents. They have a bunch of them for heat exchangers and from a quick glance at one of them, it appears to be about controlling ice formation.

Admittedly patents aren’t exactly a riveting read and are probably best read by somebody who at least has some clue about the technology being discussed (spoiler: that’s not me), but I’m not sure how much of this secret sauce is actually secret.

[Nuke]

11 hours ago, Single stage to ocean said:

or i got it, a centrifugal thing that spins ice to the sides where it is pushed out by ramps, and air stays in the center and goes to the engine.

would be digested fine by the ring of ramjets that they use to vent the extra hydrogen. 

8 hours ago, KSK said:

I’m going to be terribly boring and suggest looking up Reaction Engines’ patents. They have a bunch of them for heat exchangers and from a quick glance at one of them, it appears to be about controlling ice formation.

Admittedly patents aren’t exactly a riveting read and are probably best read by somebody who at least has some clue about the technology being discussed (spoiler: that’s not me), but I’m not sure how much of this secret sauce is actually secret.

i dont really have time to do that right now. got another anchorage trip here in a couple hours. but il look that up first thing when i get back. unless i forget, i will probibly forget. 

[magnemoe]

On 5/10/2021 at 1:42 AM, Nuke said:

i think a more practical application of the engine is to launch a sub orbital space plane as kind of a first stage for a second stage disposable rocket. you can seriously upgrade the payload capacity if you dont have to take the whole plane to orbital velocity.  essentially its another carrier aircraft, but one capable of getting out of the atmosphere and with more velocity than something like stratolaunch. you still get most the benefits skylon would give you, and some of the advantages of a 2 stage rocket. 

Yes the old idea for an reusable first stage was an mach 6-8 space plane, use jets to get to mach 3-4, then rockets to get into space, now you can deploy an second stage in vacuum who reach orbit. No reason why it should not work, however it will be an very expensive plane to develop and build. 
As in it would be an at minimum bomber sized plane with x-15 performance. None wanted to put up the money as in the B-2 was cheap  

Falcon 9 happens, yes an Skylon will be more efficient, but the development cost and time.