New type of jet engine

[vulcanised]

Looks interesting.............

British company claims biggest engine advance since the jet - Yahoo! News UK (http://uk.news.yahoo.com/british-company-claims-biggest-engine-breakthrough-since-jet-145733539--finance.html)

[MG23]

Reaction Engines seem to have some pretty clever people working for them; I watched an interesting documentary about them on Youtube a while ago.

They still have the problem that going from the engine to a space plane would cost billions of pounds, with no guarantee of success. SpaceX claim a reusable Falcon would launch payloads for about the same price and they can make money with the non-reusable version while they build up to it.

What I don't understand is how the heat-exchanger would help current jet engines as mentioned in the article; I can see that cooler intake air might be beneficial, but wouldn't the airliners have to carry tanks of liquid hydrogen to operate it? If they could make that work in a profitable manner, maybe it would give them a means of building up capital to put into space plane development.

[G&T ice n slice]

Intercooler - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Intercooler)

one assumes they are hoping to incorporate something between the compressor stages & the combustion stage?

[beamender99]

Reaction Engines Limited (http://www.reactionengines.co.uk/) Some video clips

Reaction Engines Ltd - About Us (http://www.reactionengines.co.uk/about.html)

Recently I attended a presentation by Alan Bond and it was very impressive.

Reaction Engines Ltd - News Updates (http://www.reactionengines.co.uk/news_updates.html)
Press release

[Lyman]

Howdy

"What the company has right now is a remarkable heat exchanger that is able to cool air sucked into the engine at high speed from 1,000 degrees Celsius to minus 150 degrees in one hundredth of a second."

How much of this air can be cooled that quickly? The rate of cooling is missing some important data. The aircraft could (will) utilize its LOX and LH tanks surely, in some form of interface with a manifold that contains the transiting air.

The challenge is to expose the air to the cold fuel by maximizing the area of the tubes containing the liquid combustants. So the word "nesting" is instructive. Will the tubes be concentric, perhaps a complement of 7-10 in an axial/helical arrangement? Given enough room, the startling "rate" in the press release becomes a little less dramatic?

The speeds whilst under turbojet propulsion are transient, so for how long can this exchanger function? If the need is for only five or so minutes between the critical Mach 2.5 and Rocket mode, then an evaporative manifold could be used to store the the rocket fuel as a gas, to be reinjected into the chamber at rocket speeds.

Would the Turbo jet's fuel be Hydrogen? Why not, that would simplify the inter- modal concept's fuel architecture.

We are now back to the classic 1960 argument between Canaveral and Edwards.

Why waste Rocket mode off the pumpkin patch if an aerodynamic platform could launch the Rocket at 50,000 feet?

Back to heat exchange. I see a nested helical tube arrangement whose only limit would be space, enough room to accomodate the airflow requirements of combustion. Manufacture? Carbon?

Maybe they should apply for some patent protection. Then again, since it is only on "paper", it sounds suspiciously like a wind-up.

[Landroger]

There was a guy on the radio this morning, saying that this wasn't just computer modeling any more - they have hardware on test rigs apparently.

Roger.

[Wirbelsturm]

Anywhere on earth within 4 hours

There goes Long Haul pay then. :(

[fox niner]

Anywhere on Earth within 4 hours

Not only long haul pay goes down the drain, so do all lay-overs! The whole Earth can be reached on a return trip within current FTL limits.:ooh:

[Agaricus bisporus]

The headline of this post is more than somewhat adrift.

Reaction Engines have been promoting this concept for - what? - three decades now?

It may be many things but "new" is most definitely not one of them.

[MG23]

Maybe they should apply for some patent protection.

I forget the details, but according to the documentary I watched they had some problem with the HOTOL patents preventing them from continuing to use the work they'd done there while developing the new engine, so this time they decided not to patent it at all and keep it a trade secret.

[Lyman]

MG23, hi

the sense of the news release is the "new art" involved in the cooling of the inlet air. SR71 operated to Mach 3 without inlet cooling, so the gap in performance can be assumed to be between 3 and 10, or so.

from the pic, the new device seems ponderous, and relies on separate refrigerant than the liquified H or O. Quite a bit of extra weight. So my conjecture is around Rolls' "exchanger". The inlet air appears to be linear. There must be some payoff to extend the useful phase of the turbojet, rather than ignite the rocket earlier.

Has anyone talked to Rutan? He relies on mother/payload, turbojet rocket hybrid architecture. Unifying the two modes must have some benefit I cannot see.

Rolls does have some recent ad hoc experience with water ice and fuel at the heat exchangers. (BA 038) That is actually why I thought it to be a wind up, initially. You know, kind of an inside joke?

Mr. Bond has been working at this since 1989?

[Fzz]

from the pic, the new device seems ponderous, and relies on separate refrigerant than the liquified H or O. Quite a bit of extra weight.My understanding is that the liquid nitrogen is just for the ground tests of the heat exchanger. An actual engine would use the liquid hydrogen fuel for this purpose.

Edit: I think you're talking about a picture like this one:

http://www.reactionengines.co.uk/images/sabre/sabre_cycle_610.jpg

There is indeed a separate helium circuit to transfer heat in two stages rather than just one. I thought you were referring the the ground tests where they are using liquid nitrogen in place of liquid hydrogen fuel.

Still, if the weight of the heat exchanger is less than the liquid oxygen you'd have needed to carry, it's still a win. For a conventional rocket to do single-stage to orbit, you'd need around 89% of the take-off mass to be fuel:
Tsiolkovsky rocket equation - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation#Examples)
Only 11% can be engines, tanks, structure, payload, re-entry heat shield, etc.

For a two-stage to orbit rocket, the number becomes 84%, which is a bit more manageable. Of this, 67% of the launch mass is first stage fuel. Oxygen has an atomic weight of around 16, so you have 8 times as much mass of oxygen as hydrogen. So about 58% of your launch mass is liquid oxygen for the first stage. If you can air-breath for the time the first stage would normally fire for, you can save most of this mass (but you have to add on the weight of the heat exchanger and the extra hydrogen tanks you now take to orbit). Still, it's not hard to see why this might be a big net win.

What the diagram doesn't show is what happens to the nitrogen from the air. Presumably this has to go though the engine too. Wonder what that does to the combustion chamber design - having nitrogen in the mix for the first half of the burn and not for the second?

[Lyman]

Hi Fzz...

Well that makes sense, although I thought the test cell refrigerant was Helium.

Hydrogen would be an extreme hazard in test.

Wait a minute.

[Machinbird]

FYI, This subject was discussed on Tech Log a while back.
http://www.pprune.org/tech-log/444778-reaction-engines-sabre-scimitar.html
Very interesting subject. The design makes complete sense from the thermodynamic standpoint.

The trick is to implement all this thermodynamic theory in a real engine. How to keep the heat exchanger from freezing up with atmospheric moisture must be one of the key challenges of the design.:confused:

[Lyman]

Hi Fzz...

Many thanks for the great schematics. I had envisioned a turbo jet mode for aerodynamic flight; so actually there is pure rocket thrust only.

I see where the advantage is in pirating ambient oxidizer from the atmosphere, but one also gets 65% Nitrogen by volume, 5% water, and only 20% Oxygen.

Why not squirt Oxy in from the LOx tanks directly? What is shown is simply a 'supercharged' rocket chamber. Premixing Hydrogen and Oxygen in a chamber that relies on plumbing to exhaust its products through the engine to the chamber gives one great pause. I see a lack of technical respect for the energy contained in the preburner exhaust; it will not transit safely without great care....

At first glance, aren't we looking at RamJet technology that depends on a downstream compressor? Doesn't that defeat the concept of ram air?

If the compressor is utilized 'pre RAM', aren't we looking at thrust that is not sufficient at the outset to propel the airframe? If it is merely additive to a throttled down rocket in this phase, why not just throttle up the rocket?

If the purpose is to husband the Oxidizer, shouldn't the rocket simply not come on line until it is "pure"? Isn't a purely ballistic rocket well past most atmosphere with a velocity of 2.5 Mach? Not enough to heat the skin, let alone support air fed combustion? So a "derated engine" to launch a payload to escape velocity?

It will take some time for me to grok that....

I'm sure these questions are addressed by the developers, should I simply go to the thread Machinbird refers to? Should this one 'go to' Tech Log?

Many thanks Fzz.

BF

[A A Gruntpuddock]

"Anywhere on Earth within 4 hours"

Would all the passengers have to wear G suits - surely acceleration & stopping would be pretty traumatic?

[Nemrytter]

I fail to see how this is terribly different to the designs that we already use on rockets - yes you're cooling air instead of the chamber and nozzle but as long as you can get enough surface area exposed to the hot air then it's not that big a problem, in my opinion. It just seems to be a mix of technologies already in existence.
Still, maybe they're keeping the cunning part secret.:E

[cwatters]

Would all the passengers have to wear G suits - surely acceleration & stopping would be pretty traumatic?

If we assume longest flight is 20,000km then the average velocity needed to make it in 4 hours is about 1388m/s. If you accelerate at a comfortable 1g from a standing start you reach that velocity in just 139 seconds. No g suits needed if I've done my sums right.

[Torquelink]

I forget the details, but according to the documentary I watched they had some problem with the HOTOL patents preventing them from continuing to use the work they'd done there while developing the new engine, so this time they decided not to patent it at all and keep it a trade secret.

Watch for 2014 roll-out of Chinese Sabre-powered Skylon copy . . .

:)

[Lyman]

250Million? Dollars? "Mr. Bond, Alan Bond," needs to find a billionaire investor who hates Carbon (at least ostensibly), for this erm, 'project' must be worth its weight in Carbon credits.

Paging Mr. Gore..... Gore could turn around and sell credits for a billion. Nice tidy profit.....

Seriously, I am quite sceptical of the "pre-cooler". Slowing and cooling that massive inlet air......

Are the costs of the Carbon credits passed along to the 'passengers'? I feel like I've been taken for a 'ride', already.....

[fdr]

What the diagram doesn't show is what happens to the nitrogen from the air. Presumably this has to go though the engine too. Wonder what that does to the combustion chamber design - having nitrogen in the mix for the first half of the burn and not for the second?

nitrogen or He2 injection into the LOX is able to give a throttling of the thrust output, without having to change the geometry of the fuel injectors... on a standard engine. Passing N2 into the fuel continuously will lower the thrust output for a given fuel injector geometry, therefore the base geometry would need to be adjusted to accomodate that, and it would need to be variable as operation in rarefied atmosphere would alter the N2/LOX mixture, and would result in increasing thrust at higher altitude...