Reaction Engines

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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ladajo
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Reaction Engines

Postby ladajo » Fri Jan 31, 2014 2:09 pm

I was just checking up on these guys in regards to another project and found an interesting update.

They have signed CRADA with AFRL and also appear to be well on the way to a full engine prototype.

If this flies, which it looks like it might well, that means SSTO and increased access to space for manned flight. That in turn drives requirements for high density power solutions for increased burdens on persistnetly manned orbital complexes. I would think that small fission or workable fusion would get some increased attention as a result.

http://www.reactionengines.co.uk/news_updates.html
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

GIThruster
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Re: Reaction Engines

Postby GIThruster » Fri Jan 31, 2014 10:32 pm

Good news, but don't hold your breath for it to fly. They haven't even begun to work on anything but the engine, and the real work has all been in the heat exchanger. They're a long way from flying.

Still, it's good USAF has taken an interest.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

ladajo
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Re: Reaction Engines

Postby ladajo » Sat Feb 01, 2014 12:27 am

This past year has seen them develop beyond the heat exchanger.
They have aquired and stood up two subsidieries for manufacture of components.

If they don't test a full up engine by the end of the year, it will be front half of next year.

The heat exchanger was tested functional in 2012.

I think this engine will fly in about three years.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)

What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

GIThruster
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Re: Reaction Engines

Postby GIThruster » Sat Feb 01, 2014 1:54 am

What would it fly in? Can it be dropped into an existing frame? Last I saw of SABRE they were still using art work with landing gear that could not possibly support the mass of the craft. It's easy to get SSTO numbers if you cheat on things like the requirements for taking off.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Betruger
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Re: Reaction Engines

Postby Betruger » Sat Feb 01, 2014 2:07 am

Image
Paging Dr 93143
You can do anything you want with laws except make Americans obey them. | What I want to do is to look up S. . . . I call him the Schadenfreudean Man.

paperburn1
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Re: Reaction Engines

Postby paperburn1 » Sat Feb 01, 2014 5:50 am

GIThruster wrote:What would it fly in? Can it be dropped into an existing frame? Last I saw of SABRE they were still using art work with landing gear that could not possibly support the mass of the craft. It's easy to get SSTO numbers if you cheat on things like the requirements for taking off.


I think your still holding out for that polywell powered firefly class of ship. :D
I am not a nuclear physicist, but play one on the internet.

GIThruster
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Re: Reaction Engines

Postby GIThruster » Sat Feb 01, 2014 7:05 am

I am, just so long as I can get a bunk bigger than what Mal had. :P
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

93143
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Re: Reaction Engines

Postby 93143 » Sat Feb 01, 2014 7:19 am

Betruger wrote:Paging Dr 93143

Uh...

...okay. Let's do this.

GIThruster wrote:They haven't even begun to work on anything but the engine, and the real work has all been in the heat exchanger.

We discussed this a bit in this thread, but I suppose a little rehash never hurt anybody, and there were things that weren't said...

REL has done extensive work on the airframe. If you read the papers, it's obvious that it's much more than an artist's conception. The structure and TPS concept and layout is quite detailed. The truss framework has been designed to maximal load cases using a safety factor of 1.5. TPS samples have been tested, and Pyromeral Systems Inc. has been engaged regarding upgrading Pyrosic to System 2 standards. CFRP truss elements have been tested, and titanium composite truss elements have obsoleted the CFRP ones (a visitor to their booth at a recent show got to hold one, and accidentally threw it at the ceiling because it was so light - it was rated for 15 tonnes in compression). Local solutions for high heating rates have been developed, including a promising effusion cooling concept that seems to have replaced a liquid metal cooling solution on part of the leading edge of the wing which was subject to a shock-shock interaction. The whole airframe shape has been tested to Mach 12 in a wind tunnel, and high-fidelity reentry simulations have been done.

Shape-wise, Skylon seems to be a counterexample to von Tiesenhausen's Law of Engineering Design (#30). Everything about the external shape is an obvious result of engineering decisions. The fuselage is a modified Sears-Haack body, and the reasons for the modifications are clear (trim, tank volume vs. payload width, area ruling, OMS accommodation). The wing is a standard delta in low-wing configuration. The engines are mounted in nacelles at the wingtips to solve the centre-of-gravity problem HOTOL had without cooking the fuselage with the exhaust, and they're curved because of a mismatch between the desired angle of attack and the desired angle of thrust. The intakes are a simple shock-on-lip design that allow the bypass ramjet trick while eliminating spillage drag and providing just enough pressure recovery to maintain the compressor face at a nearly constant pressure over the whole trajectory; the translating spike design also allows them to be closed for reentry. The canards vs. tailplanes are less clear to me, but the D1 went with canards after messing with rear stabilizers for a while, so plainly it was an engineering decision, probably related to trim. The tailfin is apparently sized for engine out, if I'm reading the ESA report correctly... and that's the whole thing. No V-tails or cranked deltas or waverider shapes here...

Logistics have also been looked at. They envision a standard payload canister that would eliminate the need for clean-room conditions when loading. The User Manual has specifications for payload CoM limits, power supply, acoustic and thermal environments, and so on. Propellants are loaded subcooled to allow substantial holds without the need for venting. The OMS and fuel cells use hydrogen and oxygen, just like the main engines but stored in separate insulated tanks - no toxic hypergols. The 2-day turnaround time is currently driven by TPS inspection, and could potentially be reduced. And Mark Hempsell recently left REL to start a consulting firm to try to sell a universal docking standard that doesn't suck, which could be used on everything from satellite deployment and refueling mechanisms to moon base modules.

Skylon C1 was only a proof of concept, but still involved a lot of design work and bench-scale risk reduction. In contrast, the D1 design effort was/is an attempt to come up with a high-resolution design that is essentially guaranteed to meet its payload target. It is reportedly "consistent with" AIAA standards for mass growth margins, and incorporates a 2.5-tonne performance margin on top of that. It benefits heavily from the new SABRE 4 thermodynamic cycle, which wastes a lot less hydrogen than previous iterations; it turns out this broke their old trim strategy from C1 (which involved draining the rear hydrogen tank first to counter forebody lift at high Mach numbers) and they had to rework it, resulting in some subtle changes in the shape. Last I heard it looked like about a 325-tonne vehicle (with margins) with a 15-tonne payload (also with margin). Oh, and apparently due to the better engines and larger wings, it's now expected to be capable of intercontinental self-ferry on straight hydrogen...

As for the engine, it's not just the precooler they've been working on. They've done experimental work on contra-rotating helium turbines, air cooling and LOX cooling of rocket combustors, high-temperature SiC secondary heat exchangers and their manufacture, a preliminary inlet design that was tested in a wind tunnel... even a nonessential like the expansion-deflection nozzle has been bench-tested and is shortly getting a dedicated sounding rocket (the Valkyrie) to try it out over a Skylon-like trajectory with Skylon-like exhaust (the thing is an ammonia/nitrous/LN2 triprop!). The thermodynamic cycle itself is on its fourth major revision since the Rolls-Royce RB545, and at least two detailed computational models of the previous iteration are publicly known to exist, one at REL and one at the von Karman Institute.

GIThruster wrote:What would it fly in? Can it be dropped into an existing frame? Last I saw of SABRE they were still using art work with landing gear that could not possibly support the mass of the craft. It's easy to get SSTO numbers if you cheat on things like the requirements for taking off.

Okay, let's see your calculations.

Skylon is not "art work". It's the product of a decades-long low-level design effort that has involved an attempt to get the landing gear mass down, largely because the HOTOL team had such a bad experience with the launch trolley idea. The big issue was apparently braking energy during an abort, which the water cooling solves. And the ESA did look at the airframe design, including the landing gear, and concluded that it made sense.

From erblo on the other thread:

ESA assessment report wrote:6.9 Undercarriage

A water-cooled under carriage is assumed as, without it, the brakes were originally sized by the abort case fully laden. Nitrogen (N2) is used for inflation. High pressures are required for takeoff however; for landing, the vehicle only needs around 5 bar, 66kg of N2 is required for take off and it is foreseen to vent to the lower pressure level for the trip to orbit (The effect of a failure to depressurise is not assessed but the mass penalty will be small).With water cooling, the brakes are now sized by the landing to 25.8 kg per wheel.

From you, on the other thread:

GIThruster wrote:That landing gear looks like it came off the Concord, not off a cargo plane which is what the mass of a loaded Skylon would be like. It needs landing gear like a C-17 or C-130--short and heavy with huge tires. If you put the kind of weight necessary for a fully loaded Skylon on the kind of gear they have portrayed, it would snap like a twig; and the people who did the drawing know this.

Actually, Concorde is 68% of the mass of Skylon C1 and 4/5 of its length. In other words, the static compression loads in geometrically similar landing gear (scaled with vehicle length) would be on average maybe 6% higher for Concorde. There are dynamic loads and bending moments to consider, of course, and of course the Skylon gear isn't just a scale-up of the Concorde gear, but this plainly isn't the sort of situation where someone with little or no real engineering experience or training could simply glance at the design and know that it's wrong.

Remember, the vehicle is mostly full of liquid hydrogen, and the heavy stuff (engines, LOX tanks, payload bay) is all clustered around the wings and main gear. It's not as heavy as it looks.

It is a big aircraft for such a low footprint. That's why they need a specially strengthened runway. Cargo planes can't require that, so they make sure not to overload the ones they want to be allowed to use.

...

Skylon D1 actually seems to have enough margin to triple the mass of the undercarriage, assuming nothing else goes wrong. But I don't expect them to have to do that.

ladajo wrote:If they don't test a full up engine by the end of the year, it will be front half of next year.

Unless you have information I don't, I wouldn't expect the SABRE to actually be ready for testing that soon. Last I heard they were targeting 2017 for stand testing. I'm not sure they'd be able to get a test stand ready this year anyway - it's a big engine, and loud.

It is encouraging that they got enough investment this time around to make them decide (provisionally) to forgo the subscale demonstrator, which wouldn't have been representative in some ways, and go whole hog...

Oh yeah, that reminds me:

GIThruster wrote:SABRE is billions away from happening

Actually, it looks like an investor commitment of less than £400M is enough to go for the full-scale prototype...

GIThruster
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Re: Reaction Engines

Postby GIThruster » Sat Feb 01, 2014 8:29 am

I bow to your obviously superior knowledge on this subject. It has been several years since I examined Skylon and I was never exposed to this kind of detail.

I am still skeptical of the landing gear and noted you're comparing against C1 and not D1. Are the numbers similar and are you sure those weights are of fully fueled craft?

Still, count me astonished they have come so far. And the target cost. . .can you imagine what NASA would need to accomplish such a thing? Tens of billions at least. . .and they would lie about it. . .and they would deliver a decade late. I just can't say how disappointed I am NASA has made themselves so irrelevant.

Did you know the first gen Solid Rocket Boosters for the Senate Launch System are throw away? More evidence that NASA is in the pocket of the military-industrial complex and everything Eisenhower warned us about is coming true.

"This conjunction of an immense military establishment and a large arms industry is new in the American experience. The total influence — economic, political, even spiritual — is felt in every city, every statehouse, every office of the federal government. We recognize the imperative need for this development. Yet we must not fail to comprehend its grave implications. Our toil, resources and livelihood are all involved; so is the very structure of our society. In the councils of government, we must guard against the acquisition of unwarranted influence, whether sought or unsought, by the military–industrial complex. The potential for the disastrous rise of misplaced power exists, and will persist. We must never let the weight of this combination endanger our liberties or democratic processes. We should take nothing for granted. Only an alert and knowledgeable citizenry can compel the proper meshing of the huge industrial and military machinery of defense with our peaceful methods and goals so that security and liberty may prosper together."
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

93143
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Re: Reaction Engines

Postby 93143 » Sat Feb 01, 2014 9:36 am

GIThruster wrote:I am still skeptical of the landing gear and noted you're comparing against C1 and not D1. Are the numbers similar and are you sure those weights are of fully fueled craft?

Well, we have no pictures of D1, so it's hard to say what exactly the landing gear looks like...

And yes, those are fully-fueled weights. C1 was 275 tonnes at start of takeoff roll. D1, last I heard, was looking to be about 325 tonnes. Concorde's max taxi weight was 187 tonnes according to Wikipedia...

Did you know the first gen Solid Rocket Boosters for the Space Launch System are throw away?

Yes. But it was never cost-effective to retrieve and refurbish them even at Shuttle's realized flight rate.

ladajo
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Re: Reaction Engines

Postby ladajo » Sat Feb 01, 2014 1:12 pm

Yes, the test stand/complex. I forgot about that.
I move my mark to late 2015. I think they may surprise us all.

Lots of ground level work completed, and significant portions of the advanced work are done or in progress.

As for flying the engine. It does not need a Skylon to fly on. It can fly on a test vehicle.

As for Skylon flight, that is more like 2025 IMHO.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)

What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

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Re: Reaction Engines

Postby Aero » Sat Feb 01, 2014 8:21 pm

As for flying the engine. It does not need a Skylon to fly on. It can fly on a test vehicle.


Interesting thought.

What would constitute a valid flight test vehicle and where would we find one? Physically the Sabre engine is huge and it gulps propellant.

Add: My vote is to build a full capacity engine test bed flight vehicle. That would most likely be a full sized Skylon engineering development flight vehicle, something less than a prototype. Using such a vehicle would have some advantages.

1 - Avoids the problems of constructing a subscale Sabre engine for engine testing.
2 - Avoids the problems of constructing a subscale Skylon airframe for subscale engine testing.
3 - Provides a platform for testing throughout the subsonic, transonic, supersonic and hypersonic flight without expectation of orbital capability.
4 - Allows the construction of a robust (and maybe heavy) airframe with a very useful result.
5 - Allows real world heavy brakes and landing gear on the test airframe.
6 - In fact, maybe the Mach 5 LAPCAT airframe would work as a Sabre test bed. Unfortunately that airframe takes 4 Sabres. I still vote for full sized Skylon engineering development flight vehicle.

JMO
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93143
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Re: Reaction Engines

Postby 93143 » Sat Feb 01, 2014 10:39 pm

ladajo wrote:As for Skylon flight, that is more like 2025 IMHO.

Maybe. They say the first prototype could fly in 2020 given ideal funding availability, but 2022 is more likely. A few slips could put them at 2025...

Aero wrote:In fact, maybe the Mach 5 LAPCAT airframe would work as a Sabre test bed. Unfortunately that airframe takes 4 Sabres.

It takes 4 Scimitars. It's much bigger than Skylon, and much harder to design (lower minimum component/subsystem TRL). If it's a boilerplate test vehicle you're after, a Skylon-like one would probably make a lot more sense.

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Re: Reaction Engines

Postby Aero » Sun Feb 02, 2014 5:09 am

If it's a boilerplate test vehicle you're after, a Skylon-like one would probably make a lot more sense.

Is that what it would be, a boilerplate test vehicle? I don't know about the name but I want a vehicle with enough hydrogen/ lox capacity to reach the flight regime where the Sabre can transition to full rocket mode. That means a hypersonic flight vehicle but not one designed for the hard part of reaching LEO. Just enough to be able to check out the engines and maybe confirm some of the flight characteristics of the Skylon. And of course rugged enough to fly a lot of test missions so that the engines can be checked out thoroughly. How nearly that describes a prototype I'm not sure, but I think a Skylon prototype airframe would be to delicate to withstand all of the flights and especially landings that will be needed for the engine test program. And you can't strap a Sabre engine on just any old airframe.

I guess a "Skylon-like boilerplate test vehicle" will serve as a name until a better one comes along.
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Re: Reaction Engines

Postby 93143 » Sun Feb 02, 2014 11:56 pm

Aero wrote:
If it's a boilerplate test vehicle you're after, a Skylon-like one would probably make a lot more sense.

Is that what it would be, a boilerplate test vehicle? I don't know about the name but I want a vehicle with enough hydrogen/ lox capacity to reach the flight regime where the Sabre can transition to full rocket mode. That means a hypersonic flight vehicle but not one designed for the hard part of reaching LEO. Just enough to be able to check out the engines and maybe confirm some of the flight characteristics of the Skylon.

The latest plan I can find (early/mid-2012) was to have:

1) a nacelle test vehicle (NTV) to test the inlet in flight up to Mach 4.5. It would be a standard aluminium monocoque design with a nominal TPS and a pressure-fed rocket engine. Much smaller than a real Skylon; the concept renders have the nacelles looking cartoonishly large...
2) a pair of boilerplate Skylons, or "Y-planes", with real SABRE engines. Probably not orbital. Referred to as "full-scale development vehicles", probably because they are test vehicles for Skylon as a whole rather than just SABRE (which can be more or less fully tested on the ground).
3) a pair of production prototypes, fully orbital, for the qualification test flight programme. Between them they do more than 400 flights, including 30 abort tests.

They were considering not doing the NTV if ground testing looks capable enough, and the plan in general seems to be a bit in flux, so I'm not sure what they'll eventually end up doing.

And of course rugged enough to fly a lot of test missions so that the engines can be checked out thoroughly. How nearly that describes a prototype I'm not sure, but I think a Skylon prototype airframe would be to delicate to withstand all of the flights and especially landings that will be needed for the engine test program.

Why? The production models are supposed to be able to last for 200 orbital flights without a significant decrease in reliability, so if the prototype can't, we have a problem and it needs fixing. Considering that the engine is not a scramjet and doesn't need to fly to be tested, I can't imagine the engine test programme requiring more than that...


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