New Engine Technology

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

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303
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New Engine Technology

Post by 303 »

nothing to do with polywell or lenr , interesting nonetheless,

http://www.theengineer.co.uk/news/sabre ... 83.article

Skipjack
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Post by Skipjack »

Yeah, they have been arround for a very long time. Glad that they got another big milestone done. Now they should just go an build it already!

GIThruster
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Post by GIThruster »

They're still looking for money.

http://www.huffingtonpost.com/2012/11/2 ... mg00000029

and that's not enough to build the plane, just they hope the engine.

And still they're stuck with the common sense analysis that Musk has offered each time asked abut Sabre. What you want to do with going to orbit is get out of the atmosphere as quickly as possible, because its like soup, and get in relative vacuum where it's easier to go fast. The weight that Sabre loses because it doesn't have to carry all its oxidizer, it loses by staying in atmo, breathing mostly nitrogen, and having this huge intake that is essentially a break. For very small possible advantage you have enormous complexity and maintenance. Not a good trade.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Skipjack
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Post by Skipjack »

I do understand Musks reservations, but there are also some operational advantages that should not be forgotten. Plus the technology is said to increase the fuel efficiency of jet engines for atmospheric flight as well and allows for efficient hypersonic flight. So there is a lot of uses for this technology. We will see whether all that will really result in anything any time soon. The development cost sure is enormous.
From what I understand though, they did get the money for the development of the full engine from investors already, but it was tied to the validation that they now have.

GIThruster
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Post by GIThruster »

SABRE always reminds me of VASIMR and TRITON. All of them are "just engineering" in that there are no new physics involved. One expects you can just throw money at the problem until its solved. The problem comes when it's private money and the program is at risk every day. If instead of half a billion you need a billion to solve the issue, that can scrap the entire investment. The people raising the funds and doing the work get paid either way, so no harm no foul. They get to do what they love to do as long as the money comes in. The problem only comes when the investors have extended themselves too far and can go no further. If they don't find people to buy in, they lose everything.

And really think about it: for a billion dollars you could have VASIMR before SABRE and you could have TRITON as well. Since SABRE is at very best only a marginal advance beyond Falcon/Merlin tech, and probably will end up costing far more, wouldn't TRITON be a far better investment?

And of course if you are willing to gamble, isn't M-E tech far more promising than any of these and the investment a tiny fraction? Sometimes I think SABRE has gotten the support it has merely because it's a British enterprise. That is after all why during each interview Musk had in the UK, someone asked what he thinks of SABRE. There's a lot of pride tied up in that project.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Skipjack
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Post by Skipjack »

TRITON and VASIMIR can not take the place of SABRE. They are not suitable for transport to orbit, which is the biggest problem right now. I would not bother with a mission that requires TRITON or VASIMIR, unless we have solved the transport to orbit.
ME- tech would be great for that and I wished they had more funding for the research.

303
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Post by 303 »

reservations yes, about any technology, but at least sabre provides observable propulsion; more than can be said for this mach effect GIT is so fond of

GIThruster
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Post by GIThruster »

Yeah, we'll see about what SABRE can do after another couple hundred million dollars investment.

M-E tech hasn't had $10 investment past the people involved. That's the way Jim wants it.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

cgray45
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Post by cgray45 »

GIThruster wrote:SABRE always reminds me of VASIMR and TRITON. All of them are "just engineering" in that there are no new physics involved.
I'd like to take some issue with this-- there have been many programs, where the "just engineering" part actually turned out to be the stumbling block. We think Sabre will work, but until there is a 1:1 model actually working, nobody can say it for certain.
Check out my blog-- not just about fusion, but anything that attracts this 40 something historians interest.

zDarby
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What to do with SABRE

Post by zDarby »

In 1995 Robert Zubrin and Mitchell Clapp wrote an article in Analog Magazine, "Black Horse: one Stop to Orbit":
http://www.risacher.org/bh/analog.html

In short, the paper described the design of a rocket plane that would take off the runway with enough fuel (in this case, JP-5) for the entire mission (in this case, a trip to LEO for itself and its crew but little or no payload) but only enough oxidizer (in this case, hydrogen peroxide) to take off, go to 40,000 feet and then land under power. Once the plane got to 40,000ft it would rendezvous and connect up to a tanker plane that would fill it with oxidizer. The plane would then detach, circle around the tanker and complete its mission burn to LEO. Once its mission was completed, it would deorbit and land at any runway was needed.

But the paper didn't finish there. It also described what they hoped might be possible later. This included an engine that burned hydrogen and breathed air to mach 5.5, then switched to rocket mode to complete its orbit.
http://www.risacher.org/bh/images/analog-f5.png
This hard-to-read graphic claims such a rocketplane could achieve a payload/dry-mass ratio of 0.45. Of course, that's assuming an ISP of 450 seconds --not likely. But even a far more likely 385 sec --represented in the graph as CH4/O2-- the ratio is close to 45%. This is outstanding. And I think it's kinda crazy to go the Skylon course --as well designed as it is-- when a Black Horse, stage-and-a-half flight plan seem just as possible.

With a Black Horse flight plan, SABRE engines and Stratolaunch tankers, the inner solar system would be ours for the colonization....IMHO.

KitemanSA
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Post by KitemanSA »

Add a HASTOL or hypersonic skyhook and things get REALLY cheap.

Oh, and a kite-launcher would do most of what the mach 5.5 craft would do, and maybe more.

Skipjack
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Post by Skipjack »

I remember the Black horse, or Pioneer rocket plane which all used that technology. Of course I have to wonder why they think that you would save that by doing the refueling. The energy needed to reach the altitude and speed until refueling is minor compared to the energy needed to continue to orbit from there. For the same reason Elon Musk is sceptical of Skylon and I have to somewhat agree with him. Also read up on HOTOL and HOTOL2 in this regard and how they switched concepts, because of these notions. Now Skylon is switching to pure rocket mode at much higher speeds and altitude than any of the other concepts. So I think that it will do a better job. It certainly is better than nothing (which is what we have had for the past 30 years) in regards to RLV technology.

KitemanSA
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Post by KitemanSA »

Skipjack wrote:Of course I have to wonder why they think that you would save that by doing the refueling.
For the same payload, the vehicle could be MUCH lighter and smaller because it didn't need the take off with all the oxidizer. The landing gear could be lighter, the ox tank could be thinner, they wouldn't need the fuel and oxidizer to lift those items so the two tanks could be smaller and lighter still...

The numbers worked out right.

Jded
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Post by Jded »

GIThruster wrote: And still they're stuck with the common sense analysis that Musk has offered each time asked abut Sabre. What you want to do with going to orbit is get out of the atmosphere as quickly as possible, because its like soup, and get in relative vacuum where it's easier to go fast. The weight that Sabre loses because it doesn't have to carry all its oxidizer, it loses by staying in atmo, breathing mostly nitrogen, and having this huge intake that is essentially a break. For very small possible advantage you have enormous complexity and maintenance. Not a good trade.
Well, the reusable version of Musk's rocket is supposed to stage at Mach 6, about where Sabre goes to rocket mode. Saving the equivalent of 80% of first stage's fuel mass is quite a lot (half the take-off weight?). Not to mention that operating an airplane that can glide without power and can turn back at any point of flight envelope should be more convenient (=cheap) and safer than operating a rocket, even a reusable one. Not to mention SSTO has it's own advantages in reusability.

Of course Musk is ways further towards his goal, and if he achieves it, it would be harder for Skylon to justify the huge investment (paying back R&D costs needs operating near current launch costs at least initially), though on the other hand maybe the market will finally grow...

Skipjack
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Post by Skipjack »

For the same payload, the vehicle could be MUCH lighter and smaller because it didn't need the take off with all the oxidizer. The landing gear could be lighter, the ox tank could be thinner, they wouldn't need the fuel and oxidizer to lift those items so the two tanks could be smaller and lighter still...
But how much less oxydizer is that really? Think about how small of a raction of the energy required to reach orbit is spent by the time you have reached the altitude and speed for refueling and then you are going to be stuck at that for a while, while you are refueling, burning more fuel that would otherwise be used to reach orbit. I just dont think that it gains you THAT much. I think that you will gain something, but would the gains justify the effort?
Well, the reusable version of Musk's rocket is supposed to stage at Mach 6, about where Sabre goes to rocket mode. Saving the equivalent of 80% of first stage's fuel mass is quite a lot (half the take-off weight?).
I would assume that it is much less than 80% of the first stage fuel mass.
You still need to burn H2 and you have to fly through the atmosphere for longer while you are accelerating thus exposing the vehicle to more drag.
Plus H2 tanks are larger than RP1 tanks due to the lower density of H2. That means even more drag.
All that will cost you. You might save some LOX, but you will spend more H2. I still think that Sabre and Skylon make sense (I am sooo eager to an SSTO), but it is not going to be that huge of a gain as some assume.

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