Polywell: We'll know in 7 months time?!

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

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Betruger
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Post by Betruger »

Alan Boyle wrote: But now, with more Navy money on the line, Nebel has been constrained from saying anything about the project.

ladajo
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Post by ladajo »

Nebel is busy. Polywell is NOT classified, I promise.
Be patient boys.
It's almost Christmas, maybe Rick will give us a stocking stuffer.

Converting current ships to Polywell is not practical cost wise. It is possible that conversatoin of a CVN may be cost effective (with some time for payback), SSN's could go either way. Hard telling unless yourun some hard numbers. And cost estimates on submarine renovations are hard to pin down. I don't think anyone has a hard number on what was spent on Parchee's hull mods. It got a little silly.
The new ship design (DDX) is electric drive. That would be more feasible to work int ot the build program. Burke's are about done for build cycle. They have 4 LM2500 GTE's running two per plant. There is no space for a polywell/direct convert/electric drive, and certainly not a polywell/steam configuration. Electric direct drive (reductionless) may play, but it would mean a total gut and rebuild of the engine room, and it still may not fit.
Fact is, an LM2500 module just ain't that big. You could gain some real estate from the air intake and exhaust systems for the GTE's, that is a fairly large chunk of space. But, the support systems, and power conversion package (steam or direct) would certainly task the engine room volume. Unless someone comes up with some whamadyne High Temp, High density superconductor magnets in the next ten years, it will be too late to get a polywell small enough to retro into the existing DDG platforms. DDG51 popped out of new construction in 89, the first flight of the class is rapidly approaching long in the tooth status. In contrast, the Perry Class FFG's finsihed their build cycle in 89, and might actually be better platforms for a trial conversion to polywell. The Main Engine Room, is easy to access and the superstructure is aluminum, much easier/cheaper to work with for a conversion overhaul than the all steel DDG's.
My money is on the last of the DDG's, or DDX as a test platform if polywell proves out as a viable system in the near future. Otherwise, CVX, or what comes after DDX (it will be a short build program). LCS is not a player. A submarine refit might play, but the cost would be RIDICULOUS. Gutting a reactor compartment, and then restuffign with polywell to drive the steam plant...my goodness, what a contract that would be.
Polywell may well have to wait to for a ship designed around it, the expense (artificial and real) of retro'ing it into existing hulls, mmmm, I think not.
Of course all that said, I would love to see a BB un-museumed, and stuff polywell into that...now that would be COOL! Can you say flying volkswagon? How about nine of them at the same time? That will get your attention if you are misbehaving.

Betruger
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Post by Betruger »

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TallDave
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Post by TallDave »

There is no space for a polywell/direct convert/electric drive, and certainly not a polywell/steam configuration.
How big are you asuming they need to be?

ladajo
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Post by ladajo »

With current technology, I think we are well established with the 1.5M (say 4.5ft) minimum (D-D), 3M (say 9.5ft) (pB11)for the Magrid. For an overall power producing D-D "primary" plant, I keep a high bay two car garage volume (roughly 20x20x15ft) in mind. But this does not really account for a full up steam secondary or power capture system. This space requirement is obviously dependant on pB11, and steam or direct conversion. Steam = More Space Requirements.
<cue hand waving for following discussion>
For an actual marine polywell, from Magrid we start adding layers (neutron energy capture <water?> or direct conversion), culimnating in the vacuum chamber wall. I think that you are looking at a core reactor system (read vacuum chamber) of at least double or more of the Magrid itself. Things we still don't know in this realm include vacuum gaps to limit arcing (driven by steady state gas denisities, interfering system equipment obstructions, etc.) for a steady state polywell. I default to more space is better in this case, although it certainly drives up your vacuum system requirements. Now add the actual support systems to operate the magrid reactor, vacuum system, magnet power sources (must include ability to start up plant from all lights off condition to steady state, ie: big battery bank (not ideal) or GTG/SSDG(better) setup with enough nut to drive the polywell and support systems as well as if not propell the ship, then at least fight the ship to some degree), polywell and line shaft cooling support (pumps/heat exhangers), line shaft equipment (thrust and line shaft bearings, plus support), reduction gears (big chunk-o-metal/space), space for line Shaft drive motors on front end of reduction gear, or space for direct drive line shaft mounted electric motors (spac gain from removal of reduction gear), lube oil/oil cooling for rotating machinery, air services (GTE/SSDG startup suuport), fuel supply/storage (interesting point here, as to what would happen to existing bunkerage tanks ISO polywell), ER control and monitoring systems and stations, controllable pitch system (maybe not needed for electric drive, but the navy loves the ship stopping/reversal capability of it), hydraulics, etc. For arguments sake the main engineering spaces in a DDG equate roughly to about a 100ft by 50ft by 40ft tall volume. It is a similar volume on an FFG (narrower 45ft beam vice 59(max) on DDG)/taller), but has essentially the same schtuff in it. An SSN is about 280ft of people pressure hull, with about 180 or so of it ER. About 50ft of that is RC with a 33ft (effective 32ID) diameter.
Short of the long of it, a Polywell primary may well fit into the "notional volume", however, alot of stuff is already there, and a good bit of it will need to stay in some fashion. The gut/re-arrange of the package is a lot of work and money. Plus you start to mess with ship stability at that scale, and it will have to be taken into account as well.
This is where I have been thinking, for proof of concept, if you are going to use an existing hull, maybe an FFG would be a good call. Steel hull, aluminum superstructure, one engine room, single shaft/prop, easier access, less stuff to mess with. Much less cost and navy mission impact overall as a proof of concept platform than a DDG, SSN or CVN. Plus, if you have issues, you can re-work at much less cost than the others. The other choice would be DDX. Risky technology leap already in that one, adding polywell could tip the risk equation enough to set the navy up again for another build program failure.
<hand waving ends here>
:)

MSimon
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Re: Polywell on ships

Post by MSimon »

DennisP wrote:
Regarding crusiers and amphibious assault ships, would a polywell reactor be cheaper to buy/operate than gas-turbine or diesel turbines + electric motors? Would it require similar or smaller crew sizes? Would the increased time it could run without resupply be operationally significant for the missions those types of ships are usually sent on?
I have a buddy on an aircraft carrier. He says that polywell fusion would revolutionize naval warfare.

Nuclear carriers are among the fastest ships in the world. Top speed is classified, but they can go really amazingly fast, for as long as they want, without ever refueling. The trouble is, a carrier likes to be surrounded by the other ships in the group, and those ships can't keep up. Their top speed is a lot lower, and even the top speed they have is very expensive in fuel. So the carrier ends up mostly going at a pace that's economical for oil burners, and only really opening up for occasional quick maneuvers.

That's why the Navy is interested in Polywell.
Yep. I'm a former Naval Nuke and have been a Polywell fanboy since I found out about it. I know exactly what a Polywell plant would mean for fleet operations. It was discussed a lot at NASA Spaceflight as well as here from time to time.

One thing is that it will cut operator training time in half. Three months theory. Three months operational training.

And the above is not even the best. The fuel is so cheap that high tonnage 50 or 75 knot vessels could be contemplated. Four ships and you can move a division any where in the world in 7 days or less. Another division 14 days later etc. The Army will take on some of the characteristics of Marines.

It would mean the relaxing of some of our forward deployment commitments.

===

ladajo,

Thanks for all that.
Engineering is the art of making what you want from what you can get at a profit.

MSimon
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Post by MSimon »

I see a CV conversion as a first step. If the Navy is going to get cautious: one engine room.

As far as start-up. I think a 1 MW DMG set would do the trick With a 5 MJ flywheel for start-up. At 100 KW for the flywheel you could do 1 start up a minute.

Of course you might want a bigger DG for other loads. You can get 5kts from a very modest amount of power.
Engineering is the art of making what you want from what you can get at a profit.

KitemanSA
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Post by KitemanSA »

ladajo wrote:Converting current ships to Polywell is not practical cost wise.
Truly depends on final size. Recent SC magnet work suggests a 100MW plant may be smaller than the 2m radius previously suggested.
ladajo wrote: It is possible that conversatoin of a CVN may be cost effective (with some time for payback), SSN's could go either way. Hard telling unless yourun some hard numbers.
They work now with fission. Why mess with a working system until last?
ladajo wrote: The new ship design (DDX) is electric drive. That would be more feasible to work int ot the build program.
Taking this to it's logical conclusion, I have wondered whether the CG(X) delay is related to Polywell. There is a law that says it must be nuclear unless... The law doesn't say it must be fission.
Further, a recent GAO report has indicated that L-Ships could be viable for nuclear fission plants if oil reaches a steady $170/bbl. There's plenty of space in them thar hulls. I suspect they would use a Polywell nicely, if Polywell is cheaper than fission (and I can't see how it wouldn't be if it works).

ladajo
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Post by ladajo »

L-Ships are a good place for polywell. However the current build program is the LPD17 class, 4MPDE, and 5 SSDG. They would need to convert to electric drive as space layouts don't really support steam. That means pB11 is the better way to go.
As for speed, full displacement hulls have a theorectical speed limited by the length. Hull Speed = 1.34 * (LWL) to the power 1/2.
The 1.34 can be up to 1.54 for conventional hulls, and is a function of the length width ratio. Standard cruiser style hulls (read warships) fall into this constant.
What this really means is that a ship can only go so fast for its length, and then it must go on step. The bow wave falls back and merges with the stern wave, and the ship must climb out of the hole. It takes a phenominal amount of horsepower to get a ship up on plane. We do not have the techology to push full sized ships up yet, not horsepower, but shaft torque and propeller limitations.
Now, we could go to large scale hydrofoils, or catamaran/trimaran style hulls with "holy-cow" jet drives. But this is not really feasible for current full size ship designs. The LCS Trimaran stlye has some deep ocean stress issues just like its high speed ferry cousin. Not really meant to run at speed in deep ocean swell and sea states.
With consideration, I am thinking that an FFG test bed might play. CGX is dead in the water, funding issues. If we are lucky, we will get 3 DDX hulls.
A BBP, would be really cool though, love the picture.

kunkmiester
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Post by kunkmiester »

A BB would also have plenty of space for the capacitors and stuff needed for rail guns and lasers and the like.

Could you imagine 9-12 megajoule class rail guns? :shock:

A pity we couldn't armor them properly, the equipment to make armor plating that thick that big has been gone for decades.
Evil is evil, no matter how small

energyfan
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Post by energyfan »

kunkmiester wrote:A BB would also have plenty of space for the capacitors and stuff needed for rail guns and lasers and the like.

Could you imagine 9-12 megajoule class rail guns? :shock:

A pity we couldn't armor them properly, the equipment to make armor plating that thick that big has been gone for decades.


you mean we don't have the technology to make instruments we made in the past / that sounds odd some guys in a factory could probably remake whatever it was the metal armor things are

olivier
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Post by olivier »

ladajo wrote:Polywell is NOT classified, I promise.
I remember that the DOC has a specific legislation which prohibits exports not because of the technology itself, but because of its end-use. Among the restricted end-uses is naval nuclear propulsion (for instance this restriction is famous for appearing on many software licenses).
A US Navy Polywell looks very much to me like a naval nuclear propulsion end-use. Publishing anything on an open forum looks very much like an export. So, I am not an export control expert but I cannot see how this could be allowed. Has anyone a better understanding of this?

chrismb
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Post by chrismb »

Microsoft OS could be used to manage the operation of a nuclear powered ship. Does that mean I could petition US Govt for them to stop Bill Gates shipping us his software!? I could see certain benefits in that regard!!

I think that would be a very selectively-used condition; it could pretty much cover anything you like. I guess the real question is how much profit is there in allowing it to ship!

D Tibbets
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Post by D Tibbets »

chrismb wrote:Microsoft OS could be used to manage the operation of a nuclear powered ship. Does that mean I could petition US Govt for them to stop Bill Gates shipping us his software!? I could see certain benefits in that regard!!

I think that would be a very selectively-used condition; it could pretty much cover anything you like. I guess the real question is how much profit is there in allowing it to ship!
That has been done with various software packages. Certain levels of encripting has been forbidden in export versions of software, based on the foolish assumption that forgeners were too stupid to do it on their own.
Or more acuratly, that they woud be too lazy to protect their data beyond that aviable it the export software product, and thus be more vunerable to snooping.
Dan Tibbets
Last edited by D Tibbets on Mon Dec 07, 2009 1:38 pm, edited 1 time in total.
To error is human... and I'm very human.

D Tibbets
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Post by D Tibbets »

We will know in seven months, 18 months? Perhaps. The same could be said that we will know 12 months ago- the time the review of WB7 was completed. Certainly more diverse and detailed data leading to more confident and acurate predictions will be aviable, but not nessisarily to us!

Our speculations and expectations may be mostly dependant on examination of details of contracts. The saying goes something like-"If you want to know the truth, follow the money trail". Of course, if that was always accurate, the Tokamak approach would have to be absolutely certain.

Dan Tibbets
To error is human... and I'm very human.

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