Talk:Pykrete

Moved from a bad edit to the main article:

FWIW: This reference documents some of the "citation wanted" tags in the pykrete article.

I don't seem to have the book any more, but this is how it appears in the British Library site:

LAMPE, David. Pyke, the Unknown Genius. [With plates, including portraits.] 1959 010601.a.14.

Hope that helps someone! Sorry, I don't know offhand how to edit this to taste. Possibly someone at your end can use the information at leisure.

Cheers,

Jon

--Ry Jones 18:29, 6 October 2007 (UTC)

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Is this a myth?

http://www.GoodeveCa.net/CFGoodeve/pykrete.html

The test ship made in the canadian rockies was just regular ice, not pykrete.

Pykrete can be made using any fiberous material. You are not limmeted to sawdust or woodpulp.

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how long is "quite a while" ?--GregLoutsenko 18:27, 10 Jun 2005 (UTC)

Cold compress of pykrete

The article suggests, "You could use it to make cold compresses that mold to your body and last quite a while." Maybe I'm wrong, but wouldn't the low thermal conductivity of pykrete (i.e. why it melts so slowly) prevent the "cold compress" from doing its intended job? To be effective, a cold compress should be thermally conductive, draw heat from your body, and melt itself rather efficiently, shouldn't it? --Ds13 July 3, 2005 05:03 (UTC)

Actually, no. If you wanted a compress to absorb as much heat as possible as quickly as possible, you would apply ice directly to your skin. That would be uncomfortable, of course, so people insulate the ice (making it melt more slowly) with a thick cloth. What you want is for the compress to absorb some heat for a long time, which Pykrete might do just fine in a thinner cloth. --Tysto 07:19, 11 November 2005 (UTC)

mix ratio

14% by volume or weight? volume would be mostly ice, weight would be predominantly sawdust.

I used a 50/50 mix of water and shredded wood mulch by volume and had excellent results. Since wood is lighter than water (it floats) the weight is predominantly water. I am currently soaking the wood at room temperature until it is water-logged to see what effect it may have when frozen.

Do you have any idea as to the weight of the mixture itself? (say per square inch?)

Sorry, I don't have any way of weighing the mixture. According to the web, one cubic inch of water weighs 0.036126842 pounds so the mixture would weigh half that plus the weight of the wood which is significantly less than the weight of water alone.

–== Freezing/melting temperature? ==

When the pykrete melt and freeze? Because if the ship was made then this might effect the areas it can travel to.

It was going to have cooling pipes running throughout the ice, making it, in theory, last indefinetly.--Lewk_of_Serthic 16:07, August 29, 2005 (UTC)

Wouldn't a lot of pipes be needed? If Pykrete conducts heat badly, the cold of the pipes would not reach afar. --Error 17:17, 1 October 2005 (UTC)

Yes it would need many cooling pipes, but such a large floating platform would allow for a very large cooling plant, at least according to the theory. The ineviatable melting could simply be repared with water taken from the sea, again, in theory.--Lewk_of_Serthic 22:06, 24 October 2005 (UTC)

The term "cooling pipes" is probably misleading anyway. It would make sense to mold sections of the ship with channels, in which case, you could have as many as you want. As for its operating area, it's unlikely that anyone intended the Habbukkuk to venture into tropical waters. In the North Atlantic, it would last indefinitely. --Tysto 07:19, 11 November 2005 (UTC)

Nope -- part of the problem was the vast amount of steel that would be needed for the refrigeration plant and its piping... apparently on the order of what would be required for an equivalent conventional carrier! Pete G. 128.32.198.8 00:00, 17 December 2005 (UTC)

According to The History Channel, the cooling pipes were made of cardboard. Josh-Levin@ieee.org 14:58, 13 February 2007 (UTC)

Agreed. The problem with ice (and pykrete) is that it creeps under pressure. So if you just form channels they will close up over time. That's why you need steel pipes for refrigeration. -- Derek Ross | Talk 00:15, 3 May 2006 (UTC)

I'm wondering if the stuff could be used as a coolant for inside of a cooler since it lasts longer then ice --Atomic1fire 20:11, 26 August 2007 (UTC)

Does anyone know how long it takes for pykrete to freeze? ––User:Muchachos

Durability of ice

I was curious about this sentence in the article:

Of course ice always slowly deforms under pressure anyway, and this isn't really affected by the presence of the pulp.

Does this mean under pressure, such as when a bullet slams into it, ice is not readily pushed out of the way of the bullet, like say flesh might be? If so, is the presence of the wood pulp just to keep the ice from shattering, such as rebar in concrete, instead of the wood actually adding bullet-stopping capability on its own? --Fxer 09:36, 25 December 2005 (UTC)

The presence of the wood pulp has two effects. 1) It slows down melting 2) it stops propagation of cracks and thus drastically improves the toughness of Pykrete over that of pure ice. The deformation statement refers to the behaviour of ice when subjected to prolonged, steady pressure. It has no relevance when discussing the impact of a bullet. -- Derek Ross | Talk 16:16, 11 March 2006 (UTC)

Melting Point

The article says that the sawdust raises the melting point but not by how much. Does anyone know what the melting point of Pykrete is?

I doubt that adding sawdust changes the melting point. The sawdust acts as an insulator, which slows the rate of melting.

Mixtures always have higher melting points than the pure solvent. I know pykrete isn't technically a solution but this still applies. —Preceding unsigned comment added by 141.219.76.65 (talk) 01:32, 19 November 2008 (UTC)

Other Materials

Would the type of material used affect the durability of the pykrete? For example, by using a material like pieces of Kevlar instead of sawdust increase the pykrete’s strength?

Larger fibers of the material = stronger solution

The water overlaps the fibers causing a bond. So if the individual fibers are bigger the Pykrite will have a bigger tensile strength and will be able to support more weight.

Sailingsumo (talk) 06:12, 17 April 2009 (UTC)

It would make for an interesting experiment if one had a cheap supply of shredded Kevlar. Otherwise it would substantially increase the expense and if Kevlar is less of an insulator than sawdust, most likely increase the melting rate making it less effective overall.

Cutting Kevlar into small bits might reduce its impact-dissipating qualities anyway. —Preceding unsigned comment added by 94.192.242.70 (talk) 01:51, 28 December 2008 (UTC)

Is the basic product cheaper than concrete?

There is no discussion of the costs of the basic pykrete in comparison to concrete, nor that of a pykrete craft that would be maintained for a longer time. -- Cimon avaro; on a pogostick. 11:09, 10 July 2006 (UTC)

I can't imagine how concrete would ever be cheaper in terms of either material or transportation costs. When I bought the bag of shredded wood mulch to test pykrete's resistance to bullet impacts, it was somewhere around a dollar per cubic foot from the local garden supply. If I had wanted sawdust by the bag it would have been about 50 cents per cubic foot. If I had bought enough to fill my pickup it would have cost much less per cubic foot. The maintenance and operating costs are design dependent. Personally, if I were to make a craft out of Pykrete, I would design it to be unmanned and disposable.  :-)

Is pykrete stronger than wood?

Without a grain it might strangely be true.

It depends upon how one defines "stronger." A .223 or .30 calibre bullet will easily rip through a plank of wood but not Pykrete. So in that sense, it is stronger than wood. It would be interesting to measure the relative crush, shear and tensile strengths of the two materials but, alas, I have neither the equipment nor time to do so. It would also make for an interesting experiment to try other binders in place of ice. A bag of sand will stop a bullet far more effectively than wood, bricks or concrete blocks. One wonders how effective a mixture of sawdust and wood glue would be? Or sand and ice? Or sand and glue? Or...?

Sand and ice wouldnt have the strength of Pykrete because while using sawdust it absorbs the water and becomes an emulsification, whereas the sand would merely be ice and sand, with all the physicall weaknesses of ice and without the insulatory properties of wood. On conclusion it is stronger than wood as in harder. However Pykrete is more brittle than wood. Oh, and it melts. In the end it depends what you want it for. Something that can withstand his pressures, Pykrete's your composite substance. If you want to build a house, then maybe wood.

Missing images

This cleanup just wiped out two of the four pictures. Does anybody know where they came from to re-list them as fair use? I'm linking to the diff so we won't forget the descriptions. — RevRagnarok ^{Talk Contrib} 12:31, 1 May 2007 (UTC)

I hate to say this...

... but has anybody here read WP:NOR?

Or to put it another way, just because the block shown allowed bullets to penetrate doesn't mean the historical formulation might not have actually created ricochets. 204.186.14.45 23:02, 17 May 2007 (UTC)

I agree, but i don't see where that assertion is being made. ·:·Will Beback ·:· 23:16, 17 May 2007 (UTC)

Montbatten shot the block with a pistol, not a rifle. It may have also been from an angle. User:Muchachos

A mixture of sawdust and ice...

Since sawdust is lighter than water it would float on the water prior to freezing - hence the pykerete would have to actually be a block of ice with a layer of sawdust frozen on one side of it, right?

Apparently not. Saturated wood is barely lighter than water, so keeping it mixed may not be that hard. ·:· Will Beback ·:· 23:55, 29 December 2007 (UTC)

Durability

The article stated: "Pykrete has a crush resistance of greater than 21 megapascals (3,000 psi) so a 25 mm (1 in) column could support the weight of a typical car." - This sentence made no sense. If the 25mm/1 inch dimension referred to the cross section, as one can infer that it did, then the units should have been square mm or inches. However, the sentence was still misleading because it assumed some unspecified short column length without stating so. As the column gets longer, at some point the increasing slenderness ratio (Kl/r) would dictate a buckling failure long before the crush resistance could be reached.Rodney420 (talk) 19:33, 19 May 2008 (UTC)

Major Reversion...

I haven't visited the Pykrete page for a while, but I just did, and found that a lot of dubious facts seem to have crept in (and some cautionary statements removed)! This apparently was the result of a major edit by one 'Rich257' on 18 Oct 2006. Consequently I've just reverted the article back to its state before that point. A few new reasonable-looking facts have been added since then, which should be merged in, but I think it's more important that the errors be erased [as much as one can talk about "errors" with Pykrete -- nothing is certain in that area!] If anyone (such as Rich257!) has reason to think the removed stuff should in fact be included, *please* use this talk page to explain why! Thanks -- Pete G. (talk) 02:07, 10 July 2008 (UTC)

OK -- let me expand a bit... I actually came in to fix up a URL that has changed, and found that it had been completely removed, as had other cites -- no reason given. Then I started noticing that researched facts, like who actually invented Pykrete, had been changed to what is known to be untrue. Like this:

[Original -- from Perutz' own writings] "The properties of such a composite were apparently first noted by a couple of researchers at Polytechnic University of New York, and were investigated more thoroughly by Max Perutz."

[Changed version -- untrue] "invented by Max Perutz"

There were other discrepancies, but maybe that indicates why I was worried.

-- Pete G. (talk) 03:31, 10 July 2008 (UTC)

A wholesale reversion to a two-year-old version may not be the most helpful fix. It lloks like your dispute is with a few small matters - whether the Mountbaten incident is verifiable or not, and the original inventor. OTOH, it looks like you deleted quite a bit of sourced material. ·:· Will Beback ·:· 05:52, 10 July 2008 (UTC)

Major reservation. I have long had reservations about the pykrete article, it seems to be the sort of topic that attracts the wrong sort of attention - something that has put me off from trying to edit it. However, the reversion of nearly two years of edits does seem inappropriate to me. Meanwhile, I have been quietly expanding the biography of Geoffrey Pyke (fortunately nobody seems to have noticed). I might modestly claim that there is some well phrased and well cited text on pykrete there that other editors may find useful here. Gaius Cornelius (talk) 08:26, 10 July 2008 (UTC)

Great article on Pyke, actually! (My only quibbles are peripheral -- like please don't equate "Boffin" to "Mad Scientist"! (:-/) All the "Back Room Boys" were often referred to as Boffins...) Meantime, I am in the process of merging in the valid info that was added to the Pykrete article after the version I reverted to. Give me a few hours, but I hope the result will be satisfactory. Pete G. (talk) 21:30, 12 July 2008 (UTC)

I've now merged in all the important stuff (I think) that got deleted by my reversion. Checking of the result appreciated... Pete G. (talk) 23:38, 12 July 2008 (UTC)

no factual evidence of new york poly

hi there, there is no factual baisis for the nyp prior claim —Preceding unsigned comment added by 77.44.114.50 (talk) 13:31, 8 January 2009 (UTC)

Well, let's see... Does the attribution by the major researcher (Perutz -- see the refs in the article) count as 'factual'...? Pete G. (talk) 01:33, 27 January 2009 (UTC)

Mythbusters Super-Pykrete

Anybody know if mythbusters Super Pykrete (made with newspaper instead of woodpulp/sawdust for its longer fibers) deserves some honorable mention and/or if they really invented it? —Preceding unsigned comment added by 12.226.245.40 (talk) 21:00, 16 April 2009 (UTC)

Mythbusters

I think a section with the latest Mythbusters experiment using Pykrete to build a boat would be a good addition to the page. Sailingsumo (talk) 01:37, 17 April 2009 (UTC)

After watching that episode, I think the pictured block in the article is an incorrect mixture. It's described as "50% water, 50% wood pulp by volume", whereas on Mythbusters they use 14% wood pulp, 86% water by weight. It looked significantly different and (based on the picture) held up better against having a bullet fired at it. Basically, I think the picture is probably inaccurate, and most likely disqualified as original research. 71.42.29.11 (talk) 07:16, 21 April 2009 (UTC)