Pykrete & Habakkuk

[KJ_Lesnick]

I actually posted this initially on a science sub-forum because I was fascinated how strong the stuff was, yet how simple it was and was curious to understand what gave it such incredible strength: As I understand it, it was 14% Sawdust and 86% water and was able to produce a substance nearly as strong as concrete with a higher freezing/melting point (which is of course why it was proposed for a gigantic aircraft carrier that would be as close to unsinkable as possible).

Nobody answered: I guess nobody knew about it, or nobody had any interest.  I'm basically posting it here because more people here would know about it.


BTW: I probably know more about the Habakkuk than the Pykrete itself even despite the fact that I know little about the Habakkuk other than it's basic design

[PR19_Kit]

Do a search on here under 'Habakkuk' and you'll come up with all sorts of stuff. There's one guy on here who may know more about it than Geoffrey Pyke!

[KJ_Lesnick]

I did that and I only found this thread

[Gondor]

Try this instead. The spelling was different. In fact if you go to the Home and enter Pykrete into the search you will find lots of entries. It's simply a matter of checking all options rather than just one and sticking with that spelling.

Gondor

[seadude]

What would you like to know specifically? Maybe I can help out. Pykrete is wonderful stuff. Too bad it has languished in obscurity for decades.
It has amazing properties due to low thermal conductivity:
Is unsinkable.
Can float.
Can be molded, shaped, and cut to almost any shape or size.

But the main problem in it's use is that it must be kept at or below freezing temperatures. This is why the Habakkuk ship required refridgeration plants and miles of pipe ductwork in the design in order to keep such a ship hull frozen. And if pykrete is damaged in any way, it is easy to repair with additional sources of wood pulp and water, then frozen. And most forms of bullets, torpedoes, etc. will just bounce right off of the stuff and/or make small dents or craters. But the damage done to pykrete is determined by the type of armament used and the thickness of the pykrete. I'll post more tomorrow when I'm at the library.

[Zombolt]

It also makes a mean looking Pokemon http://bulbapedia.bulbagarden.net/wiki/Avalugg_%28Pok%C3%A9mon%29
Ice Type, Heavy Defense, Compared to a carrier in the Pokedex?

Whiffemon!

[KJ_Lesnick]

seadude

What would you like to know specifically?

Well, several things actually

• What gave it such extreme strength?
  
• What was it's freezing point?
  

Also, while slightly off topic: I remember hearing stuff revolving around the idea of using cotton or newspaper.  Why would that make it stronger?

But the main problem in it's use is that it must be kept at or below freezing temperatures.

Well, I'm not going to build anything out of it so it's more of an academic curiosity than anything else.

[seadude]

The strength of pykrete is most likely determined by the right combination of water and wood pulp, plus how cold it is kept. As you said earlier, 14% pulp and 86% water (by weight) appears to be the prime combination, at least according to Max Perutz and other scientists who studied pykrete long, long ago.
The right kind of wood pulp is also a factor. Wood pulp that has long fibres, sheets, etc.  and gives good tensile strength is generally best. Sawdust is not good. Newspaper, cotton, etc. is.  Mythbusters did a pykrete special a few years ago. I think the episode was titled "Alaskan Special 2". It might be worth watching if you can find it. Might have been in Season 7, 8, or 9.  Also, if I remember correctly, I think Max Perutz suggested that spruce or fir wood pulp was best, but I don't remember. And last, the colder pykrete is kept, the harder and better it is.

[KJ_Lesnick]

Seadude

The strength of pykrete is most likely determined by the right combination of water and wood pulp, plus how cold it is kept. As you said earlier, 14% pulp and 86% water (by weight) appears to be the prime combination, at least according to Max Perutz and other scientists who studied pykrete long, long ago.

The ratio I know actually

The right kind of wood pulp is also a factor. Wood pulp that has long fibres, sheets, etc.  and gives good tensile strength is generally best. Sawdust is not good. Newspaper, cotton, etc. is.

Fascinating: Woodpulp is made by either mechanical grinding, steaming then grinding, or chemical processes correct?

As for newspaper: Why is that so effective?  Is that because it's made from wood-pulp?

Cotton makes sense oddly: Long lengthly fibers

Mythbusters did a pykrete special a few years ago. I think the episode was titled "Alaskan Special 2". It might be worth watching if you can find it.

Yeah, I heard about that: The skin was too small for the purposes intended and didn't involve active refrigeration

Also, if I remember correctly, I think Max Perutz suggested that spruce or fir wood pulp was best, but I don't remember.

Spruce is currently used a lot in carpentry and wood.  It was used in wooden aircraft too, out of all the trees of the fir family: Canadian would be best right?


While a little off topic: Wood pulp is finding itself as a new wonder material as it can be reduced into a compound called Nano Crystaline Cellulose.