Pycrete is frozen water mixed with sawdust. It is amazing stuff-stonger than ice, and melts slowly (the sawdust acts as thermal insulation).
It was invented by a Canadian engineer during WWII-the original plan was to make a gian aircraft carrier out of it-to be used as a floating airbase to proted allied convoys against U-Boat attack.
Has anybody found a use for the stuff?
I’m not aware of any practical uses for it.
There is a bit of an issue with the “melts slowly” property that you listed. While I would agree that it does melt more slowly than pure ice, it still melts fairly quickly. Mythbusters and a BBC show called “Bang Goes the Theory” have both tested it and found that it melts too quickly to be practical as a shipbuilding material. In the case of the BBC show, they planned to cross a small strait, but their pykrete ship melted and came apart before they even left the harbor. Mythbusters had a bit more success but still found it to be impractical.
Why use a material that “melts slowly” instead of one that doesn’t melt at all?
Joe
They did build a test platform in a lake near Jasper Alberta during the war’s early years. My guess is the test’s results were not promising.
Because of material shortages in WW2. Why you would use it now, I have no idea.
Someone on the board once suggested it would be a good material for a space station. Given proper shielding on the sun side, it might work.
Also, maybe to build structures in Antarctica?
I can’t imagine the stuff would work well for the space station. Wouldn’t the ice sublimate into space? And that’s ignoring the weight of the stuff.
I assume you would put an impereable layer on it to prevent sublimation. And it is really part of your water supply and oxygen supply, so much of it’s weight is a safety buffer for those things. Anyway, it’s not my idea.
Space stations generate a lot of heat. If you look at this picture of the ISS, for example, all the “horizontal” panels are radiators for shedding excess heat, just to keep the machinery and crew modules at moderate temperature.
Also, light elements (like oxygen and hydrogen) aren’t very effective as radiation shields.
Again, this is not my idea.
Depends on the type of radiation. Lightweight elements are actually very good for stopping charged particle radiation, which is the main concern in space. They aren’t very good for stopping gamma or neutron radiation, but that’s not as big of a concern for a space station.
I think it was Stranger on a Train, in this thread. Or this one.
The way I’d read about the plan on Wikipedia, is a little bit different than what the Mythbusters tested. No matter how resistant to melting pycrete was supposed to be, the proposed aircraft carrier was to have cooling coils embedded withing it, to keep the ship frozen. The goal was to have a monstrous aircraft carrier, that was unsinkable by virtue of being made of ice. Some of the biggest wartime resource problems – ammonia refrigerant, copper for coolant pipes, massive amounts of cork insulation – because, newsflash, humans don’t function very well surrounded by ice, are the objections given at the time…
I’m not an engineer, so I can’t really wrap my mind about the plan and its problems. But I can’t help but wonder …
Can you really pump enough coolant through the entire ice hull so that it won’t melt? What sort of redundancy do you need? How do you repair it – if it works, the pipes must be embedded in ice. Either it works flawlessly, and you can’t reach the coils for maintenance, or it fails utterly, so what’s the point. Won’t friction against the ocean be constantly polishing away the ice … unless its cooling system is cold enough to freeze ocean water, in which case, won’t it just grow too big and misshapen?
So its can’t sink because its made of ice. So what? If you shell the crap out of it, you can make it useless as a ship of war by killing enough crew or damaging enough of the support systems. What if you torpedo it enough to split it in half – great, each half still floats.
Was this just a propaganda move. To show the Nazi’s that we’ve turned the very Earth against them? The proposed carrier made of prycrete was to have been larger than modern supper-carriers – by 3 to 5 times. Was it to project so much air power that it would resist anything the Nazi’s could field? Or again, just a morale crusher?
When I’d hear of pycrete, I kinda wished for a ship, with active cooling and all. Something canoe or sailboat sized – just to see if it would work. But the Mythbuster’s boat, although it was wise of them to use newspaper for more laminated strength, didn’t have a cooling system. So its meager success doesn’t really answer my questions.
You have to remember, this was proposed during the Battle of the Atlantic against U-boats. And what was needed was just a way to get an aircraft base into the middle of the North Atlantic (while not using too much steel and shipbuilding resources). So the pycrete carrier wasn’t supposed to go up against a fleet of battleships; it was supposed to be able to stay afloat in the North Atlantic in winter, and at most take a torpedo hit or two. So pycrete wasn’t that crazy an idea: it can take a few torpedoes (and icebergs!) before any real structural damage; and it could be big enough to take on Atlantic storms. Since the water temperature is going to be close to freezing a lot of the time anyway, keeping it cold wouldn’t have been that big a challenge. And building some wooden forms and pouring in sawdust and water is a lot easier and cheaper than carefully riveting together a while bunch of steel beams and plates to make a conventional steel-hull ship.
Now, of course there are drawbacks to pycrete, and I’m not going to second-guess the guys who at the time looked at the results of the scale tests and decided not to go ahead: it was probably the right decision. But it wasn’t completely crazy to look into the idea.
I believe it’s spelled “Pykrete” with a K, after it’s inventor Geoffrey Pyke.
Thanks for the correction. I’m too used to working with X-rays…
It just seems to me the flow of water over the haul would increase the rate of melting…
There seem to be niche uses.