The outcome of this project is an illustration of a rule of thumb from materials science: many solid materials begin to lose their mechanical properties at about half their absolute melting point. This is why (for example) ordinary steel should not be used above about 550 C; there's too much creep.
I thought the "failed" result of the project was more due to economic factors, and the reduced need due to other actions in the war meaning a waterborne carrier was less useful. Not some issue with the mechanical properties of pykrete. If the tested properties were already past that 1/2 absolute temperature point and considered acceptable, it doesn't really matter what the behavior would have been at less than that.
Did I read it wrong?
Also what looks like insane scope creep.
"The full-sized ship would also need to have a range of 7,000 miles, support heavy bombers and be torpedo-proof. It was to be over a mile in length, weigh as much as 2.2 million tons and require as many as 26 electric motors to move and steer across the ocean."
That's a crazy target growing out of "cheap to produce aircraft carrier"
I'd add in that ot would have been difficult to operate as well.
For starters aircraft carriers face into the wind for takeoff and landing. So that means either engines for maneuvering (noted in the article) or support vessels. Presumably support vessels are vulnerable so not in the picture.
It would sail like a pig ā with 90% underwater it'll pretty much go where the current goes. And very slowly.
I imagine the engines would either be small (slow maneuvering) or large (need fuel etc).
Once you need significant fuel you need to store it. Plus of course all the men, and their stores. And a lot of this doesn't like freezing temperatures.
To be useful the thing presumably has to be far from land, presumably closer to the enemy. So the enemy deploys a bunch of anti-aircraft ships to basically follow the thing. Returning aircraft are sitting ducks.
I'm no mechanical engineer, but none of this makes any sense to me at all.
I'm even less an admiral or air marshall but I dont see any tactical or strategic advantage here either.
Yeah itās like a mobile midway pacific war at that point!
Sailing midway all the way!
As I understand it, they found out they needed to refrigerate the ice to keep it from creeping too much, and this increased the cost too much for the idea to work.
The US did make some vessels out of concrete because of constraints on steel production. A famous example was a barge in the Pacific (I think at Ulithi?) that was devoted to making ice cream.
The article seems to make it clear that the refrigeration requirement was known from the start (how could it not be?) but that the amount of steel required had to be increased substantially to avoid creep in the ice.
Can you expand on this comment in the context of ice/water? It implies ice changes behavior at about 140K, but that isnt close to a phase change boundary, so what would you expect to be seeing here?
The glass transition temperature of amorphous ice is approximately 140 K.
At a guess, movement like that seen in glaciers and ice sheets?
That's right -- plastic deformation under stress.
Also same with cold . Up north itās a fools errand to run heavy machinery past about -55c. The steel develops tiny fractures, and six months later the ten ton loader will just break in half.
Most stop as it approaches -50c
This is that how jet fuel melted steel beams?
Here's a blacksmith demonstrating this exactly: https://www.youtube.com/watch?v=FzF1KySHmUA
Not melt, soften slightly
Soften "slightly", but enough to make the building which that steel is holding up collapse...
Well there goes that conspiracy theory..
Conspiracy theories are like religions, theyāre an act of faith not rationale
Check out Hobart's Funnies [0] and the great Panjandrum [1] for some other awesome WW2 British out-of-the-box thinking.
> they called it Project Habbakuk, in reference to ... "I am working a work in your days, which ye will not believe though it be told you."
This is a slightly more subtle way of calling it Project You Ain't Gonna Believe This
How many regular mass attending, God fearing Anglicans could even recognize on the spot the minor prophet Habbakuk?
Bizarre project all around.
Every war should have a role for the Panjandrum.
It was either going to be ice or concrete https://warfarehistorynetwork.com/article/the-concrete-fleet...
The material they used (water mixed with wood, frozen) is called pykrete.
> Blocks of ice containing as little as four percent wood pulp were weight for weight as strong as concrete; in honor of the originator of the project, we called this reinforced ice "pykrete". When we fired a rifle bullet into an upright block of pure ice two feet square and one foot thick, the block shattered; in pykrete the bullet made a little crater and was embedded without doing any damage. My stock rose, but no one would tell me what pykrete was needed for, except that it was for Project Habakkuk.
(from I Wish I'd Made You Angry Earlier by Max Perutz, via Wikipedia: https://en.wikipedia.org/wiki/Pykrete)
Unfortunately it turned out to be basically impossible to keep a ship-sized block of it frozen, and modern attempts at replicating it have found the strength claims to be a bit "optimistic".
This is one of those āso cool yet so sillyā brainstorms that Iām grateful someone was audacious enough to entertain. Iām both relieved and saddened that it never came to fruition.
Thereās a word, chindogu, to describe things that are less than useless. In some sense this project engendered more problems than it solved. Like so many other attractive brainstorms.
Can't get sunk by an iceberg if you are an iceberg. taps side of head
It's probably worth the trouble to try making some DIY pykrete.
Take a chain saw to it. Take a sledgehammer to it.
Unsurprisingly, Mythbusters have tried it - not at the scale of an aircraft carrier, but a boat displacing a few tons:
"Some leaks sprang here and there, but a few sprays from carbon-dioxide fire extinguishers sealed them pretty well, at least for a little while."
Excellent!
This reminds me of my favorite part of this story. In 1943, the first Quebec Conference between the US and UK military brass was a very contentious and heated affair, with the top generals and admirals on either side almost coming to blows. At one point they all dismiss their aides and go into a closed session, and Lord Mountbatten takes this opportunity to brief everyone on Project Habbakuk, using some samples of pykrete to demonstrate its resilience compared to ordinary sea ice. At one point in the demonstration, he draws his service revolver and fires at the pykrete.
Now, both the US and UK aides and staff officers are outside the room where this is happening, and they donāt know whatās going on, but they all remember how heated the earlier discussions were, so naturally, when they start to hear gunshots from inside the room, they all panic and assume the worst and burst through the door. Fortunately, everyone was unharmedāthe bullet ricocheted off the pykrete and embedded itself into the wall, only grazing the trouser leg of Ernest King.
Pykrete is one of those things that makes sense in theory, but in practice and from a practical perspective just isn't great.
There aren't a lot of places in nature where you have tons of trees and easy to get ice. So a society would never default to pykrete because those two things tend to be the opposite of each other. Its a somewhat unnatural thing to do.
Industrialized societies just can make steel and steel doesnt start to soften until 500-600 degrees F. There's no need for a 24/7 refrigerator power plant to keep steel from melting. Steel also is strong and rigid. Steel is of course still used today for both war and civil ships, and has been since the day it became technically and economically feasible to do. Its really hard to beat steel. This project has some nice technical merits and pykrete itself is interesting, but it just doesnt seem to ever have a practical use.
> There aren't a lot of places in nature where you have tons of trees and easy to get ice.
I take issue with this - there are vast swathes of canada, sibera, and northern europe where this is the case. I would say however finding all three year-round near liquid water may be harder, although not exactly an insurmountable challenge compared to say, moving quarried rock 5 miles to build a house
This could be straight out of the Command and Conquer: Red Alert series. [1] https://en.wikipedia.org/wiki/Command_%26_Conquer:_Red_Alert
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