sven hassell
Active member
Have just read about a substance called Pycrete.
Pykrete
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Pykrete is a composite material made of approximately 14 percent sawdust or some other form of wood pulp (such as paper) and 86 percent ice by weight. The properties of such a composite were apparently first noted by a couple of researchers at New York Poly, and were investigated more thoroughly by Max Perutz. Its use was proposed during World War II by Geoffrey Pyke to the Royal Navy as a candidate material for making a huge, unsinkable aircraft carrier, Project Habakkuk, actually more of a floating island than a ship in the traditional sense. Pykrete has some interesting properties, notably its relatively slow melting rate (due to low thermal conductivity), and its vastly improved strength and toughness over unmodified (crystalline) ice, actually closer to concrete. Pykrete is slightly more difficult to form than concrete, as it expands during the freezing process, but can be repaired and maintained from the sea's most abundant raw material.
Contents
[hide]
[edit]
History
Pyke managed to convince Lord Mountbatten of the worth of his project (actually prior to the invention of Pykrete) some time around 1942, and trials were made in two locations in Alberta in Canada. Blocks of Pykrete were attacked with various explosives and it was found that a charge corresponding to a torpedo warhead would have made only a minor dent in the planned Habakkuk carrier.
Tradition asserts that Mountbatten managed to convince Winston Churchill of its usefulness by bursting in on Churchill when he was having a bath, and plunging a block of pykrete into the bathwater. This probably did not happen. Another tale is that at the Quebec Conference of 1943 Mountbatten brought a block of Pykrete along to demonstrate its potential to the bevy of admirals and generals who had come along with Winston Churchill and Franklin D. Roosevelt. Mountbatten entered the project meeting with two blocks and placed them on the ground. One was a normal ice block and the other was Pykrete. He then drew his service pistol and shot at the first block. It shattered and splintered. Next, he fired at the Pykrete to give an idea of the resistance of that kind of ice to projectiles. The bullet ricocheted off the block, grazing the trouser leg of Admiral Ernest King and ending up in the wall. The Admiral may or may not have been impressed by Mountbatten's unorthodox demonstration. According to Perutz's own account, however, the incident of a ricochetting bullet hitting an Admiral actually happened much earlier in London and the gun was fired by someone on the project — not Mountbatten. The small pilot project was given the go-ahead, but the main Project Habakkuk was never put into action. The funds simply were not available due to other WWII projects.
The idea of ice warships was around before Pykrete, and the United States and Canada were so impressed with the idea of assembling ice warships that a 60-foot-long, 1,000-ton ship was built in one month on a Canadian lake and took slightly more than an entire hot summer to melt. This model was built of ice, before the discovery of Pykrete; if the Habakkuk had been constructed it would have been made of Pykrete.
[edit]
Durability
The durability of Pykrete is up for debate, but it is often asserted that Pykrete has a crush resistance of greater than 3,000 pounds per square inch (21 MPa) so a one-inch (25 mm) column could support the weight of a typical car. The wood pulp also makes the pykrete stable at higher temperatures. A British service rifle bullet (a .303 caliber) will only penetrate 6.5 inches (16.5 cm) of pykrete. Of course ice always slowly deforms under pressure anyway, and this isn't really affected by the presence of the pulp.
For example:
The above image shows a 1 gallon milk jug filled with a 10% mixture (by weight using sawdust).The above image shows that same milk jug after being shot with a .243 rifle at approximately 100 meters. The Winchester catalog lists stats for a .243 bullet: 100 grain (6 g) bullet 1,945 ft·lbf (2637 J) energy.
The above image shows a one inch (25 mm) thick 50% mixture (by volume using shredded wood mulch) hit by a single 7.62 x 39 mm rifle round fired from 30 feet (10 m) which bounced off the surface. It took an additional 15 rounds of .223 fired from 15 feet to crack the block.The above image shows a two inch (50 mm) thick 50% mixture (by volume using shredded wood mulch) hit by a single 7.62 x 39 mm rifle round (lower impact mark) fired from 30 feet (10 m) which bounced off the surface. It took an additional 7 rounds (upper penetration mark) of 7.62 x 39 mm fired from 15 feet (5 m) to penetrate the block.[edit]
Manufacture
Pykrete can be easily formed using water and common pulp, such as toilet paper or paper towels. The mixture can be molded into any shape and frozen, and it will be extremely tough and durable, as long as it is kept cold.
Pykrete
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Pykrete is a composite material made of approximately 14 percent sawdust or some other form of wood pulp (such as paper) and 86 percent ice by weight. The properties of such a composite were apparently first noted by a couple of researchers at New York Poly, and were investigated more thoroughly by Max Perutz. Its use was proposed during World War II by Geoffrey Pyke to the Royal Navy as a candidate material for making a huge, unsinkable aircraft carrier, Project Habakkuk, actually more of a floating island than a ship in the traditional sense. Pykrete has some interesting properties, notably its relatively slow melting rate (due to low thermal conductivity), and its vastly improved strength and toughness over unmodified (crystalline) ice, actually closer to concrete. Pykrete is slightly more difficult to form than concrete, as it expands during the freezing process, but can be repaired and maintained from the sea's most abundant raw material.
Contents
[hide]
- <LI class=toclevel-1>1 History <LI class=toclevel-1>2 Durability <LI class=toclevel-1>3 Manufacture <LI class=toclevel-1>4 External links
- 5 References
[edit]
History
Pyke managed to convince Lord Mountbatten of the worth of his project (actually prior to the invention of Pykrete) some time around 1942, and trials were made in two locations in Alberta in Canada. Blocks of Pykrete were attacked with various explosives and it was found that a charge corresponding to a torpedo warhead would have made only a minor dent in the planned Habakkuk carrier.
Tradition asserts that Mountbatten managed to convince Winston Churchill of its usefulness by bursting in on Churchill when he was having a bath, and plunging a block of pykrete into the bathwater. This probably did not happen. Another tale is that at the Quebec Conference of 1943 Mountbatten brought a block of Pykrete along to demonstrate its potential to the bevy of admirals and generals who had come along with Winston Churchill and Franklin D. Roosevelt. Mountbatten entered the project meeting with two blocks and placed them on the ground. One was a normal ice block and the other was Pykrete. He then drew his service pistol and shot at the first block. It shattered and splintered. Next, he fired at the Pykrete to give an idea of the resistance of that kind of ice to projectiles. The bullet ricocheted off the block, grazing the trouser leg of Admiral Ernest King and ending up in the wall. The Admiral may or may not have been impressed by Mountbatten's unorthodox demonstration. According to Perutz's own account, however, the incident of a ricochetting bullet hitting an Admiral actually happened much earlier in London and the gun was fired by someone on the project — not Mountbatten. The small pilot project was given the go-ahead, but the main Project Habakkuk was never put into action. The funds simply were not available due to other WWII projects.
The idea of ice warships was around before Pykrete, and the United States and Canada were so impressed with the idea of assembling ice warships that a 60-foot-long, 1,000-ton ship was built in one month on a Canadian lake and took slightly more than an entire hot summer to melt. This model was built of ice, before the discovery of Pykrete; if the Habakkuk had been constructed it would have been made of Pykrete.
[edit]
Durability
The durability of Pykrete is up for debate, but it is often asserted that Pykrete has a crush resistance of greater than 3,000 pounds per square inch (21 MPa) so a one-inch (25 mm) column could support the weight of a typical car. The wood pulp also makes the pykrete stable at higher temperatures. A British service rifle bullet (a .303 caliber) will only penetrate 6.5 inches (16.5 cm) of pykrete. Of course ice always slowly deforms under pressure anyway, and this isn't really affected by the presence of the pulp.
For example:
The above image shows a 1 gallon milk jug filled with a 10% mixture (by weight using sawdust).The above image shows that same milk jug after being shot with a .243 rifle at approximately 100 meters. The Winchester catalog lists stats for a .243 bullet: 100 grain (6 g) bullet 1,945 ft·lbf (2637 J) energy.
The above image shows a one inch (25 mm) thick 50% mixture (by volume using shredded wood mulch) hit by a single 7.62 x 39 mm rifle round fired from 30 feet (10 m) which bounced off the surface. It took an additional 15 rounds of .223 fired from 15 feet to crack the block.The above image shows a two inch (50 mm) thick 50% mixture (by volume using shredded wood mulch) hit by a single 7.62 x 39 mm rifle round (lower impact mark) fired from 30 feet (10 m) which bounced off the surface. It took an additional 7 rounds (upper penetration mark) of 7.62 x 39 mm fired from 15 feet (5 m) to penetrate the block.[edit]
Manufacture
Pykrete can be easily formed using water and common pulp, such as toilet paper or paper towels. The mixture can be molded into any shape and frozen, and it will be extremely tough and durable, as long as it is kept cold.
