Cthulhu
01-10-03, 06:03 AM
http://www.globalgallery.com/images/aa-2366.jpg
Giant Catapult as envisioned by Leonardo Da Vinci.
Yes, I realise this is insane and can never ever work, but I still want to build it and launch things into space anyway.
The early rocket pioneers used to employ catapults for gaining extra altitude from their models. Back in the middle ages huge siege engines were employed for knocking down castle walls. Large boulders were sent sailing through the sky from a distance that was beyond longbow range. Perhaps they were on to something. Forget the Jules Verne cannon with its monstrous barrel and explosives. Just use a long lever and a counter weight.
http://www.pbs.org/wgbh/nova/lostempires/trebuchet/images/trebuchethome3a.gif
NOVA's successful attempt to build and shoot a giant trebuchet (http://www.pbs.org/wgbh/nova/lostempires/trebuchet/), the most destructive war machine that ever laid siege to a medieval castle.
Giant Medieval War Machine Is Wowing British Farmers And Scaring the Sheep. (http://www.interweavers.com/brett/humor/trebuchet.html)
With surprising grace, the grand piano sails through the sky a hundred feet above a pasture here, finally returning to earth in a fortissimo explosion of wood chunks, ivory keys and piano wire.
Nor is the piano the strangest thing to startle the grazing sheep this Sunday morning. A few minutes later, a car soars by - a 1975 blue two-door Hillman, to be exact - following the same flight path and meeting the same loud fate. Pigs fly here, too. In recent months, many dead 500-pound sows (two of them wearing parachutes) have passed overhead, as has the occasional dead horse.
It's the work of Hew Kennedy's medieval siege engine, a four story tall, 30 ton behemoth that's the talk of bucolic Shropshire, 140 miles northwest of London. In ancient times, such war machines were dreaded instruments of destruction, flinging huge missiles, including plague-ridden horses, over the walls of besieged castles. Only one full-sized one exists today, designed and built by Mr. Kennedy, a wealthy landowner, inventor, military historian and - need it be said? - full-blown eccentric.
History of Catapults. (http://home.t-online.de/home/d.baatz/catapult.htm)
Catapults were invented about 400 BC in the powerful Greek town Syracus under Dionysios I (ca. 430-367 BC). The Greek engineers first constructed a comparatively small machine, the gastraphetes, sort of a crossbow.
http://home.t-online.de/home/d.baatz/gastr1.jpg
http://www.trebuchet.com/articles/ron/treb.gif
To ride a Trebuchet. (http://www.trebuchet.com/articles/ron/trebuchet.html)
According to physicists this is quite impossible so don't try it at home.
http://www.catapults.info/trebuchet1.jpg
Ok. Time for some math.
http://www.school-for-champions.com/science/images/machines1.gif
If EA = 10 m, RA = 1 m, and you drop R = 200 kilos at 32 m per second, weight E = 20 kilos will fly in the air at 320 m per second!
If we multiply the long arm by a factor of ten to an impressive 100 m then we get 20 kilo's launched at 3.2 km per second!! To increase payload we mutiply both it and the counterweight. Changing R to 2000 kilos(X10) and E to 200 kilos(X10) for example.
So we would need something in the order of this:
Long arm EA = 400 metres.
Short arm RA = 1 metres.
Counterweight R = 10,000 kilo's.
Payload E = 1,000 kilo's.
Launch velocity of payload = 12.8 km per second.
Required velocity is only 11.2 km per second but that gives us a margin of error and should counter air resistance. I hope I didn't fudge up those calculations. I had to look over some websites on mechanical levers. Its more complex than I thought it would be. Is there a mathematician in the house? Hopefully this is correct.
One metre might be too short to place 10,000 kilos on so we might have to lengthen the short end. Ofcourse whatever we lengthen it by has to be taken into account for the long arm. Unless ofcourse we get around that by increasing the weight further. Changing it from one metre to two metres would mean having to change the 400 m long arm to a monstrous 800 m arm. Jeepers. Even 400 m looks too long to me. I would rather increase the counterweight as much as is possible. Theres no reason it couldn't be like a long rod running parallel to the ground. This would give more size and yet not interfere with the machine. So we might end up with this:
Long arm EA = 80 metres.
Short arm RA = 2 metres.
Counterweight R = 100,000 kilo's.
Payload E = 1,000 kilo's.
Launch velocity of payload = 12.8 km per second.
After launching 1 metric ton, the counterweight can be lifted and another payload placed on the pitching arm. Preferably encased in heat resistant material to reduce burnup.
The weight of the arm would have to be taken into account so I expect the counterweight would actually be a lot more than 100 metric tons.
Please feel free to shoot this down if you see any flaws in my calculations. I want to know if it's really a practical solution for cheap launches. I know that a model built that was a reproduction of the largest type ever used had a lead counterweight weighing 6.5 tons, and the overall weight for a similar machine in England was 30 tons so it would certainly be an ambitious project but by no means an impossible one.
Using a hinged pivotal counterweight to increase the straightness of descent will increase power. I am in love with this idea. No detailed plans exist for siege engines. Only out of scale drawings and brief outlines written by the ancients. It's a forgotten technology. Those building them today are relearning the art. For instance, many carvings and reliefs show Trebuchets with wheels. It was assumed this was for transportation but when reproduced it was quickly realised these monsters could never have travelled on ancient roads. When fired, those without wheels would upend and damage themselves crashing back down. Those with wheels would smoothly transfer momentum to the arm and the rolling forward was like a running baseball pitcher, it would add about a third as much distance to the range. This doesn't help for our vertical space shot, but does demonstrate how much we have forgotten about catapults.
At this point in my rambling at Treb.com some smartpants stuck their hand up and pointed out the acceleration of gravity was 32 feet per second. Not 32 metres.
http://198.144.2.125/Siege/OtherSiegeEngines/Full/TrebLarge2.gif
Back to the drawing board.
By that reckoning my machine is only one third as powerful. Instead of the original math resulting in 320 m per second it actually reads 98 m per second. So the scaled up model will need an arm just over 3 times as long or around 250 m. I'd rather stick with 80 m so the only other option is to increase the counterweight to 300 metric tons. Still have to get permission from the city parks commission, a union waver, NASA clearance, EPA approval, coordinate press coverage (without sigining away book and movie rights!), get scheduled on Jay Leno for "free" ad time, etc., etc.
P.S. ... with the tip velocity of the arm, can you imagine the sonic boom???
Giant Catapult as envisioned by Leonardo Da Vinci.
Yes, I realise this is insane and can never ever work, but I still want to build it and launch things into space anyway.
The early rocket pioneers used to employ catapults for gaining extra altitude from their models. Back in the middle ages huge siege engines were employed for knocking down castle walls. Large boulders were sent sailing through the sky from a distance that was beyond longbow range. Perhaps they were on to something. Forget the Jules Verne cannon with its monstrous barrel and explosives. Just use a long lever and a counter weight.
http://www.pbs.org/wgbh/nova/lostempires/trebuchet/images/trebuchethome3a.gif
NOVA's successful attempt to build and shoot a giant trebuchet (http://www.pbs.org/wgbh/nova/lostempires/trebuchet/), the most destructive war machine that ever laid siege to a medieval castle.
Giant Medieval War Machine Is Wowing British Farmers And Scaring the Sheep. (http://www.interweavers.com/brett/humor/trebuchet.html)
With surprising grace, the grand piano sails through the sky a hundred feet above a pasture here, finally returning to earth in a fortissimo explosion of wood chunks, ivory keys and piano wire.
Nor is the piano the strangest thing to startle the grazing sheep this Sunday morning. A few minutes later, a car soars by - a 1975 blue two-door Hillman, to be exact - following the same flight path and meeting the same loud fate. Pigs fly here, too. In recent months, many dead 500-pound sows (two of them wearing parachutes) have passed overhead, as has the occasional dead horse.
It's the work of Hew Kennedy's medieval siege engine, a four story tall, 30 ton behemoth that's the talk of bucolic Shropshire, 140 miles northwest of London. In ancient times, such war machines were dreaded instruments of destruction, flinging huge missiles, including plague-ridden horses, over the walls of besieged castles. Only one full-sized one exists today, designed and built by Mr. Kennedy, a wealthy landowner, inventor, military historian and - need it be said? - full-blown eccentric.
History of Catapults. (http://home.t-online.de/home/d.baatz/catapult.htm)
Catapults were invented about 400 BC in the powerful Greek town Syracus under Dionysios I (ca. 430-367 BC). The Greek engineers first constructed a comparatively small machine, the gastraphetes, sort of a crossbow.
http://home.t-online.de/home/d.baatz/gastr1.jpg
http://www.trebuchet.com/articles/ron/treb.gif
To ride a Trebuchet. (http://www.trebuchet.com/articles/ron/trebuchet.html)
According to physicists this is quite impossible so don't try it at home.
http://www.catapults.info/trebuchet1.jpg
Ok. Time for some math.
http://www.school-for-champions.com/science/images/machines1.gif
If EA = 10 m, RA = 1 m, and you drop R = 200 kilos at 32 m per second, weight E = 20 kilos will fly in the air at 320 m per second!
If we multiply the long arm by a factor of ten to an impressive 100 m then we get 20 kilo's launched at 3.2 km per second!! To increase payload we mutiply both it and the counterweight. Changing R to 2000 kilos(X10) and E to 200 kilos(X10) for example.
So we would need something in the order of this:
Long arm EA = 400 metres.
Short arm RA = 1 metres.
Counterweight R = 10,000 kilo's.
Payload E = 1,000 kilo's.
Launch velocity of payload = 12.8 km per second.
Required velocity is only 11.2 km per second but that gives us a margin of error and should counter air resistance. I hope I didn't fudge up those calculations. I had to look over some websites on mechanical levers. Its more complex than I thought it would be. Is there a mathematician in the house? Hopefully this is correct.
One metre might be too short to place 10,000 kilos on so we might have to lengthen the short end. Ofcourse whatever we lengthen it by has to be taken into account for the long arm. Unless ofcourse we get around that by increasing the weight further. Changing it from one metre to two metres would mean having to change the 400 m long arm to a monstrous 800 m arm. Jeepers. Even 400 m looks too long to me. I would rather increase the counterweight as much as is possible. Theres no reason it couldn't be like a long rod running parallel to the ground. This would give more size and yet not interfere with the machine. So we might end up with this:
Long arm EA = 80 metres.
Short arm RA = 2 metres.
Counterweight R = 100,000 kilo's.
Payload E = 1,000 kilo's.
Launch velocity of payload = 12.8 km per second.
After launching 1 metric ton, the counterweight can be lifted and another payload placed on the pitching arm. Preferably encased in heat resistant material to reduce burnup.
The weight of the arm would have to be taken into account so I expect the counterweight would actually be a lot more than 100 metric tons.
Please feel free to shoot this down if you see any flaws in my calculations. I want to know if it's really a practical solution for cheap launches. I know that a model built that was a reproduction of the largest type ever used had a lead counterweight weighing 6.5 tons, and the overall weight for a similar machine in England was 30 tons so it would certainly be an ambitious project but by no means an impossible one.
Using a hinged pivotal counterweight to increase the straightness of descent will increase power. I am in love with this idea. No detailed plans exist for siege engines. Only out of scale drawings and brief outlines written by the ancients. It's a forgotten technology. Those building them today are relearning the art. For instance, many carvings and reliefs show Trebuchets with wheels. It was assumed this was for transportation but when reproduced it was quickly realised these monsters could never have travelled on ancient roads. When fired, those without wheels would upend and damage themselves crashing back down. Those with wheels would smoothly transfer momentum to the arm and the rolling forward was like a running baseball pitcher, it would add about a third as much distance to the range. This doesn't help for our vertical space shot, but does demonstrate how much we have forgotten about catapults.
At this point in my rambling at Treb.com some smartpants stuck their hand up and pointed out the acceleration of gravity was 32 feet per second. Not 32 metres.
http://198.144.2.125/Siege/OtherSiegeEngines/Full/TrebLarge2.gif
Back to the drawing board.
By that reckoning my machine is only one third as powerful. Instead of the original math resulting in 320 m per second it actually reads 98 m per second. So the scaled up model will need an arm just over 3 times as long or around 250 m. I'd rather stick with 80 m so the only other option is to increase the counterweight to 300 metric tons. Still have to get permission from the city parks commission, a union waver, NASA clearance, EPA approval, coordinate press coverage (without sigining away book and movie rights!), get scheduled on Jay Leno for "free" ad time, etc., etc.
P.S. ... with the tip velocity of the arm, can you imagine the sonic boom???