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Post by Deleted on Feb 28, 2009 16:30:55 GMT
I came across this series of video's which I thought some of you may find of intrest particularly, if you would like to see what a trbuchet can do to a stone wall:
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Avery
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Post by Avery on Feb 28, 2009 16:45:17 GMT
Me and a group of guys build a new treb every year to compete in the local pumpkin chunkin competition. Nothing that big, but it'll sail a 5 pound pumpkin 200 yds.
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Post by Deleted on Feb 28, 2009 16:58:15 GMT
Me and a group of guys build a new treb every year to compete in the local pumpkin chunkin competition. Nothing that big, but it'll sail a 5 pound pumpkin 200 yds. Yeah built a few myself and always wanted to test them against a stone wall, after all thats what they are for.
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Post by Deleted on Mar 1, 2009 22:44:36 GMT
I haven't built any trebuchets or mangonels, but I have built and used the smaller field catapult. What it could do with a 5 Lb rock while still being small enough to be carried 100 yds by 4 12 yr olds is impressive...
The same BSA campout, I saw some bamboo trebuchets that worked well, too. But they shook themselves apart very quickly. Probably due to being designed and built by children rather than a failure of the materials, themselves...
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Avery
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Post by Avery on Mar 1, 2009 23:09:02 GMT
Have you guys heard of a floating arm treb? Thats the design we built for the past two years. They aree far more efficient than a classic treb. with a classic we were throwing about 100yds with 380# counterweight. With a F.A.T. we threw the same distance with only 250# couterweight.
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Post by Deleted on Mar 2, 2009 1:34:21 GMT
Care to explain the difference between a Floating Arm Trebuchet and a normal one?
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Post by Deleted on Mar 2, 2009 5:28:25 GMT
Those are awesome videos, +1 for posting them.
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Avery
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Post by Avery on Mar 2, 2009 22:52:29 GMT
Care to explain the difference between a Floating Arm Trebuchet and a normal one? With a classical trb there is a fulcrum point where the arm is attached to the base. When fired gravity pulls tha weights down, spinning the arm at the pivot point. With a F.A.T. the arm isn't actually attaced to the base at all. Take a close look at the video below. The weights are attached to a rod that glides along the vertical tracks. As the weights fall the arm rolls along a track in order to fire. The one in the video is very small, but its easy to see the basic operation.
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Post by Deleted on Mar 3, 2009 6:20:05 GMT
Great episode Kingrat. I saw a while ago but watched again.
Avery, I have never seen his floating arm design. Is this a modern invention or based on some medieval reference?
I was looking at this larger version:
I was also wonder how well it would scale in weight. The swinging treb has either wheels or a swinging basket that sort of lets it follow through and keeping it from tipping over. It seems to reduce structural stress because motion does not come to a sudden stop. It is a natural fluid motion. The FAT treb seems to stop the arm cold. I am wondering if this places any added stress on the structure that would become unmanageable if you scaled it up to throw a 200 lb shot? I noticed in your small model you corrected for this allowing some follow through. I would love to see a full scale model.
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ExtremeDeathman
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Post by ExtremeDeathman on Mar 3, 2009 10:35:38 GMT
I guy I know has built trebuchets 17 Years ago and he still does it. He owns the biggest trebuchet in the world. (11m high) He wants to build an even taller one now, a MONSTER TREBUCHET with 18m height!!!
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Post by Deleted on Mar 3, 2009 19:50:19 GMT
I think floating arm is a modern adaptation, I’ve never seen any historical reference to one.
I agree about the scaling up, if you had an arm and counter weight which weighed several tones I wonder whether such a range of movements would just rip the thing apart.
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Avery
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Post by Avery on Mar 3, 2009 22:44:11 GMT
Well, first I must clarify. the treb in the video isn't mine, I've never made one that small. Yes, The FAT is a modern adaptation, its been around since the late 1990's. As for scaling up the model its completly do'able. If you make a FAT and a classic with the same overall helght and counter weight, the FAT should win every time. The arm shouldn't come to an abrupt stop, it needs a little follw through. The biggest prblem people have is the opening in the track where the weights fall through. The wheels will"jump" the opening but it shocks the arm. How we fixed this was to put a hinged flange so when the wheels hit it, they act like a bridge and gives the arm a smooth trasition. Look for a FAT2K on you tube, those are pretty wicked too. Theres also a "scissor jack" treb, but they're not very efficent.
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