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designing a catapult for physics class.

M

MikeMike

Lifer
1kg weight limit
.5 meter arm length.
has to go over a 1.5m wall 3 m away.
cannot be a slingsot dsign.

i was thinking of making it a sidearm throw, as that would allow me to have the most pull back.

i will be using surgical tubing for my force to appl to my arm.

any hints???

MIKE
 
Originally posted by: Howard
Originally posted by: DrVos
Make a trebuchet, its supposed to be one of the more powerful/efficient catapults out there.
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I would recommend a trebuchet if it is allowed.
Click to expand...

true, but I've never seen a trebuchet without a slingshot.

But I guess I could be done.
 
Given the short arm length, a trebuchet would likely not be the best design. That generates it's force from the length of the arc and is generally a heavy design. If you can use rubber bands like surgical tubing to apply the force a mangronel would be far more powerful.
 
Originally posted by: GagHalfrunt
Given the short arm length, a trebuchet would likely not be the best design. That generates it's force from the length of the arc and is generally a heavy design. If you can use rubber bands like surgical tubing to apply the force a mangronel would be far more powerful.
Click to expand...
The arc is derived from the length of the sling, not the arm.

 
Originally posted by: GagHalfrunt
Given the short arm length, a trebuchet would likely not be the best design. That generates it's force from the length of the arc and is generally a heavy design. If you can use rubber bands like surgical tubing to apply the force a mangronel would be far more powerful.
Click to expand...
You mean a mangonel?
 
Arm length, sling length. It doesn't matter. A trebuchet will be hampered by the weight limit.


A mangonel would be an excellent idea.

link to a "sort of" mangonel project.

I only consider the above to be a good example because it clearly shows how a mangonel works with the rubber bands
 
Just build your standard counter catapult but instead of using a counter wait get like 30 CO2 cartigies set up 30 nails to punture the CO2 watch object go flying oh and try and minimize the angle that you shoot it at. The key to pointless physic class is to bend the rules so just put your .5m arm on top of a 10 foot base and you should be all set.
 
When I made one in physics class I used wood and rubberbands used for planes that you get in a hobby store. The egg went way further then it had to go and I could just add or remove bands as I pleased.
 
I would go for the mangonel-type design. It's easy to build, and would have sufficient power for what you are describing.
 
yea, i just wanna set the record. record happens to be like 210ft.

would the sidearm, type lauch work? i would have to adjust for the spin of the ball no?

MIKE

 
I would say make it out of PVC piping, have the arm function as a spring, or see if the Home Depot has some kind of cheap torsion springs. If you use torsion springs you will have to figured out some kind of cheap bearing set up. Perhaps a peice of PVC inside another, with graphite lube.
 
I made a trebuchet for a physics class a couple of years back... it turns out that to properly model and optimize your design you have to know lagrangians (or was it hamiltonians). Either way you needed some pretty potent math/physics so our teacher just gave us a base design and told us to tweak it as best we could. That mostly involved messing with the counter weight/projectile weight/string length...

oh btw, you should definitely make it a trebuchet, it's pretty impressive how far it'll shoot something if properly balanced
 
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