Making a Catapult...

Kurt_ · Post by **Kurt_** » Sun Mar 04, 2007 6:54 pm

I made a trebuchet with internet plans. It sucked, launching a foam ball MAYBE 3 times its length. Make a crossbow!!!

vskid · Post by **vskid** » Sun Mar 04, 2007 6:57 pm

Kurt_ wrote:I made a trebuchet with internet plans. It sucked, launching a foam ball MAYBE 3 times its length. Make a crossbow!!!

Crossbows are pretty sweet, I've fired one before. Even cooler would be a 150 pound longbow and being strong enough to pull it back and fire accurately.

Edutainment · Post by **Edutainment** » Wed Mar 07, 2007 2:58 pm

Kurt_ wrote:Make a crossbow!!!

I wanted to, but spring steel is expensive... I think?

Kurt_ · Post by **Kurt_** » Wed Mar 07, 2007 5:05 pm

Make a really big one with some car suspension.

vskid · Post by **vskid** » Wed Mar 07, 2007 5:50 pm

Kurt_ wrote:Make a really big one with some car suspension.

Ohhh, nice idea, have steel cable for the string and a winch to pull it back. Make it a recurve too, like this -<( . -=stock <=string (=leaf spring

Rototiller · Post by **Rototiller** » Wed Mar 07, 2007 6:17 pm

Are you going to use a large wooden Rabbit?

Post by **Sparkfist** » Thu Mar 08, 2007 9:07 am

http://www.siege-engine.com/

http://www.trebuchet.com/

Both sites have a ton of information on the subject, and I used them a lot when I built two in wood shop a few years ago. Also if go to build a torsion siege engine I would suggest parachute cord, it's very strong and has just enough give to serve the purpose.

Electric Rain · Post by **Electric Rain** » Thu Mar 08, 2007 11:33 pm

Woah...

Who are you people trying to kill!?

Post by **Sparkfist** » Fri Mar 09, 2007 8:40 am

Electric Rain wrote:Woah... Who are you people trying to kill!?

The neighbor's cat.

Really you want to get technical, these are no more dangerous then a car. When operated in the right setting and by the right operator they can be fun and enjoyable. However if it's in a situation that screams trouble (suburbia/crowds) and is operated by a careless individual(s) it can be a very deadly/dangerous weapon.

I think that a 1/10 scale trebuchet would be an awesome item to have fun with. Though I understand that should anyone be in any range of it's fire, lobbing wooden/metal projectiles is out of the question, even golf balls could be a stretch.

Electric Rain · Post by **Electric Rain** » Fri Mar 09, 2007 1:41 pm

Sparkfist wrote:
Electric Rain wrote:Woah... Who are you people trying to kill!?
Really you want to get technical, these are no more dangerous then a car.

Which you need a license to operate... >.>

Post by **Triton** » Fri Mar 09, 2007 2:27 pm

the trebuchet im builing now (tech physics again whee!) will have an arm length total of about 10.5 feet (8 on the long side 2.5 or so on the short) use an appx 330-400lb counterweight a 5 foot long sling and stand about 6.5 feet tall at the fulcrum. we estimate it will throw a 2litre bottle full at least 280 feet. woo! (dimensions may not be 100% accurate, this is an approximation)

Post by **Triton** » Fri Mar 09, 2007 4:17 pm

yea yea double post, so sue me!

with my latest calculations with this the catapult i am building in my team (2 people) for tech physics will have:

Code: Select all

main weight          200kg - 440lbs
beam weight          15kg  - 33lbs (probably be more)
short arm            1m    - 3.2ft
sling length         2.5m  - 8ft
projectile           2kg   - 4.4lbs
main weight strap   .75m   - 2.5ft
long arm             2.75m - 9ft
pivot height         2m    - 6.5ft
135 deg sliphook

an estimate approximate range around 575 feet with an initial projectile velocity approaching 90mph!

Gamerdude · Post by **Gamerdude** » Mon Mar 12, 2007 2:26 pm

vskid wrote:Mythbusters used surgical tubing.

that wasn't a catupult, it was a slingshot. Mythbusters are cool, I am wathching a rerun right now.