How Do I Make A Catapult To Shoot A Tennis Ball?
My teacher assigned us to build a catapult. It needs to shoot a tennis ball at least 30 feet. The only size specifications are that it must be larger than hand-held and smaller than a washing machine. Really specific, huh? Also, we are not allowed to use elastic or bungee cords. I’m thinking springs. Any tips or directions are appreciated! Thanks.
*I have already looked on google and youtube, and I havent found anything too useful.
Do a trebuchet.
This site has complete plans:http://www.tasigh.org/ingenium/medium.ht…
http://ca.images.search.yahoo.com/images...
Try this website
Well, a trebuchet and a catapult are two different things. Your teacher probably won’t care, but a trebuchet uses gravitational energy to launch things, and a catapult uses mechanical energy stored in springs to launch things.
However, it definitely would fall under the definition of catapult as you’re using the wood/metal as a spring. A trebuchet, on the other hand, may or may not be acceptable, and is at least as complicated as the mechanism I described above. (Also, I’m not sure a trebuchet of such a small size would launch something 30 feet anyway, but maybe).
Anyway, I think metal springs are an excellent idea. What you’ll want to do is use torsional springs with an arm you can pull back to launch the tennis ball. That’s what I would do anyway. I’ve linked to a pic showing my idea in “sources”. The way you attach the arm to the spring is critical, and will depend on what type of spring you get. If you don’ t have someone with a welding rig, you could try lashing the arms to the spring, but you’ll just have to experiment until you get something adequately stiff.
Also, just so you know, the stiffer the springs and the longer the catapult arms, the farther the tennis ball will go.
Another option is to just get a flexible tree branch and put a sling at the end of it. Fix it at one end, pull back and release. The problem though is you’ll need a pretty long arm to launch the ball 30 feet and may be over the size limit. You can experiment with other materials like steel or aluminum. This would be a simpler method than the spring catapult, but would be less awesome.