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View Full Version : Help me make a good projectile launcher



Cloud
12-19-2004, 09:43 PM
This is for a project for physics. I have to design and build a projectile launcher that uses a golf ball to hit a 3 ft. diameter traget at a range of 18 to 36 ft. The target will be on the ground, and the golf ball must clear a 3 ft. high obstacle located 10 ft. down range.
Anyone have any tips, suggestions on how I should go about this?

Mikus
12-19-2004, 09:45 PM
I suggest a manganel... not exactly sure how to spell it. It's basically a catapult that operates on tension of a coiled rope, or something... look it up...
...
/me gebs it.

Pagewizard_YKS
12-19-2004, 09:47 PM
maybe something like a small-scale potato gun?

Cloud
12-19-2004, 09:50 PM
Originally posted by Pagewizard_YKS
maybe something like a small-scale potato gun?

Yes, that's what EX-Massassian Correction suggested to me, but I'm not sure if it's "school acceptable". I'll google what you said Mikus.

kyle90
12-19-2004, 09:51 PM
Some sort of catapult would probably work best. I would suggest a potato gun, but if you need it to hit a target then you have to be able to accurately predict the flight path, which is easier to do for a catapult.

Mort-Hog
12-19-2004, 09:59 PM
Trebuchet all the way.

BV
12-19-2004, 11:47 PM
I made a catapult once that could do that out of one of those hunting slingshots. It could shoot really really far, and I'm sure you could do some simple tests to figure out the stretch:distance fired ratio.

Greenboy
12-19-2004, 11:58 PM
I made a 3foot trebuchet once. It could throw a tennis ball around 50 feet.

tofu
12-20-2004, 12:24 AM
Originally posted by kyle90
Some sort of catapult would probably work best. I would suggest a potato gun, but if you need it to hit a target then you have to be able to accurately predict the flight path, which is easier to do for a catapult.
...My air cannon is damn accurate.

darthslaw
12-20-2004, 12:27 AM
Originally posted by Cloud
EX-Massassian Correction Wait, what?
He was banned?

Axis
12-20-2004, 01:12 AM
Ballista/crossbow style?

Steven
12-20-2004, 03:15 AM
A small sized potato cannon would be difficult. I suggest a type of slingshot. Strips of a bycicle inner tube work well as the band, and a simply automotive fluid funnel works well as the ammo container. A pair of stakes, and you're set. Just practice your aim.

dalf
12-20-2004, 03:43 AM
Explosive (cannon) propulsion is overkill but most accurate.
Centrifugal (catapult,trebuchet) propulsion if released at right point can travel large distances. Accuracy depends on release point.

Your best bet is potential propulsion (slingshot). I say potential is because you're using potential energy of a device to launch a projectile. Fairly accurate and easy to build. The Work-Energy Theorem can provide you with a lot of information on these launchers.

Tyler
12-20-2004, 04:22 AM
Originally posted by Darth Slaw
Wait, what?
He was banned?

(Quick aside from the projectile launcher topic)

Actually, if I remember correctly, he left on his own terms because he didn't like the way certain people were being treated by certain admins. I think.

Anyway, it's a shame. I was really good friends with Roy for awhile, and was sad to see him gone when I sauntered on back towards Massassi. I used to talk with him over AIM, too, but I don't use AIM anymore...heck, I barely use the computer at all anymore.

Anyway, sorry. Just wanted to answer Slaw.

Brian
12-20-2004, 04:54 AM
Arm.

Spork
12-20-2004, 07:37 AM
We had to do something like that in physics. I wanted a trebuchet, but we ended up with this spring-loaded thing that was fired with a trigger. Pretty cool, actually. We spent a whole day firing ball bearings at a whiteboard eraser positioned in many varying spots all over the classroom. We ended up with it positioned behind chairs and desks and stuff requring bank shots. Good times.

Elana14
12-20-2004, 01:45 PM
we had to make door sized trevoshayes for our physics class. that was a fun day. especially when we broke one of the legs of neighboring group's trecoshay. oops. :p

Martyn
12-20-2004, 02:16 PM
Trebuchets are superb, but possibly overpowered for what you want: you'd throw it too high to make it accurate.

Crossbow type tension device is what I'd use for a golf ball at that range with only a 3ft obstacle.

UltimatePotato
12-20-2004, 02:34 PM
How exactly does a trebuchet release the shot? And how do you aim one? The look pretty awesome and in every RTS they are in they can level a building in seconds.

UltimatePotato
12-20-2004, 02:37 PM
Could you use a modified bow and arrow? Bows are great for acuracy if you know how to use one. A bow and golfball...
If you didn't have a bow though the slingshot would be the next best thing in my mind.



Nuclear Golfball Attack Submarine....hmmm....

Martyn
12-20-2004, 02:42 PM
Originally posted by UltimatePotato
How exactly does a trebuchet release the shot? And how do you aim one? The look pretty awesome and in every RTS they are in they can level a building in seconds.

It releases via an angled hook at the peak of the arms arc, and you aim it by trial and error, adding or subtracting weights. Not very scientific, but tres cool.

MaxisReed
12-20-2004, 04:06 PM
Originally posted by Brian
Arm.

Quoted for Truth and Humor.

Oxyonagon
12-20-2004, 04:12 PM
Originally posted by Mort-Hog
Trebuchet all the way.

I'm building one in my crafts class, It's great fun, i'm starting to put it together! :D

The teacher isn't too pleased, but he'll be no longer bothering me soon as I attach the harness, he might not fit - it's a model.

lateralus
12-20-2004, 04:17 PM
Magnetic Rail launcher

Overlord
12-20-2004, 04:48 PM
I'd suggest using compressed air. Make it like a large paintball gun. Possibly fired over the shoulder like a bazooka.

Avenger
12-20-2004, 06:03 PM
Originally posted by Martyn
It releases via an angled hook at the peak of the arms arc, and you aim it by trial and error, adding or subtracting weights. Not very scientific, but tres cool.

The length of the sling also can be adjusted to affect the release point of what ever you're throwing.

They are awesome machines.

Dj Yoshi
12-20-2004, 06:25 PM
Originally posted by lateralus
Magnetic Rail launcher

I'm with him.

Oxyonagon
12-20-2004, 06:35 PM
I'm guessing a magnetic rail launcher might just beat a trebuchet. :(

Cloud
12-20-2004, 09:08 PM
Thanks for the suggestions. I'll try to go with whatever is easiest to make.

lateralus
12-20-2004, 09:11 PM
http://www.oz.net/~coilgun/theory/electroguns.htm
Here's the theory... now build it. Before I do.

Squirrel King
12-20-2004, 09:15 PM
"Good" and school freindly don't mix.

I can offer a range of suggestions.. and ways to make it.
What do you want to "power" this project?

Counter-Weight
Tension
Explosion
Pressure

JediKirby
12-21-2004, 11:13 PM
I believe Kyle09 has a few microwaves....

Ric_Olie
12-21-2004, 11:31 PM
Last year for Engineer's Week we made a catapult that used a garage-door spring to toss eggs and hit a target about 75 feet away. It was quite accurate (though we missed the frying pan, but then so did everyone else) and consistent.

Basically, we used a wooden frame and two long screw rods. One was in front, and the spring was attached to that. The other was set to pivot at its base and acted as the arm. By having nuts we could move up and down the rods, we were able to adjust the power the spring delivered.

Let me dig up a couple of pictures...

Here:
http://www.missouri.edu/~msc42/gaddypult3_640x480.jpg
http://www.missouri.edu/~msc42/gaddypult4_640x480.jpg

Note: Those are my friends in the first picture, neither one is me.

This took us about two days to make. One day to design and shop for parts, one for construction. One more day to calibrate it, and we won $50 for it. Maybe you could use something similar. A golfball is somewhat similar to an egg in size, shape, and weight.

ECHOMAN
12-22-2004, 07:00 AM
Neat. How far did it launch? (and what was the weight on item?)

Martyn
12-22-2004, 07:01 AM
Originally posted by Ric_Olie
Last year for Engineer's Week we made a catapult that used a garage-door spring to toss eggs and hit a target about 75 feet away

And they missed their fryaing pan sized target, but at 75 ft, that would have been impressive!

Ric_Olie
12-22-2004, 08:06 PM
Yeah, no frying pan hits for us. Though I forgot to mention, we did manage to hit the distance judge, who also happened to be the community advisor for our floor, in the leg. Much hilarity ensued. I have a video somewhere, but I don't have space to host it I'm afraid.

kyle90
12-22-2004, 08:15 PM
Originally posted by jEDIkIRBY
I believe Kyle09 has a few microwaves....

Hmm... a microwave powered golfball launcher... reminds me of the SG-1 episode where the alien builds a miniature stargate in Carter's basement... "By the way, you're going to need a new microwave."

I'm just trying to work out how to turn the radiant energy in the microwaves into translational energy of the golf ball. Works well enough for plasma, but...

Cloud
12-22-2004, 08:16 PM
Apparently everybody at Massassi are physic students or something...

BV
12-22-2004, 10:10 PM
We had a cool project this year in physics where he gave us springs, and we found its spring constant, and then we had to build a ramp, and launch the spring into a box without doing any test firing, using only math to figure out how far to pull the spring back. It was awesome.

kyle90
12-22-2004, 11:32 PM
Heh, BV, I did that very same thing in Gr. 12 physics last year. Although I had an incompetent lab partner, I managed to hit the little square of cardboard every time.

Oh, and next year (if you take engineering), you'll get to learn that the so-called spring constant ISN'T ACTUALLY CONSTANT!!! *GASP*

Well, it kind of is.

Martyn
12-23-2004, 06:38 PM
Originally posted by Cloud
Apparently everybody at Massassi are physic students or something...

ENGINEER!!!