Best catapult/launcher for the following?

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So i need to launch a ball into a target using a personally created launcher using Autodesk and wanted to know the best design type and/or an idea (8th Grade Tech)

- 3 inch diameter ball
- weight of ball will be updated soon
- 25 feet distance
- has to be 1 foot by 1 foot or smaller
- only 2 feet tall when pulled down (max)
- the scoring system is setup like skiball, there are 3 circles that i need to land in, getting smaller as i go. Any help? i need to make it out of wood and cant use anything like motors or gas tanks. Old style catapult or trebuchet. I get to make it how i want to based on the top criteria. It could even be a slingshot. The scores are 100, 50, and 25. If i hit the edge of a circle and dont go in it is 25 points and i have 10 shots per round and 3 rounds. If possible i would like to score 750+ as a school record and have my average be 600+

Edit: I have 5 weeks to craft a CAD and cut it out and do tests. Thanks for reading
 
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anorlunda

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Fun project. I'm sure you don't want us to do it for you, you want most of the design fun for yourself and your team.

So begin by telling us, what research have you done so far.
Which do you think is best and why?
Do you get to calibrate it with practice shots beforehand?
Let's say both catapult and trebuchet can handle the distance, which one has the reputation as being most repeatable?

We'll reply with hints.
 
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Fun project. I'm sure you don't want us to do it for you, you want most of the design fun for yourself and your team.

So begin by telling us, what research have you done so far.
Which do you think is best and why?
Do you get to calibrate it with practice shots beforehand?
Let's say both catapult and trebuchet can handle the distance, which one has the reputation as being most repeatable?

We'll reply with hints.
Thank you for the response.
Yes i don’t want you to do the project for me lol. I was thinking trebuchet would be the better option because the catapult would need us to manually pull it down leaving more room for error in the repetitiveness. The trebuchet has a same weight counterweight that drops from the same height, although it would be hard to design a counterweight holder out of wood. I have to make it manually. I am unaware if i get practice shots beforehand, probably if i have finished early yes. I will double check tomorrow. Sorry for long writing

Edit: Catapult is most used in previous projects
 

anorlunda

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Can the ball roll on the floor to the target, or must it fly through the air to the target?

There are many videos on youtube about design of catpults and trebuchet. You should watch some of them.

If the device must be 25 feet from the target, no more, no less, then the ability to adjust the distance thrown is of primary importance. Which gives you greater flexibility to adjust, catpult or trebuchet? What is the adjustment mechanism?
 
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Can the ball roll on the floor to the target, or must it fly through the air to the target?

There are many videos on youtube about design of catpults and trebuchet. You should watch some of them.

If the device must be 25 feet from the target, no more, no less, then the ability to adjust the distance thrown is of primary importance. Which gives you greater flexibility to adjust, catpult or trebuchet? What is the adjustment mechanism?
The target is elevated about 1 foot and curved at a 40 degree angle. It cant roll. What do you mean about adjustment mechanism? There will be a 1x1 foot square that we can move the launcher in.
 
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anorlunda

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Suppose you test it and it throws the ball 30 feet or 20 feet, what then? You need an adjustment.

I presume that you can't adjust by moving the whole thing back and forth. The device must toe the 25 foot line.
 

jrmichler

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If you decide to use a trebuchet, here is a good link: http://www.algobeautytreb.com/. There is a link to a manuscript on that site that tells you everything you need to know to build a trebuchet.

You do not need to understand, or even use, all of the math. Just read through and get the important points, such as the ratio of the length of the short arm to the long arm. I once built a small trebuchet from that document. It fit in my hand, and was able to throw a nickel into a light fixture in the far corner of my office. I gave it to a friend for his kid, who was in 8th grade at the time. That kid is now a senior in mechanical engineering.
 
7
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Suppose you test it and it throws the ball 30 feet or 20 feet, what then? You need an adjustment.

I presume that you can't adjust by moving the whole thing back and forth. The device must toe the 25 foot line.
i may be able to adjust the weight of the counterweight and if not i can do it in between sessions, each sessions is a day, so 1 test 1 day, 1 the next so on
 
7
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If you decide to use a trebuchet, here is a good link: http://www.algobeautytreb.com/. There is a link to a manuscript on that site that tells you everything you need to know to build a trebuchet.

You do not need to understand, or even use, all of the math. Just read through and get the important points, such as the ratio of the length of the short arm to the long arm. I once built a small trebuchet from that document. It fit in my hand, and was able to throw a nickel into a light fixture in the far corner of my office. I gave it to a friend for his kid, who was in 8th grade at the time. That kid is now a senior in mechanical engineering.
thanks, will check it out if i go down that route
 
73
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So i need to launch a ball into a target using a personally created launcher using Autodesk and wanted to know the best design type and/or an idea (8th Grade Tech)

- 3 inch diameter ball
- weight of ball will be updated soon
- 25 feet distance
- has to be 1 foot by 1 foot or smaller
- only 2 feet tall when pulled down (max)
- the scoring system is setup like skiball, there are 3 circles that i need to land in, getting smaller as i go. Any help? i need to make it out of wood and cant use anything like motors or gas tanks. Old style catapult or trebuchet. I get to make it how i want to based on the top criteria. It could even be a slingshot. The scores are 100, 50, and 25. If i hit the edge of a circle and dont go in it is 25 points and i have 10 shots per round and 3 rounds. If possible i would like to score 750+ as a school record and have my average be 600+

Edit: I have 5 weeks to craft a CAD and cut it out and do tests. Thanks for reading
If you are trying for maximum accuracy, try to make it a linear launcher so it will be easy to aim and judge the range when shooting on a certain angle.
 
7
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If you are trying for maximum accuracy, try to make it a linear launcher so it will be easy to aim and judge the range when shooting on a certain angle.
Lol no, i wish. like i said in the thing, i have to make it out of wood after designing a cad and it has to be oldschool type. The ball is a hackey sack
 
7
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ok so, potato launcher with compressed air or spring loaded launcher, my new 2 ideas. Which is more accurate
 
105
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Both have fairly large issues with repeatability. They are also less fun than a catapult!

Compressed air relies heavily on getting a consistent seal, weight of charge, pressure and release of pressure to have consistent shots. Any one of these will throw it out somewhat.

The spring is more repeatable, needing that you get a smooth movement of it and a clean release. you can draw back further or adjust the angle to adjust your aim.

I build a small beast of a catapult in my youth - I built a lot of different ones, including a trebuchet which used 2 breezeblocks as a weight (~40Kg). The most powerful I made was essentially the same as a floating-arm trebuchet, but instead of a weight, the whole device was turned on its side, and the "weight" end of the arm was pulled across by elastic bands. The arm was hinged on another arm which connected it from ~1/3 of the way up the arm to the back of the device, allowing the arm to move up & down so the elastic band end can slide in a horizontal slot.

The result was a small catapult (about a foot long) with about a hundred elastic bands powering it, which could launch with a heckuva flick & send a small marble a good quarter mile. It used a disposable sling which hooked onto the end of the arm.

The whole thing (bar some bolts & screws) was made of wood.
 

anorlunda

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The result was a small catapult (about a foot long) with about a hundred elastic bands powering it, which could launch with a heckuva flick & send a small marble a good quarter mile. It used a disposable sling which hooked onto the end of the arm.
What fun as long as no neighbors or their windows were endangered. Did you actually measure the longest throw?
 
105
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What fun as long as no neighbors or their windows were endangered. Did you actually measure the longest throw?
Fortunately, my old back garden opened out into countryside, so there was little to no risk of hurting anyone.

Unfortunately, there wasn't a hope in hell of finding the marble once it was gone! the most you saw was a dwindling speck, if you were looking hard enough to see it at all! a quarter-mile was my best rough estimate, based on my garden being ~150yds long, and as best I could tell it was still climbing when it went past the end!


Obviously, this would be seriously overpowered for the task at hand - 10-15 elastic bands might be a better bet!
 

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