Trajectory B/C

[andrewwski]

I think so (it's been discussed before) as they are relying on the elastic properties of the materials to work.

[SuperSherbertxxOtaku]

Hey, people. is my firsdt time doing this and I have one question:
What the heck is a calibration chart?

[captbilly]

Hey, people. is my firsdt time doing this and I have one question:
What the heck is a calibration chart?

A calibration chart is simply a bunch of data that you have gathered that tells you how you need to set your device to reach a certain distance and elevation target. If you built the best catapult ever conceived but you didn't "calibrate" it, you would not have any idea how to adjust it when you brought it to competition. With some very good knowledge of the physics involved in your device it is possible to simply calculate the impact point of your ball, but it is extremely unlikely that anyone here is using materials and methods that would allow a reliable mathamatical model to be made without some trial data to be generated. If you were given many many practice shots at competition then no calibration would be needed. You could simply keep firing until you found the correct settings and then tell the event coordinator you were ready, but that's not how it works.

I would say that for most competitors generating the data necessary to build accurate graphs or tabular data, take much more time than building the device. This is just as true for scrambler, electric vehicle, wheeled vehicle, storm the castle, etc. as it is for trajectory. Again, the exception is when you have a device who's performance can be completely mathamatically modeled. Some wheeled vehicles that I saw a few years ago simply used formulas for distance and time, because these parameters were completely predictable (there may have been a requirement for calibration graphs in the rules anyway). But I would say that it is highly unlikely that with the projectiles that are legal this year, and the materials that are likely to be used, it would be far fetched to think that anyone would be able to predict in advance of calibrating what settings it would take to hit the target.

By the way for trajectory there are very specific requirements for the graphs you must submit to the event coordinator (they are int he rules). Without any calibration graphs you would be penalized 400 points befor you even started launching.

[SuperSherbertxxOtaku]

Thanks, dude!
I couldn't find it anywhere else, so you really helped a lot.

[madscientist]

hi first timer any tips HELP me and my partner are trying to brainstorm

[binary010101]

First of all, the quality of your catapult depends on how far you're expected to go with it. If you are only going to compete at regionals, (I'm sorry to say), you'll only need a medium-quality device that will serve your needs.
There are two main methods to building a catapult. First of all, you can use elastic materials (bungee cords, rubber bands, etc.). This will look like your standard catapult, except for the facts that 1. You're pulling back and relying on the material's elastic properties as opposed to the wood's elastic properties, and 2. You may also need to loop another bungee cord around the throwing arm to prevent the arm from cracking against the ground.
The other option would to build a ballista-type catapult, much like SeigeLord's avatar. These generally use torsion springs, and (I'd imagine) that they are rather expensive to manufacture, especially by hand (you need metal parts). There is also the potential problem of overpowering the catapult.
Once you have the catapult, make a calibration table so you can determine how many degrees from horizontal or how many inches back to pull the pouch depending on the target distance.
Please correct me if I'm wrong.

[madscientist]

thanks for the tips we are trying to figure out our materials list and to fit our budget any more tips on this

[madscientist]

by the way our teachers say a budget helps because you think more about your materials think about the money

[trombonegirl23]

Last year we made a catpult and used bungee cord but we had like peg board and then had like a few different spots to move the pole the arm was on. hmm I wish I had a picture. Then we had a thing on the arm that slid up and down the arm to adjust the power. It was so heavy it weighed like 55+ pounds and was really awkard to carry. So remember that..try not to make it huge and awkard to carry if you don't have to. Like we used huge chunks of wood that we didnt need which was a bad idea cause we were going to make something else then changed our minds in the middle.

[andrewwski]

I don't worry about the budget...unless you go all-out to an absurd level, you shouldn't be spending more than $50...and that's the high end.

I think we can come up with $50 pretty easily...