Trajectory B/C

[starpug]

No trajectory is a little more general in design than STC, you can build anything powered by a nonmetallic elastic solid. Last year we built a slingshot/wrist rocket type device that worked quite well so it's not just limited to catapults, which is a large category in itself.

[hollyberries230]

How would one even begin going about building such a device? This is my first time trying Trajectory C, and my partner and I are completely overwhelmed as to how to start out. Catapults, slingshots; how would we learn how to build such things? Library books and hobby guides only give generic models of irrelevant mechanisms. Any help would be much appreciated.

[captbilly]

Look on the SO website, there is probably a link to a WIKI. Look on youtube (search, science olympiad trajectory), there are some videos there. There are also the more adult sites (not as in X rated, just for adults interested in catapults and trebuchets) with lots of info on assorted "siege engines" (weapons that throw heavy things). But to put it as simply as possible, just picture some sort of rubber band (maybe lates tubing or bungy cord) powered catapult. A simple lever with a large rubber band pulling it with a cup to hold your ball attached to it will do the job. There are many many other possibilities, and many fine touches that will contribute greatly to the accuracy (really repeatability) of the device, but the basic idea is a catapult powered generally by rubber bands or tubes.

You can try a torsion powered device as well, which would just be an arm (with the cup to hold the ball at one end), that rotates due to the force of winding a large rubber band or rubber tube or rope. You can also look up tons of info on trebuchets (was called strom the castle in Science olympiad jargon), and just change the power source from a falling mass to a rubber band. A basic trajectory device could be built in an afternoon, although the National winning ones probably takes dozens if not hundreds of hours to build and calibrate. Plan your time so that you have lots of time left after building to find the right settings to get your device to reach a certain distance and height target. For the more competitive teams the adjustments (calibrating) generally takes more time than building does.

[starpug]

I wouldn't say hundreds, maybe a hundred knowing Arden and the way they do things. Yeah look at the wiki, I even added a section on a push type trebuchet the other day Trajectory Wiki.

[guerillagorilla]

Does anyone know where I can directly purchase surgical tubing (like form Walgreens or Home Depot instead of Amazon.com?

[jazzy009]

I'd say Google for random junk stores in your area. They usually have surgical tubing as well as many other things that could benefit your structure.

[trombonegirl23]

My partner was saying he was buying it in bulk somewhere but I think it was online. Maybe try a medical store or maybe like a hobbie store. Some people online were saying pet stores but I think that is a different kind of tubing (for like fish tanks).

[alltimelow1]

I didnt do this event last year but im working with a highschooler that did so i think im ok.

[hollyberries230]

Look on the SO website, there is probably a link to a WIKI. Look on youtube (search, science olympiad trajectory), there are some videos there. There are also the more adult sites (not as in X rated, just for adults interested in catapults and trebuchets) with lots of info on assorted "siege engines" (weapons that throw heavy things). But to put it as simply as possible, just picture some sort of rubber band (maybe lates tubing or bungy cord) powered catapult. A simple lever with a large rubber band pulling it with a cup to hold your ball attached to it will do the job. There are many many other possibilities, and many fine touches that will contribute greatly to the accuracy (really repeatability) of the device, but the basic idea is a catapult powered generally by rubber bands or tubes.

You can try a torsion powered device as well, which would just be an arm (with the cup to hold the ball at one end), that rotates due to the force of winding a large rubber band or rubber tube or rope. You can also look up tons of info on trebuchets (was called strom the castle in Science olympiad jargon), and just change the power source from a falling mass to a rubber band. A basic trajectory device could be built in an afternoon, although the National winning ones probably takes dozens if not hundreds of hours to build and calibrate. Plan your time so that you have lots of time left after building to find the right settings to get your device to reach a certain distance and height target. For the more competitive teams the adjustments (calibrating) generally takes more time than building does.

Thanks; that really does help my visualizing the general aspects of the event. But after looking at the coach's power point, I had a few more questions. Could anybody explain how the targets are oriented? The powerpoint expresses that they're placed at different elevations, but I'm not really sure if that means the targets are still flat, or if they're held up like dart board targets. And are there specific graphs that we should make? Or is it open to anything that shows some sort of relationship between any variables in the event? Thanks again.

[starpug]

Look on the SO website, there is probably a link to a WIKI. Look on youtube (search, science olympiad trajectory), there are some videos there. There are also the more adult sites (not as in X rated, just for adults interested in catapults and trebuchets) with lots of info on assorted "siege engines" (weapons that throw heavy things). But to put it as simply as possible, just picture some sort of rubber band (maybe lates tubing or bungy cord) powered catapult. A simple lever with a large rubber band pulling it with a cup to hold your ball attached to it will do the job. There are many many other possibilities, and many fine touches that will contribute greatly to the accuracy (really repeatability) of the device, but the basic idea is a catapult powered generally by rubber bands or tubes.

You can try a torsion powered device as well, which would just be an arm (with the cup to hold the ball at one end), that rotates due to the force of winding a large rubber band or rubber tube or rope. You can also look up tons of info on trebuchets (was called strom the castle in Science olympiad jargon), and just change the power source from a falling mass to a rubber band. A basic trajectory device could be built in an afternoon, although the National winning ones probably takes dozens if not hundreds of hours to build and calibrate. Plan your time so that you have lots of time left after building to find the right settings to get your device to reach a certain distance and height target. For the more competitive teams the adjustments (calibrating) generally takes more time than building does.

Thanks; that really does help my visualizing the general aspects of the event. But after looking at the coach's power point, I had a few more questions. Could anybody explain how the targets are oriented? The powerpoint expresses that they're placed at different elevations, but I'm not really sure if that means the targets are still flat, or if they're held up like dart board targets. And are there specific graphs that we should make? Or is it open to anything that shows some sort of relationship between any variables in the event? Thanks again.

You probably should go here http://www.scioly.org/phpBB3/viewtopic.php?f=16&t=163
The targets are flat.
Also I believe that as long as your graphs show whatever variable your using tested at distances should be sufficent. I'll see about uploading some of our graphs to the wiki if I get the chance.