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starpug wrote:

karatekid44 wrote:Surgical tubing would also work for a catapult, my team used it and they did pretty good.

Actually, something that is built to withstand high tension and return to the same length is preferable. The elastic I'm refering to is excercise tubing.

Xertube is what I used last year
The year before that it was Theraband

How are Xertube and Theraband different from surgical tubing? What makes them return to the same length?

Paradox21 wrote:

starpug wrote:

karatekid44 wrote:Surgical tubing would also work for a catapult, my team used it and they did pretty good.

Actually, something that is built to withstand high tension and return to the same length is preferable. The elastic I'm refering to is excercise tubing.

Xertube is what I used last year
The year before that it was Theraband

How are Xertube and Theraband different from surgical tubing? What makes them return to the same length?

Exercise tubing is made for exercise and is thus suppose to return to form more reliably. It also can be bought in many different resistance levels.

We used surgical tubing last year and it seemed reasonably consistent, but we did seem to have trouble tuning it in exactly and the humidity in Augusta seemed to really mess with it. Exercise tubing seems like a promising new frontier to explore this year.

Paradox21 wrote:We used surgical tubing last year and it seemed reasonably consistent, but we did seem to have trouble tuning it in exactly and the humidity in Augusta seemed to really mess with it. Exercise tubing seems like a promising new frontier to explore this year.

Well it's not a huge difference. The main reason I use it is because I can get more power out of it then I can out of normal tan surgical tubing.

I also think that we had to exceed the spring constant of our tubing in order to make the 10 meter shot. We avoided that by doing very few tests that far out. I think thicker surgical tubing or thicker exercise tubing should work well. If your surgical tubing has a high enough spring constant (which can be adjusted by using a thicker piece of tubing, or doubling it up) it should work just as well as exercise tubing.

Paradox21 wrote:I also think that we had to exceed the spring constant of our tubing in order to make the 10 meter shot. We avoided that by doing very few tests that far out. I think thicker surgical tubing or thicker exercise tubing should work well. If your surgical tubing has a high enough spring constant (which can be adjusted by using a thicker piece of tubing, or doubling it up) it should work just as well as exercise tubing.

As noted there is a lot of different resistances avalible http://www.thera-band.com/faqs_consumer.php#faq_19

Does surgical tubing retain its tension well to make testing consistent? I was thinking about using bungee cords, but they don't offer very consistent data.

ncha13 wrote:What are the requirements for the length height and with of a catapult in trajectory?

That's in the rules. If you do not have a copy I advise you get one. I will answer your question this one time, for further simple questions like this please refer to the rules.

It has to fit in a 60 cm cube.

by starpug on Mon Oct 26, 2009 2:55 pm

ncha13 wrote:
What are the requirements for the length height and with of a catapult in trajectory?

That's in the rules. If you do not have a copy I advise you get one. I will answer your question this one time, for further simple questions like this please refer to the rules.

It has to fit in a 60 cm cube.

Unless, of course, ncha13 is competing in B as indicated in which case it is a 70 cm cube.

Don't post 10 times in a row. Just edit your post. (NICE AVATAR!)

I can't really help you much with logistics, however may I recommend that you use surgical tubing rather than bungee cords?