Catapult Optimization Tutorial

[sspoldi]

Originally Posted by dardeshna

This is really awesome. I'm hoping we will do some more numerical driven design this year and a great example to use.

One question though (I may be stupid and have missed something), but this method doesn't seem to account for the torque on the arm due to gravity. Was it negligible in the grand scheme of things?

Hi Devin,
Yes there are a few things missing. The short list is:

1. Effect of gravity
2. Arm starting angle (more like -10 degrees)
3. Actual ball release angle (I don't really what this is)
4. Actual height the boulder leaves the catapult (at least 1.5 feet up)
5. Aerodynamics

I intentionally kept it simple to illustrate that basic principles are all you need to effectively optimize. The Octave script we used last year actually covered 1 thru 4, and pretty much came up with the same results and gear ratio.

I spent a few minutes yesterday installing Octave on the Windows 7 side of my laptop, If you're a glutton for punishment install it and run the attached script (ignore the warnings!), that's what we ran. You'll notice a lack of useful comments, but it does have gravity (and a cool 3D plot).

Cheers,
Steve.

P.S. Remove the .txt extension, CD won't upload a .m file, not sure why.
Oh yea, gravity wasn't a big factor!