/diy/ - Do It Yourself

Hi all.
My brothers and I came up with an idea for the next time we rally. We want to build a G-Force / Centrifuge type contraption. We have ran through a few ideas but this one seems to be perhaps the simplest.
Ideally, we get a heavy plate and weld some type of gear box to it. On top of that will be a large arm with a counter weight on one end and a seat on the other to throw you outward. Any ideas that could work better? Or design flaws I may be missing.