[EricH]

Originally Posted by zrop

safety cage we are going to use is designed to keep balls outs rather than keeping blade shrapnel in.

The inspectors will be looking for both. One piece of prop shrapnel gets through, and <S01> is probably going to be called. Then you have to remove both.

Let's say those are 9" blades going at 7000 RPM. That's C=pi*d=pi*9=28.26" per revolution. That's about a 2' circumference (rounded down to emphasize the need for protection here). So, the tips of that prop are traveling at 7000RPM=116.7RPS over a 2' circle. That's a tangential speed of 233.3 feet per second--or about 4 FRC fields in one second. If a tip breaks off at that speed, you WILL get a safety violation if it leaves the robot! And, if I were the head ref, I'd make you either remove the props or add protection to the cage. Play it safe and add material now.

Edit: I just saw this: http://www.chiefdelphi.com/forums/sh...049#post812049
I would consider this, or something similar, much safer than your current setup.