You *could, *but the easiest assumption to use is the motor/tranny speed to the wheels. Problem with using the ball’s throw is that you must estimate he distance, then the power transmission efficiency, then backsolve for RPM. Lots of error, though either way. it’s hard to guess.
Based on my team’s prototype, 2885 RPM
EDIT: I’m assumming 8’ wheels too there…
EDIT 2: Whoops, forgot to add in sprockets
Well, I dont have a guess, But i will say that thing looks pretty sweet. Have you guys looked at the difference between running 2 spinwheels on each side as opposed to one?
A couple of more hints.
-The wheels are 8 inches
-We assumed that only 75% of the distance covered by the spinning wheel gets to the ball. We were looking for the speed limit.
It’s too easy now. 
Dave
2560 rpm?
Wait… does 37 feet mean 37 feet horizontally?
From the video sound it sounds as if you need to grease the gearbox ours was the same until it was well greased.
Anthony Peck,
Integration Manager
Team 1806
The gear boxes are greased but haven’t been checked since last year. Most of the noise is coming from the chain.
Yes, 37 ft horizontally.
Looks like 1269 RPM to me
gear ratio * free speed of kit transmisson
3:1 * 423 rpm = 1269 rpm
edit - I estimated that the larger sprocket was 36T and the smaller one was 12T by looking at the picture.
I know I’m coming late to the party, but 1,250 rpm, plus or minus two weeks.
(Bonus if you recognized the obscure movie reference.)