[Craig]

I like to think ours is successful.

used 2x ø4" AM stealth wheels 50A durometer

Driven by 2x 775 pros geared 1:2 (we run them at 4800 rpm no load), overkill for sure as they only draw about 50% of available power, we were going for consistency & speed of spool up

Compression: ours is a 135° 'U' shooter which is more time in contact with the ball than most flywheel shooters, compression starts at 1" and tapers to 2" at exit from the hood

Additional note: we have a 3 or 4 lb solid aluminum flywheel on the shaft to help build up inertia and this improves consistency of the shot

It should be noted that much of this is overkill just to make the shot to the high goal, ours is designed to impart a lot of ball speed at a lower launch angle to improve the range that the ball's arc will make the goal (currently makes from 15' out to right up at batter)

cheers and good luck at Toronto central!

*edit: in response to your design, in prototyping we found that a mini CIM needed to be geared up 2:1 to generate enough RPM for somewhat reliable shots. I know this is contrary to my stated RPM above, but the RPM required came way down when we doubled the 775 drive input.

One major factor we found in prototyping was that too much compression sapped the inertia to compress the ball leaving very little left to launch it