Hello! What would you say is the best distance between a dual flywheel system? I’ve seen lots of different spacings due to different ball squishiness (S), but I am wondering if any of you have found that optimal distance between flywheels for a short range shooter.
Thanks for any help! 
Well, the short answer is there is no ideal spacing between the wheels. Here’s what I would recommend. Make the compression rate about 0.5" and get 3 very dense balls and 3 very soft balls. Then, get the flywheel up to speed and feed the balls through. If the harder balls go farther, the compression rate is too low, while if the softer balls go farther, the compression rate is too high. Once all of the balls go almost exactly the same distance (probably within a few inches of one another,) take a set of 10 balls and feed them through. Then adjust the motor power so that they are all shooting into the high goal. Hopefully, you will have perfect consistency.
Hope this helps. 
Testing is the most optimal distance, in simpler terms it varies from robot to robot. Somewhere under 4 in. Though.
Team 7090 from China still has the best dual in the world even 2 months after their last competition.
(Judging from match scores and skills scores. They still have the #1 programming skills score.)
Wheel spacing must have something to do with that at least in a small way.
Although they do have a very unique and wonky looking design.
Link to their highest scoring match (It was the highest scoring match ever for about a month)
What was the score?
323 – 20
Updating list of highest scoring matches
Thanks to @nallen01
First of all what wheels are you using if you are using 4 inch wheels our spacing is 14 with this launcher we get a 95 percent accuracy and an insane fire rate.
We are planning on using the 5in wheels, however that is not set in stone. We weren’t planning on competing this year, however, we were offered a grant for this season only that we couldn’t pass up so we are just now designing XD.
As far as I know, 4" wheel dual flywheels have been much more successful then their 5" counterparts.
At least in my region and in matches on youtube that I’ve seen.
The only one that I can think of that’s been successful and revealed is team 1727B from maryland.
well your friends at 1115 will with what ever considering D team has an field sweeper like never seen before.
I am actually having a problem that involves this thread, and I think your reply might be able to help me. What is a compression rate of 0.5?
It basically means the ball will be compressed .5" or the ball will be ~3.5" when it goes through the wheels.
WOAH, 5 inches smaller than the ball?! How would it even fit through?!
0.5" of compression, not 5".
Ours compresses an inch sometimes. Not healthy but works