We just finished building and are now testing different ball shooters. We don’t have an actual field kit, just caps and balls.
We marked the flags on the wall and have observed that the launchers are consistently hitting them.
What we don’t know, however, is how much resistance the flags have.
Can someone help us out?
No, I’m don’t believe anyone can help you out. The resistance varies from field to field. Fields used more often will have less resistance than brand new fields. It’s one of the unknown when traveling to competitions. However, posting a video or two might give us a guess as to whether you would be fine or not.
It is very difficult to give a good reference to how much you need to push a flag, but I can try with the resources I have. If you were to grab a piece of notebook paper and rip the paper with your index finger, that’s about the amount of force required to push a flag with your finger right in the middle of the flag at the same speed of turning. I uploaded an unlisted video, if this helps(I’m at school, finished all assignments so I’m bored). Keep note that the force required varies, BUT at worlds I am fairly positive that by eliminations the flags would be easier to turn. Also I really hope this doesn’t turn into a thing where everyone is ripping papers as reference for flipping flags, but i can say it is far better than making a flag out of wood. (fun fact: 125-250 Ibs of paper is produced by only one tree, which is not bad)
https://youtu.be/2B5ofGPKPu4
Hopefully this helps 
Kind of a annoying variable
He’s just salty that he has to constantly switch rubber bands for his puncher
Seeing that you’ve marked a spot on the wall where the flags will be, if you haven’t already mark the green area on the far sides of the flag (see below) as well, since flags turn easier when hit in that area.
I just want to point out that the green area is not necessarily the easiest to turn the flag. In theory, with stiff flags, it would be, as you get more leverage there. However, the flexible nature of the flags often means that the energy of the ball is not transferred fully into turning the flag and instead to bending and vibrating it. I have personally found the middle of the flag to be the best for turning them, but obviously this should be determined experimentally for your specific shooter
I shoot at the outside third of the flag. It seems to work fine for me.
Just make your launcher as fast and consistent as you can, and during competition try to get closer to the flag to increase your chances of actually turning it.
Look at the bolded quote in my signature
In a match a couple weeks ago a puncher was hitting flags so hard the flag flipped back to the original color. The driver adopted the policy of shooting the other color when close. I think they removed some rubber bands after that match.
How’d that work? If it’s toggled for, say, blue, it would bounce back to blue. Blue would be facing out. If the driver is on the red team, how would they toggle it in their favor?
My teams double catapult works fine with 3 rubber bands. We had the same issue as @rpm where we hit flags too had at times though.
Sorry I was not clear. It happened if the flag was not fully to one side or in the detent (as the center set of flags start out).