Can we change drive wheels during competition,for use in different missions?
Back when I was involved with FLL teams, there weren’t really restrictions on what could be changed when teams were at the table, as long as they had the parts there. I’d check the rules to make sure that parts changes aren’t prohibited, and if they aren’t, have at it.
And while you’re at it, this is a great chance to teach the kids how changing one element often requires changing other elements… if encoders or timers are used to control distance, changing wheels could very well throw them off if they’re set for the original wheels. That should be easily manageable, though, so it’s a teaching experience instead of a learning experience.
You can change the wheels, but typically teams don’t do that because it can be time consuming to make sure that they are aligned so your robot doesn’t veer off course.
You can change anything you want when in base, as long as your robot is still legal when it leaves. We did something very similar to what you’re asking during my last year of FLL. In order to traverse the obstacles during the last 30 seconds, we would remove the NXT brick from it’s base and attach it to another drive base that was more suitable for obstacles.