I've noticed that the blue twin engine bombers need three hours to reload/refuel, while the red ones just need two. Is there any historically reason?
For balanced starting armies, this extra hour is a light disadvantage for the blue team.
I can't remember now - surely not all Red twin engine bombers have 2 hour rearm times? Let me look, OK the B-25 and the IL-4 have 3 hour delays. So, no there is no hard rule about it. Anyway, those numbers are only meant to be a guide, we expect you to change them to suit your needs.