"As you state, it is a complex multidisciplinary problem, with many variables. However, assuming you want to use commercial off the shelf (COTS) components, your variables are quickly reduced. The first thing to do is write down the requirements. …"
"If the ONLY thing you changed in the upgrade, was the size of the propellers, it may be they are too large for the motors. What voltage, motor, ESC, and props are you using and how much is the total weight of the UAV? Can you put the original…"