just adding some information, when you want to build a UAV you need to know what your purpose, whether you need a copter or fixed wing, both have advantages and disadvantages
I give you example from our project
copter, easy to navigate, easy to control, suitable for small area, relative detail since copter can fly in low altitude. travel only in short distance compare to fixed wing
fixed wing, suitable for large area, can fly in tenth of kilometers, hard to control especially at landing, cannot fly in low altitude,