I need some advice on designing a propeller for a UAV and choosing the right motor for it. I am doing a project which requires the fix-wing UAV to travel at cruise speed of 20 m/s and weighs a total of 12kg, the propeller will have to be a pusher and the aircraft has a L/D of 35 at cruise. I am told by the lecturer to ignore take off velocities as it takes off on a separate VTOL system before the propeller is activated at 300m for horizontal flight.
As a mechanical engineering student, I don't have much experience in aerodynamics. So far I've looked into blade element theory and airfoil designs, but there are many different variables to consider such as airfoil profile, pitch, angle of attack, diameter, and I'm at a bit of a loss on how to determine these values to match the UAV requirements. So I would like to ask, what is the best way I can go about doing this? The ultimate goal is to maximise flight time by designing a propeller and reducing power requirements.