If you are making a UAV, then you will also have programs that can calcualte performance with a given configuration. If you don't have this, create it otherwise you are pissing in the wind. Obviously this is a school project, because anyone who is doing this for real, wouldn't be asking this Basic question on how to do a simple design. In short, create that program if you don't have it, or simply open an aero text book and start reading! Because you aren't going anywhere without that knowledge, ESPECIALLY IF YOU ARE MAKING AN AUTONOMOUS UNMANNED AERIAL VEHICLE! you will have to program the onboard processors with the proper inputs and equations for the UAV to actually fly...

Open a book you might learn something

Success is when it comes back in a paper bag