Hello, I would like to ask your comments and help with regards to our thesis project in school. Our project is to make an unmanned helicopter. It will be controlled by a microcontroller.

Our problem is in selecting the design or shape of the helicopter. Initially we have proposed designing an electric helicopter (to be flown in a gym) based on a coaxial rotor design. But instead of tilting the blades, we were proposed of putting four motor/props in four quadrants to provide tilt and direction change by changing its motor speed.
We will be building the body of the aircraft unless there is a rc model of this kind. In this setup, the batteries of the motors will be tethered to reduce load. The helicopter will only fly low heights. Below is a rough design of the helicopter.

But we dont have that much idea about flight and aerodynamics (but we are researching more ).

Then, we thought about purchasing a single rotor helicopter kit and from there, we will construct the navigation system and computer system to make it fly unmanned.

I'd like to ask your help, ideas and comments on which approach would be better and more feasible. If possible please add theories/discussions or mathematical computations to support it.

We are actually leaning on choosing the 2nd option of purchasing a single rotor heli so any proofs, ideas that will show that the 1st option is not feasible (stability, design, capability to turn/tilt, etc) is ok.

Thanks! Any help will be appreciated