This goes a long way toward clarifying your questions of Feb.13th. Last fall I was visiting the Georgia Tech School of Aeronautics and a class there was working on a similar project. They had chosen a helicopter of conventional configuration with a large main rotor and tail rotor. Part of the decision seemed to be that there were enough problems to solve in the control design without trying at the same time to invent another kind of flying machine.

Efficiency of the coaxial configuration is the least of your problems. By tethering the batteries and keeping things light, you should have no problem producing enough lift to hover. The biggest problems I see are the mechanical complexity and problems of stability.

There is nothing indicated in your sketch that would provide any inherent stability. A microprocessor would have to be dedicated to providing stability in addition to the control functions you describe. This is certainly possible. It is similar to the problem faced by the inventor of the Segway People Mover. But you are biting off a lot to be accomplished in a school year with limited resources.

Although differential power on the outriggers will tilt the machine, they won’t supply a force to rotate it about the axis. Therefore, at least two of the outboard engines would have to be mounted on gimbals to supply directional control. Igor Sikorsky’s first successful helicopter (the VS-100 I believe) had a single main rotor with a tail rotor and four smaller vertical outriggers similar to your proposed layout except they were open rather than ducted. Although it flew after a fashion, only when he provided cyclic pitch control for the main rotor and eliminated the outriggers could it be considered a practical flying machine.

If I were on your team, I would vote to use a helicopter of more or less conventional configuration. My reasons would be:

1. The proposed machine is not inherently stable and would require design of a stability augmentation system
2. The numerous fans and motors are an unnecessarily complex solution to the assigned problem
3. Inventing a new type flying machine is a different task than designing an autonomous control system and the increase in scope makes it unlikely that it could be completed in the allotted time.

I hope this helps.