Is it possible to achieve torque equilibrium in order to fly? I am trying to create a tricopter which will be used for SLAM, but my main problem is that before starting to construct it I am not sure whether or not it will work at all. The problem is that I need a sensor to be rotating on an axis vertical to those of the rotors. Moreover that part will not be on top or below the drone but rotating around its "chassis axis"(blue line on second ppicture), because the sensor must not have anything blocking its view. Is it possible to achieve it? If yes what is the optimum placement of the motors and the moving sensor? Since English is not my native language I understand that some things may not make sense please feel free to ask me anything you don't understand.
If I understand the problem correctly, there will be a camera attached around the perimeter of the copter, which must have an uninterrupted view.

If the camera just swings around a perimeter, there will be two problems: 


Trim of the device. There are only three rotors. If the device is in a trimmed hover and the camera swings around, the device needs to be re-trimmed rapidly to prevent roll/pitch.
Reaction yaw. The device starts spinning the other way that the camera is swinging.


Best way is to give the camera a fixed place and make the whole device spin, via gimballing the main rotors or using two vertical propellers. A counter-weight to the camera will put the CoG in the centre.