That turbine drum idea is nuts. I have no idea if it would be successful or not but would love to see it come to fruition. Obviously experimentation would be required but it might benefit from a few venturi nozzles on the outlet (perhaps hinged) to accelerate the air flow and allow you to get the optimal angle for air to vane contact. If the drum is well balanced and spins very freely on its mounts then I don't imagine it would take too much to get it turning, at which point momentum becomes your friend.