Don't put the heat in the same tube, it is difficult to get a convection current flowing with that set up. The heat will go both directions, unless you have invented an air diode, in which case, you should patent it immediately, not the same as a flap. The method I described, if it worked, would turn the vanes very slowly, or fast, not sure, it is essentially a different engine. How much of a difference, not sure, but the separation of the exhaust from the intake should be as far as possible. One low (cooler air) being heated from the top, and drawing air up and out through the slots, rotating the vanes, in theory. If it is all in the same tube, the air would have to know which direction to go, which it doesn't, that's why we need to use the heat rising.