Paul's nozzle was made of poly ply. It was a double layer set up with the turkey feathers on the outside and the real convergent nozzle petals on the inside. It used cables to pull the nozzle closed and used the engine thrust to open it. You could use the knob on the transmitter, but without realtime feedback, there would be no way to get the max performance out of the nozzle. The programming for the microchip would be very simple and would only require some minor testing to maximize the setup. Remember, Paul did this many years ago and technology has risen a bunch since then, so doing it without the "computer gizmos" would be a shame. I'll try to get a hold of Paul this weekend and see what he has to say. If I can't, I can probably remember enough of the setup to help you get started anyway. The other option that I had explored when Speed Runs were the thing, was making a variable inlet design for my Vortex jet. The reason the DF models run out of speed is because of the pressure drop in front of the fan unit at high speeds. As the speed increases, the thrust availabe drops off dramatically. Exhaust velocity is important, but you still have the airframe drag to overcome. The only way to do that is to apply more thrust to the airframe. With a DF model, that means choking the inlets off to allow a pressure increase by slowing the inlet velocity down before it reaches the fan, thus giving the fan more air to grab. Anyway...I'll see what I can find out.

Regards,

Dan