Flingwing & Mart,
Sorry for not replying to your comments that the gyro community considers the tractor configuration to have better longitudinal stability. This may be very true.
I was thinking about a Rotary Wing thread from 4 or 5 years ago where, as I recall, the consensus was that the tractor configuration provided higher speeds than the pusher. However, it was also mentioned in the thread that the few existing tractor gyros had fuselages that were more aerodynamic than the pusher configurations had.
Perhaps the gyrocopter should not even be considered in this discussion. This is because the air is flowing through the rotor in the opposite direction to that of the helicopter.
__________________________
Mart I agree with your wave comment. In fact bulbous bows are now used below the waterline. However, an analogy between air and water environments may not be valid due to the large differences between the viscosity of the mediums, and the difference between their velocities.
I cannot agree with your second argument. Doubling an induced velocity involves more than doubling the required power. Passing air through two disks will be increasing the velocity of that air. Reference the previous comparison between the [parallel] side-by-side rotors and the [serial] close-centered coaxial rotors.
Dave