Gear ratio *is* the critical component, specifically prop pitch vs. forward motion, but not exactly for the reason you describe. Xyla Foxlin built a working mo

Gear ratio *is* the critical component, specifically prop pitch vs. forward motion, but not exactly for the reason you describe. Xyla Foxlin built a working model and provides a bit more info here: https://youtu.be/VUgajGv4Aok?t=432 https://youtu.be/VUgajGv4Aok?t=432 In short the working model she built has approximately a 2:1 ratio between forward wheel motion and propeller pitch. IOW if the propeller pitch is 5" per revolution, the wheels will require 10" of forward travel to spin it one time.