Stupid Question 
Other than the obvious what is the difference between a Pusher Prop and a Standard prop ?
Ie. If you use a Standard prop and just run it in reverse will it be ok. ?..
Nope!
an "airscrew" (lets get pedantic
) and in our case a fixed pitch Airscrew is designed to work in one particular direction of rotation only, the surfaces of each blade are curved and if you were to take a cross section through a blade it is usually an airfoil section just like a plane's wing (thicker near the leading edge, thinning to nowt at the trailing edge of the blade) so it produces the maximum amount of thrust as it screws through the air, like a wing produces lift. if you run it in the wrong direction of rotation it will produce thrust (because it has a pitch) but it will be very inefficient.
now
lets look at an I.C. powered plane, engine facing forwards, prop at the front, a "normal" tractor prop is required say it runs anti clock.
that I.C. engine will only run in one direction of rotation (anti clockwise) so if you put it in a pushing configuration the tractor prop will be running backwards.. very inefficient so you need a "pusher" prop designed to run backwards
in the case of our electric airboats we can reverse the rotation of the electric motor by swapping the supply leads +/- over and it will run either clock or anti-clock rotation no problem so if the motor shaft is facing forward use a standard tractor prop, if the shaft is facing aft take the standard tractor prop, keep it facing the same way as if it was on the front, put it on the motor, and reverse the polarity.....
and thats just how Dave's airboat is at the minute
if you are still awake after that
can i please have some thunderbolts over Taylor park now!
seriously though... anyone who has had owt' ta do with aviation in an engineering sort of way (for the last 37years) can just look at a prop and read a lot of information about what it is fixed too!
db
