MombasaFlash
Heli's & Tele's bloke
I am just giving an X-8 an overhaul and the question of rotation for upper and lower props came into my mind. It is currently set up as two independent quads with the lower quad rotated 90° so that each boom has a CW prop and a CCW prop.
Theoretically this means that you can lose the entire top or bottom set and it will still operate as a normal quad - albeit with half (or thereabouts) the lifting power.
I believe this is the MK way, with the DJI default being all top props rotating in one direction and all lower props rotating the other.
Anyway, my question is this.
Why should the two props on a common boom rotate in different directions? Why can they not rotate in the same direction, i.e. with both props rotating CW on booms 1 & 3 and CCW on booms 2 & 4?
We can all appreciate that the lower prop has to deal with air that has already been accelerated by the top prop, but why can it not continue to push that air downwards in the same 'spiral' instead of reversing it? Does the conventional way produce more lift, is it to avoid the rudder being too effective, does it make the flying characteristics smoother ... or what?
Theoretically this means that you can lose the entire top or bottom set and it will still operate as a normal quad - albeit with half (or thereabouts) the lifting power.
I believe this is the MK way, with the DJI default being all top props rotating in one direction and all lower props rotating the other.
Anyway, my question is this.
Why should the two props on a common boom rotate in different directions? Why can they not rotate in the same direction, i.e. with both props rotating CW on booms 1 & 3 and CCW on booms 2 & 4?
We can all appreciate that the lower prop has to deal with air that has already been accelerated by the top prop, but why can it not continue to push that air downwards in the same 'spiral' instead of reversing it? Does the conventional way produce more lift, is it to avoid the rudder being too effective, does it make the flying characteristics smoother ... or what?
