first 180º the cable will hardly pull on you
next 180º the cable will pull you a lot
why?
cause in one your giving away cable while in other youre recovering, outwards or inwards spiral made by the cannonball
you gotta visualize it traditional fisics say both halfs pull the same but even my physics teacher admited from this explanation you would got one pull bigger in one half than the other and therefore thrust
as a matter of fact i got a patent granted for a mechanical(instead of fluids) vortex engine like schaubergers but lost it for not paying the fees
edit:
a 40% probablity is gravity being produced by looping electrons like this so you can achieve this mecanically with fluids of directly on atoms making the electrons loop the loop:
if this guy looped the looped fast enoguh he would be propelled up: