Hi Gang,
The old saying that, "There is more than one way to skin a cat" is true both in general and in this case, but choosing whether to start at neck, tail or a leg has to do with your priorities.
Kim is absolutely right when he says that voltage overhead is the key to excellent (not merely wonderful!) performance.
In my not-so bashful opinion, the combination of Kv and battery voltage should be much more than adequate for the chosen propellor and its pitch: so that there is at least 200 Wats per pound available under static conditions.
No, you'll never run that kind of power dissipation in flight, but "my" eventual goal is to end up with power management that will hit close to that figure for tenths of a second in critical places in the schedule.
Braking is improved with lower Pitch: Diameter ratios, especially in runway wind.
The downside is that prop efficiency and noise suffer.
It will make me quite sad if meaningful numbers of Electric Stunt flyers start running prop/pitch/RPM combinations that howl loudly.
(Historically speaking, the tuned pipe setup was largely created in order to deal with the criticisms heard in Hungary that the dominant 60 setups were too loud;
but eventually a fair number of pipe users adopted prop-noisy setups just because they liked the way they flew.)
My take on this is that prop tip velocities should be limited to prevent transonic tip noise (which also limits the prop efficiency loss some) so that RPM times diameter in inches is less than 130,000.
So 13" props should turn 10 grand or less ... Given a lap time and line length, we have a lower bound on pitch, and then it's a matter of picking a motor Kv and battery voltage that runs on 70 to 75% of the battery voltage.
Yes, motor efficiency and peak versus average battery currents will be higher than they could be with a system optimised for efficiency or battery weight but us lunatic fringe types like that!
On the other hand, if you are perfectly happy with a system biased in the "super quiet / super efficient / super light battery / low component stress" direction, then have at it! After all, it still runs great, time after time after time ...
Have I ranted long enough?
Actually, I will be happy to see the whole constellation of setups developed as time goes on, but please let's keep the prop tip howl at bay...
The rule makers bent over backward to make competitive E-Stunt possible, and the justification was and continues to be QUIET.
later Friends,
Dean Pappas