"Theoretically the lower prop should have a higher pitch than the upper prop. With the correct setup there is no loss. All full-size coaxials use this approach. Obviously they have to as they are on the same shaft. IMHO it is better to have all at…"
"Thanks. Is it possible to make all the top props CW and all the bottom CCW? The reason is there are limited CW (pusher) props but lots of CCW prop choices. This will give more options for tuning the lower prop pitch.