H-Copter 1.4 Kg with four SunnySky V2216-12 KV800 motors
I’ve been flying above setup for awhile via APM 2.5 module and latest FW and decided to increase APC prop size from 10 x 4.7 to 12 x 4.5 inch for purposes of lowering the mid throttle hover towards 50 % vice the 70% that would occur half way through a flying session with the 10 inch props. Going to 12 inch improved mid throttle hover, now at 50%, and a very slight improvement in flight time ( 13 minutes ).
However, now when flying without any camera gear it quickly bounces up and down (1 to 3 feet) to maintain altitude. The duration or quantity of the applied power is excessive for the correction required to maintain altitude or maybe also due to greater prop mass there is now greater delay with required altitude correction. With the 10 inch props, altitude hold was rock solid.
Motor and prop combo are well within spec; however, for this airframe size I should have gone with a slightly more KV rated motor or fly with 4 cell vice 3 cell lipo with 10 inch props to improve mid throttle but I wish to keep 3 cell setup.
Tried playing with PIDs but have yet to see any visible signs of improvement, the only way to stop this bounce was to install 70 grams of lead weight. Throttle mid range is still acceptable at 55%
What would the consensus be on which PID values should I concentrate on; Throttle Accel PIDs, Throttle Rate P or Altitude Hold P?
I tried 11 x 4.5 props; however, they did not lower the mid throttle power band close enough to 50 % the 12 props are good the auto-tune results are good but I would love to resolve this bounce via PID manipulation vice adding the extra dead weight when not flying with any camera gear!
Replies