Discussions

First off, I have found that I am not the first person to run into this problem.

The setup:

Frame: Hexacopter

Motors: SII-3020-890KV

Propellers: APC 10x3.8SF

Power: 3x5000mAh 20C, 3S

Bottoms Up Weight: 10.17lbs 

Thrust to Weight Ratio: 1.83

ESC:  HobbyKing Blue 30Amp

Transmitter: JR X9503

Receiver: R921X

So I know from performing a static thrust test using just the receiver, ESC, and motor/prop combination that I could theoretically obtain about 1450 grams of thrust per motor. This thrust draws a current of approximately 22 Amps.  Obviously you would not want to pull that much power from the thrust control because then you wouldn't be able to maneuver the aircraft.  

The problem becomes that I cannot get out of ground effect, and after checking the on board data, I have found that I'm only drawing 80 Amps at full throttle.  Theoretically, I should be able to draw 132 at full throttle.  I have also noticed that after about 70% throttle, moving the stick up to 100% doesnt add anymore power to the system.  

I have adjusted the thr_mid setting, and that has done nothing for me, as well as the thr_max.  Neither have shown any improvement.  I have also tried changing the value of the PWM range on my TX.  I adjusted it to use a range of 1000-2000.  This didnt help either.  I have also read to flash to 2.7.3, but I have been unable to figure out how to do that, any help with this would be helpful.  These were all recommendations from another forum post: 

http://diydrones.com/forum/topics/why-are-motors-not-getting-full-power-from-arducopter?commentId=705844%3AComment%3A1099678

It seems to me that the controller is simply limiting the max PWM value being sent to the motor for use from the throttle control on the TX.  This becomes an apparent problem with somebody as myself who is using a slightly under powered system or designing something for heavy lift applications.  I should add that I am not looking for lots of maneuverability in the system so I'm OK with using a little more power to dedicate to thrust.  This is just my first iteration on the build and I plan to make it more power efficient in later iterations.  

If you have any suggestions I would love to hear them. This problem is very frustrating and I feel like it shouldn't be that hard of a fix to tell the APM to use more amount of throttle.  I'd love to be able to fly my system at more than 2ft above the ground..