When am gave the full throttle it is not given full thrust

am using pixhawk cube black . frame is flyingwing . am initially change the parameters is L1 period is give 19 and airspeed cruise is 20 then after arspd _autocal gave 1, then after takeoff in FBWA mode then after some altitude (60 meters) a changed to auto tune , then after my plane is speed is very low not going forward . am observed my airspeed ratio is 3.876like that . why its happen speed automatically reduced when am give the full throttle the the plane is not going that much of speed .

@Sampath_kumar_Chirut
AUTOTUNE is not an auto throttle mode: http://ardupilot.org/plane/docs/flight-modes.html.
your log shows your throttle output well matches your RC control’s stick input. your airspeed readings seem well within expectations too at a rough glance. in AUTOTUNE, there isn’t any automatic throttle handling beyond that.

Thank you for given reply @ vierfuffzig
Am given RTL It come and circuling at 100 meters radius and 100 meters altitude 3 or 4 rounds completed it’s going very low speed almost motor is not rotating on that time take manually glide it and safely land it . We are using 4s battery but that battery is actually 6s battery 7000mAh so on that battery 2s are damaged so I removed and convert for 4s battery .after every this is completed in ground I checked I give loiter without propeller motor was rotating on that time when I blow that air the air speed reach 25m/s and above the throttle speed is zero. What is problem please help me

@Sampath_kumar_Chirut adding a log that actually shows these issues will make it a lot easier to help.

@vierfuffzig
I think this is battery issue maybe . Because intially it give high power and after 2 or 3 minutes later motor rotation is very slow

@Sampath_kumar_Chirut that was a good hint!

actually, i think it rather might be your ESC that’s giving you issues. your batt voltage does not even drop that dramatically, going down to 14V on 24A load max. but your current curve does not follow your throttle curve. your measured amp draw subsequently goes down, first to about 9 amps, finally to not more than 2 amps even though you’re on full throttle. i’d say it’s your ESC shutting down. any additional information about your motor / prop / esc setup maybe?

cheers, basti.

Propeller is 126
Motor is Emax Grand Turbo GT3520/05
Kv-925
Weight -220g
No of cells 3-5
Max thrust is 3000g
Prop 11
5.5 or 12*6
ESC Emax 60A
Simon series ( UBEC 5A 5V)
LIPO 2S -5S

@Sampath_kumar_Chirut so given that your batt mon data are correct, something is wrong in your drivetrain. it is supposed to pull over 60A on full throttle with a 12 x 6 prop on 4S. what exact battery are you using? have you tested your drivetrain prior to first launch?

@vierfuffzig
Actually the battery is 6s battery so one day the was damaged due to crash on that time 2s are damaged so I removed the 2s and convert the 4s battery .battery name is (tattu 6s capacity 7000mAh )
Right now the battery convert to 4s capacity 7000mAh