Ranger EX 757-3 (Auto Tune & Auto Trim)

I finally completed "AUTOTUNE" and "AUTOTRIM" activities on my Ranger, after fixing a self-induced configuration mistake.  Once "AUTOTUNE" was completed, FBWA mode flights were stable and responsive, ready to test an "AUTO" mode mission next.  Once "AUTOTRIM" was complete I ended up with a nice "MANUAL" mode trim and stable flying characteristics.   

Final PID's from "AUTOTUNE"

Note:  The initial problems with the Ranger being underpowered were most likely caused by my selection of a 3S battery pack.  I then replaced the motor, followed by changing the battery pack to 4S.  I have not switched back to the original motor, but I think the 4S pack and the original motor would also provide good flight characteristics.  (and saved me $$'s)

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Comment by Ravi on April 9, 2017 at 3:45am

I have been flying ranger for quite sometime. I like it because of it's sturdy design and high landing gear. I fly it with pixhawk. very important observation is that you have to keep elevator at 4deg+ even at neutral RC elevator stick trim by adjusting the servo push rod. I am flying it with skywalker parameters and have only changed the NAVL1_PERIOD from 15 to 20. I use 3S battery with the included motor. I hand launch it at 20 degree pitch. using 10x6 APC propellers. I suggest you use a good APC propeller. this reduces the sound to quite a bit. it is very sensitive to CG. Keep the CG at 96mm from leading edge as described in the manual. use flaps for landing. I have flaps enabled in Auto Takeoff. They retract once it achieves the Takeoff altitude. In landing I deploy the flaps manually. For manual flaps you have to mix the flap channel with down elevator of about 8%. Wish you happy landings and takeoffs and RTL (if nothing works).

Comment by Ravi on April 9, 2017 at 3:49am

thanx for posting those PID numbers. It is lot of effort to generate those numbers even with auto tune. I think you have to lower the FBM min air speed to a lower value otherwise you will have problem landing it in FBW mode. the throttle will not cut below this unless you change to full manual mode.

Comment by Marc Halcomb on April 9, 2017 at 6:42am

Thanks for the inputs!!  I have received several great tips from other users as well, again thanks for the details of your experience!

Questions: 

  1. What flap setting for takeoff?
  2. What is your airframe weight at takeoff?  
    • Mine turned out to be 6lbs or 2700g

Comment by Ravi on April 9, 2017 at 6:16pm

I use flaps at 60deg in full auto takeoff. I have never weighed it. buy my battery weight is 750 grams. I am using 16000mAh Li-Ion pack at 11.1V. The original motor is suited for 3S because of high KV.

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