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

Posted by Marc Halcomb on April 8, 2017 at 1:00pm

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"

3689714017?profile=original

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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Comments

  • Ravi 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.

  • Marc Halcomb 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

  • Ravi 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.

  • Ravi 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).

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