Two different quad, two different problems

Ok, out doing some PID tuning on both my quads, and uncovered a problem with both that I couldn't fix in the field, and am looking for some pointers. PID tuning complete, but have issues elsewhere.

Quad 1: 450 size, 3S 11,000mAh, APM2.5, T-motor 2216-11 (900kv), 1145 props. Total weight 1.8kg.

Good: Loiters well. Handles ok

Bad:

-  very difficult to fly on throttle in stabilise. Needs lots of stick, but very fine control. Random "land" events.

- Alt hold involves loss of altitude, even at small pitch/roll events.

Can I tune the throttle PID's to improve stick performance? Needs more even power, but with less sensitivity. Just doesn't want to stay in air, it feels like.

Quad 2: 650 size, 6S 11,000mAh, APM2.5, T-motor 3508-29's (380kv), 1455 props. Total weight 3.8kg. First flight back after breaking an arm and prop.

Good: Handles and flies like a total dream in stabilise; can land it in my sleep, it's so easy. Best it's ever flown, after Dave C's tuning guide.

Bad:

- won't alt hold or loiter. Just climbs. Throttle stick down, it descends. Simply won't fly level - it's climbing or descending. Sticks only seem to control descent - 50% stick (where it should be level) = slow climb. Vibes not an issue: two moongel pads per corner = between -8.5 and -11.5 in stablise hover. Where to start the tuning on that one? Had another APM2.5 on here a while ago, and would alt hold and loiter perfectly, so not the airframe.

- applying throttle causes a brief yaw to the left event for a fraction of a second. Stab the stick 5-6 times, and it will have turned 90'! Ideas???

I know it's a lot for one thread, but I'm just translating from notes. Any helpful tips appreciated.

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Replies

  • T3
    Check your THR_MID. You might need to adjust for altitude hold. Default is 500 or 50%. You might need to lower it. Easy way to test. When in altitude hold lower throttle and if it holds then you need to change THR_MID setting.
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