AC-3.1 autotune support discussion

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- - - - George Roberts > Frank Vitale November 23, 2015 at 12:12pm
        
        Just keep in mind that upside down props still thrust the same direction as right side up props. Just less efficiently.
        
        Frank Vitale > George Roberts November 23, 2015 at 12:34pm
        
        Thanks, I'll reverse them
      - Frank Vitale > leonardthall November 23, 2015 at 4:01am
        
        Thank you Lenard, I will. Pretty big, I think I'll strap it down first. I will post back on my findings. Frank.
- Gregmaan > Frank Vitale November 23, 2015 at 12:01am
  
  I am using nearly the same setup, but with blheli esc´s. So I think its not really compareable. With BLHeli I got several Vibration issues with fast rpm changes and sync issues with the braking features activated. I think the right setup of the esc settings I essential. Motor Brake/ Low Brake should be disabled.Motor advance should be 12 to 15 degrees.These settings based on my personal experience with BLHeli 14.1 so if you like to tweak your esc´s be very careful to test them on the bench before flying them.
  
  Cheers Gregor
  - Frank Vitale > Gregmaan November 23, 2015 at 2:51am
    
    Already had vibe issues. On first flghts, stabilize flights were good until I went to post hold, and it would just land. Balanced props, and all went well. .
DG November 17, 2015 at 6:14pm

The barometer is understandable, but it is well covered inside the case (CUAV Pixhack). This acts more like tuning than altitude as it gets wobbly, but I think the choice of props matters too. Also, I believe it was suggested decoupling the GPS from the barometer for altitude estimates.

I'm sure we don't get as many windy days as Cala, but we do live near Lake Huron and have bird chompers wind farms everywhere in this county. Today it was 25+ mph.

When I put Xoar wood props on the 750 Y6, it made a huge difference over the APC's and just kind of sways around but holds nice instead of jerking around, but also used larger props on top than the bottom. I have 15x5 T-Motor props but they are too large for his quad; also have Gemfan CF but have found over 400-500g thrust are just horrible for flexing from the hub outward and act like spring boards. Tarot props are the worst. Maybe the APC's are doing the same thing to an extent. They are well balanced, but still cause higher vibrations compared to CF that are well balanced. The problems arise, I suspect, when the wind works on the props they oscillate rapidly and erratically causing the craft to "bounce" and the FC is constantly trying to adjust but cannot predict what the props are doing. Smaller plastic/composite props on a lighter craft may be more forgiving? Much less surface area to fight the wind, hence the heavier copter needs stiffer props?

In calm winds the copter flies great, and with the last AT does not wobble on faster descents, but I'm really starting to think it needs some high quality CF props even for this weight for flying in high winds. I'm sure frame flex contributes, but I've added support columns inside the frame to strengthen it even more; it seems quite stiff.

I may order some T-Motor's for this quad to test, but am scouring the forum for information on PID's to help.
DG November 17, 2015 at 3:16pm

What is the secret to stability in wind? This would be an Alien 680 frame, which is not a traditional design.

Would using ESC's with reactive braking help? I don't expect it to be like a Y6/X8, but it seems to almost want to lose control in pos hold while stationary. Granted it was quite windy, but just doesn't look to be as stable as it should be considering the 2.7kg weight.

One guess is the APC MR props are not stiff enough. It's had 3 AT done, the last being AGGR .1 which seemed to be pretty stable on descents and general flying.
- Developer
  
  leonardthall > DG November 18, 2015 at 12:59am
  
  Hi DG,
  
  This depends on your weight and prop size. I can probably give you a bit of an idea of how much esc breaking will help if you have a photo of your copter, tell me what your hover throttle and motor expo setting is, along with the specifications of your battery, motor, and prop.
  
  I don't think think your problem will be the APC MR props.
  - DG > leonardthall November 18, 2015 at 6:07pm
    
    Well Leonard you're probably right as usual, and after over 1 1/2 years I have still not mastered tuning AC, but was getting better with 3.1.5 then you guys had to throw in EKF and all that new stuff :)
    
    Hover throttle:
    
    Motor Expo (I think this is what you want)
    
    Battery: Lumenier 12A 4s 20c
    
    Motors: KDE 2814XF-515
    
    ESC: HobbyWing Quattro (could not get KDE ESC's to work right)
    
    Props: APC 13x5.5 MR
    - DG > DG November 18, 2015 at 8:47pm
      
      I did some reading on MOT_THST_EXPO. Quite interesting.
      
      So it appears I may need a bit higher number than .65? I thought maybe increasing the ESC timing to High might help, but the motors are not high pole count.
      
      So much to learn.

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