All motors perfectly level or FC level?

Discussion in 'Cinestar 6' started by Gary McCready, Sep 7, 2013.

  1. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Back in the Dim Times, I'm sure I understood those strange squiggles. Now, I don't even remember whether I understood them or not.

    Appendix A1 is an interesting (and relatively non-technical) read though. Intuitive Explanation of Alternating Rotor Spin Direction. It aids understanding of the Mixer table for N-copters.

    Andy.
     
  2. Casey Van Nyhuis

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    I personally found pages 1-25 the most challenging; but after some very intensive research i was at least able to understand almost all of the works cited on page 26. MLA formatting a works cited page was never really my thing. I also managed to vaguely understand the photo on page 2 ;)
     
  3. Dave King

    Dave King Well-Known Member

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    Gary

    Thanks for starting this post as a lot of great info as come to light. What I didn't see anyone mention to you is that 2.0 has some documented issues with PH drift. From what I'm reading from the responses the motor angle offset won't necessarily help the GPS drift you are seeing alothough it certainly sounds like it will help balance the motors and the controllers. Most of us have reverted back to 0.90J until the PH drift issue has been resolved. I posted on the MK site hoping to get some insight on whats going on.

    thanks

    Dave
     
  4. Gary McCready

    Gary McCready Active Member

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    Yea Dave I think I'm one of the ones having a bit of difficulty with PH and the Cinestar 6. Not nearly as stable on the CS6, as .88 that I was using. I've taken just about everything apart, re-leveled, re-tightened, re-balanced the copter and the gimbal, recalibrated ACC, and recalibrated compass. Didn't really help that I could see.
    I might revert back to .88, till I upgrade the ACC with the new board, as going to.90 mean putting in all my values again, which is alot of trouble. (going through and checking each screen) With .88 I can just reload them from a saved config file.

    The good news about 2.0 is that my Quad , upgraded from .86, flies much better, more stable. The ESCs used to get a bit hot, and now they don't. The PH and AH are alot better. Go figure? I didn't do any reconstruction, just copied over MKTools settings, recalibrated ACC, redid compass and off I went! No clue why it flies cooler but during the summer I'd get alot of over heat errors, with Esc over 100c. Took it out and flew it in 90f weather, checked the GPX file, and the Esc didn't go over 80c.
     
  5. SteveWilson

    SteveWilson Member

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    Just to confuse things, I run my motors at about a 5° tilt on a CS8. The way we usually film is in PH with a lot of zoom. The additional bite the props have with the tilt really cuts down on uncommanded yaw. As you might imagine with full zoom, it doesn't take much to screw up the shot. We pay with a bit of efficiency lost, but it seems to be very roughly on the order of 30 seconds off of a 20 minute flight.
     
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  6. Shaun Stanton

    Shaun Stanton Active Member

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    It would seem that if you Coax config then you would want the motors straight with no angle, because they are counter rotating and canceling out the torsion force.

    I have also read somewhere in infinite pool of wisdom, that having the boom arms canted up a few degrees like the DJI S-800 is supposed to make small lateral movements smoother without aggressive pitch and roll moments. Not that it matters since our booms are level with the frame.
     
  7. Dave King

    Dave King Well-Known Member

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    This is all such great info. I think I'll try the 3 degree motor tilt idea soon. Not to change the subject but I sure wish I had the time to play with a coax configuration as I am so sick and tired of getting boom 1 in the shot when I dont' want it. It also makes it just about impossible to get a shot going forward where you want a upward camera angle. You guys think there will be such a thing as a heavy lift CS6?
     
  8. Janne Hoglund

    Janne Hoglund Member

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    Hi Andy, I know Holger did show the maths behind tilting the motors 3°, and the result was 5% gain in Yaw forse and 0.3% loss in lift forse, something like that...
     
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  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Good to know, Janne. 5% gain in yaw seems a little high considering only a 3 degree change. I'll need to draw up a vector diagram and revive what's left of my trigonometry.... :)

    Thanks
    Andy.
     
  10. Steve Maller

    Steve Maller UAV Grief Counselor

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    Andy, I'm no mathematician, but a flat motor config generates yaw purely (or at least primarily) through the side effect of centrifugal force of the prop rotation, right? Tipping the motor seems like it would provide at least a small amount of actual lateral thrust as well. So I'm not sure it's purely a math problem in that sense (kind of apples and oranges). But I'm a college dropout, so what could I possibly know? ;)
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    As a college dropout, you could know as much as Steve Jobs and Bill Gates.... ;)
    Oh, and Abe Lincoln, John Lennon, and F. Scott Fitzgerald, to name a few....
    Andy.
     
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  12. Steve Maller

    Steve Maller UAV Grief Counselor

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    Or my friend Zuck...
     
  13. Casey Van Nyhuis

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    Hell....i never even went to college....i think that means i'm already well on my way to $billions then, right? ;)
     
  14. Janne Hoglund

    Janne Hoglund Member

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    Second you thinking Steve.
     
  15. Colin Snow

    Colin Snow Active Member

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    I'm game to try this. Here is my "before" where motors are straight up (+/- 0.25) as measured by the Angle Meter app on an iPhone 5.

    Motor1: 1.4 8.0 10.2 A Temp: 25 51 68 °C
    Motor2: 1.5 4.7 6.7 A Temp: 25 44 54 °C
    Motor3: 1.6 9.9 13.8 A Temp: 24 58 78 °C
    Motor4: 0.4 5.2 6.3 A Temp: 23 54 70 °C
    Motor5: 0.6 10.0 12.9 A Temp: 22 65 86 °C
    Motor6: 0.2 4.0 6.1 A Temp: 22 44 54 °C

    Colin
     
  16. Steve Maller

    Steve Maller UAV Grief Counselor

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    Whew, Colin, those numbers look pretty badly skewed. This is a CS6? Using what version of the MK stuff?
     
  17. Colin Snow

    Colin Snow Active Member

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    MK Version: FC HW:2.2 SW:0.90h + NC HW:2.0 SW:0.30h

    It just started doing this after hitting a bush due to a severe drift right at landing. Before that the motor pulls were pretty even.

    The mishap corrupted the GPX file, so I don't know what else happened. Did I forget to turn off AH before landing? I wouldn't be surprised. My voltage was dropping fast and I just wanted it down. At any rate. I broke two blades and trimmed a hedge, but that's all I could see. I recalibrated ACC and Compass and re-leveled the motors. Did one flight and noticed the odd motor pull. I did the Compass Calibration again before this flight thinking that might be it.
     
  18. Steve Maller

    Steve Maller UAV Grief Counselor

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    Colin, silly as it sounds, I'd check to make sure your props are all on right-side-up. Don't ask me how I know that.
    I'd also listen closely to your motors. If you got close enough to do some landscaping, you could have either bent a prop shaft or gotten some pine sap in one of your bearings.
    I have been dealing with some anomalous current readings from my PDB, but I'm pretty sure one or two BLs are defective (it is a temp replacement for my other one that's in the shop). But in your case, the copter looks like it's trying pretty hard to yaw in one direction, based on both the currents and the temps. So I'd be careful...the data rarely lies. Well, actually, it lies often, but...
     
  19. Colin Snow

    Colin Snow Active Member

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    Hi Steve - All props are right side up. I learned that lesson early on a GAUI 330.

    I blew motors with air and tested for vibration. Only #6 was relatively different than the others but ever so slight. I've encountered this odd motor pull before and chased it for six months, replacing motors, FC boards yada, yada. See this thread. I ended up sending kopter back to QC. They were unable to fix we ended up replacing the entire thing because it had been there from day one.

    I just now attempted to reload 90h but I didn't find it in the Subversion Repositories (I call it the suppository reversion. Cause after reading the 2.0 thread I can see that you gotta be careful...). So, I updated to Flight-Ctrl_MEGA1284P_V0_91L_SVN_ACC-HH_MartinR.hex. That required me to update to the new MKTool 2.00a and then Navi-Ctrl_STR9_V2_00a. Thanks to the posts in your thread I manually checked all values, but still not sure what to do with SD card. I'll pick up the questions there.
     
  20. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Not sure if this helps any Colin, but I'm using 0.91J -- the L version sounds like someone's custom tweaks.
    The 0.91J doesn't require the use of 2.00 for MK Tool and Navi-Control.

    ANdy.
     

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