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1 km round trip with my X8

Discussion in 'Cinestar 8' started by Steve Maller, Aug 23, 2014.

  1. Steve Maller

    Steve Maller UAV Grief Counselor

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    Did a land survey yesterday, and it was quite interesting. I had to fly about 550m from the takeoff point at about 120m in altitude. I carefully monitored the Graupner receiver strength, as that was the weak link in the chain, so to speak. The copter performed brilliantly. I used a slightly heavier lens than usual (oops) on my M5, so I was also a little concerned about power and heat, but neither was a concern. I had a perfectly clear picture in my downlink through the entire flight (1.3gHz CP on both ends). I did have to do a little dancing to keep my mx20 TX a few feet away from the video RX, as the receiver signal strength varied from 30% to 60%. I flew the entire flight in Dynamic Position Hold and Altitude Hold because I was concerned about staying perfectly on course. I also had an Xbee hooked up so I could monitor the location of the copter on the map and make sure I was exactly at the edge of the property. Below are a few photos showing my friend's rough outline of the flight path, the trace in real time from MKTOOL running on my Mac under Parallels, and the animated flight path from Google Earth tracing my actual KML file. The GPX data below does show motor 7 lower than the others, but that's because of a miscalibrated BL. I just haven't gotten around to recalibrating it.

    Flight date: 8/22/2014 11:46:05 AM
    Flight time: 11:46:05 AM.0 - 11:56:57 AM.8 (652 secs, 00:10:52)
    Batt. time : 649 secs, 00:10:49

    Elevation(GPS) : 0 80.81 119.487 m (min/avg/max)
    Altitude(Barom.): -0.1 86.14 127.8 m
    Vertical speed : -3.14 -0.01 2.81 m/s
    Max speed : 23.9 km/h
    Max target dist.: 16.8 m
    Max distance/LOS: 517 m / 531.8 m

    Sats : 9 10 12
    Voltage : min. 21.2, max. 24.9 V
    Current : 0.5 69 93.2 A
    Wattage : 11 1547 1994.48 W
    Capacity: 12361 mAh

    Motor1: 0.0 8.3 13.7 A Temp: 28 31 36 °C
    Motor2: 0.0 7.4 14.5 A Temp: 24 30 35 °C
    Motor3: 0.0 9.6 16.1 A Temp: 28 35 42 °C
    Motor4: 0.0 9.4 16.5 A Temp: 27 35 42 °C
    Motor5: 0.0 9.8 15.9 A Temp: 26 35 39 °C
    Motor6: 0.0 8.3 13.7 A Temp: 26 33 40 °C
    Motor7: 0.0 5.4 11.5 A Temp: 28 33 38 °C
    Motor8: 0.0 8.5 14.0 A Temp: 27 31 36 °C

    Magnet Field: 97 100 106 % (ok)
    Magnet Inclination: 57 62 70 deg
    estimate.jpg Parallels Desktop-snap001.jpg

     
  2. MIke Magee

    MIke Magee Active Member

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    Nice work Steve. Ummm... How does one, and when does one calibrate a BL?
    -m
     
  3. Steve Maller

    Steve Maller UAV Grief Counselor

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    The BLs' current sensing can be adjusted by connecting to a BL in MK Tool, feeding it a signal, measuring its current draw on a meter of some sort, then adjusting its current sensor to match what the meter says. I've not done that, partly because I don't have a meter that'll measure amps that way.
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I can see the window in the "Settings" section here: http://www.mikrokopter.de/ucwiki/en/Single-BL-Ctrl_3
    but what signal do you feed in?
    Perhaps you use the MK Tool Motor Test and set the Motor Throttle to 50% and then use an Ammeter in series with the LiPo to measure what the motor (and the flight avionics) are pulling out of the battery?
    But if you have the motor test running, can you keep it running while you switch to the BL-Ctrl window shown on the web page above?

    Andy.
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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  6. Steve Maller

    Steve Maller UAV Grief Counselor

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  7. Jason Smoker

    Jason Smoker Active Member

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    "Strg" Is German For The CTRL key.
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Thanks. I knew I should have taken German in school instead of Art.

    Andy
     
  9. RichardFoersom

    RichardFoersom New Member

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    Strg is in German short for "Steuerung" which translate to control (as mentioned by others).
     
  10. Ozkan Erden

    Ozkan Erden Distributor

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    Steve,

    Did you have any telemetry loss on the transmitter while flying this course?
     
  11. Steve Maller

    Steve Maller UAV Grief Counselor

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    No, it was solid for the whole flight. I was listening intently to the Fraulein (Graupner mx20's voice prompts) telling me the receiver signal strength and it never dropped below 30%. I noticed dramatic differences as I was flying if I moved ever so slightly or tweaked the antenna. And before I flew I moved my GR24 to a more diagonal configuration relative to the launch point, which helped.

    I know of at least one guy who's moving to UHF for his big octo because at these distances the 2.4 signal is not as reliable as UHF. But of course you lose the telemetry, so it's a tricky proposition.
     
  12. Ozkan Erden

    Ozkan Erden Distributor

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  13. Steve Maller

    Steve Maller UAV Grief Counselor

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    I use something similar, too.
     
  14. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I think the issue is that the telemetry from the copter to the ground is coming *back* from what is the Graupner radio *receiver* being used as a transmitter. I'm not sure of the details, but I suspect the *receiver-acting-as-a-transmitter* is not radiating anything like the same power level as the Graupner transmitter in your hands. What I suspect this then translates to is that the telemetry signal from the copter is much, much weaker than the command and control signal from the ground-based transmitter.

    This would explain why you lose telemetry but do not lose command and control.

    Andy.
     
  15. Steve Maller

    Steve Maller UAV Grief Counselor

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    I have had times when listening to the voltage level, the Fraulein would say "Input voltage 0.0 volts", which needless to say sent chills up my spine. I wonder if that was a temporary loss of the telemetry signal. But ever since I got more conscientious about the placement of the receiver and the antenna, I've not heard that particular hiccup.
     
  16. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I've noticed that too. I figured it was just a feature where the Fraulein wanted to see if I was paying attention. I'm not sure whether it's signal loss or just a momentary glitch in the telemetry system. It does, how does one say, focus the mind when you hear 0.0 volts, doesn't it?

    Andy.
     
  17. Steve Maller

    Steve Maller UAV Grief Counselor

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    My telemetry interval is set to 5 seconds, which about as long as I can stand, frozen in terror, without any pulse or vital signs.
     
  18. MIke Magee

    MIke Magee Active Member

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    Certainly gets my attention in a hurry.
    -m
     

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