Flying a Red Epic/Scarlet

Discussion in 'Cinestar 8' started by Rick Marcus, Oct 19, 2012.

  1. Rick Marcus

    Rick Marcus New Member

    Joined:
    Sep 20, 2012
    Messages:
    16
    Likes Received:
    0
    Has anyone successfully flown a Red Epic or Scarlet on the standard Cinestar 8 Kit? I just flew a payload weight test with the equivalent weight of a Red camera, lens, battery, and gimbal attached to the Cine 8 frame. I had two 8000mAh running in parallel. After about 2 min of flight time, I lost complete power (Fortunately, I was only 4 feet off the ground...still managed to snap an arm). The main lead wire to the board got so hot that it melted the solder right off the deans connector.

    My understanding was that the Cinestar 8 would be able to fly the Red Epic. Is it only possible to do that with modifications, ie: different FC, motors, etc?

    Thanks,
    Rick
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,369
    Likes Received:
    1,162
    Ouch. Sorry to hear about that "landing," Rick.
    Out of curiosity, what was the simulated payload weight you used?

    Do you have the GPX file from the micro-SD card -- I would be interested to see what the battery voltage and motor currents were doing...

    Thanks
    Andy.
     
  3. Rick Marcus

    Rick Marcus New Member

    Joined:
    Sep 20, 2012
    Messages:
    16
    Likes Received:
    0
    Hi Andy, Thanks. Yeah a much rougher landing than I like :(.

    Entire weight below the frame totalled 10.8 lbs. That is 3lbs for the gimbal, 5lbs for the camera body, and that leaves 2.8 pounds for the lens, camera battery and various cables.

    I have attached the gpx file. I would love to hear your thoughts. Thanks.
     

    Attached Files:

  4. Rick Marcus

    Rick Marcus New Member

    Joined:
    Sep 20, 2012
    Messages:
    16
    Likes Received:
    0
    I am also attaching a GPX file from a "normal" day of flying....Cinestar 8, 360 gimbal, t2i, 1x 4s 8000mAh battery.

    The motor current in my weight test compared to a normal flight is much higher (2x as much). I am guessing that is whats leading to the increased BL Temps as well.

    Here are my questions. Do my motor current and BL Temps for a "normal" flight seem right? I have nothing to compare them to.
    Second, what steps can I take (besides lowering the payload :)) to get the motor current and BL Temps down?

    Thanks,
    Rick
     

    Attached Files:

  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,369
    Likes Received:
    1,162
    Hi Rick:
    Firstly the normal flight looks normal -- even down to the fact that, like one of my C8's motor 8 seems to be drawing less current than the other motors. I don't know why it does that, but it does. The BL Temps also seem nominal.

    As to the crash, the GPX file is incomplete and it prevents MK_GPX from opening it. There is a partial "track point" (data logging point) right at the end which reads:
    <trkpt lat="+34.2808884" lon="-118.4987269">​

    If I delete this line from the end of the file, then MK_GPX will read it.

    However, the MK GPX file does reveal a couple of interesting things. The last complete "track point" is at:
    <time>2012-10-19T19:36:57Z</time>
    (That's Greenwich Mean Time, derived from the GPS system.)
    The first track point in the GPX file is at:
    <time>2012-10-19T19:35:16Z</time>
    So you can figure out how long an elapsed time occurred before the partial track point occurred (which I suspect is when the crash occurred.

    The BL Temperatures also give a clue:
    At the start of the flight they read:
    <BL_Temperature>30,29,31,32,32,31,32,32,0,0,0,0</BL_Temperature> (Temps are degrees C)

    At the end of the flight they are:
    <BL_Temperature>110,102,103,94,109,99,93,103,0,0,0,0</BL_Temperature>

    The hottest is 109 degrees Celsius.

    For the last complete track point (at 19:36:57 GMT), the Motor Currents are shown as:
    <MotorCurrent>168,130,181,118,158,135,209,136,0,0,0,0</MotorCurrent> (these are units of 0.1A so 209 is 20.9 Amps)
    That shows those motors were working pretty hard....motor 8 was pulling 11.0 Amps, for example.
    That also means that at this point you're pulling 123.5 amps in total from the battery.

    The battery voltage is shown as being at 14.9 volts. So that means there was 1,840 watts being pulled from the battery. So, the cause of the crash was, as you probably realized the lead on the Deans connector getting so hot it melted the solder.

    I think you might want to consider converting over to EC5 connectors -- they can carry far more power.

    Hope this helps.
    Andy.
     
  6. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,369
    Likes Received:
    1,162
    I should have mentioned that the typical maximum current rating for a Deans connector is 50 Amps.
    For the EC5 it is "over" 120 Amps used with 10 gauge wire.

    You were "overcooking" the Deans connector a tad.... :)
    OK, by a factor of at least two!

    Andy.
     
  7. Rick Marcus

    Rick Marcus New Member

    Joined:
    Sep 20, 2012
    Messages:
    16
    Likes Received:
    0
    Ha! I like a well done Deans :)

    Thanks so much for your help.

    Even with the EC5 connectors I am still concerned about those BL Temps. Will a bigger motor run cooler?
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,369
    Likes Received:
    1,162
    Also, I should have clarified two things:

    1. If you want to use MK_GPX to look at the data, you have to both delete the last line from the crash GPX and add the following three lines to "close off" the data structure:

    </trkseg>
    </trk>
    </gpx>

    2. If you do that and open up the crash GPX file with MK_GPX, you will see that you started to get Error 24's towards the end of the flight:
    24 "BL Limitation"

    • A BL-Controller is in limitation - either overtemperature or overcurrent
    So, in addition to the melt-down, the BL Controls were over temperature.
    You will have to add heat-sinks to the MOSFET transistors on the PDB board to try and reduce their temperature.
    Depending on the ambient air temperature this should be sufficient, but "your mileage may vary...."
    To do that you'll need: http://www.quadrocopter.com/Aluminum-ESC-Cooler-for-MK_p_324.html
    You get four heat sinks per package, so you will need to four packages (there are two sets of MOSFETs, top and bottom, per BL Ctrl on the PDB).
    You glue the heat sinks on with [Edit: I really do know how to spell Arctic -- I just don't know how to type it!] Arctic Silver -- a thermally conductive epoxy: http://www.quadrocopter.com/Arctic-Silver-Premium-Silver-Thermal-Adhesive_p_318.html
    Hope this helps.
    Andy.
     
  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,369
    Likes Received:
    1,162
    I'm afraid I don't know whether a bigger motor will run cooler -- perhaps you meant to write, "with a bigger motor, with the BL temps be cooler?"

    Again, I'm afraid I don't know.

    You should know that there is a sign in my office that reads:

    There has been an alarming increase​
    in the number of things​
    about which I know absolutely nothing.​

    :)

    Glad I could be of some help, though.
    Andy.
     
    Steve Maller likes this.
  10. Rick Marcus

    Rick Marcus New Member

    Joined:
    Sep 20, 2012
    Messages:
    16
    Likes Received:
    0
    I appreciate both your help, and your sense of humor. I think I need that sign.

    Thank you.
     
  11. Tabb Firchau

    Tabb Firchau Administrator
    Staff Member

    Joined:
    Jun 28, 2012
    Messages:
    911
    Likes Received:
    472
    Hi Rick, in my opinion the stock MK ESC's and distribution board are not up to the task of flying the EPIC. I think it can be done but the components are right at the edge of their envelope.

    Tabb
     
  12. Rick Marcus

    Rick Marcus New Member

    Joined:
    Sep 20, 2012
    Messages:
    16
    Likes Received:
    0
    Hi Tabb. I certainly found the edge today :)

    Do you have any suggestions on which components might be up to that task. I really need to be able to get that kind of weight in the air.

    Thanks,
    Rick
     
  13. Wolfgang Armin

    Wolfgang Armin Active Member

    Joined:
    Sep 20, 2012
    Messages:
    291
    Likes Received:
    25
    Hi Rick,
    you might want to search for "Herkules" powerboard or "Aerodrive" powerboard. I don´t have no experience with these, and they don´t seem to be easily available but from what I read that might be your solution.
    I also read that flying with 5s batteries reduces the heat too, but you have to change some things on the MK powerboard to be able to fly with 5s.
    Cheers,
    Wolfgang
     
  14. Josh Lambeth

    Josh Lambeth Well-Known Member

    Joined:
    Jun 29, 2012
    Messages:
    1,313
    Likes Received:
    214
    Actually flying with a 5S will INCREASE the temps of the MOSFETs. This is why I haven't switched to the 5s. In Phoenix during the summer I have to worry about temps already. :(

    Josh
     
  15. William Johnston

    Joined:
    Oct 2, 2012
    Messages:
    140
    Likes Received:
    5
    A fellow Deans plug melter. You me and Josh should form our own club. :D

    Here is my analysis of your GPX file:

    Flight Time: 2012-10-19T19:35:16Z
    Flight Duration: 1 minutes 41 seconds
    Average Current (Amps):
    17.0 13.6 15.4 11.5 15.3 11.8 16.7 13.4 0.0 0.0 0.0 0.0 Total=114.7
    cw=64.4 ccw=50.3 cw/ccw=1.3
    Copter has a clockwise moment.
    Average Temperature (Celsius):
    88.4 80.2 82.4 76.3 84.7 77.1 75.3 78.2 0.0 0.0 0.0 0.0
    Maximum Temperature (Celsius):
    110.0 103.0 104.0 96.0 109.0 99.0 95.0 103.0 0.0 0.0 0.0 0.0

    You can replace your deans plug with an EC5 or EC6. That will keep the cinestar from falling out of the sky when you draw too much current. You still have a problem with ESCs getting too hot. If you have altitude hold on when the ESCs over heat your cinestar will start flying in the direction of the overheating ESCs, even if position hold is on. With altitude hold off the cinestar will land itself when it the ESCs overheat.

    In my tests, the Mikrokopter ESCs overheat when the continuous current draw is over 8 amps. Using Tab's weight current measurements here:
    http://www.rcgroups.com/forums/showthread.php?t=1487242&page=5
    to keep a continuous current of less than 8 amps means that you have to have less then 8 pounds payload (including the gimbal). And Tabs numbers might be a little optimistic since according to his chart your cinestar should have only been pulling about 83 amps.
     
  16. Tristan Twisselman

    Tristan Twisselman Active Member

    Joined:
    Jun 30, 2012
    Messages:
    416
    Likes Received:
    25
    Out of curiousity, what does the epic/scarlet weigh? I have flown my D4 around and it is 4.7lbs and my motors and esc are pretty cool when coming down. About 12 minute flight time with that weight.
     
  17. Tabb Firchau

    Tabb Firchau Administrator
    Staff Member

    Joined:
    Jun 28, 2012
    Messages:
    911
    Likes Received:
    472
    EPIC with a nice lens can be around the 8lb mark, it really depends on how you rig the camera. I think I have had it as light as 6.5 at some point??

    Best,

    Tabb
     
  18. Nico Turini

    Nico Turini New Member

    Joined:
    Aug 14, 2012
    Messages:
    22
    Likes Received:
    6
    We've got some successful flights with a RED-Scarlet under Cinestar8 (but with DJI WK-M).
    Total weight for the Scarlet + Zeiss lens + special Lipo (for powering the RED and video signal TX all in one) + 360cinestar was 4,7 Kg (10,36lb). Total weight of the combo is around 23lb (10,5Kg)
    Flight time is about 6 minutes with 2 x 6s5000mAh and with 14inch props, and could be better with 15 or 16'' or even 3x 6s5000mAh... But for bigger props the stock booms are to short for that purpose ;)

    We've got MT3515 motors / ICE50 Castle : everything is near to "cold" after a flight, really nice!
     
  19. Tristan Twisselman

    Tristan Twisselman Active Member

    Joined:
    Jun 30, 2012
    Messages:
    416
    Likes Received:
    25
    Sounds like we have the exact same setups but I am running 6s 6600 and thought about trying the 6s7800 but never did.
     
  20. Janne Hoglund

    Janne Hoglund Member

    Joined:
    Oct 4, 2012
    Messages:
    364
    Likes Received:
    23

Share This Page