New Project: MK X8 coaxial heavy lifter

Discussion in 'Cinestar 8' started by Dave King, May 3, 2014.

  1. Michael McVay

    Michael McVay Active Member

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    Sorry - normally it is on the primary board.
     
  2. Dave King

    Dave King Well-Known Member

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    No problem. I figured it out its the alexmos 3rd axis extension board.
     
  3. Michael McVay

    Michael McVay Active Member

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    Sure, but you might want to get it from the same manufacturer. Several companies make them and I am not sure if they are all interchangeable between manufactures or if the cables are universal.
     
  4. Michael McVay

    Michael McVay Active Member

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    Possible common choices:

    Flyduino

    iFlight

    ViaCopter


    Actually here is the full list from their website - (not sure all specifically make boards that are for resale though):
    Partners
    Our partners produce the controllers by themselves using our license.
    Viacopter, www.viacopter.eu Denmark
    Gimbals, controllers and motors. Partner with Flyduino and E-copter on electronics and motor production and development. More
    Flyduino, www.flyduino.net Germany
    Gimbals, controllers and motors. Partner with Viacopter and E-copter. Electronics and mechanics design and manufacturing. More
    E-Copter, www.e-copter.com France
    PCB and gimbal mechanics manufacturing.
    Be Steady, www.besteady.pro United Kingdom
    Handheld camera stabiliser for filmmakers.
    MultiwiiCopter, www.multiwiicopter.com Australia
    Gimbals, controllers and parts. More
    XCESSHOBBY, www.xcesshobby.com Italy
    Gimbals. controllers and motors.
    iFlight Model, www.iflight-rc.com China
    Manufacturer of the motors, the controllers and gimbals.
    Actioncamz, actioncamz.com Hong Kong
    Gimbals and controllers.
    ArmBGC, www.armbgc.com Armenia
    Gimbals, controllers and motors.
    LaserBGC, www.laserbgc.com Turkey
    Gimbals and controllers.
    Team Rebel Design, www.teamrebeldesign.com United States
    Beholder Gopro Brushless Gimbal with SimpleBGC controller.
    Elite Power, www.etecpower.com China
    Gimbals, motors manufacturing and OEM/ODM manufacturing.
    Dong Yang Servo Power Model Co.,Ltd, www.dys.hk Hong Kong
    Gimbals, controllers, motors and parts.
    Роттор, www.rottor.ru Russia
    Gimbals and controllers. More
    Kinematik, www.kinematik.pro Russia
    Gimbals and controllers.
     
  5. Jose Luis Ocejo

    Jose Luis Ocejo Active Member

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    Hi Dave and Steve just curious on your X8 conversions I did you use your exsisting 450mm booms or did you go with the 500mm I suspect that you both kept the 450mm just want to make sure
    thanks
     
  6. Steve Maller

    Steve Maller UAV Grief Counselor

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    500mm.
     
  7. Dave King

    Dave King Well-Known Member

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    500mm here as well.
     
  8. Tim Sessler

    Tim Sessler Active Member

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    I am flying the KDE 4014 with Tmotor CF 17" props, MK FC, i2C converter and 50A Castle ESCs.
    AUW is 25lbs.
    Tested today and the hover throttle is around 55%.
    According to the KDE numbers that should give about 15kg lift - minus 15% efficiency loss it should lift 12750g or 28.1lbs at 55% throttle.

    So at least in my case the numbers aren't that far off - probably its just the "real-world" difference ;)
     
  9. Bryan Harvey

    Bryan Harvey Member

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    seems pretty far off to me. 3 lbs means a lot. it's more or less 30% of your potential payload. it's the difference between carrying a RED versus a DSLR (safely)....and I was carrying a DSLR just fine back on my standard 4S Cinestar. So now I've built this 6S X8 with the KDE's and I'm scratching my head, wondering what it got me. not longer flight times. just a whole lot more heavy batteries to travel with on my shoots.
     
  10. Michael McVay

    Michael McVay Active Member

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    Apparently air density plays a significant factor as well. KDE did all their testing at sea level so if you are not flying at sea level you are not going to achieve their numbers. KDE also mentioned advancing the timing even further (they suggested as far as 30 degrees) to get more thrust. In doing so you might see some efficiency loss as that is the general trade off to advancing the timing. But, you could get more thrust out of the motor that way.
     
  11. Dave King

    Dave King Well-Known Member

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    KDE is also factoring in 5% for BL or ESC electronic inefficiency, not really sure why this is not taken into account into their specs. The real question though is that we are all questioning these specs and we are all assuming that there is a 15% efficiency loss for the X8 configuration. How do we really know this is a tested in flight number. I know that in general the motors are bench tested and have proven to have a loss but has anyone proven that the inefficiency doesn't increase as the GAW increases or as the density altitude increases? I would like to know if anyone has done back to back tests with a flat 8 and a x8 with the same motor at the weight? Or at different weights to see if it changes? These are the questions that I'm thinking about.

    I can understand that air is an important factor in the thrust efficiency, if you experiment with different DA numbers in E calc you can see the effects of hover throttle. There's 5% difference in hover throttle between sea level and 2000 feet. Weather can drastically change the Density altitude for the same location up to 1000 feet too. I guess you need to have the specs for sea level because there are some people that will fly at sea level or even below depending upon weather conditons.

    I guess that the bottom line is that you need to take these specs and reduce by a rather large number if you want to get a ball park figure.

    I plan on retesting my setup at 28 degrees timing and see what effects it has if any.
     
  12. Bryan Harvey

    Bryan Harvey Member

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    I guess my feeling is why bother with all that testing, parsing out minute differences and justifying KDE's published specs. The only thing that matters is true life results, and the KDE 4014 have already proven their limit is about 28lbs AUW. If you want a true heavy lifter then its the U7s or U11 with huge props. I do wish someone would make a 19" or even 20" prop. There's hardly a difference between 17" and 18".
     
  13. Dave King

    Dave King Well-Known Member

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    I understand your frustration as I am a little disappointed myself but I think you are not comparing apples to apples. I was carrying a 7D with my 4S MK flat 8 last year too but my hover throttle was almost 70%, with high ESC temps over 100, and 8 minute flight times. Now carrying that same exact load and gimbal combo (7D), I get 23 minutes of flight time on the same combination (flat 8 versus flat 8). I haven't tried yet this weight or combo with the new X8 4014's but I bet I would get about 20 minutes of flight time and extremely good ESC temps.

    I have been able to get 18 minutes flying time with my red scarlet payload 6S batteries, and improved 3.0 BLS. ESC temps have been in the 30 degree range. With the same payweight using the X8 I'm getting 15 minutes flying time which means that the 4014's are definitely more efficient than the U5's because with everything being the same I would expect more than 3 minutes drop off with the same weight. The U5's are definitely better, and more efficient than the Tiger 4014's and the 4014's are definitely more efficient and powerful than the U5's.

    So for me its a win win because I am getting over double the flying time, ability to have a much heavier payload, and in a more compact, stable X8 platform.
     
  14. Dave King

    Dave King Well-Known Member

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    I"m not trying to justify the KDE specs as I too am a little disappointed that I can't carry 30 pounds as hoped for but I definitely think 28 pounds is safe and practical with this motor combination. For me that's all I really need because I'm usually around 25 pounds with my Red Scarlet setup with 24mm prime lens. This will give me enough head room if I want a heavier lens package and or remote FF. I agree I wish there were 19 or 20 inch props.
     
  15. Bryan Harvey

    Bryan Harvey Member

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    Dave, that's interesting and I think different from what I experienced. I was flying 16,000mah 4S on my flat Cinestar 8, flying a 5dm2 on Radian 3 axis gimbal I was getting at least 10 minutes flight time. I honestly can't remember my throttle percentage, but my motors and ESC's were always at a comfortable temperature range.

    Now with my new X8 6s and 16,000mah KDE 4014 Im getting about 10.5 minutes flight time carrying exact same camera setup, granted the MoVI10 gimbal is a bit heavier than the Radian gimbal. Perhaps I'll get a bit more time when I switch from my 17" Xoars to the 18" carbon props.

    Wow, I don't see how your rig could be that much lighter than mine! I assume you are carrying 20,000mah? I'm at 26.25 lb with 20,000mah battery and just the same 5dm2 camera setup. I think the RED body is at least 3 lbs heavier than the 5dm II body, but Im not sure. Plus you need another lipo to power it. That would put me near 30lb, so somehow you are 4-5lbs lighter than me? Is the Scarlet lighter than the Epic?
     
  16. Dave King

    Dave King Well-Known Member

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    Hi Bryan

    Last year I was using (2) 6200 batteries with the QC motors which probably the difference. My gimbal weights 10.5 pounds and its just bare bones Scarlet with nothing but a prime 24 IS lens, 3800 mah battery (280 grams), home made brushless motor gimbal with GR85's, a amazon HDMI converter, and 1.3 transmitter. I don't think the Scarlet is lighter than the Epic. I don't run longer legs or extenders on the legs. The copter is using 2 QC 10,000 batteries. I was hoping to run 2 QC16,000 batteries but I think that would be too much weight.
     
  17. Dave King

    Dave King Well-Known Member

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    I did some timing comparison tests between 24 degrees and 28 degrees at both a 10 pound payload at 25 pounds and a 12.5 payload at 27.5 pounds. I saw no difference between hover throttle, maybe 1% at the most but I'd have to really average out all the points to see precisely the average stick position. Not enough to spend the time thats for sure.

    I also played around with GPS gain with the 2.06A firmware. 90% seems to work the best for me, 95% was a little less planted, and 100% was skating around just a little more than 95%. Overall I am pleased with the PH hold with the X8 combo. It is especially good higher than 15 feet to get out of the prop wash of the lower motors.
     
  18. Ashley Fairfield

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    I thought I'd put up a GPX file for my first flight with RED EPIC and KDE 4012. 16" Tiger props. Just kept it at hover as you can see. I haven't had a chance to look through it yet so if you see anything interesting let me know. Battery was 1 x 10,400mah. AUW 11.10Kg. Kept the RED side mount on with battery rather than Lipo. Recently changed timing to 24 degrees from 28.
     

    Attached Files:

  19. Dave King

    Dave King Well-Known Member

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    I have been flying the X8 and got about 30 flights on it. It's been working good. I did experience a motor restart when I yawed very fast but Holger says that's rather normal and told me to increase the minimum gas to 12 and haven't experienced it since.

    On another note I did some measuring of the heat off the motors and the board after a flight as soon as it landed. The outside temp was 83 degrees and I was seeing motor temps of the top motors around 130 fahrenheit and the bottom motors of about 105. The Mosfets on the power board were also about 125-130f which is right around the reported 50-55Calcius that the datalogger reports.
     
  20. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Does anyone have any data on how to determine the timing angle for a given motor? I'm just curious how it might relate to motor geometry or whether it's an "adjust to taste" parameter. I've been searching the Internet but not found a good algorithm for determining what the optimal timing angle should be given a particular number of coils/magnets.

    Andy.
     

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