Converting To Heavy Lift CS8 - BUILD THREAD

Discussion in 'Cinestar 8' started by Josh Lambeth, Nov 4, 2012.

  1. Gary Haynes

    Gary Haynes Administrator
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    Josh looking at your config in ecalc (5s, 50amp esc, MT3515, 15x5 props) says at 11800g you would be pulling 98% throttle but only pulling 15.47amps per motor. So appears that your results are right on target... and maybe a typo on ESC output at 90%?
     
  2. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Hey TFCM,
    When you did this... other then the TSR1-2450 (which I already have) What exactly am I doing to the board? I am slightly confused by your message... I think I will be buying a few 6s batteries to try out.

    Also with your modification will it still run correctly on 5s? Thanks.

    Josh
     
  3. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Ok,
    Did my first flight today with camera mounted to the copter. Flew with the 5DMKII and 20mm F2.8 lens. Total flying time was 14min 49seconds with 10% left in the batteries. I was doing a lot of 80-100% power ascents to test the responsiveness of the copter and to push the copter to the limits with its payload. I was also doing a lot of fast descents with it then full power to get it to stop. HOLY COW THIS THING IS POWERFUL!!!! It would stop almost instantly from a fast descent. I was also able to descend much much quicker then I ever was able to with the MK BL setup. There wasn't any jitters/flutters during the descents. I looked back through some of the flight data from the ESCs after the flight and the numbers are awesome! The average amps pulled per motor was between 6-7amps with a max amp of 11! Also the max temp the ESCs reached was 44*C which is half what the MK BLs were when flying the same camera setup. This was under almost the exact same temps as before. Average temp was around 37-38*C. The motors were cool to the touch and the batteries were just slightly warm.

    I need to play around with the PID settings a bit. There is some unwanted sitter in the copter and it feels a little sluggish and doesn't 100% hold it's yaw heading. I'll start to play with those tomorrow. So far though I am very very happy with the I2C-PWM converter. For $16 to be able to use these ESCs with the MK FC it's completely worth it. Just need to tweak some things a little more in the Gyro area.

    I have video's of the first few flights which I will edit and post tomorrow maybe.

    After seeing what people have been saying about running with a 6s batteries I am planning on modifying the MK FC to accept the 6s batteries. I am talking with TCFM to help learn how to convert the MK FC to accept the higher voltage. This should take care of the extra heavy loads. I will use the 5s batteries with the 5D and the 6s with heavier cameras.

    Oh and the total flying weight was 19 1/2 lbs or 8.84kg tonight.

    Josh
     
  4. Thijm

    Thijm Member

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    PM send
     
  5. Jose Luis Ocejo

    Jose Luis Ocejo Active Member

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    hi Josh other than re-use your existing MK FC I think you have 2, did you consider on this new build switching to hoverfly FC or DJI Wokong FC
    thanks
     
  6. Josh Lambeth

    Josh Lambeth Well-Known Member

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    I did consider that but wanted to stick with MK. Plus I think there will be a new contender in the game in the coming months... ;)
     
  7. Howard Dapp

    Howard Dapp Active Member

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    Interesting. if so, the question would be: do I jump on board right away or wait at least 6 months while all the bugs are worked out, there are ALWAYS bugs with new flt control solutions even after a long run of beta testing. Switching flight controls is a major consideration these days, especially having used a particular hardware for years of trouble free performance. It's not like the old days where you're flying a camera costing only a few hundred dollars and cost risks weren't as high. A faulty new gimbal IMU solution will not bring down your $15k investment but a newly released flt ctr with a few bugs will.

    This new flight controller would have to have some major advantages and improvements.

    Ok enough of my babbling...
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Howard: you're not babbling. You're speaking the truth. What you're describing is what I call "The Minimum Cost of Change." For example, almost all of us are still typing on keyboards, the layout of which was deliberately chosen to slow us down (from the days of mechanical typewriters where you could easily jam two hammers in the gate if you typed too fast).

    Better keyboards are available, but are rarely used because the cost of change (learning to type all over again) is too high. There are numerous other examples, such as switching the USA to metric, etc. (It cracks me up when people here say "I don't understand metric" and yet seem quite happy with dollars and cents and grade point averages...)

    Anyway the thesis is: It's not the survival of the fittest -- it's the survival of the minimum cost to change -- unless the benefit of the change represents a huge leap forward (e.g. the CD replaced the phonograph record).

    This thesis seems to apply to flight control systems as well -- if the cost of change is high, even if the solution is better, it will not happen unless the benefits of change outweigh the cost of change.

    We shall see.... :rolleyes:

    Andy.
     
  9. Brad McGiveron

    Brad McGiveron Active Member

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    I am with you on this... I have a Cinestar WK and Cinestar MK and they both do better what the other can't. In the end I can get footage with either and after awhile you realize, running around changing platforms every 3 months becomes somewhat counter productive. Something new from the ground up is going to be fresh but with its pitfalls for sure.

    Btw... if you can please post some info on change you are doing on MK FC for 6s? I have a spare frame, CC ESC's, FC and the I2C-PWM converter and am gonna give that a go as well until the Hercules comes. Maybe a few more KV on the motors or are you thinking you went the right route for the payload?
     
  10. Josh Lambeth

    Josh Lambeth Well-Known Member

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    I believe once I have the 6S batteries I will have an excellent setup for the payload I am wanting to fly. According to ECalc it will be about 65% throttle for hover with a 12lb payload. With the 5S batteries I am about 90-95% throttle for hover... which obviously isn't flyable...

    Josh
     
  11. Thijm

    Thijm Member

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    What is your flying range > elevation/height above sea level?
     
  12. Josh Lambeth

    Josh Lambeth Well-Known Member

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    I'm about 1200ft or 325ish meters.

    Josh
     
  13. Thijm

    Thijm Member

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    Forgive me if I'm wrong. I'm not a scientist and my experience is only based on flying with heavy lift, MK electronics and http://www.ecalc.ch/xcoptercalc_e.htm?ecalc. as guide.

    It looks to me if you want to stay at your current setup > 400kv/15.5. You might want to consider to use 6s when flying with <9/10Kg and with 7s <11-12KG (you be the first :)) Can't test this myself. Herk's 6s max.

    Almost 92% efficiency :D
     

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  14. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Thanks for that info TFCM,
    Why does it say im over the limit on the motors with the 7s? The MT3515 can handle up to an 8s according to their website?

    Did another flight yesterday while adjusting the PID settings in MK Tools. Had to drop Gyro P way down from where I was before (First flight was 120 with some oscillation, now it's at 80 and flies pretty darn rock solid). More tweaking to come though. I still have a slight random yaw from the copter so I'm looking into that. I also need to figure out what is going on with the ALT. hold. As soon as I turn it on the copter shoots straight up... :confused:

    Josh
     
  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    The random yaw sounds like a gyrocompass issue, doesn't it Josh?
    Also the AH/head to space problem -- I'd start by checking all the legs on the FC board's pressure sensor and make sure they're not broken...

    Interested to hear what you find.
    Andy.
     
  16. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Josh: There's also this thread regarding the yaw.

    Could it be increased current now causing compass problems?

    Andy.
     
  17. Josh Lambeth

    Josh Lambeth Well-Known Member

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    I'm sure it's not a compass issue. I have it disabled in MK tools so it doesn't do anything.

    I'll check that but I have also heard it could be a setting that the converter doesn't like... we shall see.

    Josh
     
  18. Thijm

    Thijm Member

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    Don't bother. We never fly on the max > full throttle. Maybe in an emergency! less then 4sec max
     
  19. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Josh:
    Check out this thread on "Uncommanded Yaw." Message #7 says (I've added the emphasis):
    stu
    does the uncommanded yaw generally happen near the end of the flight? this yaw will happen when the battery power is low and the FC is near brown-out conditions when you're leveling off from a descent of just using the batteries beyond their normal time/capacity.
    i also saw a lot of it with the I2c to PWM converter installed

    Andy
     
  20. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hey TFCM:
    I've been meaning to ask you. When you said "Add 2x 35v" can you clarify that -- 35 volts is obvious, I think the 2x means "you need two capacitors," but what I don't understand is what size caps in terms of microfarads?

    Also, when you wrote "connected ground cap" -- do you just mean connect these two pads together with the negative side of the cap?

    Thanks
    Andy.
     

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