Help to choose new heavy lifter

Discussion in 'Cinestar 8' started by Michael Braun, Jan 16, 2014.

  1. Michael Braun

    Michael Braun Member

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    What do you guys suggest for Red Epic heavy lifter?

    I would like to build one Cinestar which is capable of:

    - Flight time 10min
    - 6S battery
    - Not bigger than 100cm end to end on booms
    - Would rather go for flat than X8 due to loss in power

    - What do you think about standard Hexa with U7 and 17" props?
     
  2. Gary Haynes

    Gary Haynes Administrator
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    Michael take a look at the Quadrocopter Facebook page. That have two posts in the last week with two different motor setups that might help you. https://www.facebook.com/quadrocopter
     
  3. Dave King

    Dave King Well-Known Member

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    Michael

    Do you mean 50 cm? 100cm would be 1000mm.
     
  4. Howard Dapp

    Howard Dapp Active Member

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    1000mm is about right for a big lift rig. My own coax is about 975mm
     
  5. Dave King

    Dave King Well-Known Member

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    Sorry my bad I just realized you were thinking end to end like end of boom 1 to boom 5. Sorry, I will put my foot back in my mouth now.
     
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  6. Michael Braun

    Michael Braun Member

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    Yep, 1000mm. That is the MAX that goes in the car :)
     
  7. Michael Braun

    Michael Braun Member

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    Thanks for the links
     
  8. Michael Braun

    Michael Braun Member

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  9. Michael Braun

    Michael Braun Member

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    I did a test with flat octo and MT3515 motors. Weight was 11.1 kg with 2x 6S 5800mah cells.

    I had 62A in hover with 15" and flight time 7min

    With 16" props I also had 62A in hover. How is this possible? I didn't try the flight time with 16" yet.

    Ecalc shows that it should draw 0,7A less per motor with 16"
     
  10. Dave King

    Dave King Well-Known Member

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    When you are running the 3515's at that weight they are really being worked too hard there's absolutely no headroom. What electronics are you using? Which16" props? Which 15" props? You will need to look at your data more closely such as did you do testing back to back the same day? What was the difference in weather between the tests? Any difference in wind speed? Any difference in pitch on the props? Difference in prop balance?
     
  11. Michael Braun

    Michael Braun Member

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    It was one flight after another, just hovering 4m above the ground.

    -DJI Wookong
    -balanced T-motor CF 16x5.4
    -balanced T-motor CF 15x5.5

    It looks like I will have to go with U5 motors to save some weight to achieve flight times like Quadrocopter did with their CS HL. With some modifications I could save up to 400-500g on the total weight.
     
  12. Dave King

    Dave King Well-Known Member

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    U5's are not big enough at that weight. Did you see my build thread?
     
  13. Michael Braun

    Michael Braun Member

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    I read your tread.

    But mine would be lighter. Yours was 11.1kg total. Mine total weight would be 1kg less, if I calculated right.

    Well all three CS8 from Quadrocropter on facebook seem very good in numbers. But in reality you say that none of them is powerfull enough to carry 5lbs (5300g)?

    At the moment mine is also 11.1 kg and I get throttle reading in manual flight at 60%.
     
  14. Dave King

    Dave King Well-Known Member

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    Hello Michael

    5 pounds is 2.3KG not 5.3KG. 11.7 pounds is approx 5300 grams. My copter's flights so far have been at a weight of 11100 grams and hovering around 68-70%. I don't believe the U5's are not enough motor for my weight with 15" props. 3515's are close in spec to U5's but I believe U5's are more efficient in keeping the temperatures down at X load. I could have gone with 16 inch props and 550 booms and kept the U5's but it would still be around 62-63% throttle at hover not leaving much headroom for wind or higher temps. I want to hover at 50% for the greatest safety margin. I also went with the U7's because I will be actually carrying about 1pound more than I initially thought and have tested so far.

    Quadrocopter has been testing the U5 motors at all up weights (GAW) of about 9.9KG which is about 1.2KG more than myself. That makes a big difference. IMO the U5's and 3515's are good at the weight QC is testing.

    So to answer your question, in my opinion, flight weight of 11KG is a little bit much for the 3515's and U5's.
     
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  15. Michael Braun

    Michael Braun Member

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    Dave,

    thanks for your thoughts. I agree with you and U7 motors. I was just looking for options to have light weight setup. But I see that I will have to go with bigger motors. I am looking forward to your tests with new motors.
     
  16. Steve Overstreet

    Steve Overstreet New Member

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    Dave King: I agree with your assessment of the 3515's. To add fuel to this fire i have an Octo (Cinestar 8) configuration with 3520's and can lift an enormous amount of weight (a payload of 25 lbs.) but flight time makes this not workable. With a 10 lb payload and 18" blades I have to run 20 amps of 6S batteries (at a cost of 10 lbs) to fly for 6 min. (AUW is 44 lbs.)

    Something you don't mention is flight time and batteries used. Can you fill us in using the U7 motors?
     
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  17. Dave King

    Dave King Well-Known Member

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    Haven't tested the U7's yet. Maybe tomorrow :)
     
  18. Chris Fox

    Chris Fox Active Member

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    U7, 17" props, 5kg payload, 12.9kg AUW, maiden flight successful, no temp issues, and plenty of headroom. More testing to follow next week ;)
     

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  19. Steve Maller

    Steve Maller UAV Grief Counselor

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    Congrats, Chris. Your config looks similar to mine, although I’m going with smaller motors. I don’t need to go that heavy, and many have said that you should not overbuild the power system, as they all seem to have a sweet spot. I’m looking for 8-10KG AUW, so I am going with an X8 with Avroto 3515 and 15” props. Should hopefully be airborne this week or next.
     
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