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Motor and prop comparison: QC-3328 vs. AXI 2820-14, APC-SF vs. APC-MR

Discussion in 'Cinestar Misc' started by Márcio Senger, Aug 13, 2014.

  1. Márcio Senger

    Márcio Senger New Member

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    I recently put together a simple rig for motor testing. The initial idea is to find the best motor/prop/esc/battery combo for longer flight times and/or maximum thrust.

    The rig consists of:
    -Digital scale
    -The "L" structure with ball bearing pivot, leveled and well aligned
    -Kontronik JAZZ 80LV 80A ESC
    -Hitec servo tester
    -Bantan e-Station Voltage & Wattmeter

    [​IMG]

    The first test I have made with this rig compares a QC-3328 and an AXI-2820-14. I also took two measurements for each motor using two different props: APC 14X4.7SF (Slo-Flyer) and APC 14X5.5MR (Multi-Rotor). A thrust of about 850g is what I was looking for, as our typical AUW is around 6800g (cinestar 8 platform, with cinestar three axis gimbal, Canon 7D body, Canon 28-135 glass and Gens Ace 10.000mAh 4S).

    [​IMG]

    [​IMG]


    The results are as follows:

    [​IMG]
    AXI-2820-14 with APC 14X4.7SF
    Thrust: ~850g
    Power: 80.0W
    Current: 5.3A
    Voltage: 15.28V
    [​IMG]
    AXI-2820-14 with APC 14X5.5MR
    Thrust: ~850g
    Power: 82.4W
    Current: 5.4A
    Voltage: 15.27V


    [​IMG]
    QC-3328 with APC 14X4.7SF
    Thrust: ~850g
    Power: 87.0W
    Current: 5.7A
    Voltage: 15.22V


    [​IMG]
    QC-3328 with APC 14X5.5MR
    Thrust: ~850g
    Power: 90.0W
    Current: 6.0A
    Voltage: 15.17V


    I was really surprised by the results. The AXI motor is quite surely overproped - readings at full throttle have shown that a conservative approach would use smaller props. Have said that, a mutch older motor, that was built to be used on model airplanes, not multi-rotors had better efficiency on static thrust test than a motor that was developed almost exclusively for multi-rotor application. In this test, AXI motors shown about 10% better efficiency compared to the QuadroCopter ones.

    But not only the motors, the prop comparison is also confusing. Again, from a efficiency ONLY perspective, the Multi-Rotor series from APC performed worse than the Slo-Flyer, sucking more power to give the same static thrust when compared to the Slo-Flyer series.

    The digital scale used in this test is not ideal and further testing will be proceeded with another one that gives better resolution to the readings with the force magnitude that we are working on (the one used in this test measures up to 65kg which is a total overkill, with increments of 5g).

    I will share further testing but for today I can say that I'm really happy I have built this rig as it looks like performance is not a matter of putting "obvious" equipment together and real world figures differ from what one would expect.

    Cheers,

    Márcio
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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  3. Janne Hoglund

    Janne Hoglund Member

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    ¨the QC-3328 motor (also known as the MT 2814)¨
    I have both of them Andy and ideed they are identical twins. Other than paint I cant tell them apart from the outside.
    But the Qc is spec 3-6 s an the MT 3-4 s.
    Is there a differense in the thicknes of some wire inside?
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Janne: I'm afraid I don't know. I only have the QC-3328 and have not had a chance to inspect the MT-2814.

    Andy.
     

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