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Heavy Lift Quad

Posted by William Bishop on March 8, 2011 at 10:40am

What kind of weight could I expect to move with four AXI Gold 5345/14s, or four Hacker A50-14L 8-poles or similarly large motors?  I know the battery sizes will be heavier too.

I am trying to get help on finding info on motors, prop sizes (18 - 21"??) and overall limitations/lift requirements of motors and batteries for a 30 - 40 lb platform.  Flying time of course would be under 30 - 40 minutes.

I know this is going to get expensive as four of the Hacker motor/ESC/Battery combos is around $3300.00..  Cheaper ideas with similar power are welcomed. 

 Will the APM and mated electronics handle a platform of this size this the same as they would a 1/2 pound drone?The Freewave radio system is very interesting too.  

If I can get a reliable and stable flying platform, I will go further with all of the cool ideas that are on DIYDrones. 

Thanks in advance for assistance or help in any way.

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Replies

  • john bero December 13, 2018 at 12:34pm

    https://youtu.be/t0A6qdpEFIQ

  • john bero December 13, 2018 at 12:30pm



    Denny Rowland said:

    When it comes to evaluating motor prop efficiency it is pretty much a case of trial and error as the numbers given out by some manufacturers are to be taken with a large pinch of salt. However as a guideline to what your looking for consider this. Maximum lift efficiency is about the airspeed that you will be flying at i.e. if you are flying at 120 mph you need to absorb all of your available power into the maximum dia. that will provide at least that speed. In our case that speed is almost zero so we need to absorb our available power into the largest dia prop with the least amount of pitch. i.e. not a toothpick small dia. with a high pitch, but a large dia. slowflight wide section low aspect ratio prop. with a very small pitch angle. As props start to get very large the tip losses which act with a high leverage from the hub and become a significant drag factor so it becomes a trade off. I made this simple test rig dyno. to check the lift/watt performance of various props. From that data you can see on the MK site a simple formula for calculating battery endurance against the total current drawn.

    This MK 3538 could lift 2.5 kilos at max 14.8 v. power which was almost 500 watts with a 14x4.7, clearly at that level of stress it would not last very long. It could however run all day at about 13-1400 grams of lift.3702449487?profile=original

    Heavy Lift Quad
    What kind of weight could I expect to move with four AXI Gold 5345/14s, or four Hacker A50-14L 8-poles or similarly large motors?  I know the battery…
  • john bero December 13, 2018 at 12:29pm



    Denny Rowland said:

    When it comes to evaluating motor prop efficiency it is pretty much a case of trial and error as the numbers given out by some manufacturers are to be taken with a large pinch of salt. However as a guideline to what your looking for consider this. Maximum lift efficiency is about the airspeed that you will be flying at i.e. if you are flying at 120 mph you need to absorb all of your available power into the maximum dia. that will provide at least that speed. In our case that speed is almost zero so we need to absorb our available power into the largest dia prop with the least amount of pitch. i.e. not a toothpick small dia. with a high pitch, but a large dia. slowflight wide section low aspect ratio prop. with a very small pitch angle. As props start to get very large the tip losses which act with a high leverage from the hub and become a significant drag factor so it becomes a trade off. I made this simple test rig dyno. to check the lift/watt performance of various props. From that data you can see on the MK site a simple formula for calculating battery endurance against the total current drawn.

    This MK 3538 could lift 2.5 kilos at max 14.8 v. power which was almost 500 watts with a 14x4.7, clearly at that level of stress it would not last very long. It could however run all day at about 13-1400 grams of lift.3702449487?profile=original

    Heavy Lift Quad
    What kind of weight could I expect to move with four AXI Gold 5345/14s, or four Hacker A50-14L 8-poles or similarly large motors?  I know the battery…
  • Dean Lamborn March 10, 2011 at 9:01am

    As long as you are using a standard ESC it doesn't matter what the size of the vehicle might be.

    The reaction to inputs is a function of the PID tuning. Fast response is a function of how much power you have in reserve. If you are committing most of your power to lifting you don't have a lot of reserve for maneuvering.

     

    As with anything that lifts you run into a weight spiral. "I need bigger batteries, and they weigh more so I need more lift so I need bigger batteries . . ." You will have to pick something that you think will be in the range that you need and then calculate total lift and then start subtracting all of the things that support that lift. Nothing but fun.

     

    The 8 rotor in the second picture by Denny could be flown as a 4 rotor for maneuvering with the other 4 in a throttle only mode for lift.

  • Overwatch March 8, 2011 at 2:57pm
    Trying to give your german shepherd the Pixar's "Up" experience?
  • Phil Cole March 8, 2011 at 1:21pm

    With big motors and props like you're describing I'd be worried about moment of inertia making the system response sluggish. At the very least think about variable pitch with the motors running at constant speed.

     

    A single rotor helicopter lifting 40 lb would have a rotor diameter of around 2 m, maybe a bit smaller if you wanted to compromise efficency -> rotor disk area = 3.14 sq m. Four rotors with the same area would have a diameter of 1 m each.

     

    http://us.vario-helicopter.biz/shop/product_info.php?cPath=23&p... should give you an idea of the scale of these things and the power required.While the link points to a scale model, its weight and flight envelope is in the class you're looking for.

     

    Once you to large model helicopters the efficiency of a single rotor turning as slowly as you can manage is going to be an advantage, particularly if you want it to be electric.

  • Moderator
    Gary Mortimer March 8, 2011 at 11:56am
    Well best get your COA first else you will have invested alot of money in a platform you can't use.
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