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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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.



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.

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