How do you calculate quadcopter lifting capability?

I am planning to build a Quadcopter for some time, I have all the required gear and an airframe completed. Before I start assembling the entire quad I would like to know what the lifting capability will be when complete.


I know that one motor with a 2 blade prop will lift 2Kg whithout any hassle at approximately 70% power (thrust test, not in airframe). Does this mean that for a quadcopter I can assume that four motors will lift 8Kg @ 2Kg per motor or is there some other calculation to accomplish this?

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I'm interested in this calculation, for my own rig:

8Ahr 6S 35/50C = 176watts per hour

3508-29's at 100% with my prop is 310watts, according to t-motors charts.

1240 watts total = 0.14 hours or 8.8 minutes at max power

Pulling 57 amps? or "7.125 C (57/8)"? Have I got that right?


Edit: No I don't. Amps at 100% = 7.2A. 4 x 72.A = 28.8A. Battery can do 8 x 35 = 280A. "C" draw is therefore 9.7C

Err...rather *percentage* draw is 10.2% of max C. Just to be pedantic. I'll shut up now.

You should calculate lift at ~50% throttle. In other words the copter and payload should hover at 50% throttle. The reason for this is that the copter needs a lot of thrust headroom to maneuver properly. You also get very short flight times if you push the system to much.

I have a standard 3dr quad, with gimbal, telemetry,850kv motors , 3,300 mah lipo, 20amps esc, 1047 props
Total wight is 2100grs, I am very disappointed with flight time and also lifting capability , it hovers at very hight throttle, and is difficult to control when it goes down even at low vertical speed .

The way it is now is almost useless, then I know I have to decrease weight to solve all the other problems, but what is the fun of taking all the equipment out, then the questions is , what is the logical way to go , ? , bigger props , 4s instead of 3s , larger motors , ?
Or just quad was a mistake and should go to exa.?


The link you shared here, does not have any units. What should I be filling under Thrust/ RPM. Is this RPM/ volt or maximum RPM.

Should I be filling Altitude (in meters or feet), and how does this relate??


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