# Endurance of drone

Hi there
I made a small quadcopter using MN4006 380KV motor with 15 inch propeller and i fly it using 6s 16000mah battery ,mtow 3.6kg as per calculation the endurance of the drone should be atleast 50-55mins but i get only 36 mins of endurance ,May i know the reason and is there any way to increase the endurance , i have attached the log file , i wanted to check the endurance first so no tuning has been done , can anybody help me out

1. Calculations are always estimations that canâ€™t take all factors into consideration. Motor/ESC efficiency, battery properties, prop design and material, frame air resistance, wind speed, wind direction, flight direction, flight speed, air temperature etc. etc. â€¦ The map isnâ€™t the territory.
2. Tune it. If your motors constantly have to counteract forces created by an unstable drone behavior itâ€™s no wonder they soak up power.
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What calculation did you use?

When I put that through eCalc with the values you gave and assumed everything you didnâ€™t mention, I get a hover flight time of 17 minutes. What TOW did your drone have during the test flight you did?

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The Mtow is 3.6kg sir .

what battery are you using? is it flat cell lipo or round li-ion cells?

going by the Tmotor spec sheet it should only be using around 4.1A per motor for 900g per corner giving 3.6kg total at 16.4A but your using around 5.3A per motor using around 21A total.

The only thing i can see is some imbalance in your motor output. If itâ€™s round arms, then I would guess one is twisted a little.

Tattu 16000mah Lipo battery sir, Level checked all the motors sir , but still consuming higher amps

Is 3.6 kg the take-off weight for that test flight or is it the maximum take-off weight the drone will ever have? Just to clarify confusion, you wrote in the original post that you have an MTOW of 6 kg.
MTOW â‰  TOW

With a TOW of 3.6kg eCalc agrees with your observation of 36 minutes.

What calculation did you use originally?

we used to calculate as Amps consumption during flight/MAH of battery and the 60/(Amps consumption during flight/MAH of battery) ie 16.4/16=1.025 and then 60/1.025=58mins

I think a major difference with reality is that you cannot empty a LiPo completely. It would kill your battery if you emptied all 16Ah. Draining 16Ah of your battery will lower the voltage to 0V (dead). Another major difference with reality is as you lower the voltage of your battery during flight, you consume more amps to turn the rotor at the same RPM.

From experience, using test data is never 100% accurate. The arms holding the motors block airflow from the rotors. Airflow being sucked in your props can interact with the airframe. Also, test data doesnâ€™t account for any other electrical component (but that usually makes only a minor difference though).

eCalc probably has a better battery model than yours, making it more accurate than your back-of-the-envelope calculations.

@Oli1 has another point. If your drone is untuned, and keeps making minor oscillations, that will drain your battery faster. Heck, if you use BLHeli ESCs, there are parameters in the ESCs firmware you can play with to make your ESC/motor/prop combo more efficient. Itâ€™s not impossible that your default ESC params are badly set for the motor/propeller combo youâ€™re using.

You also have 3 motors at a higher throttle, and 1 motor at a lower throttle. Current consumption is exponential with thrust. If your drone is unbalanced, the total power consumption is greater than if your drone is properly balanced (center of mass at the geometric center between your 4 motors).

But, no matter what you do you wonâ€™t get anywhere near 58 minutes.

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@bobzwik @dkemxr @Janno @geofrancis @amilcarlucas @Oli1 thank you all for your time and suggestions,i will try with different motor and frame and will update you . And i want to make a drone with 1hour endurance with Tow of 5kg including battery, please give me suggestion for selecting perfect propulsion system and other components

Lighter frame and Lithium Ion batteries instead of LiPo batteries. They hold more capacity per kilogram, but their maximum output current is less. They are also more expensive.
Otherwise, larger props = better efficiency. The motor tables from motor manufacturers are good enough to compare motors, just not 100% accurate to estimate current draw. If you donâ€™t need a huge maximum T/W ratio, choose propellers that aim for efficiency instead of max thrust.

And then to squeeze the endurance to the max, properly balance your quad and properly tune it.

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To get over 1 hour you need to be ruthless with weigh saving, you will need to get the lightest components you can get,

starting with the battery. your current battery is almost 2kg. you can drop that down to around 1.3kg with a 6s3p pack using 5000mah li-ion 21700 cells.

for my light builds
use the lightest flight controller, it doesnt sound like much an orange cube is almost 80g where you can get a matek h743 thats 9g.
Lightest ESC 4 in 1s are usually lighter than individual ESC, and you dont need a big one, a 4x20a would be enough.
lightest GPS with a thin carbon mount, the folding mounts are heavy.
lightest VTX and camera
titanium nuts and bolts.

you probably wont need to go to that extent but you should weigh every component and see where you can save weight because it all adds up.

Something else just occurred to me, what altitude are you at? Are you up in the mountians? Because the thinner air will cause it to use a lot more power than at sea level.

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Buy a subscription to eCalc and get to work. You will find it difficult to achieve your goal.

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I think his best idea would be to go to ecalc and set his motors and a 6s 15ah battery then work out how light it needs to be to fly for an hour by changing the weight on ecalc. once he gets the weight he can then start weighing parts to work out where the weight can come off to get down to where it can fly for an hour.

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I had a 14â€ť quad that would â€śflyâ€ť (hover) for 45 minutes but thatâ€™s all it would do as it carried nothing. It flew some impressively long missions to nowhere and backâ€¦

Or the YouTuber whoâ€™s craft hovered next to a clock for 1hr. Like watching paint dry.

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thatâ€™s all mine to do these days, I like building and designing them more than actually flying.

That was essentially how I tested my endurance quads, I was so happy when I got optical flow working so I didnt need to manually fly it.

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I am with you on that!

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