# Incredible Flight Endurance!

I came across this video on my youtube feed today. How is this kind of endurance possible with standard LiPos? The last best flight time of 45 min was achieved by Holger Buss with his hexa mikrokopter if I'm not wrong. Can anybody shed light on how microdrones managed in excess of an hour?

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Comment by Rana on February 12, 2012 at 8:29pm

Whatever I have mentioned above is the approach used by Microdrones, who have achieved 1 hr, 28 min flight endurance in the video of this blog post.

Ellison, that,s nice approach, but in real practical, ejecting the empty packs from the airborne quad wont be economically wise.

Comment by David M Eno on February 13, 2012 at 12:59am

There would be a way to make this work I believe.  It would be like drop tanks with airplanes.  I also agree that it is totally unfeasible.

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Comment by John Arne Birkeland on February 13, 2012 at 1:00am

Dropping empty battery packages is a "chicken or the egg" problem.

If you have multiple batteries and plan to switch out and drop empty ones in air, you have to lift fresh unused batteries as deadweight until you switch over to them. So the gain from dropping empty batteries is already lost. And if you use all batteries in parallel, there is no empty batteries to drop unless you want the copter to drop with the battery. :)

The only scenario that might work is using two or more batteries of uneven size at the same time, dropping the smaller battery when it is drained. The larger battery would then continue without the deadweight of the smaller one.

Comment by Ellison Chan on February 13, 2012 at 8:26am

Well, chicken or egg is obvious, right.  The egg always drops from the chicken.  Then General Relativity says all inertial frames are equivalent, so maybe the chicken is dropping from the egg.

Seriously, auto-switching to, and drop of empty battery packs is equivalent to the gas tank on your car.  As you start with a full tank, you are less efficient, and as you progress, and the tank empties, you become more efficient.  Same situation, with regards to the batteries.  To make it economical, you can equip the batteries with small parachutes and have the drone drop to a minimum height before jettisoning the pack.

The other alternatives are either charging stations at various waypoints, or have the drone automatically exchange batteries from battery storage stations.

Don't say this is impossible, because ten years ago, if you told me that I'd make a VTOL, self-stabilized, autopiloted, quadrotor aircraft, in my house from parts that I bought in a hobby shop, I'd have said you were crazy and find out what you're been smoking, and where to get it.

Comment by Sebastian Gralla on February 13, 2012 at 11:33am

as you see in the video, there is no battery dropped from the drone ;)

and they mein parallel for parallel, not for selective battery switching, that means the lipos are hardwired which menas that all batteries drain at the same time, no empty batteries while the others are still fresh.

I can't think of a way you could switch between empty and full batteries without loosing power in between (at least not in this power range of a hundreds of watts)

Comment by David M Eno on February 13, 2012 at 1:03pm

No one was questioning them about dropping a battery.  There was just a debate as to if it would allow a longer flight time if the craft was to drop batteries in a similar way to an aircraft using drop tanks.  The consensus was that it might be effective, but it would be over complicated for the application.

Comment by Squalish on February 13, 2012 at 8:58pm

Here's how you do an endurance 'record' run, in order of importance:

1) Saturate payload capacity with battery, sacrificing maneuverability, useful gear, and wind compensation

2) Tune. Test combinations of prop, motor, and battery until ideal combinations are achieved.  Large, slow rotors are preferred.

3) Run the batteries until absolutely dead (damages them)

4) Perform the test indoors, where there's no wind

5) Streamline the frame in vertical airflow

Comment by Russell - ScoutUAV.com on February 13, 2012 at 9:06pm

Well said Squalish!

Comment by Denny Rowland on February 13, 2012 at 10:46pm

I expect the model was also a special  lightweight build stripped of everything not essential.

Comment by Ehren on February 14, 2012 at 2:36pm

There is always cheating.

Hook the charging reciever to your power system.

Wow look at the incredible endurance!!

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