Microdrones claims 60 min of flight time for a Quadcopter ?

This must be the best sell pitch ever or just their fantasy.
But still, if somebody can come up with a formula ( battery size , prop size,
motor ) to get at less 50% of that it would be great .

 This are the specs for the MD4-1000 from the MicroDrones
Empty weight 2650g
Max payload weight 1200g
Take-off weight ~5500g
Size 102cm rotoraxis-rotoraxis
Flight duration up to 60 min
Operating distance up to 2000m
Battery cell LiPo 9000, 18000 or 27000 mAh   
Wind tolerance 12 m/s

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@jani, the iBM4006Q looks very promising.  I have been working with larger diameter motors for the last year on my builds.  They are simply more efficient and produce less noise/vibration.  They are much more versatile than motors that have smaller diameter, but longer stators.  I have had no issue with over heating ESCs' or motors.  I am turning 14"APC slow fly props on my MT3506 motors on 3 cells.  Wind is an issue though with this setup, but it can be easily alleviated by switching to 12" APC slow fly props and 4 cell pack (only small adjustment in PIDs').  If you start stocking the iFlight motors I will surely buy some to give them a try.  The thrust to weight ratio for these motors are hard to beat given their current draw. 

Robert, Some simple calculations would show this improbable with those motors.  But good idea non the less.  At best you would have to drastically change your gear ratio.  For a 450 CCPM Heli you would need more torque than these motors are capable of producing for a direct drive setup turning rotors that large.  200-250 size heli is more probable.  

I remember Graupner or Multiplex has helicopter with large motor like these...I was thinking about putting them on multicopter !!! :)

One potential negative point to these motors, don't they have significantly higher inertia, and thus slower response, which leads to a reduction in stability?

These type of motors simply have a higher thrust to weight ratio, plus it takes them less force to produce it.  As far as stability goes that depends in large part to the motors resolution and the ability of the flight controller.   Because of the higher number of stators and magnets these types of motors generally have a higher resolution .  From what i have experienced the APM is fully capable.  

@ Maximus

I want to order 4x of your w4822-390KV and 1x of your w4822-520KV but when I a add to cart all that is showing up is a 590KV?

Please advise as I need to evaluate these motors asap.



Hi Brian,

I am preparing the international webshop...

Please try here


what's up with the price ? 

would also expect better prop mounts, not prone to bending, even if the price were half.

actually it's now up to 88 min flight time check the website

Hi Todd,

I have similar results with larger props and larger diameter higher torque motors. Makes a significant difference in noise, efficiency, and stability. As you found I predicted they would be a bit less stable in high wind because I saw the same thing with traditional single main rotor helicopters when I decreased the RPM and increased the rotor diameter. Everything is a tradeoff of course. For quick maneuverability you want small rotors turning fast for flight endurance and efficiency you want big and slow.

Anyhow, I just built an Octo with the MT3506's and I'm having an issue related to the motors starting and loosing sync. Reading through RCGroups I'm finding that a lot of people are having the same problem. I found that with simonk ESC firmware they have a hard time starting and severe sync problems and with stock ESC firmware they are better when I choose "High" timing but still fall out of sync on rapid RPM changes (like in turbulence) so they are unusable. What ESC's are you using and have you experienced the sync problem at all?

BTW, to add to your answer to Rob, larger diameter motors trade off RPM for torque because they have more torque they compensate for the small amount of higher inertia and have no penalty in terms of reaction time. THe only real penalty is when using larger props because there is a larger disc area for the wind to push on which is why they are more sensitive to the wind that's why the 12" props work better in that respect but then you have to go to 4s to make up for the lift reduction..



When traveling fwd in an normal heli, you have relative wind due to the fwd movment throuh the air. The blade angle of the blade moving fwd is reduced, and the blade moving back is increased due to the decrease of relative wind speed.

Since we do not have this on quads, I would guess that this principle would be valid due to the rigid rotors we use.

But I am not 100% sure!

@Andke, get these motors from Himodel, $39.95 vs $99


There the same motors

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