FlightTime 
Siehe auch: AntriebsTheorie, Einsteigertipps
Inhaltsverzeichnis
Flight time of MikroKopters
The flight time depends on the following factors:
 Lipo capacity
 weight including payload
 Motor/propeller combination
 losses (wind, hovering or sportive flying,...)
To estimate the theoretical flight times of the Mikrokopters, there are these possibilities:
 use the curves of the sets below
 use the calculation software
 calculate it manually
how to read the curves
The curves were made with a software too by marc.
They use measured motor/propeller data.
Flight time vs. Lipo capacity
Here we see the curve "Flight time vs. Lipo capacity" of a Quadro XL
On the lower scale we see Lipo capacity and on the upper scale we see the flight time.
If we want to find out, what flight time we can get with a 6600 Lipo, we need to do the following:
 find the 6600 on the lower scale
 now we go up until we reach the curve
 on the left scale we see the corresponding flight time (almost 34minutes)
The curves are calculated with realistic Lipoweights. They consider that higher capacity means higher weight.
You can also see on that curve, that the maximum capacity is 14.000mAh. That is the point where the additional Liposweights are negative for the flight time.
Flight time vs. Payload
Additional payloads reduce the flight time of course.
There are three curves. They depend on the flight style.
Slow hovering results in the longest flight time, because of low losses.
So if we want to find out what flight time we can expect with 500g payload, we have to read the curves as follows:
 search the payload on the lower scale [g]
 go up until you reach the curve you expect 'hovering', 'normal' or 'sportive'
 go left to read the flight time
In this excample the flight time is between 13 and 20 minutes depending on the flight style.
Theoretical calculation of the flight time
If you want to calculate the theoretical value, you can do it that way:
measure the total weight including battery
Example on a Hexa with ~2150g
> 1000g Empty weight plus 1150g Lipos
Devide the value by 6 (because six engines) > 358g per engine
Thrust per engine = Total weight / Number of Engines
reading the current from the table
Now we determine the current that the engine needs to hoover (more exactly: Input current of the BL controller) This one uses this characteristic:
(This characteristic applies to ROXXY282735 and MK283235 (formerly known as MK2832/52) on a 4S Lipo)
In the courve you can see 2,5A for about 358g
Means: Each engine requires 2.5A, to lift his part of the total weight.
There is a total current of 2.5 A * 6 = 15A.
Calculate the maximum flight time using the battery charge capacity
The Hexakopter has been used in this example with two 5000mAhLipos.
The formula is:
t (in Hours) = Lipocapacity / Total current
t = 10Ah / 15A = 0,666h
 The time in minutes is:
t = 60 * 10 / 15 = 40 minute
Power consumption and other losses
The abovedetermined value is an ideal value that specifies the absolute limit.
You'd have to really consider:
The thrust characteristic was measured with a 100% loaded LiPo. The thrust decreases slightly when the voltage drops in flight.
 Turbulence
 Losses due to regulations
 other losses (e.g. in cables, etc.)
For this reasons we estimate ~10% losses
So you have:
t = 90% * 60 minute * Lipocapacity / Total current
t = 0,9 * 60 * 10 / 15 = 36 minute
Test of the theory
This we wanted to test pratically. And here is the Video of the test.
Software tool for estimating the flight time
The calculation can be done very easily with a tool from Marc:
http://forum.mikrokopter.de/topic210521.html
Test at a timeofcompetition
With the softwaretool we calculated the following graphs:
So for the Hexa2 we calculated a flying time of about 35 minutes and for the HexaXL 40 minutes
We were able to validate this in practice:
(Video)
Weights and flight times of the (standard) MikroKopters
MikroKopter as Quadro
 with
 4 Motors Roxxy282735
 48cm
 NaviGPSMK3Mag
 GPScap
 FlexlanderL Landing Gear
weight 640g without Lipo
maximum (arithmetical) Flight times:
MikroKopter as Quadro XL
 with
 4 Motors MK3538
 56cm
 NaviGPSMK3Mag
 FlexlanderXL Landing gear
Weight 970g without Lipo
maximum (arithmetical) Flight times:
Lipo 
max. Flight time 
with 400g Payload 
with 800g Payload 
29min 
18min 
15min 
MikroKopter as Hexa / Hexa2
 with
 6 Motors
 56cm
 NaviGPSMK3Mag
 FlexlanderXL Landing Gear
weight 1000g without Lipo
maximum (arithmetical) Flight times:
Lipo 
max. Flight time 
with 200g payload 
with 500g payload 
with 750g payload 
21min 
18min 
14min 
11min 

28min 
25min 
19min 
16min 
MikroKopter as HexaXL
 with
6 Motors MK3538
 56cm
 NaviGPSMK3Mag
 Hilander26 Landing Gear
weight 1600g without Lipo
maximum (arithmetical) Flight times:
Lipo 
max. Flight time 
with 200g payload 
with 500g payload 
with 750g payload 
with 1000g payload 
with 1250g payload 
with 1500g payload 
28min 
24min 
21min 
18min 
16min 
14min 
13min 
Characteristic curve of the engines here: MK3538
MikroKopter as Okto / Okto2
 with
 8 Motors
 77cm
 NaviGPSMK3Mag
 FlexlanderXL Landing Gear
weight 1260g without Lipo
maximum (arithmetical) Flight times:
Lipo 
max. Flight time 
with 200g payload 
with 500g payload 
with 750g payload 
with 1000g payload 
17min 
16min 
14min 
12min 
9min 

24min 
21min 
18min 
16min 
13min 

35min 
32min 
27min 
24min 
21min 
MikroKopter as Okto XL
 with
8 Motors MK3538
 95cm
 NaviGPSMK3Mag
 Hilander26 Landin gear
weight 1830g without Lipo
maximum (arithmetical) Flight times:
Lipo 
max. Flight time 
with 200g payload 
with 500g payload 
with 750g payload 
with 1000g payload 
with 1500g payload 
24min 
22min 
19min 
17min 
16min 
13min 

35min 
32min 
28min 
26min 
24min 
21min 
Time vs. Lipo 
Time vs. Payload with 6600/4s 
Time vs. Payload with 10.000/4s 
Time vs. Payload with 2 * 6.600/4s 
Weight of 4SLipos
Lipo 
voltage 
capacity 
weight 
14,8V 
2,2Ah 
238g 

14,8V 
3,3Ah 
365g 

14,8V 
5,0Ah 
520g 

14,8V 
6,6Ah 
715g 
Weight of 3SLipos
Be careful, the speed curve must have been taken with 3S (the curve of 282734 does not apply here)
Lipo 
voltage 
capacity 
weight 
11,1V 
1,8Ah 
153g 

11,1V 
2,2Ah 
179g 

11,1V 
3,3Ah 
269g 