There a few ways to calculate . If you are an electrical engineer I could list all the formulas to use and explain them but this is overkill and way over the heads of most flyers .
The method listed above is a used by many and gives you a good baseline . Just don't run you packs to ESC low voltage cut-off to determine your max flight as this can harm the packs ,
The simplest way to get a basic idea on time is to use a simple formula. First you will need to know the amp draw from your system at full throttle. The easiest way to measure this is to buy an rc "Watt Meter" and plug it in-between the esc and the battery pack. It will show the amp reading at full throttle as well as voltage and power readings. Another way to measure is to connect a multimeter set on amp setting between the battery and the esc. Make sure you have the plane secured properly when taking full throttle amp readings.
Once you determine this reading you use it in this simple formula.
1)Look at you battery pack and write down the milli-amp hour rating and convert it to amp hours.
2) Multiply that ah number by 60
3) Take this number and divide by your amp draw.
4) This number will be an estimate of your total flight time .
Remember this is only an estimate as other factors weigh in such as plane weight, battery health, wind, etc...
For example :
If you are using a 2200mah pack and your system is drawing 17 amps
A 2200 mah pack would be equal to 2.2ah
2.2ah X 60 = 132
132 divided by 17 equals 7.76
Approx. 7 1/2 minutes of flight time
Last edited by flyinwalenda; 01-06-2014 at 05:12 PM.