


ITALY
Joined Sep 2004
943 Posts

Discussion
flight time and power
Hello,i have buid a new small airplane(aerosoarer design) around a 20mah lipo and 4mm motor with gearbox.The model fly very well for 12 minutes.I use a 60mm prop with 4:5:1 gear ratio.How i can calculate the Ampere that take my motor setup?Thanks
I thing around 90ma it is right? Can i use a 10mah lipo? 




20ma.h is your battery capacity. Covert that over to milliamps per minute and divide it by the flight time.
(20ma.h)*(60min/h) = 1200 ma.min Since lipos don't get fully discharged, and say 80% of total capacity was used, this decreases the usable size of the battery to: 1200 ma.min*0.8 = 960 a.min The flight time was 12 minutes so: (960 a.min)/12min = 80 ma And that's the average current consumption of your motor. An equation to find the current consumption of any motor based on battery capacity and flight time would be: Note: 60*0.8 = 48 (C*48)/T = A Where: C = Battery capacity in ma.h T = Flight time in minutes A = Motor current in milliamps Google search works as a good calculator. Stick in the Equation defining A and substitute the variables in the search menu and it will give you the result. 



i always use the mah as equal to 60 minutes, then divide by your flight time. multiply the mah by the result of your first number. 60/12=5 so you used your battery at 5C or 100ma current draw. however, your cell likely had some mah remaining when your LVC kicked in so its likely a small % less than 100 ma.

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