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Calculating Run Time

Old 04-04-2007, 06:04 AM
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waross
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Default Calculating Run Time

I am new to the electric side of the hobby but wanted a small fun electric to fly in limited area and make it quick outing unlike taking my glows out. So I got a Hanger 9 Mini Ultra Stick with the following power components. I am trying to figure out how much run time I can get out the bird before I lose it. Any help would be greatly appreciated.

E-Flite Park 400 Outrunner 920Kv

ElectriFly 1250 mAhr 11.1 V LiPo 3 Cell

E-Flite 20-Amp Brushless ESC (V2)
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Old 04-04-2007, 07:09 AM
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bp2005
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Default RE: Calculating Run Time

Waross: You have to know the amp drain on the battery. Here's a link to a flight time computer.
http://www.bphobbies.com/view.asp?id=A0320048&Nav=7
Bob
Old 04-04-2007, 11:46 PM
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jdetray
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Default RE: Calculating Run Time

If you would like to calculate it yourself, the formula is:



Current consumption and battery capacity must use the same units of current. It battery capacity is expressed in mAh, then current consumption must be expressed in mA.

Example:
battery capacity is 2000 mAh
power system draws 25A = 25,000mA

2000/25000 x 60 = 4.8 minutes

- Jeff
Old 04-05-2007, 08:31 AM
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orenda635
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Default RE: Calculating Run Time

Here's yet another online calculator
http://www.missionwings.com/flighttime.asp

Keep in mind though that milliamp ratings listed on the packs themselves are theoretical maximums. I'd be more inclined to say actual flight time is probably 80% of what the calculator gives.
Old 04-05-2007, 09:49 AM
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jdetray
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Default RE: Calculating Run Time

Yes, the calculators and formula provide rough estimates only. They don't account for efficiency, optimistically rated batteries, your LVC setting, etc.

- Jeff
Old 04-05-2007, 10:47 PM
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waross
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Default RE: Calculating Run Time

So how do I figure out power drain of the motor...???
Old 04-05-2007, 11:44 PM
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jdetray
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Default RE: Calculating Run Time

ORIGINAL: waross

So how do I figure out power drain of the motor...???
You don't figure it out. You measure it with a wattmeter. A wattmeter is an essential tool if you are serious about e-flight. Without a wattmeter, you are merely guessing about how your power system is performing.

That said, someone here may be familiar enough with your set-up to estimate the current consumption.

- Jeff

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