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04-27-2009 02:32 AM  10 years ago
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nrad2000

rrVeteran

USA

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motor RPM
How fast in RPM do the E-motors spin at at full throttle? for 30 size heli's.

example: 1100kv motor with 6s lipo

800kv motor with 8s lipo

I was more interested in the RPM differance in electric motor and the nitro.
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04-27-2009 07:51 AM  10 years ago
DKNguyen

rrApprentice

N/A

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If the motor was sized and geared properly, it's supposed to be running at around 70%-80%-90% of no-load speed.

no-load RPM = Voltage * kV
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04-27-2009 11:56 AM  10 years ago
stanc

rrKey Veteran

Conroe, TX

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motor kV x pack voltage = motor rpm

6S - 6 x 3.7 = 22.2 pack voltage
8S - 8 x 3.7 = 29.6 pack voltage

1100kV x 22.2v = 24,420 rpm
800kV x 29.6 = 23,680 rpm

Gearing a heli is important for several reasons.

Take a glow engine with a max RPM of 19,000 rpm and put it in a 50 size heli that is geared at 8.5:1, so at 100% throttle you would have a HS of 2235 rpm, less what the positive pitch on the blades takes away.

Here is a simple but accurate Head Speed calculator to help figure out what your electric heli needs as far as cell count, motor kV and gear ratio.

The basic formula is: (kV x voltage) / gear ratio
There are some other factors that need to be thrown in the equation to get a more precise number.
Stan
2- Logo 500
Ion X2
eAvro90
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04-27-2009 03:11 PM  10 years ago
nrad2000

rrVeteran

USA

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thank you. i'm learning I maybe needing a powerful motor, strong battery, and a larger pinion gear.
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