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Other › What's the KV all about?
01-22-2007 11:13 PM  10 years agoPost 1
Tommy Z

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Lubbock, Texas

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What is the difference between the Z30-800 and the Z30-1100?

Are different types of batteries required?
How does all that work?

Tommy

-Tommy Boy

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01-22-2007 11:20 PM  10 years agoPost 2
z11355

rrMaster

New England

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KV = # of motor RPM per volt applied.

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01-23-2007 12:16 AM  10 years agoPost 3
Ben-T-Spindle

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Central Illinois

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How does all that work?

There are three motor constants that you need in order to see how a motor will run. Kv is RPM per volt. Io is the no load motor current. Rm is the resistance of the windings while the motor is running.

The RPM that a motor will turn under load is Kv * (V – (Rm * I)).

The power output of a motor in watts is (I – Io) * (V – (Rm * I)).

The higher the Kv the lower the input voltage with the same gearing.

The higher the Kv the higher the required gear ratio for a given voltage.

You have to know the available gear ratios and the battery voltage in order to select the correct motor.

.

... BTS

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01-23-2007 02:44 AM  10 years agoPost 4
Tommy Z

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Lubbock, Texas

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Oh

So if the pinion is bigger, does that mean the Kv is lower?

Am I on the right track?
Thanks guys

Tommy

-Tommy Boy

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01-23-2007 11:10 AM  10 years agoPost 5
Ben-T-Spindle

rrProfessor

Central Illinois

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So if the pinion is bigger, does that mean the Kv is lower?
NO

... BTS

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01-23-2007 02:05 PM  10 years agoPost 6
Ben-T-Spindle

rrProfessor

Central Illinois

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The motor constants are independent of everything external to the motor and can’t change them. You would have to rewind the motor or change the magnets to change any of the motor constants. That’s why they are called motor constants .

Hope this helps,

... BTS

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01-23-2007 06:19 PM  10 years agoPost 7
Heligio

rrApprentice

Belgium

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Hi Ben,

So if you should take a Neu motor for 10s in a Raptor 620E, you can choose between the 1912 1Y with 825Kv or the 1912 1.5Y with 532Kv,
wich one should work best?
The 1Y with a 9T pinion or the 1.5Y with a 14T pinion?
Does'nt a motor with lower Kv have more torque?
The only thing is that if you use the 1Y with 9T pinion you have 2300 headspeed and if you want to fly lower headspeed you cant get a smaller pinion.
On the otherhand, will the 1,5Y with such a big 14T pinion be efficient?
Will it be able to run such a gear ratio?
Maybe it should be better if Neu fabricates a motor that is in between the 1 and 1,5Y with a Kv around 700 just like the 1915 1Y they have? Is that motor any good to use with the 620E?
Sorry, but i don't know much about the electric motor things.

Thanks allready,
Gio.

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01-23-2007 10:10 PM  10 years agoPost 8
Ben-T-Spindle

rrProfessor

Central Illinois

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You don’t learn unless you ask questions.

Every motor has a RPM range that it runs at maximum power and efficiency. For Neu Motors 1912 series it’s in the 20,000 to 28,000 range. Many refer to this as the “Sweet Spot”. That puts the 1912/1Y in the right range and the 1912/1.5Y a bit on the slow side. The 1912/1Y is perfect for a 10s setup and the 1912/1Y is perfect for a 12s setup.

The Z30A and Z50A motors seam to work well in the same RPM range.

As a general rule select a motor that’s runs at the low end of it’s Sweet Spot for max flight time and the high end for max power. Most of the time you are a bit restricted by the available gear ratios.

.

... BTS

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01-23-2007 11:05 PM  10 years agoPost 9
Tommy Z

rrKey Veteran

Lubbock, Texas

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Oh

That makes sense.

Tommy

-Tommy Boy

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