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Old Jul 06, 2012, 06:26 PM
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United States, VA, Ashburn
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Question
prop switch!

Hey I have a park 450 and I need a prop with good power for 3D but staying within 30 amps. Eflite suggests a 12x6 for a 1020 kv, and my motor is 890 kv. Could I use a 14x6 or a 12x7 or 8 because of the lower kv?
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Old Jul 06, 2012, 07:00 PM
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elfwreck's Avatar
United States, CA, Oakland
Joined Dec 2002
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Hey now,
Short answer. No.
Longer answer. Still mostly no. The lower Kv motor is designed to be a lower amp motor. Even a 12-6 is a bit over the top for it. It really wants nothing bigger than an 11-5 prop. That'll take up about as far as is safe for the motor generally speaking. If you use a 14-?? Prop you'll likely smoke the motor soon enough.
That said if you're really doing 3D with it and not just jamming the sticks around at speed you could get away with a 12-6 for the very short full throttle bursts used in propper 3D flight.
If this so t do it for you get a bigger motor.
RobII
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Old Jul 06, 2012, 07:06 PM
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Quote:
Originally Posted by elfwreck View Post
Hey now,
Short answer. No.
Longer answer. Still mostly no. The lower Kv motor is designed to be a lower amp motor. Even a 12-6 is a bit over the top for it. It really wants nothing bigger than an 11-5 prop. That'll take up about as far as is safe for the motor generally speaking. If you use a 14-?? Prop you'll likely smoke the motor soon enough.
That said if you're really doing 3D with it and not just jamming the sticks around at speed you could get away with a 12-6 for the very short full throttle bursts used in propper 3D flight.
If this so t do it for you get a bigger motor.
RobII
Oh. I was using an 11x 5.5 before so I think a 12x6 would be ok
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Old Jul 06, 2012, 07:27 PM
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United States, AK, Fairbanks
Joined Aug 2009
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The 1020Kv motor is a Park 480, which is bigger and heavier than the 890Kv Park 450. Their prop ranges will be about the same for a given input voltage due to the size difference.
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Old Jul 07, 2012, 02:34 AM
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Aberdeen
Joined Mar 2006
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That's only a 72g motor.. you must be joking talking about a 14" prop on it

The motor is only rated for 18A burst: http://www.channel4models.com/e-flit...tor-890kv.html On 3cells to stay anywhere near 18A you need to limit yourself to an 11" prop; the one you are using must be right on the limit.

Bottom line is you should be able to tell from the amp draw how close to the limit the motor is. You are the best one placed to tell that because you have the motor If you are already at or over 18A then you don't have any headroom for a larger prop.

The 12x6 prop listed for this motor will most likely be for two cell operation. On two cells you could probably push to 13x6.5 prop


BTW.. where did you get the 30A figure from

Steve
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Old Jul 07, 2012, 08:46 AM
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My Esc rating.
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Old Jul 07, 2012, 10:37 AM
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Quote:
Originally Posted by RCAddict16 View Post
My Esc rating.
That wont help with a motor that's only safe for 18A burst. What amps is it pulling with the 11x5.5 prop?
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Old Jul 07, 2012, 10:40 AM
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RC,

Have you ever used this program to determine prop size given battery, esc and motor specs? Not as good as a wattmeter but it is surprisingly accurate.

http://www.adamone.rchomepage.com/calc_motor.htm

Check it out and play around with it...you won't have some of the specs but you should be able to come up with cell capacity, number of cells in series, max esc amps, Kv, max motor current, motor weight and prop specs. It gives you a lot of information on motor amps versus prop specs.

Regards,

Hankg
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