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Century Radikal E640 - Swift 16 NX
› what pinion for brushless HP CP
04-29-2004 01:29 AM  13 years agoPost 1
flmgrip

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irvine, CA, United States

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hey all. what pinion would be a good start for the himax 2015-4100 and the HB CP ?

thanks

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04-29-2004 08:22 AM  13 years agoPost 2
wedge

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Victoria BC, Canada

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Depends on what headspeed you want to end up at.

Will

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04-29-2004 05:26 PM  13 years agoPost 3
flmgrip

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irvine, CA, United States

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probably between 1800 and 2000. can you give me a pointer how to do the math on that one ? i know it has to do with the voltage and all that. i will be using a 3 cell li-poly...

thanks

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04-29-2004 05:38 PM  13 years agoPost 4
Hoverup

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Golden Gulf Coast - USA

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http://dev.asdf.co.nz/RPM/

and BTW the CP H'Bird has a 140t main gear

Cheers - Boyd
AMA 80393
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Retired

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04-29-2004 11:45 PM  13 years agoPost 5
flmgrip

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irvine, CA, United States

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great... thank you

so it seems like a 8T pinion will give me max headspeed of 2600... seems the way to go...

thanks again...

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04-29-2004 11:54 PM  13 years agoPost 6
PsychoZ

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Northern, CA

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what 8T gear do you use, where do I get one

Tea Parties are for little girls with imaginary friends

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04-30-2004 03:46 AM  13 years agoPost 7
wedge

rrElite Veteran

Victoria BC, Canada

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Here is a write up I got From Walt it works very well and comes out extremely close to where you want it.

Motor KV x voltage = max RPM
RPM / head speed = motor speed for 1 blade revolution
Main gear teeth / motor speed for 1 blade revolution = pinion size

Reverse calculation
Main gear teeth / pinion teeth = gear ratio
Motor RPM / gear ratio = max rotor rpm2332.75


4300 (motor KV) x 10.5 (loaded battery voltage) = 45150 (100% rpm)
45150 x .93 = 41989.5 (93% rpm)
41989.5 / 2300 ( max head speed for acro) = 18.26 = (motor RPM per 1 blade revolution)
180 (main gear teeth) / 18.26 = 9.86 (# of pinion teeth)

Things you must consider:
(1) The battery voltage is not going to be at 12.6 volts under load, the loaded voltage is what the motor “sees”
(2) Allow for a little head room (93%) in the motor RPM because not all motors meet the “spec” plus during cyclic
inputs there is more load that can momentarily droop the battery voltage. I mix “ail” to “thr” and “elev” to “thr”
to allow for this but you must have some head room or the rpm will be topped out and drop.

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04-30-2004 07:54 AM  13 years agoPost 8
flmgrip

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irvine, CA, United States

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thanks that helps, but since the main teeth are only 140, the 8 pinion looks like a winner...

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04-30-2004 08:19 AM  13 years agoPost 9
wedge

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Victoria BC, Canada

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ya that formula I used for my Hornet 2 just substatute you own info in there.

Will

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Century Radikal E640 - Swift 16 NX
› what pinion for brushless HP CP
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