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Old 03-03-2012, 06:55 PM   #1
markosgt
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Default motor Kv...

Which one is better for scale flying for trex 500 1600Kv with 12T pinion or
1200Kv with 13-14T pinion and why?
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Old 03-04-2012, 12:51 AM   #2
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Quote:
Originally Posted by markosgt View Post
Which one is better for scale flying for trex 500 1600Kv with 12T pinion or
1200Kv with 13-14T pinion and why?
For multiblade setup the 1210kv or under, 1600kv is okay for two blade setup, the power/torque requirements for a multi-blade setup will burn the 1600kv in no time..

1210kv or 1200kv with 13T will be able to run at 85% to 90% throttle curve...
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Old 03-05-2012, 04:08 AM   #3
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In general I would say the a slower motor with larger pinion is better than a fast motor and small pinion.

Generally a slower motor is probably better as is is thought to be slightly more efficient and has more torque.

A larger pinion will have slightly more tooth contact area and be less likely to strip the main gear.

Colin
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Old 03-05-2012, 10:06 AM   #4
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I finally bought a scorpion 1400kv and i would like to ask what pinion is better 12T 13T or 14T?
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Old 03-06-2012, 03:58 AM   #5
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I finally bought a scorpion 1400kv and i would like to ask what pinion is better 12T 13T or 14T?
Are you using 6s ?

What headspeed are you looking for ? Flying style ?

Are you planning to use a good governor ?

Try this simple calc (assumes 6s, 13T pinion and 162T main gear);

1400kV x 22.2V x 0.9 (Efficiency) x 13T / 162T = 2245rpm @ 100% throttle. If you govern you will reduce this to about 90%, so 2020rpm.

I would suggest perhaps a 14T, which should enable you to run 2420rpm at 100%, or govern at between 2060rpm (85%) and 2300rpm (95%).

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Old 03-07-2012, 04:00 AM   #6
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Originally Posted by Andy01 View Post
Are you using 6s ?

What headspeed are you looking for ? Flying style ?

Are you planning to use a good governor ?

Try this simple calc (assumes 6s, 13T pinion and 162T main gear);

1400kV x 22.2V x 0.9 (Efficiency) x 13T / 162T = 2245rpm @ 100% throttle. If you govern you will reduce this to about 90%, so 2020rpm.

I would suggest perhaps a 14T, which should enable you to run 2420rpm at 100%, or govern at between 2060rpm (85%) and 2300rpm (95%).

Colin
Thank you Andy you have explained very well. I will use a 14T pinion to have around 2000-2200 rpm. Thank you very much.
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Old 03-07-2012, 11:36 AM   #7
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Well now i did some test flights and i have another problem.

I have the scorpion 1400Kv with a 14T pinion, governor at 2200 rpm
i hover for 5min and the motor comes down very hot to even touch.

Is this normal?
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Old 03-08-2012, 03:43 AM   #8
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A bit more info please ?

How hot is hot ? If you don't have a temp gun, then how long can you hold your finger on it ? I find that somewhere around 60°C (140°F) is uncomfortable to touch for longer than a few seconds. Somewhere around this temp seems to be OK for most motors.

What is the motor timing etc set to ?

What ESC ?

Is the fuselage fully enclosed (ie. all windows closed in) ?

What is the ambient temps ?

Is it only the motor that gets hot ? How are the lipo and ESC temps ?

Was it hot after one flight or did you fly back to back flights ?

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Old 03-08-2012, 05:20 AM   #9
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Quote:
Originally Posted by Andy01 View Post
A bit more info please ?

How hot is hot ? If you don't have a temp gun, then how long can you hold your finger on it ? I find that somewhere around 60°C (140°F) is uncomfortable to touch for longer than a few seconds. Somewhere around this temp seems to be OK for most motors.

What is the motor timing etc set to ?

What ESC ?

Is the fuselage fully enclosed (ie. all windows closed in) ?

What is the ambient temps ?

Is it only the motor that gets hot ? How are the lipo and ESC temps ?

Was it hot after one flight or did you fly back to back flights ?

Colin
I can hold my finger on the motor for 5 seconds.

My ESC is castle ice 75A and the timing is set to 3 but the ESC comes down warm, not hot at all. The lipo i used is warm too not a problem there.
The fuselage is not fully enclosed i kept the windows open. Ambient temperature is around 14-15 celcius degrees. Test flight was just 2 batteries hovering for about 5 minutes in my back yard. RPM is 2200 governed set, cc shows around 90%. Governor gain at 20.
(I dont know what is back to back flights)

The thing is that when i had the 1600kv scorpion with 12T pinion it was coming down like it never worked, and with this one i see much difference in temperature, but all around the heli i think flies better with this motor, or maybe its just my impression.
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Old 03-09-2012, 04:06 AM   #10
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Have you got your ESC set to Outrunner or 8kHz ? Outrunner can run hot.

I use governor gain at about 5-10. Try reduce the timing to low - you don't need lots of power and fast response for scale.

Try throttle response, governor gain, timing to low.

Back to back is simply fly, land, change lipo and fly right away without a break to allow things to cool.

Colin
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Old 03-09-2012, 08:10 AM   #11
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Quote:
Originally Posted by Andy01 View Post
Have you got your ESC set to Outrunner or 8kHz ? Outrunner can run hot.

I use governor gain at about 5-10. Try reduce the timing to low - you don't need lots of power and fast response for scale.

Try throttle response, governor gain, timing to low.

Back to back is simply fly, land, change lipo and fly right away without a break to allow things to cool.

Colin

yes i have 8khz. i will try everything you said and tell you if there is any difference.

thanks Andy
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Old 03-11-2012, 03:42 PM   #12
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Well same heat again. Should i try a 15T pinion? maybe with a larger pinion the motor will
"work" less for same rpm?
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Old 03-11-2012, 07:04 PM   #13
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No with a larger pinion the motor will work harder NOT easier.

When it comes to gearing small to big gearing = power and larger to small gearing = speed and less power. So a larger pinion will give you les torque and more speed along with more heat.

If you want the motor to run easier and produce less heat try running a smaller pinion like a 10-11t .

A 1400Kv motor is still a little high for scale use , something closer to 1000Kv would be the best bet for scale headspeed and flying as we don't usually run much over 10* + pitch , where as 3D guys can runup to 14-16* + pitch.
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Old 03-12-2012, 07:23 AM   #14
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No with a larger pinion the motor will work harder NOT easier.

When it comes to gearing small to big gearing = power and larger to small gearing = speed and less power. So a larger pinion will give you les torque and more speed along with more heat.

If you want the motor to run easier and produce less heat try running a smaller pinion like a 10-11t .

A 1400Kv motor is still a little high for scale use , something closer to 1000Kv would be the best bet for scale headspeed and flying as we don't usually run much over 10* + pitch , where as 3D guys can runup to 14-16* + pitch.

If i put smaller pinion i must give lower rpm to the motor with lower rpm i get a tail
left-right wobble and i dont know if its from low headspeed or from the beastx setup.

helis are hard....
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Old 03-15-2012, 07:32 PM   #15
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Quote:
Originally Posted by markosgt View Post
If i put smaller pinion i must give lower rpm to the motor with lower rpm i get a tail
left-right wobble and i dont know if its from low headspeed or from the beastx setup.

helis are hard....
I'm just guessing but would increasing the tail blade size help to compensate for the slower tail rpm's ?
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Old 03-16-2012, 08:45 AM   #16
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Quote:
Originally Posted by markosgt View Post
Well now i did some test flights and i have another problem.

I have the scorpion 1400Kv with a 14T pinion, governor at 2200 rpm
i hover for 5min and the motor comes down very hot to even touch.

Is this normal?
The scorpion 1400kv motor is notorious for running hot, had 1 in my gaui 425 ,great motor,but they do run hot.That motor was more designed for stunt/performance 3d, not low speed torque for a big scale bird. When I started my scale build I swapped out for a scorpion 1210.

Try all the advice from the guys on this forum first, all excellent advice, Also running inside a fuse doesn't allow it much cooling at all. You could add a fan,I forget who makes 1 for cooling esc, Something similar to a power supply fan.
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