KidNovak

DD was installed on my Jabo II. If you haven’t seen my Heli, Here it is…
http://www.rcuniverse.com/forum/My_J...2673163/tm.htm

I finally burned out the stock gear driven motor so now is the time I had to experiment with DD…
I cut 1 inch off the boom for COG and to decrease thrust, reversed polarity on the CN12-RXC Motor (I wanted the air to blow over the motor and heat sink) and since the Jabo 4in1 board has no adjustments I had to use a 3030 prop, the 4530 had too much push, I could not get it trimmed. I will probably need the 4530 when I install the GWS EDP-300H Motor.
With the above setup the rudder trim on the transmitter is centered when hovering.

The response of the DD is quick compared to the stock gear setup. I could hammer the throttle and the tail barely moves. If I did that with the stock setup the tail would have moved 90 degrees.

With the DD mod I still get 15 to 20 minute flight times. It did not decrease much.
Also the CN12-RXC Motor only gets slightly warm.

I’m impressed with this mod.
I hope everything goes as good as when I add the GWS EDP-300H Motor and wood main blades.

Question:
By reversing the polarity on the CN12-RXC motor, will this shorten the life of the motor?

Novak

fireplug1111

My Feedback: (21)

kIDNOVAK:

A D/C motor will not be harmed by the polarity. It will run backwards the motor does not know the differance. D/C motors are dumb they dont know which way to run. A/C motors (some) will not run backwards. and some will. But they are made to do so. A D/C motor will run both ways. Some people will say it will not work, it will shorten the life, yada yada yada.... Negitive Positive poles. spin spin spin. That all it know. Hope this helps.

UKgroucho

The only 'issue' is that brushed DC motors will be set up ('timed') to run in one direction. Switching the polarity reduces efficiency a little.

You can retime brushed motors with round cans - a good article on the Like90 web site discusses this http://www.like90.com/index.asp?PageAction=CUSTOM&ID=2
I think this applies to the CN12 also .. although if you've got plenty of power (and it sounds like you have) AND the motor is not getting too hot then I'd leave it alone - if it ain't broke don't fix it.

KidNovak

Yes, the motor has plenty of power and runs only slightly warm.
I even took off the heat sink for a better CG balance. Motor
still only runs warm.

Thanks for the replies.
Novak

gargoyle7

Looking good KidNovak! I have a JaboII I may try this with, where did you get the 3030 white prop? Thanks

Lee

KidNovak

@gargoyle7
O.K forget about the 3020, 3030 props. These props could not keep up when battery started
getting low. After I did more testing I found out that the best prop for the DD CN12-RXC motor
is a 4530 with 9/16" cut off each end.

Since my battery is as far foward as I can get it without modifying the canopy, I removed the
heat sink from the tail motor for a better CG balance. The motor only gets slightly warm without it.

I purchased the 4530 with adapter from Like90.com

Novak

jolllyroger

they have brushless tail motors on like 90 web site if you really want tail response