Gearing ??

[KevinM]

2 part post:::::

1) I have a question, how do you know what tooth pinion to go with?? Lets use ficticious numbers as example.  When the math is done.....
 
14t=2900 HS (ungoverned)
12t=2500 HS (ungoverned)
 
....and my target idle 2 head speed is 2000 governed.  What pinion would you go with? ..and why?

2) I started out as an E7... and its GREAT on brandnew 5000mah packs but, I'm pretty aggressive with the collective meaning I'm not allowing the heli much of a break whether doing fast full collective hurricanes or fast inverted backward loops with some smack in between, and the ESC and Motor we're pretty darn hot! The motor after 1-2 min of cooling was at around 200 degrees and the ESC was around 130-140 degrees.  The ESC is a 120HV CC and the Motor (for now) is an Align 700m.  Ideas??  I was thinking with this setup maybe I should back it down to an E6 and when money permits get into a castle 160HV and scorp/KDE motor??

Thanks in advance
KevinM

[Darren Lee]

Kevin,

The easy answer is to use this calculator and select "find my pinion instead" to input your desired headspeed:

http://www.readyheli.com/headspeed-calculator.html

I'm not sure what voltage you used in the example numbers, but I generally use 3.7v/cell, which is a reasonable average under load in flight.

44.4v x 510kv x 14T / 116T = 2733
44.4v x 510kv x 12T / 116T = 2342

The lowest pinion available that will get you the target headspeed while maintaining adequate headroom is the way to go.  Everything will run cooler and you will get longer flights.

2000/2733 = 73% (27% headroom)
2000/2342 = 85% (15% headroom)

In my experience, 10-15% headroom using 3.7v/cell is a good target range.  I'd go with the 12T pinion.

2000rpm is fairly tame headspeed for the E7 and you should have no issue whatsoever with the 120HV and Align motor.

[KevinM]

Very cool Calc!!! thank you!

Whats the danger range for temps on ESC's and motors?

[RichL]

Castle ESC max is around 180F, Scorpion motor max around 200F. 


Rich

[flyalan]

IIf you have an iPhone there is a Mr Mel app for headspeed. I believe there is also one for the Android folks.

Cheers
Alan


Sent from my iPhone using Tapatalk

[GAR]

I'm not up to speed on Align motors.

The old 700"M" is a lot different then the 700"MX". The MX is not a bad motor, it runs a lot cooler with more power. With the NEWER 700MX pick your KV, a 510KV or 530KV.

I'm guessing you will be happy with a 510KV hooked to your CC120HV. 

[KevinM]

Thanks guys, I think I just need to bone up and get a better motor and a 160 esc.  I want to run 2150 in idle2 so I think a 13t pinion would be best for efficiency. 

[KevinM]

Dropped head speed and had a big reduction in temps on both esc and motor.  After doing some reading I'll be using 120HV afterall, but my oldy align 700m surely doesnt pack any punch! 13T pinion should be here today!! ...and thank you Amy and Matt for upgrading to the Hardened pinion because the other was out of stock, very generious!  Also boned up and bought Thunder Power 65c packs (sorry darren lol), it hurt a little, but I think it will pay off!