Pinions for the HK450 Helicopter

I use the Rhino Gear 3 Pack STEEL Pinions

Pinions play a large role in the HK450, too low a pinion size and the heli doesnt have the head speed and tail wont hold etc, too high and the motor boggs down overheating your equipment efficiency losses etc. 
There are many factors that govern the way the pinion size will react in your heli, and it all has to with what I call the drive chain, and it starts in the following order
1. Battery (Can it deliver what is required)
2. ESC (Can it deliver what is required)
3. Motor (Can it deliver what is required)
4. Pinion (Ratio is it correct)
5. Pitch (Degrees is it correct)
Any one of these factors mentioned above will change the way the head works and the correct pinion will help achieve the best result.
You can calculate it but at the end of the day it’s mainly trial and error, a head with pitch of 11 degrees is going to load the motor down much more than a heli with 9 degrees. 

It also seems to me that the steel pinions run much more quietly than the brass pinions, I havent done any measurements to verify this, but it’s simply what I have noticed.

Based on an 85% efficient Motor here are some numbers, remmebering that wooden blades are only good for 2800rpm and carbon blades at 3000rpm and fibreglass  somewhere in between

3200kv 14T pinion = 2800 rpm
3400kv 13t pinion = 2800 rpm
3600kv 12t pinion = 2700 rpm
3700kv 12t pinion = 2800 rpm
4000kv 11t pinion = 2800 rpm
4200kv 10t pinion = 2650 rpm

3200kv 15t pinion = 3000 rpm
3400kv 14t pinion = 3000 rpm
3600kv 13t pinion = 2950 rpm
3700kv 13t pinion - 3000 rpm
4000kv 12t pinion = 3000 rpm
4200kv 11t pinion = 2900 rpm

Regards

Elias Gourvelos (EatAtJoes)