rh8807

Im sure this is discussed somewhere, but I cant find it at the moment.

Is it lower number pinion = higher RPM? or Lower Number pinion = Lower RPM?

a friend of mine put a humingbird 370 motor in my honeybee cp2, cause my stock motor sounded funny.LOL

Anyway, it flies great, but I was just curious...My stock Esky motor had a 9T Pinion on it, the hummingbird motor is a 10T, so is it more or less RPM with the 10T.

Another question I dont really need an answer for, pure curiosity on this one,
But does the T stand for Teeth or Turns? And if its turns what does that mean.

Example, if a pinion is a 9T or 9 turn does it mean the motor has to make 9 revolutions to equal 1 turn on the main gear? Its seems like logic, but in reality its probably something more simple then that.

And how do you find the rotor rpm using the motor rpm and the pinion size? is there a mathmatical formula for that?

Its raining outside so im trying to fill my head with knowledge I will probably never use, but you never know, so come on techies, someone enlighten me? LOL

Thanks All

Dr Kiwi

Lower pinion size, (given a fixed main gear size), the fewer rpm for the propeller/rotor.

Say you have a 9T (9 tooth) pinion and a 90T main gear, the rotor will spin 1 revolution for every 10 revolutions of the motor: 30,000rpm motor speed will give you 3000rpm head speed.

If you have a 10T pinion, the rotor will spin once for every 9 revolutions of the motor - 30,000rpm motor speed will give you 3333rpm head speed - thus the larger the pinion size, the "higher" the gearing, and thus the higher the rotor speed.

rh8807

Hey thanks. I actually get that! LOL I even understand how you determined that.

Main gear/pinion size =x

Motor rpm/x = Head RPM

Wow, I learned something.

The only problem with that is, at my age, when I learn something new I forget something else. LOL

Rick