Quadcopter gears?

[CrazyFastFlying]

Hi,

I just have a quick question about the gears on some of the quadcopters I've seen.

So my question is, why is the small gear on a motor and the big gear on the propeller shaft? I would think that if the company that make the quadcopter switches the gears around, the propeller would spin at a faster RPM with less throttle, and with less throttle you would get longer flight times.

Thanks,
-Jeremy

 

[Paracodespoder]

I don’t know for sure (I’ve wondered about it myself), but I think it’s to make it so it doesn’t overload the motor. A larger gear on the motor would make it have to work harder and in the end be even less efficient. That’s my opinion, but if anyone knows something about it I don’t please correct me.

 

[CarolineTyler]

Larger propellers spinning slower are more efficient than smaller ones spinning fast. For a longer flight its all about efficiencies.

 

[CrazyFastFlying]

Ok, that makes sense! Thanks for the help!

 

[CarolineTyler]

Ok, that makes sense! Thanks for the help!

The other thing is that this allows them to use cheap brushed motors which don't have the torque of a brushless motor to swing a big propeller

 

[PsyBorg]

5th grade math. Gear ratios and torque

 

[sprzout]

In addition, you can get a much smaller motor to do the work. Smaller motor = less weight, which means a possible higher efficiency as well.

 

[Fluburtur]

Those tiny coreless motors only spin at high speed, this is fine when you have a tiny prop on them but with larger quads like the Syma x5 you need to gear them down, because the motors can't spin slow enough and with enough torque to spin the props.

 

[CrazyFastFlying]

Thanks for all the replies!

For like 2 years, it's puzzled me why the gears are like that.