Inrunner vs Out Runner?

[gullie667]

What is the difference, design wise, between an inrunner and an outrunner motor?

[Buz Killington]

in a outrunner the outside of the motor turns an in runner is as the name applys.

i believe the advantage to outrunner is they seem to run cooler.

Buz

[JasonJ]

Also, I seem to remember it being said that an outrunner has more torque for it's size...

[davidnyuspri]

outrunner is better as it is cooler when you fly

[Mercuriell]

Its to do with which bit of the motor outputs movement - in an inrunner the coils (the rotor) are on the outside and the armature with the magnets (the stator) runs inside the windings. On an outrunner the windings are on the inside and the magnets are arranged outside the windings so power is transmitted via the case whizzing round or it can be enclosed. Inrunners are better for torque and outrunners supposedly run cooler. Check out http://en.wikipedia.org/wiki/Brushless_DC_motor

[Pinecone]

Backwards. Outrunners have more torque (larger diameter working arm) and inrunners are better for high speeds. Thats why in planks you see outrunners turning props directly (torque) and inrunners used eithe rwith very small direct drive props or in gearboxes (higher RPM, less torque)

Outrunners tend to be more open for cooling, but the coils are what get hot, and they are inside the outrunner, versus being in contact with the case for inrunners.