Inrunner

The term inrunner refers to an electric motor where the rotor (runner) is inside the stator.

The term is in particular used for brushless motors to differentiate them from outrunners that have their rotor outside the stator.

As a result, most inrunners are used in conjunction with a gearbox in both surface and aircraft models to reduce speed and increase torque In many cases the inrunner is "ironless" in that there is no iron stator core to magnetize.

The wire is run inside the can and held in place by epoxy or other resin material.

Modern brushless inrunners can have iron core windings to address the lack of torque while maintaining high r/min capability, more commonly used in radio-controlled car and truck applications