The LRP sintered rotor is nearly 14mm. However, I'm not sure if you can compare rotor diameter between motors if the, uh, "hole" in the stator where the rotor spins isn't the same between them. I didn't measure between to the two to see if there was a difference. But the smaller air gap is immediately noticeable, because it was easy to install the sintered rotor without it flopping around like it does in Novak's motor.
What's the correct term for the hole where the rotor spins? Also, is that a static size between all motors, or something that can be changed between motors to change their design? I'm guessing part of the rules standard that's being worked on will define these parameters very clearly.