Regardless of the title below my avatar, I am completely new and know nothing. I just post a lot of stuff as I'm learning this awesome hobby. What do you mean by "radial motor?" If you mean that the outside spins around the inside, that's because it's a brushless motor and they are more efficient. No brushes to wear out, there are lots of little magnets that make it work. Pretty ingenious, really. They seem to weigh a lot less, too.
I recently received my first brushless motor in the mail, and when I give it a spin with my fingers, it just stopped. All those magnets. For me it was really weird. I was so used to spinning a brushed motor to see how good the bearings were. These things are a completely different animal. Steve Austin would be proud.
If that's not what you mean by your question, then please clarify.