Now that I'm advancing a bit with my chopper I'd like to get a bit more into the nitty gritties. I'm running across some terms frequently that I don't really know the meaning of and I'm hoping you can shed some light...

The first one is head speed. The best I can gather is that "head speed" and "rotor RPM" are the same. Just wanna make sure I have this right.

Another is 370 main motor. I know this is referring to the size of the motor and that there are different sizes (like 380 for my Axe), but what's this a measure of and how many different sizes are there?

Lastly (for now), are .60 and .30 helicopter sizes. Is this a ratio of some sort? 60% scale of the real thing? 1/60th of the real thing? Does this refer to both nitro and electric helicopters? What would my Axe be classified as (or is it just a mini)?

That's all I have for now...any help would be great! Thanks in advance.