Originally Posted by HeliG
Unfortunately, there isn't really accurate info that comes with numbers. Originally, the numbers related to engine size but with the electric helis moving in, those numbers have gone away. A 450 doesn't really tell you much except that it is smaller than a 600.
I originally thought it pertained to rotor diameter, but the "450 size" rig I have has a main rotor diameter of 508mm, so by my original reasoning, would put it in the "500 size". A TREX 600 has a diameter of something in the area of 1400 or so mm, give-take, so maybe they should just do the "small-medium-large" format for them...kinda like a ordering a pizza...