ORIGINAL: Trisquire
ORIGINAL: bjr_93tz
What they mean by that is today's 40's can probably spin a bigger prop at lower rpm than what the old 60's could which is great if you want to fly around at 30-40mph, hang on the prop and do 3d stuff, but the 1000ft loop at 70-80mph still needs cubic inches (you need at least a 500ft loop to do a proper cuban 8)....
I think there's more to it than that. I've heard that the physical size of engines changed at some point. The old 60 became the new 40. The new 60 became a larger size altogether.
I'm not so sure about that or it was a really long time ago (back before the 70's).
I'd bet a good .46-.55 sized motor in a lightly built Kaos or something like that today would offer great performance over the older heavier (due to radio equipment and vibration resistance) Kaos' with something like a MAX .60RC, but I doubt any general muffled .46-.55 would hold much of a candle to the piped and pumped .61's in the 8.5-9lb rocket ships that followed.
Now if somebody wants to build a 5.5lb unsheeted wing, taildragger Curare, and fit a .55AX and 12x6 prop I'm sure it'll bounce off the ground like a scalded cat and have unlimited vertical but it's like putting a motorcycle engine in a paper mache Ferrari and boasting about the staggering 0-30mph acceleration time....