Small but not micro 1.5cc is .09cubic inch some motors such as PAW are as small as ,033 and .06 cubic inch and yes they will fly
electric conversions usuallly the equiv of a 400 size electrics lots of ARFS out there also-- built up NOT FOAMIES--
.09 and down are considered 1/2 A size engines they have been around at least 50 years cox is most likely the best known
with the advent of electrics lots of modelers are doing this your best bet is check out the 1/2A site
I have a decathalon which was on electric with a norvel 074 in it flys great martin