ORIGINAL: ragris
I still have not seen (1/2 A) defined, unless I missed it. If anyone knows what it means please add it.
Back in the beginning (no kidding), model airplane motors were classed by sizes and the sizes were A, B, C, D.
Someone then decided that .049 displacement engines would start a class and they happened to be one half the size of class A.
taa daa..... you got
1/2 A.