RE: Engine Selection Help
It looks like a Gee Bee manuf. Tiger Moth...a friend has built several.
It probably had a 4 stroke .40 in it...
My friend has flown his with .25 and .32 O.S. 2 strokes, and .30 to .40 O.S. 4 strokes...
I think the .52 would be a bit heavy for it?