Originally Posted by
tedsander
Usually bad to severely underprop an engine, so an 18x6 on the FG40 is way, way too small. The DLE would also be a bit under, but with good cooling and no prolonged use of top end probably be useable, although I might not expect maximum life out of it....
Others may have better recommendations that fit your desires.
Which is worse, too big a prop and the engine works too hard or is unable to spin it, or too small a prop and the engine can loaf? I suppose in the end, the FG-30 would be the one to go with, since it is rated to turn a prop the size I'm using.
I had always used an engine bigger than needed in my models, in order to turn a scale diameter prop, since most of my planes were scale models. But, I see your point, don't put a hemi in a Volkswagen.
It may be an academic discussion, hopefully this plane will hang from a ceiling until the glue rots.