RE: Prop choices for .020, .049 and .061
My Goldberg Ranger 42 foamy flies very well with full-size gear (RET) and a Norvel .049 with a Cox black 5X3 @ 17,500 on 25%. I also have one in a Astro Flite Mini Challenger 56" sailplane that swings a 8X4 Cox gray @ 7,500 on 15% fuel and 3 head shims. My buddy MikeSell has a clipped-wing Herr Cub with a .061 that flat cooks with a Cox 6X3 & 35% heli fuel.