RLau,


The 11x6 prop will load the engine a bit more than your current prop, reducing the RPM somewhat, but speed will be increased slightly in level flight. Prop braking will be reduced slightly and up-lines will be a bit slower.

The 10x6 size will increase RPM to about the same extent as the 11x6 decreased them, but level flight speed will be increased only slightly, because the Spacewalker is a high drag model.

Up-lines will be weaker with this prop; perhaps considerably so, due to a smaller prop disk and an inherently less efficient prop size, with narrower blades and a smaller Reynolds number.

Prop breaking will also be reduced.

I think a 11x5, or an 11.5x5 are the right size props for your model.