RE: What prop size for .15 Sport UC plnes?
In our c/l club we use the Taipan 8 x 4 white on motors like the MVVS and the STG20/15D in stunters/combat models, and the APC 7x6 in club racers. Both work well with those props.
The white Taipan is available in Australia and may be also available in the US.
The APC 8 x 5 works very well on Oliver Tigers and their clones.
Ray