Hi Phillybaby,
Prop tip plates:
20 years or so ago a propeller manufacturer reported experience
with so called tip plates. Not just a flat plate attached to tip but
more like if you took a section of the blade near the tip and bent
it around a radius upward. You want a 12" diamiter, take a 14" prop and bend 1" of each tip upwards.
Report suggested improvements but time erases details for me.
Anyhow at the time I felt the idea worth a try. I had a Quadra powered 1/3 scale RV-4 which flew well with a 20 x 6 prop.
I cut a 20" prop to 18" and installed 1/2" duplicates of what the
full scale used, now diameter was 19".
Comparative test: Was aware of normal take off distance. Rv
would complete 1 vertical roll , then stall out. This was with stock
propeller.
Tipped prop: RPM increased 700. Take off was some shorter
level flight speed was about the same but seemed brisker.
RV would now do two vertical rolls and continue a bit before
stalling out
T believe I performed a comparative thrust test and saw more
thrust with tipped prop, don't recall details.
Bottom line: tipped prop diffinitely was improvement, thinking now winglets could do even more.
Short coming: prop was wooden as was tip. Taxing in tall grass
prop clipped a tough weed, exit one tip plate!
Current thought: with the plastic props the strength problem
probably could be easily solved.
OK? Good luck!

Hal debolt