Folding props are increasingly used on self-launch gliders in order to reduce drag. Here is an example of 1m dia. props from LZ Design's FES system:
For self-launch gliders, due to minimally-sized power plants the props are optimized for the safety-critical climb phase, leaving cruise performance as an afterthought.
At full-scale power levels, i.e. 10-30kW, how are design considerations different for folding props vs. standard fixed-root props?
In specific, could an existing folding propeller be retrofit by simply having a root which pivots, or would the already-structurally optimized root of a folding propeller make this unworkable?
[*] Examples at What are the advantages/disadvantages of a forward-folding propeller?