This is the thrust results of the first Spherical Folding Propeller prototype:

The results are not so bad considering the size of the propeller (1.6cm diameter when folded) and that no air-flow simulations were done during design. I'm going to conduct simulations for the next prototype, to try and make the propeller as efficient as possible.

This is the setup used to measure the thrust. The propeller was suspended around 15cm above the scale, to eliminate ground effect.