OK, just to try to stir something up, and maybe for a little personal edification:

We've all seen various estimates of the actual advance a prop makes relative to its geometric pitch. Something like 85% is the most common estimate I've seen. We have also read that a flat bottom airfoil delivers lift even at a 0 degree angle of attack (actually down to some small negative angle, if I'm reading the charts right).

SO, if we bolted an 8x0 Master Airscrew on our OS .15 FP, what would the advance ratio be? If it's making lift it will move the thing forward, won't it? What's 85% of 0? Does that nominal 85% figure change with different pitches?

Just wonedrin'