RE: OS 140 RX...what prop?
I support what others have said:
APC 17x10 or 17x12n 2-blade
APC 16x10 3-blade (repitched)
Bolly 17.5x12 2-blade
I have tried the 15.25x12 4-blade and it was too much load and too slow transition for my taste, the 15x11 4-blade would be a better solution.
I am currently using an APC 17x10 (good acceleration after the upline snap), but also really like the APC 16x10 3-blade for slower downline and horizontal flight.