fredoyster
Well-Known Member
Any suggestions for design approaches for a very low noise, low speed propeller? The basic goal: light two-seater, nearly inaudible in overflight at 1000 ft. The YO-3A is the inspiration, it used several versions of a ~100" prop turning ~840 rpm for a maximum tip speed around 340 fps. The plane I'm thinking about would be about half the weight and power, so I'm guessing about 72-78" diameter turning around 1000 rpm in cruise, absorbing maybe 50 hp.
Most of the propeller design formulas I've seen look at more ideal conditions, with tip speeds around 0.8 Mach for best efficiency. Modeling is much simpler at those speeds, it seems to me. This can be a fixed pitch design for a limited range of speeds and altitudes. I'm hoping to do better than the ~50% efficiency that was achieved with their wide, thin paddle blades. Ideas?
Most of the propeller design formulas I've seen look at more ideal conditions, with tip speeds around 0.8 Mach for best efficiency. Modeling is much simpler at those speeds, it seems to me. This can be a fixed pitch design for a limited range of speeds and altitudes. I'm hoping to do better than the ~50% efficiency that was achieved with their wide, thin paddle blades. Ideas?
