Blade Size vs. Performance
Good afternoon,
I'm new to prop selection & motor selection, but I've been fiddling with an online calculator.
Please correct me if I'm wrong, but it looks like if I want to go fast I want a smaller prop at high RPMs.
If I want efficiency I go large and slow. I'm a direct drive kind of guy, so I'm looking into the 4410 Neumotor (low RPM) or the 2230 (high, fast).
For example, with a 7.5 kW load I could do a 36x16 prop, 3750 RPMs and have 73 lbs of thrust @ 57 MPH (so I'll assume my max speed is around 50 MPH?)
or with 7.5 kW I could choose a 18x10 prop at 11,100 RPMs and have 46 pounds of thurst @ 106 MPH (half way to a turbine, right? .78 Mach.. so max speed of around 95 MPH I'd guess?).
Is this as simple as it seems? Are there any huge nuaunces to watch out for? I realize over .65 mach gets noisier, .85 mach bad things begin to happen.