BlueBell wrote: ↑
Nov 26, 2017 11:35 am
Okay, the plot thickens.
I'm asking for propeller recommendations on a known boat forum and uncertainty has arisen over shaft RPM at reduced power levels.
In the different heats there is either ~200 watts or ~400 watts available to the motor.
What RPM's could be expected?
I thought at 48 volts the RPM would be the same, ~467 as the spec sheet indicates.
The thread is here for your reference:
Unloaded rpm would be the same.
But, under load, rpm will be restricted by a "load" line, propeller should be optimized for rpm at available watts.
I approximated up a graph comparison of 400w available vs 200w available, with comparative rpm (not to be taken as actual or optimal!)
Attempt at 200w from motor simulator resulted in a fault-flaw, lines went wonkie, so I drew in a reasonable estimate.
Wind resistance on "load" line should be somewhat similar to water resistance, for like comparison purpose ... or at least a starting point for physical trial.