Re: Proper Prop Pitch
I think that what you are misunderstanding, is that determining correct prop pitch via WOT rpm determination does tell you what you need to know about operation at less than WOT settings.
If you over-prop the engine, it will lug at all rpm settings. What will vary, is the degree to which it is lugging. When you are at the peak torque point in the powerband, you will be lugging to a lesser degree, but you will still be lugging. Above and below that value, there will be variation in the degree to which you are lugging, but absent all sorts of monitoring of various parameters, you'll never know just how much.
The question that I would ask, is whether trying to be that exact is worth the effort. Its much easier to just prop the motor to stay within the manufacturer's recommended WOT range and fine tune from there. In fact, the manufacturer has accepted the fact that there is no single WOT rpm that is optimal in all situations - that is why they provide a range.
If you are currently getting 5,300 rpm at WOT and that is within the recomended range for your motor, you are in pretty good shape. From this point, if you want to try a couple of alternative props, I would say to go for it. Just to give you something to go on - a general rule of thumb on prop pitch, is that you will gain or lose about 200 rpm per inch of prop pitch, depending on whether you go up or down in pitch. The relationship between higher/lower pitch is inverse to the gain/loss in rpm. Bear in mind also that this "rule" is general - it varies with a number of things, including prop material, cupping, etc.
You are getting good advice here - I suggest you listen to it.
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