Originally Posted by
psgugrad
I'm afraid you've lost me here...I'm not familiar with any of what you're referring to. I don't understand how a formula can measure thrust. (not saying it can't...I just don's see how) Measuring thrust would seem to require a thrust testing apparatus that physically measures pull. Otherwise, how would one take into account air density differences arising from different temperatures, humidity levels and altitude? Also, the material of the prop will matter as a propeller looses a bit of it's pitch as rpms increase...especially at the tips...due to centrifugal force. Thererfore, , are we talking a nylon, wood, or carbon fiber prop, as the prop material's rigidity will affect how much pitch is lost at elevated rpm? What is the shape of the cross-section of the prop? The shape of the blades? These factors, prop pitch, diameter, blade area, and rpm being equal, will affect how much thrust is being generated.
I don't fully understand either, (and not really that interested), in how to measure using formulas, but it can be done. Everything can be measured/calculated these days, without actually having to make/build or physically set up something to find out how it will perform. Pretty much any variable can be allowed for in the calculations to simulate different scenarios.
I still think that performance in the real world may be slightly different, but calculating first puts it right in the ball park without the expense and time involved in manually doing it.
As many of us have found in the past, theory is all well and good, but how something performs in the real world will be the final test.