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Old 05-24-2006, 07:33 AM
  #17  
da Rock
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Join Date: Oct 2005
Location: Near Pfafftown NC
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Default RE: Transitional Pitched Prop???

Hey, a prop does not have less pitch near the tip.
Actually some do and some don't. And some have different profiles and almost all have different chords. There is no single description that fits all props. And some don't have what was designed into them because the "plastic" was pulled from the mold too soon or not soon enough or the cutters were dull or poorly placed.

One of the "nicest" pitch gauges was sold for a few years with a scale that was "wrong". The answer was that there really is no definition of pitch that accurately describes each station along the prop. Pitch is mostly what the engineer thinks the prop (the whole) prop should do in the air. And they can say it's measurable with an AOA gauge, but that's just hot air.

Truth is, since every station along a prop is locked to every other station rigidly, and every molecule of the prop is moving forward at exactly the same speed, and pitch is a description of forward motion, then no matter what AOA of any single part of the prop every part of the prop has absolutely the same pitch.

for example...... the prop's hub has the same pitch as the prop's tip. It doesn't have the same AOA. It doesn't have the same zero lift angle. It doesn't have the same airfoil. It doesn't have the same camber. And it's L/D is a lot different.

"Pitch" is a good word that is most often a description of the whole and also an ok description of how each station looks. Beyond that, it's confusing to try and use it to describe each station of the prop unless you're just casually suggesting how angled the flat bottom of that station looks to you.
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