ORIGINAL: rjbob
ORIGINAL: FalconWings
ORIGINAL: p51Dpony
Well, I think you're applying aerodynamic principles in an oversimplified manner or worse yet in an out of context manner, the same way Jehova's Witness's quote out of the bible. If we can ignore drag, slippage, aircraft front to aft asymmetry, and skin slipperiness in an aircrafts design and performance it's like saying a 10-6 propeller advances 6'' with every revolution - not only it doesn't advance 6'' but the speed and efficiency and actual advance are effected by numerous variables. While to real pilots of FS I bet we're splitting hairs of things that don't matter much, in our academic discussion these things matter greatly. In summary, 2-3 equations have been applied to a 5-6 equation problem, you have an ok applied result but an absolute failure to prove the original premise.
I appreciate that some persons arguments were based on ground-reference to the pilot and agree that those arguments don't prove or disprove anything of the original premise as that's another subject entirely.
A 10x6 prop travels exactly
one inch, no more no less, on earth as well as Mars. It ia called pitch and has nothing to do with air, mass, density or whatever factor you want to pitch in. It has nothing to do with Fluid Mechanics either. It is just a simple measurement of angle, similar to threads on a bolt. Or did you think a model with a 4-40 bolt instead of a prop would travel 4'' every 40 revolutions?
Screw Jetcat I want a 4-40 bolt on my Bandit!
And furthermore, yes it would travel 1'' if it was incompressible fluid. ;-)
You are incorrect.
The pitch number on a propeller is NOT an indication of blade angle. It is a measurement,
in inches, of how far the the propeller will travel forward in one revolution if the propeller is 100% efficient. Both numbers describing a propeller size are in inches...not degrees. In other words, a 10-6 propeller is 10 inches in diameter and will travel 6 inches forward per revolution.
Since, as pointed out in an earlier post, there are many variables to consider, the pitch is used as an approximate value. A highly efficient propeller, such as an APC, will come pretty close, however.
BTW...Where did you get that ''one inch...no more, no less'' measurement from?
You just said the exact same thing I just said.
1. You can call it a measurement of angle becasue it is logarithmically proportional, and assumes 100% efficiency. (FOR A GIVEN PROPELLER SHAPE, AIRFOIL............)
2. 100% efficiency = incompressible fluid (which would make the prop close to 100% efficient). This is where fluid density comes into play.
3. One inch no more no less IS the definition of pitch of 1"( one inch for every revolution), (for a 10x6 would be 6" and so forth...I typed too fast on that one). On a model airplane prop, the losses are taken into accout when the pitch number is defined. Different airfoils = different performance = final pitch value.