RE: Graupner Vs APC prop observations (Full Version)

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Daryl Martel -> RE: Graupner Vs APC prop observations (5/17/2008 2:43:41 PM)

Ohhh - I should have added... noise is a great measure of efficiency. Quieter props are losing less energy to the production of noise. The thin tips create less tip vortex - again less loss of energy. The more energy that is transferred directly to producing thrust the better. Energy loss is next to moot in our glow/gas RC planes, but much more important in electrics were it's more dearly felt.



blw -> RE: Graupner Vs APC prop observations (5/17/2008 2:49:13 PM)


quote:

ORIGINAL: Daryl Martel

The thin tips create less tip vortex - again less loss of energy.



Not always. Shape is important. An elliptical shape probably contributes less vortices. Blunt, squared off tips such as Master Airscrew and Zinger props are very dirty, and inefficient at most speeds compared to other designs.



Daryl Martel -> RE: Graupner Vs APC prop observations (5/17/2008 2:58:03 PM)

To a point (pun intended) as the high taper permits thinness to be designed in. I agree with you. Didn't think it neccessary to elaborate on that (that's why I mentioned APC, Bolly & Mezlik - all similar shape). A long chord, but thin tip is more like a sheet of paper isn't it! Not much strength (so it'll easily twist) and produces thrust more by deflection than aerodynamic force.



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