Re: RE: RE: Prop construction

From: Phedon Tsiknopoulos <phedon21t_at_yahoo.com>
Date: Sat, 14 Sep 2013 23:43:00 -0700

Leo,
  Don't forget the Coanda effect for initial lift at the very front. The abrupt rise of the airflow due to the up curvature causes that. So it's Coanda, Bernoulli and Newton. Ciao, Phedon.


Sent from my iPhone

On Sep 8, 2013, at 6:58 AM, <leop_at_lyradev.com> wrote:

> Art,
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> I thought I might get into trouble mentioning faster airflow on the top of an airfoil. I also do not usually speak of airflow in term of Bernoulli effects but rather use Newtonian physics (just ask Kang and Bill about my rants). However, for the air to curve downward (assuming an aircraft wing flying right side up), the air on the outside of the curve must move faster than that on the inside. The air really does travel faster, relative to the wing, on the top of an airfoil producing lift than does the air on the lower side. This is a result of Newtonian laws as one can surmise from thinking about air moving uniformly around a curve (or in high-falutin terms, the airflow must have "curl" to produce lift).
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> Bernoulli effects are just outcomes from Newtonian laws but the former are often misused. Thanks for keeping me on my toes.
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> Leo
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> --- In Indoor_Construction_at_yahoogroups.com, <indoor_construction_at_yahoogroups.com> wrote:
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> Good. That all makes sense except for the air traveling faster over the vacuum side of the airfoil/blade than the pressure side (McCauley terminology). I never got how that worked on a flat airfoil because I understand Newton better than I understand Bernoulli.
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> Meanwhile, as a new pair of blades dried overnight on the mold, I took the originals with the spar on the fwd side and rotated them 180º in the spar sockets. It looks a little weird because the most area is behind the spar now, but I figured that because it's a fixed twist blade rather than a flaring one it should be fine. And it is. But a correct prop is in the works.
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> Thanks,
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> a.
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Received on Sat Sep 14 2013 - 23:43:00 CEST