Quote:
Originally Posted by tracy
My question is this, does a rough surface give an aircraft more speed? If so, why would anyone make theirs buff smooth? I do not want to polish the rest of the aircraft if it slows it down.
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The answer to your question is dependent on the airfoil section. Some sections have a 'weak' laminar boundary layer that 'holds on' too long, then, at a particular angle of attack, will form a large separation 'bubble' before transitioning to turbulent flow. Thus, higher drag, since the boundary layer aft of this bubble is much thicker than it should be. However, if that section is 'roughed up' before where the bubble normally occurs, the laminar flow area will transition to turbulent flow further forward on the wing section, and the bubble is avoided....thinner boundary layer aft...less drag.
Wings that used the 23012 section could exhibit this bubble behavior, so adding roughness would help those aircraft.
RV wings don't have this bubble issue...so polish away.