Pietenpol-List: Flop vs Cutout

An archive of the Matronics Pietenpol Listserve.
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matronics
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Pietenpol-List: Flop vs Cutout

Post by matronics »

Original Posted By: Ohbejoyful
When I first flew my Piet in 1970 it had a cutout above the rear cockpit, and I flew it that way for a couple of years. Then I re-worked the center section and installed a hinged =9Cflop=9D in order to perhaps gain a bit of lift and reduce turbulence over the tail surfaces. I cannot say that the lift was perceptively increased, but the airflow over the tail was definitely smoother (as felt in the control stick; no perceptible difference was felt in the rudder controls).Interestingly, when one raises the =9Cflop=9D trailing edge in flight, the nose promptly drops. My theory (and it is only a theory) is that raising the =9Cflop=9D spoils the airflow over the horizontal tail surfaces which are carrying a download and the nose pitches down as a result. Another theory: The in-flight photos of many Piets show the elevators drooping a bit and this may be partly due to the downwash from the wing. The in-flight photos of some early aircraft (eg. Sopwith Pup) also show this characteristic which may be caused by the downwash from the upper wing. Probably the weight of unbalanced elevators at low airspeeds is also a factor; there isn=99t enough force generated to overcome both gravity and the downwash effect.Anyway, this is largely speculation and we don=99t need to worry because the Pietenpol flies just fine, with or without a =9Cflop=9D.Cheers,Graham Hansen (Pietenpol CF-AUN in Alberta, Canada) ________________________________________________________________________________
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