A good Net effect is what I'm shooting for. I guess the tape should only be used in very specif applications where it's positive effects are worth the extra drag.
One that sticks out is, the model glider being easier to control when ZZ tape was placed ahead of hinged control surfaces. IIRC, after the ZZ tape was installed the pilot no longer needed to switch to hi-rate mode on his controls.
(Maybe he was paying a price with a lower L/D or less airspeed).
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I've seen wipers that went down out of the air stream when off. But mine are out there dragging all the time.. I guess using the smallest profile wipers I can find will be about it.
I noticed a spoiler-wing on my kid's X3 wiper. I guess it's going to provide more down pressure.. But if that pressure isn't really needed? Paying the price in drag..
Adding to the net..