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OK, I know this is off subject, but it IS on a rotary-powered
RV-6.
My static system pressure is off to the tune of 100 feet at cruise
speeds.
Every airspeed indicator I tried (2) read 10 mph too high when
calibrated using GPS triangulation. One day I glanced at my
altimeter while making a cruise speed pass down our home runway (close
to the surface) and noticed that it read 100 ft higher than at
rest. My calculations show that would also account for the +10 mph
on the ASI.
I have the standard hollow pop rivets at the standard Van's
locations. Can't imagine that the small rise on this rivet would
drop the pressure that much! I have asked other RVs to also do
this test, and they come in anywhere from 50 to 80 ft. high. I
tried pulling the static line to let the instruments use cockpit
pressure (which I already knew was lower than static) and the altimeter
read 850 ft!
With all the brainpower available on this list, surely someone can
suggest a method of attacking this problem. I could just continue
subtracting 10 from my indicated, but that is the easy way out. I
was going to drill out the rivets and use a hole in the flat skin, but I
just can't bring myself to mess up a great paint job. (Yet)
Ideas?
Bill Eslick
N268BL
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