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Subject:
RV lurking spy
From:
"Paul Lipps" <elippse@sbcglobal.net>
Date:
Wed, 04 Apr 2007 15:15:24 -0400
To:
lml@lancaironline.net
To:
lml@lancaironline.net
I just collected data from two flight tests, one an RV-6, the other an RV-9A. The six's TAS from IAS was 11 mph high, the nine's was 9-10 mph high. Another 9 builder there when we discussed it said his was also about 10 mph high. The two 9s used the Cessna-type disc on both sides of the fuselage at the recommended location, and the 6 had the Van's pop rivet port.
That's funny, mine is right on according to the test pilot school test.
Plenty of variables here. The factories have known for years that
placing the pitot below and a little behind the leading edge will result
in a cruise airspeed that is a little high, and a stall airspeed that is
a little low. The static system needs to be right though for separation
reasons.
I know the airflow over an RV (all turbulent and nasty) is not the same
as a Lancair (all the little pieces of yarn lying flat and parallel).
But the washer thing is an easy thing to try, and has taken the airspeed
readings in the direction Rick needs to go with his ES.
Of course, many enjoy an airspeed indicator that reads a little high,
that way they can brag about how fast they are without ever showing up
for one of our races. (gauntlet tossed)
By the way Paul, speaking for the RV guys, we enjoy and appreciate the
posts you and Chris Z. have been making over at vansairforce.net.
John Huft
RV8 "Nuisance"
Race 18
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