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Craig,
Interesting....... Note that the flaps will actually fly
higher than their ground rigging position because of linkage slop and in
flight air flow.
Of course, every 300 series aircraft is different. Let's
assume we are talking about a slow built (fast builds are slightly
different), Short engine mount, small tail, pre-preg glass, standard wheels,
and built according to plans. That means, by design, the flaps are in
-7 degrees reflex when faired into the fillet - that is if the fillets were
laterally located to the same position relative to the longeron. Also,
remember that the horizontal stabilizer is to be mounted between -.5 to
-1 degree incidence (relative to the longeron) - another variable.
Note that increasing the reflex results in wing forces that
want to further lift the nose. If the horizontal stabilizer is not at
the correct AOI, the elevator may be necessarily positioned for more nose
down force that may increase drag. It is not possible to know if
your rigging is "sweet" for everyone else unless all the
conditions match. Indeed, your reflex position may overcome a condition
in your tail.
If you wish to attain greater speeds, consider
also using gap seals on the rudder and elevator. BTW, where is
your rudder positioned at 215 Knots (true or indicated?).
I do have a problem with your sea level speeds as the aircraft
would have increased drag from the sea water.
Grayhawk
In a message dated 3/25/2010 2:58:23 P.M. Central Daylight Time,
craig@skybolt.net writes:
Hi Bill,
I know a lot of others are claiming that reflex is at the
faired in position. That may not be the best position. My little
320 does 215 kts at sea level. 210 is about the average cruise at
7500. I am dialing in an extra 1/2 inch (measured at the trailing edge
of the flap) of reflex. While flying in formation I have determined
that for my airplane this is the sweet spot. Too much will slow it down
and any less will too. The difference between the faired in position
and my reflex position is 7-10 kts. I also have the gaps on the flaps
taped and gap seals on the ailerons.
Craig
N73S
From: Bill Kennedy
[mailto:bill_kennedy_3@hotmail.com]
Sent: Wednesday, March 24, 2010 3:27 AM
To: lml@lancaironline.net
Subject: [LML] 320 Airfoil Reflex
I've never been certain that my flaps up position is
exactly right. I know some of you couldn't sleep if their flaps weren't in
exactly the best spot. So, here's what I would like from you:
What is the exact angle between your cockpit longeron and the top inboard
skin of your flap when it is fully up? I ask this question because it will be
easy for me to measure and correct if necessary and it is not ambiguous. My
plane is a 320.
Thanks -- Bill Kennedy
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