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Chris,
Hmmmmmm... Well lazy me ;-}
I refuse to go back and read the NASA report again - I am just going
to rely on my creaky memory. BUT, my seat of the pants scientific probing
makes me believe the drag factor is very significant. Oh drat, I now
remember that we are dealing with vehicular drag, not just wing drag. On
our slick lawn darts, a little drag has a big effect whilst on those pimply
spam cans with wing struts and wheel pants, what's a little more drag?
I retire to my quiet padded room now.
Scott
In a message dated 4/18/2012 10:01:17 A.M. Central Daylight Time,
chris_zavatson@yahoo.com writes:
Scott,
I am dissapointed.
:-)
Google can fill in the details on Reynolds
number.
It just relates kinematic
viscosity, chord length and velocity.
Low Speed is relative. Mach
and Reynolds number were right in our range.
M 0.3 = ~200
kts
Chris Zavatson
N91CZ
360std
From: "Sky2high@aol.com"
<Sky2high@aol.com>
To:
lml@lancaironline.net
Sent:
Tuesday, April 17, 2012 1:54 PM
Subject: [LML] Re: Fw: L320 flap
setting
Chris,
Ahh, too bad I can't translate Reynolds numbers into KIAS. I
thought the NASA airfoil tests were at slow speeds????
Oh well .. It does match my experience. At high speeds, flap in
reflex and nose down trim (on my airplane, small tail, actual TE of elevator
is down a bit from neutral) is a very interesting condition to
contemplate. After all, the elevator is an upside down wing (slightly
cambered on the bottom). Thus, nose down trim is actually with
the elevator in reflex. Since the chord of the horizontal stab was
positioned with a negative incidence to the longeron (-.5 to -1 degrees,
mine is -.8) and at cruise (about 180 - 190 KIAS), the longeron has
been measured to be at 0 degrees (hmmm, just like the plane
was designed), the horizontal may be at a positive AOA (relative air
flow?, think upside down) until one considers the position of the elevator and
its trim change on the AOA to a lesser AOA. Thus, less lift (anti
lift), less drag.
Egads, now my head hurts.
Blue Skies,
Scott Krueger
In a message dated 4/17/2012 8:53:25 A.M. Central Daylight Time,
chris_zavatson@yahoo.com writes:
I use the attached charts to describe the impact of reflex: Repositioning the
drag bucket, a drop of a few drag counts and a huge 3 to 1 change in
pitching moment.
Chris Zavatson
N91CZ
360std
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