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From: Chris Zavatson <chris_zavatson@yahoo.com>
Subject: Re: [LML] Re: Lancair 320/360 performance and stability
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Christian,
I wouldn't give up just yet.=20
Note that the entire horizontal stabilizer will be at a new AoA after the f=
laps are moved.   The actual elevator change will be very small.  During my=
 flap sweep (-7 to +2), the entire elevator change was less than 0.1 degree=
s. Elevator position is more strongly a function of your altitude (and lift=
 coefficient). For example on a given test flight, top cruise speed at 7.5k=
 had an elevator position of 1.18 degrees TE down, whereas top speed cruise=
 at 15.5k had an elevator position of 0.48 degrees TE down.
Chris

--------------------------------------------
On Tue, 9/24/13, Christian Meier <lancair@meier.cc> wrote:

 Subject: [LML] Re: Lancair 320/360 performance and stability
 To: lml@lancaironline.net
 Date: Tuesday, September 24, 2013, 3:19 AM
=20
 Chris,
 today I made a picture during Cruise with
 Autopilot at 7500ft with following
 configuration:770 kg =A040l in header, 20l in
 each wing (80l total), 75kg and 83kg for pilot and
 co.Flap was on 7=B0 reflex =A0CG 26,20"
 =A0My design CG is 22,8 =A0- =A030,3
 from firewall back, =A0horizontal was installed -
 0.6=B0
 So it looks like if I would add more reflex than
 7=B0, I would need more down elevator.So the gain
 with the higher reflex would be lost with the down
 elevator....
 Christian
=20
=20
 Am 17.09.2013 um 21:18 schrieb Chris Zavatson
 <chris_zavatson@yahoo.com>:
 Scott,Thanks.=A0
 Examining the=A0360 (MkII) performance and
 characteristics in greater detail as been very
 interesting.=A0The
 small tail has a very low aspect ratio and may indeed be
 subject to higher drag if the stabilizer incidence requires
 significant elevator input to trim.=A0=A0The MkII tail
 adds about 2 sqft, but more significantly has a much greater
 aspect ratio.=A0 My=A0stab was well aligned for the
 sweep of flap settings as the elevator deflection was about
 0.5 degrees TE down.=A0=A0In fact, all of the points
 were=A0inside of=A00.1 degrees of elevator
 movement.=A0 The concept of aft
 CG=A0being more efficient is by reducing trim drag.=A0
 It is used quite successfully in aircraft that
  adjust the entire stabilizer for trim.=A0 A fixed stab
 angle=A0that is too far from neutral in=A0the aft CG
 or in the 'super-reflexed' cruise=A0condition
 could negate=A0any benefit.=A0=A0In my case the
 plot of flap setting vs. airspeed showed that I had not yet
 reached a peak.=A0 Extrapolating the curve gives me
 another 2 kts at 12 degrees reflex.=A0 Extrapolating is a
 bit dangerous with any polynomial curve, but on the
 other=A0hand this one has=A0an exceptionally
 well=A0behaved 2nd order trend.=A0=A0 -7 degrees
 certainly provides a large portion of the
 benefit.It would be very interesting
 to run through the same series of tests with a=A0small
 tail=A0at the same static margins for a side by side
 comparison.Chris=A0=A0=A0=A0Chris
  ZavatsonN91CZ360stdhttp://www.n91cz.net/
 =A0        From: "Sky2high@aol.com"
 <Sky2high@aol.com>
  To: lml@lancaironline.net
=20
  Sent: Sunday,
 September 15, 2013 12:26 PM
  Subject:
 [LML] Re: Lancair 320/360 performance and
  stability
   =20
=20
=20
 =20
 =20
=20
 Chris,
 =A0
 Great research.
 =A0
 In my small tailed 320, increased flap reflex
 experimentation=A0did not=20
 result in increased top end speed.=A0 The nose=A0up
 pitch was increased,=20
 requiring increased nose down trim - probably=A0resulting
 in greater=20
 empennage drag negating any reduction in drag from the=20
 greater=A0reflex.=A0 Of course, we would have to
 discuss the angle of=20
 incidence of the small tail and its relationship to the
 elevator correcting for=20
 nose down pitching ( my incidence was at -.9 degrees).
 =A0
 By moving weights forward and aft in the same flight,
 forward CG=20
 was=A0better for maximizing speed - unlike some aircraft
 that see max speed=20
 when the CG is at the neutral point, probably a consequence
 of more standard=20
 wing/tail design that saw drag from wing/horizontal +/- lift
 factors more=20
 balanced and minimized.=20
 =A0
=20