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Hi Larry,
I think you are right about the incidence being wrong in a lot of these
airplanes. Mine will run out of down trim over 210 kts. A quick look back
and I can see the elevator counterbalance sticking up about 3/8 inch. My CG
is perfectly to spec but at 210+ it doesn't seem to matter how the airplane
is loaded. It still needs gobs of down trim. The problem is the faster the
airplane goes the more lift the wing wants to create. So to keep the
airplane flying level you have to reduce the angle of attack, that means
down trim. A full flying horizontal stab would be the most efficient way
around this.
Craig Schulze
Lancair 320 small tail.
-----Original Message-----
From: LHenney [mailto:LHenney@charter.net]
Sent: Sunday, February 22, 2009 2:36 PM
To: lml@lancaironline.net
Subject: FW: 360 in a small-tail LNC2?
Tom,
I had occasion to visit my CG limits for a son's science project. Similarly
I was assessing elevator bob weight position relative to the horizontal tail
at race speeds and comparing airspeed data.
In my aircraft, your premise would be wrong. That is, I have to move the CG
forward to flatten out the elevators to the horizontal tail (which also
increases speed (yes it's hard to believe)). As opposed to changing CG, one
might verify horizontal tail incidence. Or more precisely all Lancair 320/
360 I've flown with have this same affect (bob weights a little high at
least minimally).
Regarding your CG comments, serious pursuit of empty CG before any
additional flight would be my recommendation (imho). The phrase " way to far
forward I think" has me squirming.
Larry Henney
PS: In my estimation, several 320/ 360 builders took the tail plane template
and transferred it to an incidence guide. The subsequent mistake was
mounting one's smart level atop the guide and setting the tail plane at the
requisite 1/4 to 1/2 degree nose down. The mistake is missing the fact that
the incidence guide off the blue print was already 1/2 degree nose down.
Thus reading 0 deg on the smart level should have had the tail at the 1/2
degree nose down angle. Many are actually 1 deg nose down. This is not a
problem. It just increases stability and costs 2-3 kts.
Just my 2 cents.
-----Original Message-----
From: Tom McNerney [mailto:dudewanarace@yahoo.com]
Sent: Friday, February 20, 2009 12:51 PM
To: lml@lancaironline.net
Subject: RE:360 in a small-tail LNC2?
Works great. I have a 400! I'm sure the rest of small tail group would
agree. Might have to move your center of gravity back. (I need to) Only
thing I can say is that slow flight with full flaps isn't the most
comfortable, but now that I am aware of how it handles, doesn't bother me a
bit. My CG is way to far forward I think, so that probably makes the slow
flight a little different.
On a side note.. I turned around and looked at the tail the other day
while indicating 200KTS. I could see the elevator counter weight, or almost
all of it. I didn't expect to see that at 200. Maybe 100.. haha This
leads me to believe that I have a forward center of gravity. The big engine
would explain that. Once I get the plane on some scales, the only thing I
can think of is to move the battery. My battery is behind the passenger
seat.
Has anyone mounted a battery behind the baggage compartment? Advice?
Thanks
Tom
www.N54SG.com
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