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My understanding (some please correct me if wrong/misleading)...
In the end (i.e. in-flight), the "overall" incidence is ultimately
controlled by the position of the elevator (i.e. the actual trailing edge).
Thus, if you get the horizontal stabilizer incidence exactly "correct", then
the elevator will be straight entrail. However, this situation only holds
for a specific speed and W&B combination. At other speed and W&B
combinations, you'll need some up/down elevator position (trim) to maintain
level flight. One would guess that the Lancair/factory recommended
horizontal stab incidence setting is correct for the center of the operating
envelope (normal cruise?).
In approximate terms, if you had the horizontal "off" by 1/2 degree (up or
down), then you'll be flying with the elevator "off" in the other direction
by a corresponding amount (perhaps approx twice the degree measurement due
to the shorter chord/arm).
The elevator would still likely be perfectly entrail at some speed/weight
combination, but perhaps not in normal cruise.
A bad scenario is that you have the horizontal so far "off" (leading edge
up) that you run out of up elevator movement in the flare. The other bad
scenario is that the horizontal is so far "off" (leading edge down) that you
need "lots" of down elevator at high speeds (added drag).
-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Bryan
Wullner
Sent: Friday, May 11, 2007 9:51 PM
To: lml@lancaironline.net
Subject: [LML] Flight Characteristic Question
I am building a Lancair 360.
I just permanently bonded the Horizontal stab on. I took every
precaution to get it within the 1/2 to 1 degree of negative incidence
that Lancair specifies. I used the water level to come come up with
the proper incidence based on the plans. After cure I recheck my
incidence and Im 99% sure I have somewhere between .09 and 1.3 degree
of negative incidence
My question is:
If the Horizontal has more than 1 degree of Negative incidence, say
1.5 or higher, how does that affect the flight characteristics?
And vice versa if it doesn't have enough negative incidence what does
that do to the flight?
Thanks
Bryan
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