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Old May 6th 08, 07:54 AM posted to rec.aviation.piloting
WingFlaps
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Posts: 621
Default limit of trim = limit of travel?

On May 6, 3:36*pm, Bertie the Bunyip wrote:
WingFlaps wrote :





On May 6, 2:19*am, Bertie the Bunyip
wrote:
On May 5, 6:06*am, WingFlaps wrote:


On May 5, 8:48*am, Bertie the Bunyip wrote:


WingFlaps wrote
innews:49efc4b4-8ede-40cd-9ad3-5

:


On May 5, 3:19*am, Bertie the Bunyip wrote:
Stealth Pilot wrote
innews:u8kr141dp0o1e
:


On Fri, 2 May 2008 12:32:28 -0700 (PDT), WingFlaps
wrote:


On May 3, 12:40*am, Stealth Pilot

.au
wrote:
On Wed, 30 Apr 2008 00:12:54 +0000 (UTC), Bertie the
Bunyip wrote:


WingFlaps wrote in
news:ad8fc9c9-57cb-4733-9e97-
:


On Apr 30, 9:37*am, wrote:
On Apr 29, 2:24 pm, WingFlaps
wrote:


I don't follow this. The trim surface operates in
the opposite direction to the trimmed surface and
takes area away from it.


-------------------------------------------------------------





----


^^^
^
Explain
please?


What area stuff?


Cheers


that area stuff. ...which shows a total lack of aerodynamic
understanding.


Still don't know what you're talking about! Most of that
thread has


spooled off my main server now..


He's trolling.


Cheers


He's not, he's right. Deflecting a tab in the oppostie direction
doesn

't
remove area.


It reduces effective area.


No, it doesnīt. The area is stil there. The tab isnīt "hiding"
because


itīs going the other way, itīs just doing something different. it may
be reducing the effectiveness of the surface, but that isnīt the same
thing as reducing the area.


Nope. Effectiveness is proportional to area -from the old lift
equation.


Sure, but the area hasn't changed.


OK, then if the AOA of the stabilator is constant, and the elevator
angle is constant, why does the lift reduce when the trim tab is
deflected in the opposite direction? It's as I said, the effect is as
if the _effective_ area is reduced. You could say that CL is altered
but then it gets more messy as you have to consider different CL's and
areas for each section of the stabilator. It's much simpler to just
subtract the area taken by the trim from the calculation and that will
give a very good first order approximation for longitudinal stability
calculations.

Cheers