limit of trim = limit of travel?

WingFlaps wrote in
:

On May 7, 12:56*am, Stealth Pilot
wrote:
On Mon, 5 May 2008 23:54:37 -0700 (PDT), WingFlaps

wrote:
On May 6, 3:36*pm, Bertie the Bunyip wrote:
WingFlaps wrote
innews:4c947801-0112-4fa1-92e7-09
:

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?

because the elevator angle isnt bloody constant. what is constant is
the stick force which you maintain at the same pressure by
unconsciously moving the stick as you change the trim tab position.

It's as I said, the effect is as
if the _effective_ area is reduced.

no it bloody isnt. the area remains the same the lift force is what
varies and guess what, that's why the tailfeathers have the hinges in
the middle.

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.

you have basically started out with a faulty understanding and for
the last 100 posts have misinterpreted everything written because you
keep relating the information to the original faulty premise.


Nope. I understand it perfectly. As defined in any good book on
aeronautical design, stabilator effectiveness is _defined_ by the
horizontal tail volume coefficient which is the product of tail moment
and area divided by the wing area and it's mean chord.

From the style of you reply I can see you will have a hard time
understanding this this it really is correct -look it up.


I understand what you are saying perfectly. You might think it's a handy
way to look at the problem, but it's simpoistic and incorrect..
End of story.


Bertie