limit of trim = limit of travel?

"Maxwell" luv2^fly99@cox.^net wrote in
:


"Bertie the Bunyip" wrote in message
.. .
nospam wrote in
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Bertie the Bunyip wrote:
nospam wrote in
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wrote:
On May 5, 5:55 pm, WingFlaps wrote:

Does the elevator lift force and stall angle reflect trim
setting
at
all?
Cheers
Probably to some rather minor degree. The government just
demands
that the airplane behave in certain ways in various
configurations
and
maneuvers, so the designers have to build their airplanes to fit
within those specs. An elevator should never stall before the
wing, for example, or the whole machine could flip over onto its
back.
The
rising tail, rising because the stab/elevator stalled, would
experience an even higher AOA as it rose and things would get
very nasty. The certification guys want the nose to drop gently
as the
wing
stalls, which couldn't happen if the stab let go too soon. Some
airplanes (I.E. Ercoupe) had limited up-elevator to prevent wing
stall
and therefore the stall/spin scenario that killed so many in the
'40s
and '50s. The nose didn't drop because the wing stalled but
because the stab/elevator ran out of nose-up authority. It could
easily
have
been modified to get the stall. There was plenty of area there.
Only
problem was that guys would get slow on final and pancake into
the ground and break their backs with compression fractures.
Don't necessarily need to stall to get killed.
The Cessna Cardinal had a problem early on with the
stabilator
stalling in the landing flare and smashing the nosewheel on
pretty hard, and they fixed that with a slot in the leading edge
of the stabilator. IIRC the ground effect had something to do
with the
stab
stall problem. I never had any such thing happen at altitude in
the '68 (non-slotted) Cardinals.

Dan
Usually, in conventional aircraft, the tailplane force is a
download.
When this download is suddenly reduced, as in a tailplane stall,
there
is a sudden and probably fairly violent nose down pitch. How you
determine whether it is an elevator stall, or tailplane stall,
without
special instrumentation, is beyond me.
Cheers


You can't, and the reason you can't is because it's all one unit.
There's no difference because you can't seperate their functions.

Bertie
Well, even without instrumentation, one can determine if the
elevator power is sufficient to do a landing flare at say 1.3 Vs
minus 5kts at forward CG. Increasing elevator area may be one method
of increasing elevator power. Also you cannot treat the elevator
and tailplane as
one
unit where elevator hinge moments are needed to be of a particular
(algebraic)sign ie stick free longitudinal static stability
measurement.
Cheers



Sure you can, one without the other is notreally much of anything.
they work together.

Bertie

Of coarse you can Bertie Buttlipp, you know everything, you know
everyone, you've done everything. Gotta link?



Don;'t need one, wannabe boi.


Bertie