nospam wrote in
news:bYydndxV96btLr_VnZ2dnUVZ_vCdnZ2d@internode:

Bertie the Bunyip wrote:
nospam wrote in
newsbmdnXqirNejAr_VnZ2dnUVZ_sednZ2d@internode:

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