limit of trim = limit of travel?

On May 6, 10:52*am, wrote:
On May 5, 1:38 pm, WingFlaps wrote:



On May 6, 4:44 am, wrote:

On May 5, 9:51 am, WingFlaps wrote:

On every elevator I've looked at the trim tab is cut out of the
elevator area. It does not ADD area.. When it is deflected it creates
a force that may oppose that produced by the main elevator. In that
way it reduces EFFECTIVE elevator area. (It is not the same as horn)..

Cheers

* * * * *And every airplane that has a trim tab has an elevator that
was designed to be big enough to give all the authority needed even if
the trim tab was deflected all the way in the "wrong" direction.

While I suspect that may be true, you have a reference for that
statemeant? What happens when the elevator runs out of authority and
stalls (as in a badly loaded plane)? Does the elevator lift force and
stall angle reflect trim setting at all?

Cheers

* * * * If the elevator runs out of authority and stalls "in a badly
loaded airplane" then there were factors outside the certification
criteria that caused the accident. Outside the forward CG, for
instance. Same stupidity as overloading the airplane and mushing into
the trees.

* * * *FAR 23.145 deals with elevator authority in the trimmed
condition: (see paragraph 5):http://www.airweb.faa.gov/REGULATORY...RY%5CRGFAR.NSF...

* * * FAR 23.161 deals with trim:http://www.airweb.faa.gov/REGULATORY...RY%5CRGFAR.NSF...

* * * *FAR 23.407 deals with trim tabs deflected in the normal
direction:http://www.airweb.faa.gov/REGULATORY...RY%5CRGFAR.NSF...

* * * *FAR 23.677 deals with runaway trim and the need for adequate
controllability in any trim tab position:http://www.airweb.faa.gov/REGULATORY...RY%5CRGFAR.NSF...


Does the elevator lift force and stall angle reflect trim setting at
all?
Cheers

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

WingFlaps wrote in
:

On May 5, 8:48*am, Bertie the Bunyip wrote:
WingFlaps wrote
innews:49efc4b4-8ede-40cd-9ad3-52701
:







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


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 doesn't. it influences the airflow in a different way. I know wha
you're saying, but you're just wrong here.


Bertie

WingFlaps wrote in news:d67eeb73-982b-4030-a9bc-
:

On May 6, 4:44*am, wrote:
On May 5, 9:51 am, WingFlaps wrote:

On every elevator I've looked at the trim tab is cut out of the
elevator area. It does not ADD area.. When it is deflected it
creates
a force that may oppose that produced by the main elevator. In that
way it reduces EFFECTIVE elevator area. (It is not the same as
horn).

Cheers

* * * * *And every airplane that has a trim tab has an elevator
that
was designed to be big enough to give all the authority needed even
if
the trim tab was deflected all the way in the "wrong" direction.

While I suspect that may be true, you have a reference for that
statemeant? What happens when the elevator runs out of authority and
stalls (as in a badly loaded plane)? Does the elevator lift force and
stall angle reflect trim setting at all?


Of course it's affected, but that doesn't mean that the area changes, it
does not. The flow is affected and the forces are affected but the area
doesn't change. You can look at it that way if you like, but it will
mean that you won't grow to have a deeper understanding of the way the
surfaces work. IOW, you'll be like Ken.


Bertie

WingFlaps wrote in
:

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 doesn´t. The area is stil there. The tab isn´t "hiding"
because

it´s going the other way, it´s just doing something different. it may
be reducing the effectiveness of the surface, but that isn´t 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.


Bertie

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 doesn´t. The area is stil there. The tab isn´t "hiding"
because

it´s going the other way, it´s just doing something different. it may
be reducing the effectiveness of the surface, but that isn´t 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.


Don't be so literal, how could the actual sq feet chnage? BUT it's as
if the effective area at the AOA of the stabilator is reduced -right?

Cheers

On May 6, 3:34*pm, Bertie the Bunyip wrote:
IOW, you'll be like Ken.


OY! there's no need to get nasty!

Cheers

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 doesn´t. The area is stil there. The tab isn´t "hiding"
because

it´s going the other way, it´s just doing something different. it may
be reducing the effectiveness of the surface, but that isn´t 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

On Mon, 5 May 2008 08:59:36 -0700 (PDT), WingFlaps
wrote:

On May 6, 2:18*am, Stealth Pilot
wrote:

for heavens sake "wingflaps" as a nom de plume?????
real pilots have nome de plumes like "bertie the bunyip" or my all
time favourite "buster hyman". wingflaps is the monika of a rank
novice.

I guess that makes me an unreal pilot? Oh, I'm sorry was that an
adhominem?

LOL


Cheers

you cannot possibly be a pilot. you may have some ultralight
experience but you certainly arent a pilot.

how can I say this?
easy.
pilots learn or get taught a subject called 'basic aeronautical
knowledge' which they pass an exam on.
you do not have sufficient understanding to get even a third of the
pass mark required.

if you had studied and passed the BAK you wouldnt be so perpetually
stupid regarding the questions you ask.

if you want to progress go and do some reading of the pilot study
materials.

even now after 100 posts in this thread you have not a shred of
understanding on the questions you ask.

why do pilots have nom de plumes unrelated to aircraft parts, that's
easy, they understand how they work because they get effective
training in the theory.

Stealth Pilot

On Mon, 5 May 2008 16:55:37 -0700 (PDT), WingFlaps
wrote:

On May 6, 10:52*am, wrote:
On May 5, 1:38 pm, WingFlaps wrote:





Does the elevator lift force and stall angle reflect trim setting at
all?
Cheers

absolutely not!

the trim setting is what sets the neutral position of the control
surface. ie the position where the least or no stick force is required
to maintain the amount of lift required from the surface for stable
flight.

this may surprise you but an elevator is never stalled in flight.

Stealth Pilot