Mechanics of Elevator Trim. In Detail.

More_Flaps wrote in
:

On Jun 9, 9:06*am, Bertie the Bunyip wrote:
More_Flaps wrote
innews:64b157a9-99f5-4429-9125-d1e2
:





On Jun 9, 7:29*am, "Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way
D0t C0m wrote:
"Le Chaud Lapin" wrote in
messagenews:5c4deac0-2b92
...
On Jun 8, 11:07 am, "Robert M. Gary" wrote:

On Jun 7, 10:08 pm, Le Chaud Lapin wrote:

What exactly happens when the trim is adjusted to point the
nose upward?

What type of plane is this for? I have a Mooney and also fly a
182. Both trim system are very, very different.

For sake of those of us who only own MSFS, let's say a C172.

Does MSFS emulate the servo tab on the elevator? What does it do
when you change the trim in the air?

Trying to emulate real life trim on a simulation system that uses
spring centered control sticks isn't going to work like real life
as you may already know.

Should I post the spoiler on how a couple other mechanisims work
(besides servo tabs)?

I'll raise you one to make three additional trim systems. Any more?

I can think of four for a total of five, depending on whether you'd
consider hydraulic centering to be the same as a bungee trim system.
theothersa re of course, a tab system which is th emost common light
aircraft system. the trimmable stab, a'la Cub and most airliners and
the vane, like some early T-carts had.. There're probably some
others, but i can't think of any.


I'd count that as the same -the acutuating system doesn't count, just
the aerodynamic priciples. So, if you have four I'll raise you again
one to make five... Any raise on five basic methods?

Yeah, they;re essentially the same.

Go on. I'll call.


Bertie

On Jun 9, 9:24*am, Bertie the Bunyip wrote:
More_Flaps wrote :





On Jun 9, 9:06*am, Bertie the Bunyip wrote:
More_Flaps wrote
innews:64b157a9-99f5-4429-9125-d1e2
:

On Jun 9, 7:29*am, "Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way
D0t C0m wrote:
"Le Chaud Lapin" wrote in
messagenews:5c4deac0-2b92
...
On Jun 8, 11:07 am, "Robert M. Gary" wrote:

On Jun 7, 10:08 pm, Le Chaud Lapin wrote:

What exactly happens when the trim is adjusted to point the
nose upward?

What type of plane is this for? I have a Mooney and also fly a
182. Both trim system are very, very different.

For sake of those of us who only own MSFS, let's say a C172.

Does MSFS emulate the servo tab on the elevator? What does it do
when you change the trim in the air?

Trying to emulate real life trim on a simulation system that uses
spring centered control sticks isn't going to work like real life
as you may already know.

Should I post the spoiler on how a couple other mechanisims work
(besides servo tabs)?

I'll raise you one to make three additional trim systems. Any more?

I can think of four for a total of five, depending on whether you'd
consider hydraulic centering to be the same as a bungee trim system.
theothersa re of course, a tab system which is th emost common light
aircraft system. the trimmable stab, a'la Cub and most airliners and
the vane, like some early T-carts had.. There're probably some
others, but i can't think of any.

I'd count that as the same -the acutuating system doesn't count, just
the aerodynamic priciples. So, if you have four I'll raise you again
one to make five... Any raise on five basic methods?

Yeah, they;re essentially the same.

Go on. I'll call.


Should'nt we wait to see if there's any other raise?

Cheers

on 6/8/2008 4:39 PM More_Flaps said the following:
On Jun 9, 9:24 am, Bertie the Bunyip wrote:
More_Flaps wrote :





On Jun 9, 9:06 am, Bertie the Bunyip wrote:
More_Flaps wrote
innews:64b157a9-99f5-4429-9125-d1e2
:
On Jun 9, 7:29 am, "Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way
D0t C0m wrote:
"Le Chaud Lapin" wrote in
messagenews:5c4deac0-2b92
...
On Jun 8, 11:07 am, "Robert M. Gary" wrote:
On Jun 7, 10:08 pm, Le Chaud Lapin wrote:
What exactly happens when the trim is adjusted to point the
nose upward?
What type of plane is this for? I have a Mooney and also fly a
182. Both trim system are very, very different.
For sake of those of us who only own MSFS, let's say a C172.
Does MSFS emulate the servo tab on the elevator? What does it do
when you change the trim in the air?
Trying to emulate real life trim on a simulation system that uses
spring centered control sticks isn't going to work like real life
as you may already know.
Should I post the spoiler on how a couple other mechanisims work
(besides servo tabs)?
I'll raise you one to make three additional trim systems. Any more?
I can think of four for a total of five, depending on whether you'd
consider hydraulic centering to be the same as a bungee trim system.
theothersa re of course, a tab system which is th emost common light
aircraft system. the trimmable stab, a'la Cub and most airliners and
the vane, like some early T-carts had.. There're probably some
others, but i can't think of any.
I'd count that as the same -the acutuating system doesn't count, just
the aerodynamic priciples. So, if you have four I'll raise you again
one to make five... Any raise on five basic methods?
Yeah, they;re essentially the same.

Go on. I'll call.

Should'nt we wait to see if there's any other raise?

Weight shift?

On Jun 8, 3:39 pm, More_Flaps wrote:
On Jun 9, 9:24 am, Bertie the Bunyip wrote:



More_Flaps wrote :

On Jun 9, 9:06 am, Bertie the Bunyip wrote:
More_Flaps wrote
innews:64b157a9-99f5-4429-9125-d1e2
:

On Jun 9, 7:29 am, "Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way
D0t C0m wrote:
"Le Chaud Lapin" wrote in
messagenews:5c4deac0-2b92
...
On Jun 8, 11:07 am, "Robert M. Gary" wrote:

On Jun 7, 10:08 pm, Le Chaud Lapin wrote:

What exactly happens when the trim is adjusted to point the
nose upward?

What type of plane is this for? I have a Mooney and also fly a
182. Both trim system are very, very different.

For sake of those of us who only own MSFS, let's say a C172.

Does MSFS emulate the servo tab on the elevator? What does it do
when you change the trim in the air?

Trying to emulate real life trim on a simulation system that uses
spring centered control sticks isn't going to work like real life
as you may already know.

Should I post the spoiler on how a couple other mechanisims work
(besides servo tabs)?

I'll raise you one to make three additional trim systems. Any more?

I can think of four for a total of five, depending on whether you'd
consider hydraulic centering to be the same as a bungee trim system.
theothersa re of course, a tab system which is th emost common light
aircraft system. the trimmable stab, a'la Cub and most airliners and
the vane, like some early T-carts had.. There're probably some
others, but i can't think of any.

I'd count that as the same -the acutuating system doesn't count, just
the aerodynamic priciples. So, if you have four I'll raise you again
one to make five... Any raise on five basic methods?

Yeah, they;re essentially the same.

Go on. I'll call.

Should'nt we wait to see if there's any other raise?

Cheers

Some sailplanes, some ultralights and a few other light
aircraft use bungees or springs in the elevator control system.
Adjusting the tension of the bungee or spring will apply appropriate
force to the elevator system to achieve trim.

Tabs are most common. Some ultralights have a ground-adjustable
tab. Others use a chain-and-cable arrangement that work a small
jackscrew inside the stab that pushes and pulls a rod attached to the
tab. Cessna likes that one. Taylorcraft used a crank that drove a
cable loop that worked a pulley that had a thread through it, and ran
a screw back and forth to work a shorter push-pull cable to the tab,
IIRC. Some just use a long push-pull Bowden cable directly from a
lever to the tab. Champs/Citabrias use a lever that works two 1/16"
cables directly to the tab, via pulleys. Some homebuilts use an
electric jackscrew to work the tab. Electrical failure means no trim.

Adjustable stabilizers are not uncommon. The Supercub and Tri-
Pacer use them but also have a bungee affair that applies tension to
the elevator cables. Two systems in one airplane. The Cessna 180/185
adjusts the stab via two jackscrews at the leading edge, operated in
unison by sprockets and a chain diven by a cable loop.

I once saw somewhere a light aircraft (homebuilt ultralight, I
think) that had its battery on a sliding device that moved fore-and-
aft to change the CG and therefore trim. This sort of thing adds
unacceptable weight.

Stabilators use adjustable antiservo tabs. That tab has a lever
on it whose forward end is hinged at a point behind the stab hinge to
get the desired antiservo action, and that hinge point is on a nut
moved fore and aft by a jackscrew to get the trim action.

Mooneys used to move the WHOLE TAIL, fin and stab and all, to
change the angle of the stab. Do they still make them that way?

The Spratt Controlwing moved the wings for all control
including trim. The tail did nothing but keep the nose pointed into
the wind. See http://www.flyingflea.org/docs/SprattControlwing.htm

Didn't the Wren 260 use a small canard for low-speed trim?
http://en.wikipedia.org/wiki/Peterson_260SE

Dan

On Jun 8, 7:06 pm, wrote:
On Jun 8, 3:39 pm, More_Flaps wrote:



On Jun 9, 9:24 am, Bertie the Bunyip wrote:

More_Flaps wrote :

On Jun 9, 9:06 am, Bertie the Bunyip wrote:
More_Flaps wrote
innews:64b157a9-99f5-4429-9125-d1e2
:

On Jun 9, 7:29 am, "Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way
D0t C0m wrote:
"Le Chaud Lapin" wrote in
messagenews:5c4deac0-2b92
...
On Jun 8, 11:07 am, "Robert M. Gary" wrote:

On Jun 7, 10:08 pm, Le Chaud Lapin wrote:

What exactly happens when the trim is adjusted to point the
nose upward?

What type of plane is this for? I have a Mooney and also fly a
182. Both trim system are very, very different.

moved fore and aft by a jackscrew to get the trim action.

Mooneys used to move the WHOLE TAIL, fin and stab and all, to
change the angle of the stab. Do they still make them that way?


You're right, Dan -- through at least the Mooney 201 (M20J) there are
no trim tabs, the entire tail pivots to change the trim.

On Jun 8, 6:06*pm, wrote:
On Jun 8, 3:39 pm, More_Flaps wrote:

A very detailed responsed mostly snipped...

Since you response is very detailed, more than I was expecting, I
should say that I was primarily interested answers about why it is
that setting trim relieves pressure that pilot has to exert on yoke.

I mentioned in response to Geoffrey's post that aircraft under
question could be consider C172, whose trim mechanism is obvious, but
if one were to talk too much about that part which is obvious, then
one might inadvertently give the answer away.

Again, this isn't rocket science, but I suspect that other students,
like I, had misconception of how it might work, even though it is
written in the book how it should work.

-Le Chaud Lapin-

Hi.

In article ,
Le Chaud wrote:
Again, this isn't rocket science, but I suspect that other students,
like I, had misconception of how it might work, even though it is
written in the book how it should work.

A student who's actually sat in an aircraft and carried out the pre-flight
should have little doubt as to what moving the trim wheel actually does.

In the Warrior I fly, we're taught to put in full back elevator, then wind
the trim through the limits of its travel, watching the trim tab to ensure
it moves as it should.

Similarly, in the 'Aircraft General and Principles of Flight' exam we have
to sit in the UK, the operation of trim is expected to be understood.

Andy

On Jun 9, 3:26*am, Andy Hawkins wrote:
Hi.

In article ,
* * * * * *Le Chaud wrote:

Again, this isn't rocket science, but I suspect that other students,
like I, had misconception of how it might work, even though it is
written in the book how it should work.

A student who's actually sat in an aircraft and carried out the pre-flight
should have little doubt as to what moving the trim wheel actually does.

In the Warrior I fly, we're taught to put in full back elevator, then wind
the trim through the limits of its travel, watching the trim tab to ensure
it moves as it should.

That's interesting. How do you see the trim tab fromm the cockpit?

I've been in Tomahawk and DA-20. I did preflight on DA-20, but didn't
test trim.

Similarly, in the 'Aircraft General and Principles of Flight' exam we have
to sit in the UK, the operation of trim is expected to be understood.

-Le Chaud Lapin-

Hi,

In article ,
Le Chaud wrote:
That's interesting. How do you see the trim tab fromm the cockpit?

Umm...you move your head?

On a PA28, the trim tab runs most of the length of the moving tailplane.
Pull the yoke back with your left hand, look over your left shoulder and
move the trim wheel through the extent of its travel with you right hand and
watch what happens.

I've been in Tomahawk and DA-20. I did preflight on DA-20, but didn't
test trim.

Then you didn't do the pre-flight correctly.

Andy

More_Flaps wrote in
:

On Jun 9, 9:24*am, Bertie the Bunyip wrote:
More_Flaps wrote
innews:d998f060-3e6a-4b62-8179-88af
:





On Jun 9, 9:06*am, Bertie the Bunyip wrote:
More_Flaps wrote
innews:64b157a9-99f5-4429-9125-d1e2
:

On Jun 9, 7:29*am, "Capt. Geoffrey Thorpe" The Sea Hawk At Wow
Way

D0t C0m wrote:
"Le Chaud Lapin" wrote in
messagenews:5c4deac0-2b92
...
On Jun 8, 11:07 am, "Robert M. Gary" wrote:

On Jun 7, 10:08 pm, Le Chaud Lapin
wrote:

What exactly happens when the trim is adjusted to point the
nose upward?

What type of plane is this for? I have a Mooney and also fly
a 182. Both trim system are very, very different.

For sake of those of us who only own MSFS, let's say a C172.

Does MSFS emulate the servo tab on the elevator? What does it
do when you change the trim in the air?

Trying to emulate real life trim on a simulation system that
uses spring centered control sticks isn't going to work like
real life as you may already know.

Should I post the spoiler on how a couple other mechanisims
work (besides servo tabs)?

I'll raise you one to make three additional trim systems. Any
more?

I can think of four for a total of five, depending on whether
you'd consider hydraulic centering to be the same as a bungee trim
system. theothersa re of course, a tab system which is th emost
common light aircraft system. the trimmable stab, a'la Cub and
most airliners and the vane, like some early T-carts had..
There're probably some others, but i can't think of any.

I'd count that as the same -the acutuating system doesn't count,
just the aerodynamic priciples. So, if you have four I'll raise you
again one to make five... Any raise on five basic methods?

Yeah, they;re essentially the same.

Go on. I'll call.


Should'nt we wait to see if there's any other raise?

Cheers

Would a 100% computer controlled system like the B2 count as yet another
way? Do they even have to trim it or does the computer automatically
adjust for whatever flight regime they set?

--
Marty Shapiro
Silicon Rallye Inc.

(remove SPAMNOT to email me)