Mechanics of Elevator Trim. In Detail.

On Jun 9, 10:28*pm, Tina wrote:
Lost and Found

Found:

To the village that has lost its idiot: we've found him.

Ya, 'I'm building an airplane and want to know who the trim works.
Also how do I weld it?'

-Robert

Some students want the first approach, some may want the second - it's
probably 95% to 5%. If you assume they all want the more detailed
explanation for everything, you will have frustrated students who either
think that flying is too complicated for them to learn, or who quit because
they are bored.

When I took driver's ed in high school they didn't explain the inner
workings of a carburetor, nor did they need to in order for me to be able to
learn how to drive. Knowing how a carburetor works and having the ability
to tear one down and put it back together again does not make me a better
driver.

You want to know every detail - fine. You just need to find an instructor
who is willing and able to do that for you. As you know, not all of them
are nor do they need to be in order to be able to teach you to fly and fly
well. I suspect you dispute that fact, but history has already proven you
wrong.



"Le Chaud Lapin" wrote

It is the
instructor's choice to determine how deep s/he should delve into the
mechanics of flight.

One instructor might say, "Move trim wheel up or down to relieve
pressure on yoke."

Another might say, "Trim wheel is connected to a trim tab on elevator,
often located on one side of elevator only, and air moving across
elevator results in aerodynamic force vector on tab that acts on
elevator to position elevator so that point of equilibrium is reached,
and such force being sufficient that you no longer need the yoke to
position the elevator. As you can imagine, speed and orientation of
aircraft will have some effect on force...and therefore position of
elevator. Also, if only one tab, force applies asymetrically to
aircraft...etc."

On Jun 10, 5:04*am, "BDS" wrote:
Some students want the first approach, some may want the second - it's
probably 95% to 5%. *If you assume they all want the more detailed
explanation for everything, you will have frustrated students who either
think that flying is too complicated for them to learn, or who quit because
they are bored.

There were two extreme examples in my ground school (but not in my
class). One had failed written once already, and they other said one
day, "Forget learning...if you want to pass the exam, this is best
tool you can use: gave me link to web site. It has most of the
questions in easy-to-memorize format." I asked them why not just
learn what they need to know, at least enough to get a 70...and they
both frowned as if I has asked them to learn to change diapers.

When I took driver's ed in high school they didn't explain the inner
workings of a carburetor, nor did they need to in order for me to be able to
learn how to drive. *Knowing how a carburetor works and having the ability
to tear one down and put it back together again does not make me a better
driver.

True. I wouldn't expect explanation of GPS in ground school, or
Pascal's principle, etc, but which many situations like this, it
doesn't hurt to know.

You want to know every detail - fine. *You just need to find an instructor
who is willing and able to do that for you. *As you know, not all of them
are nor do they need to be in order to be able to teach you to fly and fly
well. *I suspect you dispute that fact, but history has already proven you
wrong.

No, I do not dispute this. I have learned that flying is like many
other things. It is very possible to get by using mostly manipulation
of that which is presented to you.

-Le Chaud Lapin-

"BDS" wrote in message
...
Some students want the first approach, some may want the second - it's
probably 95% to 5%. If you assume they all want the more detailed
explanation for everything, you will have frustrated students who either
think that flying is too complicated for them to learn, or who quit
because
they are bored.

When I took driver's ed in high school they didn't explain the inner
workings of a carburetor, nor did they need to in order for me to be able
to
learn how to drive. Knowing how a carburetor works and having the ability
to tear one down and put it back together again does not make me a better
driver.

You want to know every detail - fine. You just need to find an instructor
who is willing and able to do that for you. As you know, not all of them
are nor do they need to be in order to be able to teach you to fly and fly
well. I suspect you dispute that fact, but history has already proven you
wrong.

In general, I agree with you--one certainly didn't need to know the inner
workings of the carburetor. However, it could be very usefull to understand
what the throttle (accelerator) return spring did! That sort of information
is in the POH for any aircraft certified under Part 23.

OTOH, the answers to the original question posted by the OP might be
included over the course of an airframe mechanic's curriculum--or might not.

Peter

Le Chaud Lapin wrote in news:6b0f0604-da90-4433-
:

On Jun 9, 1:06*pm, "Robert M. Gary" wrote:
On Jun 9, 9:34*am, Le Chaud Lapin wrote:

MSFS was the means by which I discovered the mechanism.

If I had learned in actual aircraft, the question still would have
been relevant.

I disagree. I've never had a student have trouble understanding trim.
I think this is just something that is confusing for the sim guys. As
such it is more approporiate for a sim group, not a pilot's group.

I never had trouble undestanding it.

Yes, you have and stil do.


Bertie

Le Chaud Lapin wrote:

MSFS was the means by which I discovered the mechanism.

If I had learned in actual aircraft, the question still would have
been relevant.

-Le Chaud Lapin-



You never learned of trim until MSFS and you are going to design an
airplane. Fabulous!

On Jun 9, 1:19*pm, Gig 601Xl Builder
wrote:
Le Chaud Lapin wrote:
MSFS was the means by which I discovered the mechanism.

If I had learned in actual aircraft, the question still would have
been relevant.

-Le Chaud Lapin-

You never learned of trim until MSFS and you are going to design an
airplane. Fabulous!

Is it really necessary to understand the particular way it was done in
C172 to achieve the same result?

The same thing could be achieved using more electronics, less
mechanics, and the controls might be entirely different.

-Le Chaud Lapin-

Le Chaud Lapin wrote:
On Jun 9, 1:19 pm, Gig 601Xl Builder
wrote:
Le Chaud Lapin wrote:
MSFS was the means by which I discovered the mechanism.
If I had learned in actual aircraft, the question still would have
been relevant.
-Le Chaud Lapin-
You never learned of trim until MSFS and you are going to design an
airplane. Fabulous!

Is it really necessary to understand the particular way it was done in
C172 to achieve the same result?

The same thing could be achieved using more electronics, less
mechanics, and the controls might be entirely different.

-Le Chaud Lapin-

Not knowing about trim by someone who thinks they are going to design an
airplane is like someone who wants to be an electrician and doesn't
understand the difference in AC and DC.

It's just another example that you have no business trying to design an
aircraft.

On Jun 9, 3:30*pm, Gig 601Xl Builder
wrote:
Not knowing about trim by someone who thinks they are going to design an
airplane is like someone who wants to be an electrician and doesn't
understand the difference in AC and DC.

It's just another example that you have no business trying to design an
aircraft.

This is a false analogy.

It depends on what is meant by "knowing about trim". The purpose of
trim is clear, and the objective of trim can be achieved in many
ways.

It is not necessary to know all the ways that the objective of trim
can be achieved in order to implement just one mechanism that achieves
the objective.

-Le Chaud Lapin-

On Jun 9, 12:36 pm, Le Chaud Lapin wrote:
On Jun 9, 1:19 pm, Gig 601Xl Builder

You never learned of trim until MSFS and you are going to design an
airplane. Fabulous!

Is it really necessary to understand the particular way it was done in
C172 to achieve the same result?

The same thing could be achieved using more electronics, less
mechanics, and the controls might be entirely different.


#1. Learn to fly first.
#2. Study the construction of aircraft, best done by taking an
aircraft maintenance course.
#3. THEN think about designing an airplane. No worthwhile design that
I'm aware of has ever been put forward by someone who was unfamiliar
with the way things are now and why they are that way, but I have seen
designs built by folks who "knew better" than everyone else. One of
those, built by a local guy who would take no constructive criticism
of his ideas, stalled at circuit altitude and dropped him, hard, on
the surface of the earth. He was such a stubborn guy that he got up
and walked away, but he neither built nor flew any more airplanes.
Needless to say, this design was neither inspected nor approved nor
licensed to any standard whatever.
Adding electronic controls to something like a trim tab on a
lightplane is one of those "better" ideas that has no basis in
reality. It adds complexity, which adds failure points and cost and
weight, none of which are welcome. It is no more accurate than manual
trim.

Dan