On Jun 9, 6:19*pm, "Robert M. Gary" wrote:
On Jun 9, 11:31*am, Le Chaud Lapin wrote:

On Jun 9, 1:06*pm, "Robert M. Gary" wrote:
I think if the book said more about how it worked, there would be no
misunderstanding.

I think if you walked up to an actual airplane there would be no
misunderstanding.

My first experience with trim control was neither with a book or a
plane, but with the instructor. I think there are a lot of things
that students are assumed to know that they do not, which can be
frustrating, as there is no difficult in the concepts, but the
ommission of facts, which hurts more than helps. 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."

Both these explanations are true, but one of them eliminates the need
for $30 product (or $30,000 aircraft) to know what is going on.

-Le Chaud Lapin-