How much do you trim?

What I see in the literature seems to vary between warnings against
spending too much trim or flying with trim tabs, and not ever trimming
the aircraft at all. So how much and when should I trim?

I understand trim to be a convenience, so that a pilot doesn't have to
constantly maintain force against the controls for long periods. Thus
it should never be dangerous not to trim, except insofar as it can be
tiring to hold an untrimmed aircraft in a given attitude for long
periods.

The thing I wonder about is the possible distraction of trimming the
aircraft. It looks like trim controls are often in spots like the
pedestal or throttle quadrant, where presumably one must direct one's
attention in order to adjust trim. It's hard to imagine doing this
during critical phases of flight such as take-off or landing, and yet
I read recommendations for trim in both cases. Where do you draw the
line between trimming unnecessarily and not trimming enough? How
often do you actually reach for the trim controls?

Also, it seems that most trim is pitch trim. I don't see much mention
of aileron or rudder trim. Do you use it? Do you ever trim out
P-factor or torque effects? I turned both back on in my sim and
adjusted them to where the vendor says they should be to match the
real aircraft, and I find them irritating, but not overwhelming (the
vendor has apparently set the most realistic factors at 50% instead of
100%, so that masochists can increase their effects beyond real life
if desired).

Another problem I have: How do you remember where you set the trim?
I know you can look, and I know that you can guess if the aircraft is
behaving strangely, but how do you keep track of where you last set
the trim? Each time I set it I tend to forget about it until some
important moment when I'm already busy with other things.

Also, I presume that most autopilots use trim for pitch control. If
you shut off the autopilot, does the trim remain whereever the A/P set
it? If so, do you change it? Is it hard to remember that the A/P has
probably changed it?

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On Mon, 09 Oct 2006 10:05:20 +0200, Mxsmanic wrote:

What I see in the literature seems to vary between warnings against
spending too much trim or flying with trim tabs, and not ever trimming
the aircraft at all. So how much and when should I trim?

I haven't trimmed in about two years. Plane doesn't have cockpit-adjustable
trim. I just bend the metal tabs on occasion.

Ron Wanttaja

Ron Wanttaja wrote:

Plane doesn't have cockpit-adjustable
trim. I just bend the metal tabs on occasion.

I see how that makes sense with an open cockpit and all, but how do you
reach all the way back there when you're flying?

ba dum chhhh

Tom Young

Trim every time you change pitch. Trim when needed even in level
flight. Basically, you trim whenever you need it, and that is fairly
often. IDEAL airplane would have trim in all three axis, but most small
GA don't.

Doug writes:

Trim every time you change pitch. Trim when needed even in level
flight. Basically, you trim whenever you need it, and that is fairly
often.

So how do you know when you need it?

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If you can't let go of the stick without starting to climb or descend, you
need it. This is the thing I always had trouble with in sims, especially
with a cheap stick that didn't have trim on it.

mike

"Mxsmanic" wrote in message
...
Doug writes:

Trim every time you change pitch. Trim when needed even in level
flight. Basically, you trim whenever you need it, and that is fairly
often.

So how do you know when you need it?

--
Transpose mxsmanic and gmail to reach me by e-mail.

mike regish wrote:
If you can't let go of the stick without starting to climb or descend, you
need it. This is the thing I always had trouble with in sims, especially
with a cheap stick that didn't have trim on it.

Some aircraft like a 152, you could go a long time without trimming.
It's quite easy to hold pitch without even trying. Others are a
bit more demanding. I got to fly a Republic Seabee the other day.
Believe me, you want to retrim that puppy. It takes a lot of force
to hold her when she's out of trim. Other aircraft it's a convenience.

And I can tell you, I got used to the electric trim in the Navion
real fast.

On Mon, 09 Oct 2006 16:55:16 +0200, Mxsmanic
wrote:

So how do you know when you need it?

Plane doesn't fly straight & level. Wants to lose altitude, less often
to gain altitude. Or in a climb, wants to climb at an angle
approaching stall. Or in a landing, wants to dive instead of glide.

The great thing is to be able to hold the stick so lightly that your
fingers aren't really touching it; the plane flies itself.

(Can't speak for those planes with steering wheels

Not for nothing is it called a joystick!

Cubdriver wrote:
On Mon, 09 Oct 2006 16:55:16 +0200, Mxsmanic
wrote:

So how do you know when you need it?

Plane doesn't fly straight & level. Wants to lose altitude, less often
to gain altitude. Or in a climb, wants to climb at an angle
approaching stall. Or in a landing, wants to dive instead of glide.

The great thing is to be able to hold the stick so lightly that your
fingers aren't really touching it; the plane flies itself.


The thing MXMANICDEPRESSIVE won't ever see with his simulator is
how heavy the control forces will get with an out of trim aircraft.

"Ron Natalie" wrote in message
...
Cubdriver wrote:
On Mon, 09 Oct 2006 16:55:16 +0200, Mxsmanic
wrote:

So how do you know when you need it?

Plane doesn't fly straight & level. Wants to lose altitude, less often
to gain altitude. Or in a climb, wants to climb at an angle
approaching stall. Or in a landing, wants to dive instead of glide.

The great thing is to be able to hold the stick so lightly that your
fingers aren't really touching it; the plane flies itself.


The thing MXMANICDEPRESSIVE won't ever see with his simulator is
how heavy the control forces will get with an out of trim aircraft.

I forgot to set the trim to neutral once before takeoff in a C-172
(accidently skipped over it on the checklist), with my instructor on
board... started down the runway, hit 55kts, and went to pull back to
rotate, and was like "Wow!!! This is a lot heavier than normal!!!!" kind of
like when you do touch and goes, and kind of thought to myself that my
instructor had one too many doughnuts lately... Got the plane off the
ground and climbing... Then I guess my brain was quickly rationalizing what
could cause it to be so heavy, and glanced down and saw it had a fair amount
of nose down trim (probably from the person who landed it before me), and
went "Oh Crap!!!... forgot the trim!!!", and quickly took out a bunch of the
nose down trim... :-) Was much easier to fly then. :-) You can bet I
check that now everytime before take off. :-) You don't get this
experience (how hard it is to pull the plane off the ground) in MSFS, and
same for steep turns, first time I did steep turns (in C-172) I was shocked
at how hard you have to pull on the elevator to maintain altitude, it seemed
like it was probably at least a good 10 lbs, probably more.

Reason I say it felt like when you do touch and goes, is you typically don't
have time to reset the trim during a touch and go and kind of have to
wrestle the plane off the runway and trim during the climb... Or at least I
was not taught to reset the trim during a touch and go (while rolling on the
ground), but taught to trim while climbing out, probably because if you
reset it while on the ground you actually have to look down and a lot can
happen in those few seconds you aren't looking out the windshield, and
during the climb you can trim without having to look at the trim wheel and
beside if you set it you will more than likely have to retrim on the climb
anyway.

Wade Hasbrouck
PP-ASEL
http://spaces.live.com/wadehas