How much do you trim?

"Mxsmanic" wrote in message

A) Buy a book.

or

B) Pay a flight instructor for an hour, and ask him.

In article ,
Mxsmanic wrote:

How much do you trim?

For myself, not too much off the sides and just a tidy up at the back.

For my sim - a piece of card under the offending desk leg usually works
just fine.

For my plane - it's complicated to explain but easy to do - you learn
about it during flight training.

Tony

transpose Tony and "you're becoming a pain in the ass" to reach me by
email.


--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE

I flew a J-3 Piper Cub, which has a crank handle (actually the window
handle from a Model A Ford, I believe) lower left where it can be
reached from front or rear seat. While it's possible to fly without
trimming, it's annoying to continually hold stick pressure, and I
think it's a bit dangerous on landing and even on takeoff. At those
times you want a 'nice' feel for the stick, which is spoiled if you
are holding it fore or aft in order to get neutral (if you follow!).

Basically, I check the position of the stabiliator (pitch trim on the
Cub is done by moving the front of the horizontal stabilizer up and
down--with an automobile jack worm!) while doing my preflight
walkaround. My pre-takeoff checklist is CIGARS, with the A standing
for Attitude, and at that letter I eyeball the trim indicator. I have
on rare occasions adjusted the trim in the course of taking off, if I
find myself holding forward stick in order to stay about say 50 mph on
the airspeed indicator.

I trim for level flight after I've finished the climb. Most of the
time that's full forward, and sometimes full forward isn't enough and
I hold a bit of forward stick.

And I trim for glide when I cut my power on the downleg opposite the
numbers. The object is to glide at 60 mph on the airspeed indicator;
that's neutral trim with the power off.

I did some training at Chandler AZ in a Super Cub, and the instructor
insisted that I stop trimming on landing. I didn't like it much, and
as soon as I was alone I reverted to going to neutral trim on every
downwind. (I suppose he was having me adjust the power on each leg of
the pattern, so I was adjusting trim on downwind, base, and final.)

No rudder or aileron trim on the Cub.

Cubdriver usenet AT danford.net writes:

I trim for level flight after I've finished the climb. Most of the
time that's full forward, and sometimes full forward isn't enough and
I hold a bit of forward stick.

Why do you need full forward for level flight? Doesn't that imply a
badly placed center of gravity? If the aircraft is just that way, it
sounds a bit dangerous if you have to hold it like that just to stay
level.

If you let go with neutral trim, what happens?

I did some training at Chandler AZ in a Super Cub, and the instructor
insisted that I stop trimming on landing. I didn't like it much, and
as soon as I was alone I reverted to going to neutral trim on every
downwind. (I suppose he was having me adjust the power on each leg of
the pattern, so I was adjusting trim on downwind, base, and final.)

See, if I spend time adjusting trim during those phases of flight, I
lose track of everything else. I suppose it might be easier to adjust
trim on some real aircraft, but from what I've seen of the placement
of trim controls, it doesn't seem likely. I'd be afraid of getting
distracted by trim when I should be looking at other things, like the
tree approaching my windshield.

No rudder or aileron trim on the Cub.

What about torque effects and stuff like that?

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

Mxsmanic wrote:
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?

You can compare the trim thing a bit like changing gears in a car.
One knows where the gear lever is without looking and you know what to
do without thinking(release accelorator, press clutch, change gear,
release clutch while rev up engine)
Trimming a plane is about the same when it comes to distraction and
attention needed.

-Kees.

Just about every time I touch the throttle or tweak my altitude.
--
Gene Seibel
Gene & Sue's Aeroplanes - http://pad39a.com/gene/planes.html
Because we fly, we envy no one.


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 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?

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