New Pilot, new to forum - trim question

Morne

Morne

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Morne
Hi everyone!

Been lurking for awhile. Just got my PPL and High-Performance endorsement recently. Mostly trained in a 172, just bought a 182E and am getting used to it.

I've flown with 3 different instructors now, and seem to learn a lot every time I get a new CFI in the right seat. But there are some contradictory things. So for my 1st post, I'll ask this:

When in the pattern and slowing down do you just use the elevator trim or do you pull back on the yoke and then trim to alleviate the pressure?
 
I had to think about what I do. There is no real right or wrong, there are several ways. I pull the power back, and pull on the yoke to keep the pattern alt., as my desired speed nears i trim to relieve pressure then apply flaps and never trim again. In a 150 or `72 trim at 80 (mph in c150 & knts in a 172) before flaps in, seems to give me acceptable control pressures to touch down. I fly a Cherokee 180 different, trimming at 80 knts but after 10 degree of flaps. again getting acceptable control pressures. Simple but it seems to give me a good feel for a smooth landing. Those are the 3 planes I have any experience in. You will have to conform to your current CFI's way of doing things for training, but knowing more ways to get the job done is a plus for you.Dave
 
Here's an answer you'll see a lot. - It all depends. The basics are that when you pull the power the airplane will descend and maintain the same airspeed. You want to maintain the altitude and reduce the airspeed. So you reduce power but add up-elevator (by hand or with trim) until you get the result you want.

In a lot of the airplanes I've flown, reducing the power induces an immediate nose-down pitch moment... in those, I have to add back-pressure right away, and then trim comes in.

But in others, the airplane starts descending in a fairly flat attitude, and for those, I can just pull the throttle out and roll in the trim at the same time.

In both cases, what the pax feel is a gentle deceleration, not a roller-coaster down-and-up ride.

It comes with practice.
 
Morne said:
Hi everyone!

Been lurking for awhile. Just got my PPL and High-Performance endorsement recently. Mostly trained in a 172, just bought a 182E and am getting used to it.

I've flown with 3 different instructors now, and seem to learn a lot every time I get a new CFI in the right seat. But there are some contradictory things. So for my 1st post, I'll ask this:

When in the pattern and slowing down do you just use the elevator trim or do you pull back on the yoke and then trim to alleviate the pressure?
Click to expand...

It's bad form to fly with the trim. The controls are for that. The trim is to remove unacceptable control forces.

The syllabus, as taught in Canada and probably in the US, is APT and PAT. In levelling off from a climb or entering a climb, us APT: Set the Attitude first using elevator, wait for the target airspeed, then set the Power for the regime you are entering, and only then Trim to remove the pressure. Heavier airplanes will need some trim relief as the airspeed is rising. PAT (power-attitude-trim) is for entering or levelling off from descent.

When I was instructing I often had to deal with the bad habit of simultaneouly levelling off and reducing power after a climb. The student would then set the trim, and the airplane would slowly accelerate toward the cruise speed and its nose would rise. The student would mess with the trim some more. And then some more. The whole flight would be up and down, never getting stabilized. I would slow the airplane, add full power, show him what the sequence was and how nice and level the airplane would cruise that way.

http://www.tc.gc.ca/eng/civilaviation/publications/tp975-partii-ex7-5326.htm

Dan
 
I trim so as to make the aircraft fly in an attitude I want.

Trim is your friend. The 172/182 can be flown with nothing more than your feet, throttle and trim.
 
Morne said:
When in the pattern and slowing down do you just use the elevator trim or do you pull back on the yoke and then trim to alleviate the pressure?
Click to expand...
Why not both? You can anticipate the need for nose up trim when you reduce power to slow down and then fine tune the trim as things stabilize by sensing and eliminating control pressure. That's not the same thing as "flying with the trim", which is a bad habit that's likely to leave you with at least a subconscious impression that you can't make the plane do what you want unless it's trimmed.
 
Morne said:
When in the pattern and slowing down do you just use the elevator trim or do you pull back on the yoke and then trim to alleviate the pressure?
Click to expand...

Depends on how bad my airspeed control is that day. ;)

Seriously though, yoke is primary -- put the airplane where you want it to be first, trim away control forces next.

But on a good day you're doing it in unison.

If the trim fails you still put the airplane where it needs to be, control pressures be damned. ;)

An electric trim on the yoke is nice for this, but few have it. And it'll ruin your whole day and make you wish you were a weightlifter at the gym when it runs away and won't stop. ;)
 
I teach folks to reduce power with the throttle hand while raising the nose with the stick/yoke hand so altitude is maintained while the plane decelerates, and then using the throttle hand to trim to alleviate stick/yoke pressure. If you have electric trim, there's no reason not to use that with your stick/yoke hand thumb to trim nose up while bringing the throttle back, but otherwise, you have to hold the nose up with one hand while the other hand is moving from throttle to trim. Otherwise, the nose will drop and altitude will be lost before you can get that non-flying hand from the throttle to the trim. And if you trim before you reduce power, then the nose will come up and you'll both climb and lose speed before power is reduced unless you hold the nose down with the stick/yoke, and that seems a clumsy technique.
 
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Morne- Welcome to the board!

I like to get the plane at the speed/attitude I want, then trim away control pressures. I admit that on a C152 or C150, I'll only trim in cruise, but the controls are very light on that plane, but I'll trim on a C172
 
My primary instructor was pretty adamant that the yoke and the throttle were the primary controls, period. The trim and flaps are just there to make flying more pleasant.

So to answer the question you asked, I'd say you use the yoke to slow down then trim away the pressure.

However, in reality for your bird you will learn how much control input you need to do your maneuvers. Eventually, yoke, throttle, trim, and flap settings will become coordinated control inputs. There won't really be a specific order.

I tend to do a lot of trim changes in my plane, because it has pretty heavy control forces. But, I have enough hours in the plane to know exactly how many turns of trim are required when I slow to pattern speed, pull the flap handle, etc.
 
Morne said:
When in the pattern and slowing down do you just use the elevator trim or do you pull back on the yoke and then trim to alleviate the pressure?
Click to expand...
How can you 'just use the trim'? Do you mean make small throttle changes with trim changes in between, or what?
Makes me wonder if you used the trim much in the 172. Students can get to the PP level without really using the trim much, just gross pressure relief, but not really trimming as power/speed changes, as you will have to do in a heavier airplane like the 182.
 
nosehair said:
How can you 'just use the trim'? Do you mean make small throttle changes with trim changes in between, or what?
Makes me wonder if you used the trim much in the 172. Students can get to the PP level without really using the trim much, just gross pressure relief, but not really trimming as power/speed changes, as you will have to do in a heavier airplane like the 182.
Click to expand...
In the 172 I was taught to pull all power when abeam of the numbers, give 3 nose-up turns on the levator trim wheel and then deploy 10-degrees of flaps once in the white arc. Turn base, go to 20-degrees. Turn final, go to 30 degrees. Wait until the runway is made, then put 40-degrees flaps down and land it.

It worked.
 
I tend to lead with trim, but I know the trim settings for the various flight regimes.
 
nosehair said:
How can you 'just use the trim'? Do you mean make small throttle changes with trim changes in between, or what?
Makes me wonder if you used the trim much in the 172. Students can get to the PP level without really using the trim much, just gross pressure relief, but not really trimming as power/speed changes, as you will have to do in a heavier airplane like the 182.
Click to expand...

You can fly a 172 all over the place using only trim and power for pitch and the doors for yaw/roll.

A student getting to the PP level without using trim, in my eyes, isn't flying the plane, he's fighting it.

Trim can just as easily kill you. There was a change in the T-2 stall procedure after my pops was almost killed by a large Marine who during the stall, pulled the stick into his chest and while doing that the coolie hat fed all nose up trim and during the stall they wound up in a steep spiral and then upside down in a flat spin (I believe, don't remember the exact details) One of the few times my pops thought about punching. After that event, they started turning the coolie hat trim off for stalls.
 
Morne said:
In the 172 I was taught to pull all power when abeam of the numbers, give 3 nose-up turns on the levator trim wheel and then deploy 10-degrees of flaps once in the white arc. Turn base, go to 20-degrees. Turn final, go to 30 degrees. Wait until the runway is made, then put 40-degrees flaps down and land it.

It worked.
Click to expand...

As you build time in type you'll find a technique that works best for you.

Each airframe is a little different, as is manual vs. electric trim, and the conditions you find yourself in when landing.
 
Steve said:
As you build time in type you'll find a technique that works best for you.

Each airframe is a little different, as is manual vs. electric trim, and the conditions you find yourself in when landing.
Click to expand...
+1. No need for me to say anything other then repeat the above.
 
Morne said:
In the 172 I was taught to pull all power when abeam of the numbers, give 3 nose-up turns on the levator trim wheel and then deploy 10-degrees of flaps once in the white arc. Turn base, go to 20-degrees. Turn final, go to 30 degrees. Wait until the runway is made, then put 40-degrees flaps down and land it.

It worked.
Click to expand...
While power off landings are a good training exercise and will prepare you for the day when you have no other choice, they're not really a good way to land a 172 (let alone a 182). You can and should reduce power abeam the numbers, add flaps and trim up, but I wouldn't regularly close the throttle until I was over the runway.
 
Morne said:
In the 172 I was taught to pull all power when abeam of the numbers, give 3 nose-up turns on the levator trim wheel and then deploy 10-degrees of flaps once in the white arc. Turn base, go to 20-degrees. Turn final, go to 30 degrees. Wait until the runway is made, then put 40-degrees flaps down and land it.

It worked.
Click to expand...
See, that's real rote. You didn't learn to use the trim- you just slapped in a rote number of turns and ...it worked. For that specific situation.

To learn to trim, in general,

You will need to learn to make (feel) elevator pressures changing with power changes and trim the elevator pressure off as you feel it.
 
BellyUpFish said:
Trim is your friend. The 172/182 can be flown with nothing more than your feet, throttle and trim.
Click to expand...

Ain't that the truth! I've landed 152s with nothing more than rudder, power, and trim. Fun little exercise!

In all the light airplanes I've flown, I've personally found it easiest to initially use elevator to hold altitude followed by trim to alleviate pressure. But in reality, I use both almost simultaneously. Reduce power, hold altitude with the yoke while using trim to alleviate the pressure. I suppose that as you get used to your particular airplane it might be just as easy to do the same with nothing more than trim, though. Whatever works for you. :)
 
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