Trim Control (level Flying)

[TapA321 0]

Hi all,

A question for anyone here with real-world flying experience. I've just started training for my PPL, with the first lesson being all about level flying. Using trim effectively and flying straight and level. Did anybody else find it quite tricky at first to get the trim adjustments right? I'm flying in a Piper Warrior PA-28 (161) and the controls are fairly gentle, but I found the trim quite a tough one. Kept over turning it or not turning enough. It was quite bumpy aswell which obviously made it more difficult. Is this something that comes with practice?

Cheers,

George

[allardjd 1,853]

George,

The lighter the AC, the closer to the ground and the more unstable the atmosphere, the busier you'll be with trim. Eventually it becomes second nature and you do it unconciously, almost without a thought. If the right hand is not doing something else, it's probably tweaking the trim wheel, which is infinitely preferable to trying to maintain a constant control pressure against an improperly trimmed AC.

When trimmed right, or nearly so, it allows you to divert more of your attention from holding an altitude or a climb or descent rate, to do some other things. Absent that, you'll never be a "smooth" pilot.

John

[TapA321 0]

John,

Thanks a lot for that. It's early days, but I'm looking forward to when these simple movements come more naturally.

George.

[mutley 4,488]

Hi George,

You are bound to feel reticent at first, but once you get the feel for the aircraft you will be used to the feedback both visual and mechanical and the inputs you need to make will become second nature.

Happy days!!

[TapA321 0]

Joe,

The conversation over the headset sort of went something like this: "Now, George. Where is the pressure to keep the aircraft level?" .. "I'm pulling back to keep it level" ... "OK, so you need to roll the trim lever back" ... "Now I need to push forward on the yoke to keep it level" ... "Ok, well you've pushed a bit too far back, roll forward a little more" ... "Now I'm pulling on the yoke again" ... etc etc etc. :001_th_smiles48:

Cheers,

George

[allardjd 1,853]

I have some friends who made a long trip in a Piper Tri-Pacer once. The guy riding in the back seat relieved the boredom of the long flight by alternately leaning far forward, engaging the front seat pax in conversation and then leaning far back and watching the guy flying try to stay trimmed for level flight.

Remember too that small changes to power and AoA will all effect trim, as will changes in airspeed. Even leaning affects power and thus trim. As you level off in cruise, for instance, as the speed builds, the trim that was about right 30 seconds ago will no longer be so. It takes a while for things to reach equilibrium and you have to tweak, tweak, tweak for a few minutes after a change like that. Also, in a cross country flight fuel burning off can have an effect, as can subtle (or radical) changes in the air mass you're in. If temperature or pressure change, trim well be affected as well. Wind changes will NOT effect trim, except if there's an abrupt transition that creates a shear, when you'll be affected for a short time until the AC comes to equilibrium airspeed in the new air mass it finds itself within.

John

[Tim_A 996]

It's largely a matter of practice until it becomes second nature. Eventually you'll be making minor adjustments without even noticing -- just like keeping a car on the road going in a straight line.

The big tendency, especially when you're starting out, and particularly if it's bumpy, is to over control. Remember it takes a while for the aircraft to settle down to whatever adjustment you've made, so don't be too quick to tweak it some more. The less you tweak, the more stable it will become. Generally, so long as the plane is roughly in trim, you can let go of the controls and it will settle down quite quickly. There may be an initial climb or descent, but the plane "wants" to fly straight and level. And you can tweak that out; just remember small adjustments, and give them time to work through.

Also, the fundamental rule of trim is Power + Attitude = Performance. if you are climbing slightly you can lower the nose (down trim), or you can reduce the power slightly. Both will bring you into trim, although with some other differences which I'll leave for the reader to think about (clue: consider the secondary effects of controls).

[TapA321 0]

Thanks for the help, guys!

Re-reading this section in my PPL book now. Next lesson's on friday, so hopefully there'll be some improvement.

Cheers,

George

[Aircraft Aviation 2]

Hi George,

To be fair, when flying, I spent much too much time with the trim wheel than I should.

When in the cruise, my left hand handles the yoke, and my right hand is often glued to the trim wheel.

I must confess, it works, I can honestly say that my desired pitch is held perfectly. As John has said, it really is second nature. I don't even realise I'm doing it half the time.

Trim is, however, a friend not a foe, and should primarily be used to relieve the physical force on your arms through the yoke.

I fly at Netherthorpe, Warsop, where you have absolutely no room for error. A mistake means you're having a premature smash with a hedge (not surprising when you see that it's the shortest licensed runway in Europe).

Regards,

Jack

[TapA321 0]

Jack,

Thanks for that. Should be helpful for the next lesson, which should take place tomorrow. But since we're forecasted Thundery showers, it will probably be cancelled

Cheers,

George