When to use aileron and rudder trim while on cruise?

[oneleg]

Single prop GA planes have a tendency to turn left. 

Assuming the plane does not have an auto-pilot, how do I trim the plane to counter the tendency to roll to the left so as to maintain a straight and steady flight? 

Do I use rudder or aileron trim or use both? If I need to use both, which one do I use first?

[Nels_Anderson]

From my experience, most small GA planes don't have aileron trim. So rudder trim would likely be your first option.

 

Aircraft do vary though, so different planes may warrant a different answer.

[oneleg]

3 hours ago, Nels_Anderson said:

From my experience, most small GA planes don't have aileron trim. So rudder trim would likely be your first option.

 

Aircraft do vary though, so different planes may warrant a different answer.

For single props rudder trims the yaw of the plane.  Will rudder also correct for the roll resulting rfrom the propeller's torque?

I'm trying to fly straight in Just Flight's Turbo Arrow III PA-28R. It keeps wanting to roll to the left.  Now that you mentioned it, I'm not sure if it has aileron trim.



 

[Nels_Anderson]

Your initial query was about a tendency to "turn" left, but now you're asking about a tendency to "roll" left; these are not necessarily the same thing so please do be clear on what you're trying to achieve.

 

I rather doubt the Arrow has aileron trim, but a look at the manual should answer that question.

 

That said, small GA planes that I've flown have never shown a need to counter roll from the prop's torque so I've never seen what you are experiencing. Maybe someone more familiar with higher power planes will have a better answer.

[nbenford1837]

I did my commercial in a Piper Arrow and I never once touched the trim. GA aircraft are designed to not require control input to keep the aircraft coordinated during cruise flight. You need right rudder on takeoff and climb, and maybe even a bit of left rudder on descent, but no rudder should be needed during cruise.

 

That being said, I have flown a couple of beat-up 172s that needed a little rudder pressure in situations that shouldn't have needed it. That's something the mechanics need to fix.

 

But none of the left-turning tendencies have much effect during unaccelerated, level flight. You usually encounter them in slow, high-AOA, high-power flight, at least in a Piper Arrow. It's not a P-51.

[terrylawdinn]

In real life an aircraft - and I'm talking about prop GA types here - are rigged to fly straight and level at a certified cruise/power setting without control input. Inevitably things get  a little out of kilter (minor damage we called "hangar rash") and until an engineer sorted it a bit of trim, if available, would be required to keep it straight and level.

 

Also any changes to the cruise/power settings would also cause changing trim e.g. increased power (usually) results in a nose up change and maybe a small lateral change due to gyroscopic effects of the propeller.

 

In the sim, however, the trim is very dependant upon how the developer has set it up ,i.e. he/she has become the engineer who rigs the aircraft. Adding a trim control, even if the real-life aircraft doesn't actually have that facility, is a way of compensating.

 

If your sim aircraft has rolling tendencies try changing your power settings - if the dev has constructed it properly this should have the same effect as IRL. You should also check to see if there is any advice about what your power settings should be.