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I am a new private pilot in training. I've only had about two hours of flight lessons so far, so I'm still quite new to this.

In a single engine, PA-28-181 Archer, I found that the plane has a natural tendency to bank left. I did some digging and people have noted this is due to the spin of the propeller and is natural.

But that meant that holding the control wheel in neutral position caused the plane to turn left so I had to constantly keep it tilted to the right.

My question is as follows:

  1. Assuming no trim, should I constantly keep my foot on the right rudder to correct for this?
  2. If I apply trim, will it correct for the roll or does it only stabilize pitch?

I noticed that at some points in my flight, when the instructor had me trim, the plane no longer veered left. But as soon I had to change attitude, the plane had a tendency to turn left and I had to re-trim. So I'm guessing the trim will correct for roll? But when I read about trim online, documents say that it only helps to maintain equilibrium attitude.

Bit confused on the proper/best procedure here. Any advice is greatly appreciated.

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Always use rudder to keep the slip skid ball centered. Except when taking off and landing in crosswinds, that's all you ever do with it. If the airplane rolls with the slip/skid ball centered, that's a bummer because it needs some aileron trim and there is only a fixed tab that you can't adjust until you're back on the ground.

For adjustable trim, the Archer has a trim tab on the stabilator surface for pitch/speed trim (doing double duty as an anti-servo tab to provide desirable pitch feel forces), and a bungee (spring) trim for the rudder control, operated by the black knob below the throttle quadrant by the passenger's left knee. Here, we are only really concerned with the rudder trim.

The trim bungee provides a mechanical centering force to the rudder cable circuit that can be adjusted within a small range each side of actual center. When you're flying, you crank the knob to center the skid ball.

If the skid ball is to the right, requiring you to hold right rudder to center the ball, you crank the knob clockwise, which squeezes a bit of right rudder for you so you can stop squeezing the pedal with your foot (you could take a bungee cord from the hardware store, hook it over the left rudder pedal, and pull some tension on it to apply some right rudder input - it's pretty much what the internal trim bungee is doing).

So in general, you just twiddle the knob as required to center the ball so you can relax your feet. If the ball is off center, you can expect the airplane to want to roll away from the ball (ball to the right, left rolling tendency).

The Piper Cherokee family has a fairly strong rolling tendency when skidding, which is why they put the rudder trimmer in there in the first place; most light planes don't bother with rudder trim except for a ground adjustable only tab on the rudder that is normally bent (by trial and error) so as to center the ball in cruise flight.

When you have the ball centered nicely with no foot pressure with the trim knob, and you make speed/attitude changes, and power changes, it tends to change the equilibrium point in yaw so you will find that significant changes make the ball move from where you've trimmed it.

If the change is temporary and you'll be returning to your original power setting and speed, say in the next minute or two, you don't bother and just squeeze rudder with your foot knowing that you can relax it in a minute or two, but if the change is longer term, just turn the knob again to center the ball so you don't have to hold pressure with your foot.

So to answer your questions:

  1. You should be always holding whatever rudder is needed to center the ball. Without the Archer's rudder trim, you would have to hold this rudder pressure continuously except at one particular power and speed. So 3 cheers for the adjustable rudder trim. Use the trim for any changes that are more than temporary so you don't have to squeeze the pedal all the time.
  2. In the Cherokee family, keeping the ball centered will minimize rolling tendency, so it should fly straight hands-off if you have the trim set to center the ball. If the airplane rolls with the ball centered and needs aileron pressure to fly straight, in the normal cruising power setting and speed, the fixed tab on the aileron needs to be adjusted (bent up or down as required).

At some point your instructor will start having you practice using the rudder trim knob. They're just waiting until you've internalized some of the basics first.

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You really should talk to your instructor about this. Compensating for the inherent turning tendencies of propeller planes is a pretty basic skill that you should learn fairly early in your training. But, to answer your specific questions:

Assuming no trim, should I constantly keep my foot on the right rudder to correct for this?

In general, yes, that's the proper technique. Of course, your plane may be different, so check with your instructor or the POH.

Many small airplanes have a tab on the rudder that's supposed to do that for you when in cruise flight. If you find that you're having to maintain pressure in cruise, that tab may need to be adjusted. That's not going to be much help in other phases of flight, though, so you're still going to have to manually compensate.

If I apply trim, will it correct for the roll or does it only stabilize pitch?

Depends on what kind of trim you have. Most small airplanes only have pitch trim, which isn't going to help the turning tendencies any. If your airplane has roll or yaw trim, then, yes, those could be used to help.

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To a first approximation, the most efficient technique is to apply right rudder as needed to center the slip-skid ball, and apply bank as needed to counteract any remaining turning tendency.

In most aircraft, if you keep the wings level and apply rudder as needed to hold heading, you'll get essentially the same result-- the ball will be centered or nearly so, and the aircraft will be flying in a straight line.

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