Rudder Trim out of whack

As to what happens if you leave the ball out of center in cruise...

My plane has it, and needs it. On level off I adjust to remove pressure on the peddles. Then I take my feet off the peddles, as the plane continues to accelerate I watch the ball and use the trim to keep the ball perfectly centered. If I were to leave the ball out of the dead center I loose speed. Even having the ball just touching one of the lines costs a couple of knots. If I'm carefull the plane will actually make book speeds. (gasp!)
 
MadseasoN said:
I never said that. I'm not sure that I can agree with that statement about the key element to HP. Can you provide some documentation?

Edit: You're probably right in that it's a key element in HP operation but I'm not sure that it's required as much as elevator trim is. I think it depends on the plane.
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It sure is, and that's why you have rudder trim. 230hp is enough right rudder required in a climb that a 5 minute climb could prove beyond many people's physical limits. High Performance is about working smart in light of forces that can overpower you.
 
j1b3h0 said:
To the OP - Given the scarsity of single-engine airplanes with rudder trim, it's no wonder so few people know how to use it properly. Allow me to explain: If you poke your nose around the Cherokees' little rudder trim adjuster gismo in the cockpit, (down on the floor, between the rudder pedals, if my memory serves) you'll probably see that it has a marked 'takeoff' range...just like most elevator trim wheels. So, just set it for takeoff already. After takeoff, once you're in a nicely (elevator-trimmed, steady speed) climb, you'll probably notice you have to hold - some - rudder pedal pressure to accomodate the outrageous P-factor produced by that monster 235hp engine. You know, just enough pedal pressure to keep the airplane pointing straight, like it's on rails. Note: if a wing feels heavy, it's probably because you aren't holding enough rudder. Could even be left rudder, if you've put too much righ rudder trim prior to takeoff. With me so far? So, while you're keeping the airplane straight, while looking over the nose, slowly reach down - don't look at it, keep looking over the nose - and turn that little black knob so as to reduce what little rudder pressure you're holding on the pedal to zero. Just like you do with the elevator trim...while you're holding the airplane steady, slowly trim the pressure out of the controls. Contrary to some of my fellow posters, I am not a big proponent of using the ball...it can lead you astray. If the wings of the airplane are level - zero bank - AND the heading is constant, the ball should be dead nuts center...if it isn't, the ball is wrong.
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This is great info, I'll try this method.
 
Skylane81E said:
As to what happens if you leave the ball out of center in cruise...

My plane has it, and needs it. On level off I adjust to remove pressure on the peddles. Then I take my feet off the peddles, as the plane continues to accelerate I watch the ball and use the trim to keep the ball perfectly centered. If I were to leave the ball out of the dead center I loose speed. Even having the ball just touching one of the lines costs a couple of knots. If I'm carefull the plane will actually make book speeds. (gasp!)
Click to expand...

Agreed. Uncoordinated flight costs money in fuel. An inclinometer - ball is a handy instrument to have. At a glance one can tell if their machine is in coordinated flight (if the gage is correctly mounted on the instrument panel). My point about using it to trim the rudder is that it's the wrong reference...it would be like using the airpeed indicator to adjust the (elevator) trim. One should seek a pitch attitude that results in the airspeed sought, and then trim - not the other way around. If you have a way to tell the wings are absolutely zero bank, (top of the instrument panel parallel to the horizon, for example) AND keep the heading perfectly straight at the same time, the ball will be perfectly centered. Once you train yourself to see coordinated flight through the windshield, you will have acheived rudder zen.
 
My zen is not as accurate as my TC that I carefully leveled. It's amazing how often you can fix a "misrigged" plane by leveling the TC.

Just as often you can find the plane was flying crooked.
 
j1b3h0 said:
Agreed. Uncoordinated flight costs money in fuel. An inclinometer - ball is a handy instrument to have. At a glance one can tell if their machine is in coordinated flight (if the gage is correctly mounted on the instrument panel). My point about using it to trim the rudder is that it's the wrong reference...it would be like using the airpeed indicator to adjust the (elevator) trim. One should seek a pitch attitude that results in the airspeed sought, and then trim - not the other way around. If you have a way to tell the wings are absolutely zero bank, (top of the instrument panel parallel to the horizon, for example) AND keep the heading perfectly straight at the same time, the ball will be perfectly centered. Once you train yourself to see coordinated flight through the windshield, you will have acheived rudder zen.
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Where's the like button?
 
upstateny said:
Re: Thread Title

If the aircraft was flying straight, ball centered with no rudder needed, why don't we say that it's in whack? Why can things only be "out of whack" but never "in whack"?
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Apparently, at one time President Lincoln was in fine whack.

It appears in a letter by John Hay, President Lincoln’s amanuensis, dated August 1863, which describes the President: “The Tycoon is in fine whack...
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http://www.worldwidewords.org/qa/qa-out2.htm
 
Skylane81E said:
As to what happens if you leave the ball out of center in cruise...

My plane has it, and needs it. On level off I adjust to remove pressure on the peddles. Then I take my feet off the peddles, as the plane continues to accelerate I watch the ball and use the trim to keep the ball perfectly centered. If I were to leave the ball out of the dead center I loose speed. Even having the ball just touching one of the lines costs a couple of knots. If I'm carefull the plane will actually make book speeds. (gasp!)
Click to expand...

I tried to trim my rudder once, but I wasn't accurate enough with the reciprocating saw. If the silly thing would stop growing unevenly, the neighbors wouldn't complain.

Oh wait. That was the hedge.

Seriously though, ditto here. Same technique as Duncan. Can gain or lose 3-4 knots of its out of center in cruise. Only thing I'd add is that I'll do the same routine on the way up in a long slow climb.
 
denverpilot said:
I tried to trim my rudder once, but I wasn't accurate enough with the reciprocating saw. If the silly thing would stop growing unevenly, the neighbors wouldn't complain.

Oh wait. That was the hedge.

Seriously though, ditto here. Same technique as Duncan. Can gain or lose 3-4 knots of its out of center in cruise. Only thing I'd add is that I'll do the same routine on the way up in a long slow climb.
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You've probably also noticed the same thing as I that even though I know where the trim will end up once the plane has reached cruise if I just set it there before the plane starts to accelerate there is too much drag for the plane to get to the speed at which the input trim is correct. I then have to recenter the ball and keep it there while I wait for the plane to build speed. Those last few knots can take a little while too.
 
Skylane81E said:
You've probably also noticed the same thing as I that even though I know where the trim will end up once the plane has reached cruise if I just set it there before the plane starts to accelerate there is too much drag for the plane to get to the speed at which the input trim is correct. I then have to recenter the ball and keep it there while I wait for the plane to build speed. Those last few knots can take a little while too.
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Yep. Initial level-off is about a available wheel width turn and a half left, and it'll want another half after it speeds up.
 
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