trying to get N44338 to fly straight

[robbie]

here's what I got
Feet on the floor needs a lot of right aileron to keep it flying on a straight heading, but the ball on the slip indicator is off to the right 5 deg.
flying with feet on the rudders needs, a little right aileron and a little right rudder to center the ball.
I have checked the wings with a digital level and know the left wing is .6 deg.lower than the right.
My IA and I are of difference opinion on the correction of this problem.

[Guest]

Re: trying to get N44338 to fly straight

here's what I got
Feet on the floor needs a lot of right aileron to keep it flying on a straight heading, but the ball on the slip indicator is off to the right 5 deg.
flying with feet on the rudders needs, a little right aileron and a little right rudder to center the ball.
I have checked the wings with a digital level and know the left wing is .6 deg.lower than the right.
My IA and I are of difference opinion on the correction of this problem.

Hey Rob, ok I'll bite , I see many have looked and none responded.

What's the accuracy of the level?

Assuming the .6 degrees in an accurate measure, why is the dihedral difference relevent to straight and level flight? I doubt its accurate or relevent.

Why would you fly with feet off the rudders to trim the ac? The goal is to see what it takes to trim it up on at least 2 axis.

Enough rhetoric.

Having the ball centered means coordinated flight NOT straight and level, however straight and level should be your goal if you are talking trim here.

I am going to assume that when you say ball centered that you mean at the very least it is straight flight. I know of some fellows that make the airplane bank on an angle and turn with the ball centered. :-)

If I assume that then I would do this;


1) adjust the right rear strut by turning the screw out 2 turns.
2) adjust rudder trim tab by bending aft end of tab slightly to the left
3) fly it again use rudder and aileron as required to keep straight and if still left wing heavy then repeat #1 & #2 and if you over adjust then you may need to turn the screw back in a bit or bend back the tab.
4) repeat #1 thru #3 until it flys level with no aileron or rudder usage

Dave

[PT13Pilot]

Re: trying to get N44338 to fly straight

I'll bite too I guess! Dave's right too on the level, forget it at this point. The old saying, "measure with a micrometer, draw the line with chalk and cut it with a chainsaw" applies to the construction of these old airplanes when new, let alone 60 years later.
Since your roll and yaw "problems" will affect one another directly, fix one then the other. I like to stop the roll first. Fly straight and level, keep the ball centered and let go of the yoke. Adjust the roll till it flys wings level in roll, continue to keep the ball centered untill you do. Then tweak on the rudder tab to null the yaw. Trying to do both at the same time will drive you to drink. T-craft didn't give you much adjustment in the struts like Champs, Cubs and many others. Those have to be pretty crooked to not fly straight with the adjustment available. And check the basic rigging of other things like Dave said.
Also, if your butt isn't well calibrated, check obvious things. Level the airplane on the ground side to side and make sure your ball is centered. I've had customers complain about rigging only to find the ball way out sitting on the ground because the gauge was crooked. Sounds funny, but check it. The owner who's wings I rebuilt said his was left wing heavy for the 30 years he owned it before I worked on it. It still did after a complete rebuild/new spars/cover so I'm consistant at least! Managed to get it to fly hands off for him with the adjustment available. And you'd thought I'd cured cancer! 30 years and no one took the time to fix it.
Forget the digital level and such tools, go make it fly straight! There are plenty of tricks and little things too if you find yourself at the end of your rope, plenty of help to be had here. Wish I was close enough to help, I love making things fly better!

[flyguy]

Re: trying to get N44338 to fly straight

Have to go with PT on this one. Do one at a time starting with the strut/roll adjustment.

I would add, first thing for sure: Look at the strut adjustments to see where they are now. Balanced, or one in with one out more? Where they are to start with will determine whether to screw one in to correct or to let the other one out. It seems logical that you would LIKE to have them both in the center, but I suspect that doesn't happen often.

Anyway it is easier for me to adjust the struts first so the ailerons will fly hands off. Then it is easy, but time consuming, to tweak the rudder trim.
Darryl

[Ragwing nut]

Re: trying to get N44338 to fly straight

Before you go adjusting the wings, make sure the tail feathers are square. If they are square then move on to adjusting the wings. You can compensate for a crooked tail, but you will be giving up speed. Also you say there is a difference of .6*, but what is the total of both wings? I like to see 1 to 1.5* twist.

[PT13Pilot]

Re: trying to get N44338 to fly straight

Definately make sure everything else is as good as you can get it, tail rigging, cable and control rigging, and do check your current strut adjustment for where they currently are. Something else I thought of. On a Pacer I was working on last month, the rudder trim tab was bent probably 45 degrees. The airplane flew straight enough, but I found someone had used different size/strength rudder pedal return springs for some reason. So the tab was overcoming a mechanical problem. Changed the springs and the rudder tab is now in trail to fly straight. A badly maintained/adjusted tailwheel especially Scott 3200's can effect rudder trim too. I've seen them too tight and the rudder just stays where you put it around center in flight because of too much friction back there.
So in short, check everything else first!

[3Dreaming]

Re: trying to get N44338 to fly straight

Also you can only adjust for one speed/power setting. Make sure you adjust for how you want to fly it. Tom

[Pearson]

Re: trying to get N44338 to fly straight

This may seem like a stupid question, but after you have checked the tail for squareness, and the ailerons for rigging, wouldn't checking the washout according to the service manual be on the short list of things to check?

After replacing my struts, I adjusted mine according to the manual. That got it to within one turn of the adjusting screws on the aft struts.

A few years ago one of my rudder pedal return springs came off. It is amazing how much it affects things.

[mohawktipi]

Re: trying to get N44338 to fly straight

This may seem like a stupid question, but after you have checked the tail for squareness, and the ailerons for rigging, wouldn't checking the washout according to the service manual be on the short list of things to check?

After replacing my struts, I adjusted mine according to the manual. That got it to within one turn of the adjusting screws on the aft struts.

A few years ago one of my rudder pedal return springs came off. It is amazing how much it affects things.

Speaking of rudder pedal springs, When I got my plane, it would not fly straight. I was about to adjust the rudder tab when my Son-in-law noticed hat the rudder springs were different sizes. I replaced them and it fixed the problem.

[Guest]

Re: trying to get N44338 to fly straight

Before you go adjusting the wings, make sure the tail feathers are square. If they are square then move on to adjusting the wings. You can compensate for a crooked tail, but you will be giving up speed. Also you say there is a difference of .6*, but what is the total of both wings? I like to see 1 to 1.5* twist.

Good thought Mike, also the comments from Pearson on the wash in adjustment according to factory spec makes sense too.

I assumed the only issue on the table was final adjustment after a new strut installation.

It now sounds to me like a bad assumption.

I would still gamble on adjusting two axis at once though.

So Robbie, what did you prefer and what did your IA prefer?

Dave

[flyguy]

Re: trying to get N44338 to fly straight

Don't know about that Dave. Some of us have trouble working with just one axis, LOL.
I once gave my rudder trim a little bend before a flight because I knew it had been slightly off for a while, and it got worse. Back on the ground it was pretty obvious that I hadn't thought through what I was doing before I did the bend.
Darryl

[Guest]

Re: trying to get N44338 to fly straight

Don't know about that Dave. Some of us have trouble working with just one axis, LOL.
I once gave my rudder trim a little bend before a flight because I knew it had been slightly off for a while, and it got worse. Back on the ground it was pretty obvious that I hadn't thought through what I was doing before I did the bend.
Darryl

Hey Darryl,

You could be right, lol, I might have to start making my trim tabs from dead soft 1100 alloy so they don't fatigue crack from bending!

Dave

[astjp2]

Re: trying to get N44338 to fly straight

I never installed the rudder trim tab, my tail is square and I did NOT install the springs on the pedals. I set my washout to .1 degree of factory with a digital level and wound up shortening the left 2 turns and lengthing the right 1turn. My ailerons droop 1/2" because I left the cables somewhat loose and they go level when the airplane is flying. This was after the strut change, my old struts required 2 turns on the left wing. I can now sit on my hands and with the power set and my feet on the pedals fly for 30-60 minutes without touching the yoke in calm air...setting the rigging by flying it is most important when you are finished, now how it is set on the ground. Tim

[Forrest Barber]

Re: trying to get N44338 to fly straight

Rig according the service manual, remove rudder springs at pedals, fly at normal cruise, center ball with rudder, if she turns then bring the down wing up by screwing in barrel on rear strut, no more than 2 turns ( go to other wing and go out) once she flys straight and level (with your feet centering the ball) THEN put equal springs back on pedals. THEN use a rudder tab to keep ball centered, wings should stay level of course........make sure ailerons are not warped and have proper "droop" before you start.....

Find someone who knows how to rig a ship is really the best way.

[robbie]

Re: trying to get N44338 to fly straight

thanks for the input guys,
We are starting with the ailerons, They were set to tight a few years ago by and AP which was not familiars with the T-Craft.
After we get these rigged correctly will start on
the list above.
I have flow this plane since !982, and got used to it flying this way.
Due to a health problem I did not fly her for 18 months.
Now I'm flying her again I'm saying what's with this airplane did it always fly like this? Being retired now, I got a lot of time to pick things apart and drive my AP nuts .
I like the suggestion about removing the rudder springs.