Rudder and tail wheel

[Dan Michaels]

I was checking over the Taylorcraft today after mounting the rudder pedal extentions. I noticed that the rudder and the tailwheel are not lined up. The only thing I can see that could affect it is the springs on the tailwheel.

Sitting neutral the rudder should be centered?

Do the springs have an effect on this?

How does one set the rudder? before or after hooking up the tailwheel springs?

The two turnbuckles on each side control the rudder travel?

Dan

[VictorBravo]

Re: Rudder and tail wheel

The only thing I can see that could affect it is the springs on the tailwheel.

Sitting neutral the rudder should be centered?

Do the springs have an effect on this?

How does one set the rudder? before or after hooking up the tailwheel springs?

The two turnbuckles on each side control the rudder travel?

Dan

If the tailwheel springs are equal length then they will not have an effect on the rudder vs. tailwheel alignment, assuming everything else is also symmetrical... BUT, a frequent and very likely culprit is the cast aluminum control arm that is in the bottom of the rudder. These get worn out, cracked, installed at an angle to the rudder, loose mounting bolts, etc. etc.

Put the tail of the airplane up on a sawhorse, pull up a chair, and clean everything real good first. Then disconnect the springs and measure that the springs are the same length.

Once those are crossed off the list, slightly loosen the nuts holding the cast aluminum rudder arm into the lower rudder tube. Do not take the nuts off, just loosen them slightly. See if you can rotate the arm a few degrees back and forth (without any "clamping force" from the nuts). If you can rotate the arm, the holes in the arm where the bolts go through have been worn oval (very common).

If you cannot rotate the arm inside the rudder then you have to take a square and measure whether the cast aluminum arm is in fact installed at 90 degrees to the rudder. If someone replaced the arm with a new one, and didn't jig it together right when they drilled the bolt holes, that would easily cause the tailwheel to be at a different angle than the rudder.

Through all this, keep in mind that the FIN is welded onto the fuselage at a slight angle (intentional design compromise), so if you are aligning the rudder with the fin the tailwheel SHOULD be a couple of degrees off.

If you clamp the rudder and fin together with a couple of pipes or tubes to keep them straight with each other, you have a couple degrees of effective "right rudder" that old CG himself put in on purpose (to counteract torque at cruise speed).

With the rudder aligned straight to the FIN (not the fuselage longitudinal axis), it is the tailwheel that should now be pointing straight down the axis of the fuselage, which is to say slightly to the left of the rudder itself. In this condition, assuming brakes, tires, wheel bearings etc. are equal, the airplane should roll straight on the ground.

Things like the rudder pedal return springs (between the pedals and the firewall) can cause the airplane to not roll straight on the ground (and not fly straight in the air).

The T-craft was designed to fly straight at one speed, my guess is most likely at the 80-85 mph that the original B model was capable of with the open cowling and 50 horsepower, and with no thrust offset at the engine. With all sincere respects CG, it would have been a lot more appropriate for you to weld up the fin straight and adjust the engine offset as appropriate for whichever engine you had.

Using the fin to counteract the torque of the engine, he had to pick one speed and one power setting at which the fin offset would perfectly balance the engine. With no power or a lower power setting the airplane would glide to the right (fin offset overpowering low torque). With a higher power setting or more available power it would cruise turning to the left (torque overpowering not enough fin offset).

Bless your heart CG, we love you to pieces, but you should have hired a "free flight" model airplane builder in 1938 to set up that part of the model B design

[Guest]

Re: Rudder and tail wheel

Neither spring should have enough pre-tension on it to cause a ground loop if the other spring or chain breaks.

Just make them tight enough to take up the slop in the mechanism.

Sounds like one of yours in too tight.

[Dan Michaels]

Re: Rudder and tail wheel

Neither spring should have enough pre-tension on it to cause a ground loop if the other spring or chain breaks.

Just make them tight enough to take up the slop in the mechanism.

Sounds like one of yours in too tight.

Scott tail wheel no chain.

I set the rudder to the vertical fin, then adjusted the turnbuckles until the peddals were equal. This helped a little. The wheel is still off to the right.

I took the springs off and they are the same size. I also reversed them no change. I checked the bolts for slop none.

Dan

[Guest]

Re: Rudder and tail wheel

I have a Scott wheel too and chains as well.

You can add them if feasible.

Dave

[Dan Michaels]

Re: Rudder and tail wheel

I have a Scott wheel too and chains as well.

You can add them if feasible.

Dave

Next time out I will take a picture of the setup.

I was off the ground so fast I hardly think it will be a big deal.

Dan

[Joel Severinghaus]

Re: Rudder and tail wheel

Dan,

Do you have three bolts through the bottom of the vertical tube on your rudder, holding the tailwheel steering horns shaft in place inside that tube?

I'm still grateful to Tom Baker Jr., who walked up to my Taylorcraft at Oshkosh (pre-restoration), pointed at the bottom of my rudder, and said, "You're missing three bolts there." Sure enough, when I landed coming home from Oshkosh, the steering horn shaft twisted inside the rudder tube, and I couldn't taxi straight. Poking with a needle revealed three bolt holes that had been covered with fabric for decades.

[Dan Michaels]

Re: Rudder and tail wheel

Dan,

Do you have three bolts through the bottom of the vertical tube on your rudder, holding the tailwheel steering horns shaft in place inside that tube?

I'm still grateful to Tom Baker Jr., who walked up to my Taylorcraft at Oshkosh (pre-restoration), pointed at the bottom of my rudder, and said, "You're missing three bolts there." Sure enough, when I landed coming home from Oshkosh, the steering horn shaft twisted inside the rudder tube, and I couldn't taxi straight. Poking with a needle revealed three bolt holes that had been covered with fabric for decades.

Yep I have them. They are good and tight.

Dan

[Steve Pierce]

Re: Rudder and tail wheel

Anybody running a Scott?AK Bushwheels 3200 tail wheel? Friend has a BC12D with a C85 with big tires and wants the bigger tail wheel. It is approved on the AK Bushwheel 3200 AML. Wondered if anyone had any experience? Also, is there a source for rudder steering arms? called Univair and they don't have them, didn't know if they are available or is there a substitute. I hope y'all can educate a dumb Cub guy.