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Tailwheel squirrely solutions?

dmat

Well Known Member
Advertiser
So... I flew my new-to-me 6 this weekend for the first time and noticed that on touch down of the tailwheel the tail wants to veer to the right.

I am new to tailwheels so I am not sure what to check. I have a doug bell fork and vans wheel.

A couple of things I noticed after looking at the tailwheel:
- tailwheel has uneven wear (passenger side of tire is worn more)
-chain links are different count on each side (11 on the pilot and 12 on the passenger side)
- control arm (IMO) seems loose but I am not sure if that is acceptable play.

Any help/suggestions would be greatly appreciated.

My first thought was to replace the wheel and see if that does anything.

D
 
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I would also check the wear on the centering lock mechanism it might be more worn on one side than the other causing this problem.
 
RV-6 tailwheel issue

You should probably call Flyboy’s accessories and discuss this with them. They have all sorts of tailwheel products. You may have a worn out tail spring, worn out links, worn out tail wheel assembly or the wheel itself. They are very knowledgeable and I’m sure they will have what you need.

tel:888-835-9269
 
The tailwheel might be a symptom and not the whole cause. Clamp a couple of long straight pieces of angle to the brake rotors and compare them to the centerline of the aircraft. Might be an alignment issue.

The different length chains are weird. Are they tight or have a little slack? My tail lynx are rigged with a little and equal slack and I like the way it gives the rudder a chance to do some work before beginning to steer the fork.

Ed Holyoke
 
Is the wheel aligned with the rudder? I’ve flown planes where the wheel is t aligned, and when you are rolling out straight, as the wheel comes down, the plane swerves to where the wheel is pointing.
 
Things to check:

1) Make sure the attachment of the tailwheel pivot/swivel body on the tailwheel spring (stinger) is tight. There are usually two AN3 bolts through the swivel body that hold it. If those bolts have play, it will allow the tailwheel to rock to one side, causing a steering moment. Ideally these two bolts are replaced with taper pins so they stay tight.

2) Make sure the pivot/swivel axis axis is vertical. If it is not vertical, it will always steer to one side, and cause uneven tailwheel wear. One might try to compensate for this by changing the chain lengths to make the tailwheel steer the other way. This creates a strange steering geometry with abnormal handling.

3) check main wheel alignment. Without refueling the debate over whether toe-in or toe-out is better, strive to have the wheels perfectly parallel. As an example, using 3-ft lengths of channel held against each tire, my tires are within 1/16" of parallel over that 3-ft length. My tires wear evenly across the tread too. It is more tricky on the RV-6 because the rod-type landing gear will change alignment as the weight on wheels changes, so you may want to have zero toe-in at wheel-landing attitude, and accept some misalignment at 3-point attitude.
 
To me there is slack in the chains. I’m not sure what is the right amount.

D

The tailwheel might be a symptom and not the whole cause. Clamp a couple of long straight pieces of angle to the brake rotors and compare them to the centerline of the aircraft. Might be an alignment issue.

The different length chains are weird. Are they tight or have a little slack? My tail lynx are rigged with a little and equal slack and I like the way it gives the rudder a chance to do some work before beginning to steer the fork.

Ed Holyoke
 
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Tailwheel

If you have wheel pants that have minimal clearance on tires the clearance on the aft side should be 3/4". I damaged my wheel pants twice before I figured out this was necessary, especially in the extreme heat in the SW. Not trying to start an argument but Steve Wittman, the designer of the round rod gear, called for 1/16" toe in for the round rod gear. Vans apparently has a different opinion.
 
.... Not trying to start an argument but Steve Wittman, the designer of the round rod gear, called for 1/16" toe in for the round rod gear. Vans apparently has a different opinion.

Parallel alignment at wheel-landing attitude would probably give you about 1/16" toe-in at 3-point attitude. That is, 1/16" across the diameter of the wheel.
 
I spoke with the ferry pilot and he said he didn't see any issues with the landings. The only thing I can think of is, I installed a tailbeacon in the rudder and it's not perfectly aligned vertically with the rudder. Maybe 1/8" cocked. Could that act as a trim tab at landing speeds?

The airplane flies wonderful once airborne.
 
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Check bushing in wheel fork

For me, I had a lot of problems steering my -6 tail wheel initially because the bushing in the end of the stinger, where the tail "fork" (the vertical pointing rod with the threads on the end to hold wheel assembly in) goes in, had become worn and egg shaped. Also, it needed some good greasing, because the wheel would "stick" until I applied a lot of rudder input, then snap the other direction once the stiction was overcome, causing wild veering left and right. I replaced the whole end assembly, greased it well, made sure the locking pawl was greased and moved easily, and it has worked good since.
 
What Jake said is spot on.

It is possible to re-bend the spring in a press. Be careful.... it's a SPRING. You don't want it taking your head off.

If that doesn't work, Blake sells the tapered rod springs. Visit his webstore to order.

All of the springs we currently have are 0.635" diameter at the tailwheel end. Measure yours to be sure it's compatible. Use a dial caliper or a micrometer... a ruler WON'T work. Don't make me stop this car....

RV-3 and RV-14 springs are different. See Van's for those.
 
I assume I need to remove the stinger to do this. How hard of a job is it to remove? Sorry for all the questions, this is my first tailwheel. :confused:

UPDATE: I opened up the tailwheel:

1) the pin looks to be rounded instead of blunt so that needs to be ground down or replaced per Blakes maintenance instructions.
2)Grease looks old so will clean and re-grease.
3)I also noticed after tightening the top bolt that hold the fork to the arm, the nut bottoms out and there is still a significant amount of play in the arm so I need to add a washer to fill the gap.

After that, I will test fly and see how it goes.
 
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I have done a few updates to the tailwheel as I got to meet Blake at OSH and figured I pick up a few things.

- installed new locking pin (old one was round)
- added a shim
- greased everything really well
- replaced the chains with a Rocket steering Link
- figured while I was at it, replace the wheel to the lightweight wheel

Hoping to test fly ASAP to get some data.

If nothing changes, I will need to think about removing the stinger and giving it a slight bend.

D
 
Just to close the loop on this thread. After test flying the 6, looks as if the above fixed the problem 95%. I think the other 5% is rigging on my part and can be tweaked.

Thanks everyone!
D
 
What Jake said is spot on.

It is possible to re-bend the spring in a press. Be careful.... it's a SPRING. You don't want it taking your head off.

If that doesn't work, Blake sells the tapered rod springs. Visit his webstore to order.

All of the springs we currently have are 0.635" diameter at the tailwheel end. Measure yours to be sure it's compatible. Use a dial caliper or a micrometer... a ruler WON'T work. Don't make me stop this car....

RV-3 and RV-14 springs are different. See Van's for those.

Hey Vince, how would one bend the stinger?

Thanks,
D
 
I am looking for info on bending the stinger. Has anyone done this before?

Thanks,
D
 
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