Tailwheel Steering Connections

[robcaldwell]

Just curious what other are using for their tailwheel steering connectors? (Please post some pics if you have them). The 4 Place manuals suggest the Maule Anti-Shimmy Connector set.

https://www.aircraftspruce.com/catal...le_springs.php

What works best?

[jaredyates]

I don't have a photo handy, but I use tension springs rather than compression springs. I hook the springs directly into the tailwheel arm, though over time they do wear the holes a little. I've seen a few installations where folks bolt an eye bolt, or an AN115 shackle. I do add safety wire to the hooks on the springs, because I have had them come loose when the wheel shimmies.

[Mark Goldberg]

The normal tension springs are recommended instead of the compression type springs that go hard once they are fully compressed. Mark

[jaredyates]

Rob, was the Maule recommendation in the Kit Builder Manual at bearhawk.tips? If you remember where, I can update it.

[robcaldwell]

It's in both manuals. AviPro and Eric Newton's. I'm having trouble searching Bearhawk.Tips. Could be in there as well.

[jaredyates]

I couldn't find it with a search at bearhawk.tips, which is not to say it isn't there. But the KBM there is the updated version of the Avipro manuals, which have been superseded.

[N942VT]

I tried both styles and the tension springs worked better, the compression spring restricted movement too much.
Shimmy is a function of caster angle, you need positive caster when loaded

[N942VT]

[Bcone1381]

I like that pictorial. And what can make the castor angle change? A heavy load, or more weight on the tail during landing roll, or holding the stick back in my lap when taxiing fast, or a tail spring that is worn out or needs to re-adjusted.

[rodsmith]

I just purchased the Maule anti-shimmy tailwheel steering kit. The included chains are about 5" short, I found the chain at McMaster-Carr so that is not an issue. I do not know how to set these up, the instructions are worthless. Should the chains be sized so that there is a small amount of compression on the springs, or just that they are tight? The instructions didn't even say which spring goes on which side. In the aircraft spruce description, it says the lighter spring goes on the left so that is what I will do, unless someone has different information.

[AKKen07]

I haven’t flown yet but here is what I have done. I got my extra chain from Spruce as well as the springs. I set them up so that there was no slack. Taking one link out from where it was slack made it pretty tight. I also set it up so that each side was the same length which required one less link on one side. I didn’t see the spruce instruction and so didn’t deliberately put them on any particular side. And as a safety note, I’d wear gloves when pulling the chain tight to connect it. I cut my hands up pretty bad doing it without gloves. I think the chains have sharp edges - I didn’t notice until there was a bunch of red stuff on the chain.

[jaredyates]

This is one of those things where opinions vary, but for me I want a little bit of spring tension on the linkage when neutral. I found I had to add safety wire to keep the linkage from shedding parts during a shimmy event. It will surprise you with its ability to unhook itself.

[Battson]

I just purchased the Maule anti-shimmy tailwheel steering kit.

I think I've seen Bearhawk Aircraft recommend against using that kit, a long while back. I think it may be because the compression springs have limited travel, so something has to give if the system is pushed past the stop. That said, it's a very beefy system and the design has been made stronger many years ago, but it something to consider.

The springs don't know if they are in tension or compression - so they provide a linear force apart from the stop. I presume the kit can only limit the amount of shimmy (as I say, I assume) by slamming into the stop. If it completely prevents shimmy somehow, I would like to know more about how it works.

I have my springs very loose, probably a whole extra chain link on each side. I have no shimmy damper installed either, with the largest tailwheel. This is absolutely fine on all surfaces, except for sometimes on seal - but I almost never go on seal.

[jaredyates]

I have wondered if the anti-shimmy claim is based on there being non-symetrical springs, as to try to dampen better. But I also like tension springs better for the same reasons.

[Battson]

Is one spring slightly larger than the other? I can do that with tension springs from Home Depot

[marcusofcotton]

#9.2
Battson commented
Today, 02:30 AM
"Is one spring slightly larger than the other?" Yes.

[Brett795]

Here is an interesting tail wheel setup video from the Stinson Tech Channel. At 40 mins in Gary shows how the Stinson tailwheel should be set at gross and at the end shows how tight/loose the tension springs should be set. I don’t know if all planes are set this way but i know this is also how my dad taught me and had his planes set up.

https://youtu.be/AmD6iiQic84

[Bcone1381]

Wow, Brett. I learned a lot about tailwheels in that video.

[Enewton57]

Just few comments since this has come up again.

I have been building, selling and flying Tailwheels for a little over 12 years now. The subject of shimmy and steering springs comes up every once in a while. Here is what I have learned/observed over the years:

1. Bob does not recommend the compression type steering springs since they do have the ability to bottom out. I have replaced 2 steering arms with bent up arms and both has had compression springs. Please use tension type springs.

2. Shimmy is most often caused by the king pin castor angle being incorrect. At gross weight, with aft C.G., the top of your tailwheel should be angled forward. I have seen flattened out leaf springs cause shimmy and re-arching the spring eliminates it.

3. Tied to number 2 is the pilot hauling back hard on the stick, forcing the tail down at high taxi or landing speeds. The elevator on the Bearhawk is very effective and when we hold the stick back, it pushes the tail down hard, changing the camber angle and creating shimmy. If your tailwheel starts to shimmy, get the weight off the tail.
if you learned to fly in a nose wheel airplane, you were taught to hold the stick/yolk back hard after landing. This was to keep the weight off the nose wheel to prevent it from digging in or shimmying. The opposite applies to Tailwheel aircraft. Stick forward to get the weight off the tail.

4. Worn out, loose components can contribute to a shimmy. The Tailwheels that we sell have bronze thrust washer and internal spring washers to create some friction. If your tailwheel pivots loosely, it may be time to overhaul it.

5. Read number 2 again. Castor angle is the main thing contributing to shimmy. Worn, bent or loose leaf or rod springs, improper installation, and pilot technique when landing can all affect this. Load your airplane to max gross weight and aft C.G. while it is sitting on the ground. The take a carpenters square and see if it is leaning forward at the top. If not, that’s the first step. Fix that first.

These are just my observations over the years.

hope this helps,

Eric Newton
Bearhawk Tailwheels LLC
https://bhtailwheels.com

[Bissetg]

Castor angle is the main thing contributing to shimmy. Worn, bent or loose leaf or rod springs, improper installation ….

Is there a way to alter the geometry on the stinger rod spring? I’ve noticed a fellow Bearhawk that has shimmy to the point I’ve seen the tailwheel go through 360 degree rotations as he was slowing down on roll out. But short of bending the stinger it’s hard to see how to correct the king pin angle?

I agree that a tail low wheel landing suits the Bearhawk well.

[Mark Goldberg]

The tailwheel springs can be bent if needed. It is not easy since they are heat treated to a pretty hard condition. If it should be bent upward after a hard landing, it can be just turned around 180 degrees - assuming the amount bent is not much of course. Mark

[Utah-Jay]

Just few comments since this has come up again.

I have been building, selling and flying Tailwheels for a little over 12 years now. The subject of shimmy and steering springs comes up every once in a while. Here is what I have learned/observed over the years:

1. Bob does not recommend the compression type steering springs since they do have the ability to bottom out. I have replaced 2 steering arms with bent up arms and both has had compression springs. Please use tension type springs



Eric Newton
Bearhawk Tailwheels LLC
https://bhtailwheels.com

Eric

Can you give me a link to the springs you prefer?

Jay

[Enewton57]

Hi Jay here you go:

https://www.aircraftspruce.com/catalog/lgpages/tensiontype05-11457.php?clickkey=3077312

[Utah-Jay]

Thanks Eric

[Light&Sweet]

Tail wheel shimmy is one of those enduring topics. It has occurred to me that no matter the geometry of a given tail wheel, one universal trait and contributor or at least, inefficacious anti-shimmy aspects of most tailwheels designs is that they are free wheeling. Some designs have a dampener or friction device built into the pivot point, but with no rigid pivot connection between the airplane and the wheel, that tail wheel wants to swivel.

Not to say that felt shimmy can’t be reduced or eliminated with proper geometry, tire pressure, and rigging, but the inherent underlying issue should be recognized.

[Nev]

I'm wondering if having a 10° bend downwards in the stinger would help. Any thoughts ? The idea would be to recline the kingpin angle (by another 10°). My idea is to make a second stinger to try it with a bend at the aft end near the tailwheel.

I assume that reducing tire pressure would have a similar but smaller effect.

[Battson]

A few thoughts: I think correct heat treatment will be rather important. But I understand impurities present during heat treatment can cause it to become rather brittle, so you'd want expert advice on how to do this correctly. The titanium spring is a single point of failure compared to a leaf spring where you have two. Supposing the Ti spring were bent, there would be a bunch of extra stresses left in the metal which would probably cause cracking long term unless treated. Annealed Titanium is almost as hard as cast iron, and there seems to be an understanding that it's fairly brittle. I am guessing it'll crack like a regular spring can. Cracked tail springs are no fun, and a complete loss of the tail spring - as would happen with a stinger - would cause considerable damage to the rudder and tailwheel steering horns, rendering the aircraft unflyable.

[Ed.Meyer]

I did what you are proposing on our Patrol. I did not measure the angle of the bend but I think it was probably closer to 5 degrees. I put the bend as close as I could to the aft end to avoid raising the tail any more than needed. Took lot of pressure in a press to bend it. It helped the shimmy situation significantly. Have flown it that way 100 hours or so with no problems.

[Battson]

Subsequent thought, it's probably more straightforward and less risky to modify your tailwheel so the stinger attach point is 10 degrees offset, rather than bending the stinger.