Tailwheel Shimmy

[steveandmayshusky]

I agree completely with J/C. The centering springs are totally useless, as are the rudder stops. Leave about 1/2" clearance to touching elevator and it's pretty nice.

While you're adjusting stuff, mine came with almost no down elevator, but more up than could be used. Adjusting that so you can pop the tail up to get out of the dirt quickly and still leave lots of up, is worthwhile as well.


Tom D's composite tail spring is in my opinion the third best mod you can do...
1. Tom D's SGS
2. MT prop
3. Tom D's composite tailspring



Steve

 

[mikegillam]

Just flew my Husky off tarmac with new (Thomas's) tailspring. Big difference! Generally feels more solid at the rear but no shimmy - I had a real fatty in the back and held the stick fully aft after landing - no wobble. Happy.
Also, I seem to cruise about 5 kts faster

 

[KASAC HUSKY]

James,

the shimmy is caused by several factors, which I am listing here. Each factor itself can cause Shimmy, but often multiple factors add up. The sequence of the factors sorted by most possible factor.

Tailspring too flat swiveling level needs to be 3° forward
Tailwheel unbalanced
Tailwheel tire not round
Too high tailloads from pulling stick back
Too high tailloads from heavy passenger and baggage
Flaps retracted and stick backwards
Tailwheel touched down with rudder not centered.
Tailspring loose
Control springs too loose

I got rid of all this by the Composite tailspring.

Tom

Please could advise where i can purchase a composite tail wheel spring for a husky A1B and A1C therese aircraft are both fitted with an Alaskan Bush wheel wide fork and the ABI tyre .
I am also looking for 2 x set of the main gear Rebound rubbers

Noel

 

[JACK]

I believe you can get the SGS bumpers from Hancock Aviation in Baton Rouge, LA. (225) 800-2359.

 

[trapper]

The bumpers are a must along with the correct bungees for your particular plane.

 

[tbienz]

Please could advise where i can purchase a composite tail wheel spring for a husky A1B and A1C therese aircraft are both fitted with an Alaskan Bush wheel wide fork and the ABI tyre .
I am also looking for 2 x set of the main gear Rebound rubbers

Noel

I don’t believe Tom is still producing and selling the composite tail spring (but I might be mistaken).
He has replaced it with his elastomer damped spring steel single bar unit and pilots have reported good service life, less shimmy and better ground steering.

 

[tbienz]

This new product is available from Airframes Alaska. At $950 with a small metal arm under and to the side of the spring waiting to get smashed by branches, I’m not particularly interested…but if anyone has a real problem with shimmy on the BBW and wants to fix it, maybe there’s a market for this?
And it looks like they have made a solid Ti spring that looks a lot like the one Tom came up with a few years prior.

Airframes Alaska Is Now Alaska Gear Company

 

[Snowbirdxx]

I build a shimmy damper like the one AValaska is now coming out with, about 20 years ago. I used it with the Pawnee tailspring re-arced for a positive castering angle. Adjusted weal, the damper was useless, adjusted hard, it bent the steeringarm. And the link then got ripped off in high grass and with rocks.

I am not sure if going to a Titanium tailspring is the way to go, first they say adding weight in the back is welcome, then they remove weight??? But the Tianium has the preference to flex, then break. It will barely bend. But the wide single leaf design , does not torqe as much as the multi. leafes. Torquing the leafes causes shimmy too. As they say in the Vid Shimmy is complicated.

 

[David Shepard]

I was never able to eliminate shimmy with baby bushwheel. Upon installation of Thomas's tail spring, and a return to a Scott tailwheel, my life returned to normal, blood pressure dropped, anxiety diminished, and prostrate shrunk.

 

[airplanebrad]

I think the tailwheel shimmy damper from Airframes AK is an inventive idea. However, I think it is useless. A properly setup TW with the proper castor angle is the way to go. I agree with Thomas. It will cause more issues than it would correct. I would be interested in testing. I had the latest T3 tail shock on my carbon cub. I would always land that plane in 100’ and the TW rarely saw the ground until fully stopped and taxing. I never landed on asphalt or pavement, only grass, rocks, sand etc. When taxing really fast on pavement it would shimmy. Even with a positive castor angle. It may have had too much castor.

 

[belloypilot]

first they say adding weight in the back is welcome, then they remove weight???

Yes, they lost a bit of credibility with those two contradictory comments.

I've had very little problem with shimmy with Thomas's new single leaf spring and baby Bushwheels tailwheel. Only problem is when its significantly under inflated. With a tail wheel that big and soft, inflation pressure can significantly change the castor angle as the point of contact moves further forward. Inflated within the published range for the tire and its been trouble free throughout the loading envelope of my A1-B.

 

[groshel]

Not that this is the same situation but I have an ABW 3-leaf spring with a stock 3200 and tire and keep pressures at 40-45 and its never shimmied in almost a 1000 landings. One thing I did do was brass shim the looseness between the leaf spring and the 3200 casting. Needed something like .010” (or less) brass shim stock nestled into the pocket.

Now, another old Husky I flew years ago shimmied on every landing...I think they went to the ABW spring to resolve it.

Chris

 

[Jeb]

Dang. It surprises me that tailwheel setup seems to be such a mystery. Ought to be a mature technology by now.
Btw my baby bushwheel has never shimmied for me. (Fingers crossed seems the best preventative? Haha)

 

[johnaz]

Many who experience shimmy land way too fast, and as others said, correct tire pressure is many times the issue.
I do not have the problem unless improper pressure.
John

 

[belloypilot]

Dang. It surprises me that tailwheel setup seems to be such a mystery. Ought to be a mature technology by now.
Btw my baby bushwheel has never shimmied for me. (Fingers crossed seems the best preventative? Haha)

Oh, I think it’s definitely mature technology. It‘s just that there’s a lot of variables so there can be a number of different causes.