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  #21  
Old 11-26-2019, 09:02 PM
RV8JD's Avatar
RV8JD RV8JD is offline
 
Join Date: Jan 2005
Posts: 810
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Unfortunately, the shimmy event I posted about earlier was not a fluke. I had a second event today. I think I will remove the steering chains and install the steering arm I have.

As I mentioned in my earlier posts, it's possible that the JDAir bearing yoke, with its zero yawing friction, in conjunction with the steering chains (zero stiffness and damping in the deadband zone) may make the Condor2 setup more susceptible to shimmy. Removing the chains and installing the steering arm (which adds stiffness & damping) should help, but it may or may not solve the problem. It might take going back to the original Van?s yoke, with its higher friction bushing setup.

I?d hate to give up the larger pneumatic TW, but I don?t want to give up the JDAir bearing yoke and its steering ease.
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Carl N.
Arlington, WA (KAWO)
RV-8, 735 Tach Hours
(Pic 1),(Pic 2)
- Out with the Old, In with the New
(Pic)
RV-8, 1938 Tach Hours (Pic 1),(Pic 2) - Sold

Glasfl?gel Standard Libelle 201B - Sold
Rolladen-Schneider LS1-f - No longer owned
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  #22  
Old 04-28-2020, 01:23 PM
Docbru Docbru is offline
 
Join Date: Nov 2012
Location: Ontario, Canada
Posts: 17
Default Condor 2 tailwheel

I had this setup sitting in a box at the hangar for months and finally got around to installing it on my RV 8 and testing it. It was a straight forward swap with the stock tailwheel. Taxi testing showed no change in the steering capabilities and it provided a much smoother ride over bumps and cracks compared to the solid rubber tailwheel. I?m running 45-50 psi. Directional control during take-off and landing was no different. It might be my imagination but I think during landing when the tailwheel came down there was a slightly ?softer? feel...I always wheel land and hold the tail up as long as possible. It is a quality piece as I?ve come to expect from Flyboys. 5 stars.
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  #23  
Old 06-25-2020, 03:34 PM
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mike newall mike newall is offline
 
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Location: Yorkshire, England
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2 of us in the UK have just fitted the same set up and now both having big shimmy issues.

Contacted Blake - fab service as usual - he sent lots of info.

Ours is a 10 year old 500 hour spring/knuckle on a Rocket Lynx steering set up. I have ordered a new spring, knuckle and steering arm, but it wont arrive for a month as it is sea freight.

Going back to the old tailwheel and will report back when the new one is installed. We have our tyre at 50 psi and I have put tyre jizz into it to help the loss of pressure.
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  #24  
Old 06-25-2020, 09:13 PM
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RV8JD RV8JD is offline
 
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Quote:
Originally Posted by mike newall View Post
2 of us in the UK have just fitted the same set up and now both having big shimmy issues.

Contacted Blake - fab service as usual - he sent lots of info.

Ours is a 10 year old 500 hour spring/knuckle on a Rocket Lynx steering set up. I have ordered a new spring, knuckle and steering arm, but it wont arrive for a month as it is sea freight.

Going back to the old tailwheel and will report back when the new one is installed. We have our tyre at 50 psi and I have put tyre jizz into it to help the loss of pressure.
Whew, I thought I was the only one who had a shimmy problem with these (see my previous posts in this thread). I was beginning to think I was jinxed!
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Carl N.
Arlington, WA (KAWO)
RV-8, 735 Tach Hours
(Pic 1),(Pic 2)
- Out with the Old, In with the New
(Pic)
RV-8, 1938 Tach Hours (Pic 1),(Pic 2) - Sold

Glasfl?gel Standard Libelle 201B - Sold
Rolladen-Schneider LS1-f - No longer owned

Last edited by RV8JD : 06-25-2020 at 10:01 PM.
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  #25  
Old 06-26-2020, 02:46 AM
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mike newall mike newall is offline
 
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Location: Yorkshire, England
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I think the problem is a compound one.

The yoke is longer (taller), the tyre is larger so the knuckle angle changes - better viz etc, but takes the whole assembly into shimmy territory. Add in an old stinger that has sagged a bit and away we go.

Has anyone bent a stinger, either by annealing, bending and re tempering, or just by cold bending ?

Is the 14 stinger a different part ?

Scott - if you pick up on this, your input would be welcome please.
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  #26  
Old 06-26-2020, 05:06 AM
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F1Boss F1Boss is offline
 
Join Date: Aug 2006
Location: Taylor Texas
Posts: 799
Default Spring re-shaping

Heat the spring until it is just starting to turn red where you want the bend, then bend. You will not remove the temper. Piece ?o cake!
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Mark

"Not everyone needs a Rocket. Some folks, however, shouldn't live life without one.
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  #27  
Old 06-26-2020, 06:07 AM
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mike newall mike newall is offline
 
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Thanks for that - will give it a whirl.
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  #28  
Old 06-26-2020, 03:36 PM
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BlakeFrazier BlakeFrazier is offline
 
Join Date: Mar 2016
Location: Evansville, IN
Posts: 51
Default Addressing shimmy issues

Howdy folks... writing up a document to address the topic of tailwheel shimmy has been on my do-list for some time. Thanks for giving me the extra incentive to get it knocked out! I've created a post on our blog, which aggregates information from several other posts on the topic and applies it directly to RVs.

Link to the full article here: http://flyboyblog.com/2020/06/26/add...shimmy-in-rvs/

The short synopsis goes like this:
- Tailwheel geometry is the biggest contributing factor to shimmy
- Fixing the tailwheel geometry can be fairly easy and low cost.
- Another VAF user has discussed a method for putting a bend in the tail spring to improve the steering angle geometry, with good results (link here)


This is the geometry we're shooting for.

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