REFLECTOR: Shimmy on landing

[Wayne]

Mine is an old FG 173 top loader.  Those folding leg things are a mystery to 
me.
The shimmy was more likely to occur  when heavily loaded  so I guessed it 
was  when the caster was too positive.  True it could be suppressed with a 
30 pound breakout force.  Steering really sucked when I had to thrash the 
engine and stomp the brake to turn.
While repairing the NG bulkhead I made a new aluminum bracket that changed 
the attach point slightly. Now there is less positive caster.  The vertical 
section down at the fork is more nearly vertical. The last 50 hours have 
been fine.
I still have significant breakout force,15 to 20 pounds.

----- Original Message ----- 
From: "Kevin Baker" <flykb at verizon.net>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Monday, April 10, 2006 12:22 AM
Subject: Re: REFLECTOR: Shimmy on landing


> Hi Wayne,
> How did you tweak the caster?
>
> At 02:46 PM 4/9/2006, you wrote:
>>Same for me.
>>I kept thinking I had corrected the shimmy.Then I ground off the chin and 
>>the nose gear went through the prop after a greaser landing.
>>Tweaking the caster fixed the problem on the new gear leg so I don't even 
>>need the steering lock I added.
>>Wayne
>>----- Original Message ----- From: "Richard Riley" <richard at riley.net>
>>To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>>Sent: Sunday, April 09, 2006 10:44 AM
>>Subject: Re: REFLECTOR: Shimmy on landing
>>
>>
>>>At 07:34 AM 4/9/2006, you wrote:
>>>>Richard Riley wrote:
>>>>>A friend of mine snapped his front LG strut on an XL-RG last year.  It 
>>>>>was a very gentle landing, but he'd had several shimmy events 
>>>>>previously and strongly suspects it was shimmy that did it.  I looked 
>>>>>at the break under a high power microscope, there was no sign of 
>>>>>corrosion or crescents in the break, it was a sudden, complete failure.
>>>>Most likely it was already cracked from the previous events and he 
>>>>miss-interpreted the visual cues.  He would have been wiser to rectify 
>>>>it after the first event instead of repeatedly punishing the nose gear 
>>>>until complete failure.  But then hind site is always 20x20.
>>>>
>>>>Shimmy on any plane should be correct4ed immediately.  On our fully 
>>>>castering nose wheels its even more  important.
>>>
>>>He was trying to correct it from the first incident, but (in hindsight) 
>>>not aggressively enough.
>>>
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>>
>>
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