REFLECTOR: Shimmy Damper Settings

[Bob Jackson]

Thanks for the steer, Patrick!

 

I found and read Andy's excellent VOBA article.  Andy did a great job on the
article.  It was very informative and included his modifications and
settings:

*	Replace the shear pin with the much stronger one Jorge Bujanda found
(from McMaster Carr and described in Andy's VOBA article)
*	Set the damper Low Speed valve -- 1 1/2 turns back from full CW
'Hard'
*	Set the damper High Speed valve -- 1 turn back from full CW 'Most
Sensitive'

 

But what Andy didn't discuss was the relationship between his settings of
the Scott's Damper and the old Belleville washers.  When I measured the
nosewheel 'break-out' force required to just begin to turn the nosewheel
(with no Belleville washer tension) and the Damper set as Andy describes
above -- the 'break-out' force was only 5-10 lbs.

 

Prior to adding the Damper, we used to set our Belleville washer tension so
that the nosewheel break-out resistance to wheel turn was about 35 lbs.  I
know Andy said that the value of the Damper was in it's resistance to high
speed or 'impulse' shocks, but I'm skeptical that the Damper alone will
provide enough resistance and damping to prevent shimmy from these impulses.
My inclination would be to continue to use the Belleville washers, still
tensioned to provide something very close to the 35 lbs break-out force
resistance, along with the Damper as in Andy setup, or even a little
'harder' and 'more sensitive'.

 

-- Andy -- if you're monitoring the Reflector -- could you please comment on
my conclusions above, and also describe how you're setting up the Belleville
washer tension in conjunction with your Damper settings.

 

Thanks,

Bob Jackson
N2XF

 

  _____  

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Patrick Sieders
Sent: Friday, September 13, 2013 4:00 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: Re: REFLECTOR: Shimmy Damper Settings

 

There was an excellent write up on the shimmy dampener on the VOBA
newsletter written by Andy Millin.

 

Great article !

 

Patrick

 

 

Patrick & Dana Sieders

7244 Sugarloaf Drive

Nashville TN 37211

 

Tel. 615-250-2304

Cell P. 615-918-2698

 

Email. Js3201 at comcast.net

Http://www.sieders.com/sieders

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