REFLECTOR: Shimmy Damper Settings

Ron N VelocityXLFG velocityxl at fastmail.fm
Thu Sep 19 07:18:15 CDT 2013


When I flew with just the belleville springs I had my front wheel set 
with 14-16 lbs of pull at the back of the wheel. Were are you measuring
35 lbs of pull? Now with the steering dampener I have the springs set to 
8lbs of pull . This so far allows me to steer with the winglets on take off.
That was my main goal for the dampener. Brakes on take of make the take 
off roll last to long:(

Ron


On 9/18/2013 10:14 PM, Bob Jackson wrote:
>
> 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
>
> NashvilleTN 37211
>
> Tel. 615-250-2304
>
> Cell P. 615-918-2698
>
> Email. Js3201 at comcast.net <mailto:Js3201 at comcast.net>
>
> Http://www.sieders.com/sieders
>
>
>
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