MK Dual Elavator Bellcrank & Pushrod?

[Wayne Galligan]

I took a (2) pieces of foam about 2"sq x 4" long and pushed them onto the c.f rod and placed them about 6 inches from each end.   I could then move the pieces back and forth to tune out the harmonic resonants.  Just watch the rod at various engine speeds to see what it does.  When it vibrates it is amazing that any of them would hold together. 

Wayne G.
   ----- Original Message ----- 
  From: Rick Wallace 
  To: discussion at nsrca.org 
  Sent: Thursday, February 03, 2005 11:43 AM
  Subject: Re: MK Dual Elavator Bellcrank & Pushrod?


  Agree w/ John about using foam as a vibration damper. Also, someone much wiser than me pointed out that whatever is installed should NOT be halfway, 1/4 way, or any reasonable fraction of the pushrod length because these may end up as stationary nodes in the vibrating rod, and end up doing no good. 

  Rick



  >From: "John Ferrell" <johnferrell at earthlink.net> 
  >Reply-To: discussion at nsrca.org 
  >To: <discussion at nsrca.org> 
  >Subject: Re: MK Dual Elavator Bellcrank & Pushrod? 
  >Date: Thu, 3 Feb 2005 09:07:36 -0500 
  > 
  >Be very careful about alignment. An extra bushing on the shaft can cause a lock up under vibration. 
  >A foam rubber damper is safer. It can be as simple as a wad of foam or as complicated as another bulkhead. 
  > 
  >John Ferrell 
  >http://DixieNC.US 
  > 
  >   ----- Original Message ----- 
  >   From: Jerry Wilson 
  >   To: discussion at nsrca.org 
  >   Sent: Wednesday, February 02, 2005 10:59 PM 
  >   Subject: MK Dual Elavator Bellcrank & Pushrod? 
  > 
  > 
  >   I've mounted the bellcrank and will use Central's carbon fiber push rod.  The pushrod length from servo to crank is about 28". 
  > 
  > 
  > 
  >   Is it necessary to install a support of the rod  halfway down the fuselage to prevent flexing.  And if so does anyone have a simple way of doing this inside a fiberglass fuselage? 
  > 
  > 
  > 
  >   TIA 
  > 
  >   Jerry 
  > 
  > 
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