MK Dual Elavator Bellcrank & Pushrod?

[Gray E Fowler]

Bob

My set up had the harmonic vibration issue. All I  did was take a soft 
square piece of urethane foam and bond it to the top of my pipe tunnel. 
The cf rod rides in a slot cut into the foam and thus dampens any 
vibration. The 1" X 1"  foam is a 1/3 the length of the rod inside the 
fuse the middle would be better if you can get to it.



Gray Fowler
Principal Chemical Engineer
Composites Engineering




Bob Kane <getterflash at yahoo.com>
Sent by: discussion-request at nsrca.org
02/03/2005 07:57 AM
Please respond to discussion

 
        To:     discussion at nsrca.org
        cc: 
        Subject:        Re: MK Dual Elavator Bellcrank & Pushrod?


I am using a carbon elevator pushrod in the Temptation
project I'm writing up in the K-Factor. I am more
concerned about harmonic vibration in the rod than
flexing, I'm sure the compression and tension stregnth
od the rod is more than adequate for the flight loads,
but any harmonic vibration in the rod left unchecked
could break the clevis end. I have made a bulkhead of
1/4" balsa, 1-1/4" high and the width of the fuselage
at the mid-point of the rod. I put a hole in the
center an lined it with foam rubber. The hole is large
enough to let the rod slide through without touching,
but should limit the amplitutde of any vibration that
tries to develop in the rod. 

--- Jerry Wilson <JWilsonJr at houston.rr.com> wrote:

> 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
> 
> 
> 
> 


=====
Bob Kane
getterflash at yahoo.com


 
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