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1. 05:14 AM - Re: Bell crank tubing (Woodflier@aol.com)
2. 08:08 AM - Re: Re: Bell crank tubing (w b evans)
Message 1
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Subject: | Re: Bell crank tubing |
--> Pietenpol-List message posted by: Woodflier@aol.com
I used that same size streamline tubing for my bellcrank, flattened the ends
by heating the tubing with a torch and flattening in a vice when it was red
hot. It helps to take a couple of pieces of angle iron, cut it at the angle in
about 2 inches and bend the free piece into a nice curve. Put two of these
between the jaws of your vice and it'll keep the sharp edge of the vice jaws from
cutting into your tubing and gives a nice easy bend from the round tubing to
the flattened section. I think Tony Bengilis has a description and pic of this
in one of his books on aircraft construction. And I did edge weld the ends.
One advantage of the streamline tubing is that, though it looks pretty
massive, you are going to drill a big hole in it for the axle shaft, so you need
some width there to carry the loads around the shaft, and to give something to
weld the shaft to.
Regarding the attachment of the two elevator cables to each end of the
bellcrank, standard shackles don't have enough room for two cable eye, with
thimbles, at least I didn't using 1/8" cable. I ended up taking two pieces of .090
steel, about 3/4" by 1 1/2", putting about a 20 degree bend in them and putting
one on each side of the bellcrank, with the bends pointing outboard in each
case with a pivot pin through, and attaching my cables to those.
If you have trouble visualizing this, I can email you a pic of my set up.
Oh, and while we're on the subject, think about making up some pulley
brackets and using pulleys where the elevator cables and the rudder cables make
that
bend at the rear seat back. I wasn't satisfied to just drill holes in the
bottom seat support for that, but to each his own.
Matt Paxton
You wrote:
Do you happen to remember what size you use for the cabane struts. Did you
flatten
the ends on it for use on the bell crank. The plans show you should flatten
the ends. The streamlined tubing I have is 1.685 x 0.714 0.049 thickness.
Is this to big? or does the geometry of the control cables (two into one
attachment
point)require this much strength?
Speaking of flattened ends, when you pinch the ends for the rudder bar and the
bell crank do you need to weld the ends closed after you flatten them?
Chris
Sacramento, CA
Message 2
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Subject: | Re: Bell crank tubing |
--> Pietenpol-List message posted by: "w b evans" <wbeevans@verizon.net>
Matt,
Just an added 2 cents,,,
You can use just one cable eye in the center of a long cable. The cable
splits from the single eye and one goes left and one goes right.
I know a guy who flew a Piet that someone else built, and he told me that a
friend and friends wife was flying it and the weld at the bellcrank/shaft
broke with a very unhappy ending. He kept pushing me to put a "safety" tube
inside the normal one just in case.
But that's another story.
walt
NX140DL
22 1/2 down, and 2 1/2 to go
----- Original Message -----
From: <Woodflier@aol.com>
Subject: Pietenpol-List: Re: Bell crank tubing
> --> Pietenpol-List message posted by: Woodflier@aol.com
>
> <snip>
> Regarding the attachment of the two elevator cables to each end of the
> bellcrank, standard shackles don't have enough room for two cable eye,
with
> thimbles, at least I didn't using 1/8" cable. I ended up taking two pieces
of .090
> steel, about 3/4" by 1 1/2", putting about a 20 degree bend in them and
putting
> one on each side of the bellcrank, with the bends pointing outboard in
each
> case with a pivot pin through, and attaching my cables to those.
>
> If you have trouble visualizing this, I can email you a pic of my set up.
>
> Oh, and while we're on the subject, think about making up some pulley
> brackets and using pulleys where the elevator cables and the rudder cables
make that
> bend at the rear seat back. I wasn't satisfied to just drill holes in the
> bottom seat support for that, but to each his own.
>
> Matt Paxton
>
>
> You wrote:
>
> Do you happen to remember what size you use for the cabane struts. Did
you
> flatten
> the ends on it for use on the bell crank. The plans show you should
flatten
> the ends. The streamlined tubing I have is 1.685 x 0.714 0.049 thickness.
> Is this to big? or does the geometry of the control cables (two into one
> attachment
> point)require this much strength?
>
>
> Speaking of flattened ends, when you pinch the ends for the rudder bar and
the
> bell crank do you need to weld the ends closed after you flatten them?
>
>
> Chris
> Sacramento, CA
>
>
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