I did speak to one manufacturer of "quick release pins" (on an
unrelated matter) who said that the load rating only applies to the
main shaft and not to the retaining mechanism (i.e. ball). This was
the reason for my original question.
In addition, I also recall seeing an email in this group who said
something was rattling around the belly, which turned out to be the
spar socket. There was no conclusion on why it had come off, but it
could be due to the pip pin ball slipping, allowing the spar to pull
the socket off.
The spacing between the spar and the aileron crank is just a few
millimeters. So if there is enough force to pull a socket off its
araldite bond, that same force can easily flex the spar enough to
interfere with the cranks, especially since the spars have a lot of
flex in the lateral direction.
On Sun, Oct 27, 2013 at 6:48 AM, craig <craigb@onthenet.com.au> wrote:
>
>
> However to improve on the pip pin being used for this purpose I think would
> need a pin threaded for a nut to be tightened and if you can develop a way
> of access to a fully assembled aircraft for applying a bolt and nut I would
> be pleased to hear of it ! In the meantime the pip ball rules!
>
> Bob, and all others of course
> I like you and no doubt quite a few others have given the threaded bolt
> option
> You mention quite some thought, spending a lot of time traveling for work
> Gives you the luxury of time to ponder such small things, the main issue
> I have over switching to some sort of threaded arrangement is the alignment
> issues
> With the pin now can be troublesome, now say it has the be PERFECTLY aligned
> to
> Get the thread to start without cross threading it, and it just got a whole
> lot
> Harder, of course you could use some form of stepped alignment with say a
> 3/8
> Taper stepping up to the 1/2 inch thread and a caged nut that can move to
> align
> But not rotate, that was my idea anyway, but I don't think there is enough
> space
> Say 1/2 an inch, for the caged nut, plus then the tapered end of the bolt
> sticking through
> The nut. One option that did come to mind was something similar to a masonry
> anchor
> Where you slide the whole thing into a hole, and tighten the bolt(or nut)
> depending
> On the style and the unit in the hole expands at the end to lock itself into
> the
> Concrete. If you used an internal thread arrangement to pull a set of jaws
> outwards
> You could "grab" the back end of the socket where the balls are now, and
> pull both spars
> Then hard into the seat back, by simply tightening one bolt
>
> HOWEVER
>
> The device mentioned would likely be a custom made part, with springs etc to
> ensure the jaws
> Retract, I know of no such part at present.
>
> Secondly, no doubt someone will weigh in with and it is a concern of mine
> too
> It is generally accepted the seat back is NOT contributing to transfer lift
> loads etc
> To the airframe, and that like most aircraft the wings do flex and move in
> flight
> If you have the spars firmly bolted to seat back then you remove that
> movement potential
> Completely and probably make the seat back a major load bearing component,
> and who knows
> What the result of that might be
>
> Just my thoughts
> Make of them what you will, the pin works ok, sure its not perfect, but
> would
> Something else be any better
>
> Regards
> craig
>
>
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