[TowerTalk] Bolt in Hole (45 Top)

[David & Barbara Leeson]

A few years ago, in a different context, the question of holes as
stress risers and centers of fatigue failure was raised.  Since then,
I've seen a reference to the idea that a filled hole has much less
susceptibility to fatigue than an empty hole.  This reference was 
regarding riveting of aircraft skins.

It makes sense that a filled hole can't deform inward, so the idea of
filling tower-leg holes with a nutted bolt seems a good one.  The filler,
whether it's a bolt in a large hole or a rivet in a smaller one, should
be a tight fit or the effect is lost.

Re Rohn 45, I prefer the flat top sections that bolt onto a standard
section.  Besides giving a place to stand and work (assuming the mast
you're strapped to is trustworthy!), it's a more flexible logistics
situation.  The thick-wall sleeves on the top plate reduce the chance
of fatigue failure at the bolt holes, which in any event are filled by
the bolts.

Cheers de Dave, W6NL (ex-QHS)

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