[TowerTalk] Adding Expanding Foam inside boom

Charles Morrison junkcmp at gmail.com
Thu Apr 26 13:26:45 EDT 2018

Thanks All.
My questions and concerns have been answered.

On Thu, Apr 26, 2018 at 11:42 AM, Charles Gallo <charlie at thegallos.com>

> On Thu, April 26, 2018 9:20 am, Bob Shohet, KQ2M wrote:
> > I would also expect that the rate and quality of the “curing” would be
> > impacted by the ambient temperatures and humidity levels/climate at a
> > given location.  In much of New England the temperature can easily vary
> > by more than 120 degrees in the course of a year – and significantly more
> > in the great plains states.  And the climate can very enormously from the
> > generally wet/humid East to the desert SW. This has to have an impact.
> >
> > 73
> >
> >
> > Bob  KQ2M
> Of course there are foams (2 part) that mix on spray, and don't require
> water vapor to cure
> That said, what is the problem you are trying to solve?  Usually foams are
> used to stop vibration/change resonance frequency.  Here is the question
> (and I don't know the answer) - how often do we see fatigue
> cracking/failure on the BOOM of an antenna?  Not the elements - heck, they
> crack on some, but I don't think I've heard of booms failing except during
> extreme events like ice/wind storms.
> The foam might not give you ANY extra strength, and even you look at
> strength/weight, I'm going to guess it'll be a net negative.  Now if you
> know your boom has a vibration problem, we are talking another story.
> Even then, there are probably better ways to make the boom stiffer (put an
> end cap on both ends, attach a cable that runs inside the boom from end
> cap to end cap, and come up with a way to tension the cable - aka put the
> boom under compression, or put a metal ROD in, and put the boom under
> tension - both will change resonance)
> The material that interests me.  I've heard that they make tube that is
> similar to ACM sheet - basically a pair of Al tubes, with a composite in
> between (ACM siding is polystyrene or similar)
> I'm wondering if these materials might be the way to go in new designs -
> they are about 90% as strong, but also less than half the weight.  I
> wonder if we could go to some of the carbon fiber/aluminum composite
> tubes, and get MORE strength, for LESS weight (for the same size), or
> downsize, to go SAME strength, but less area and load.. (of course at
> greater expense)
> _______________________________________________
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk

More information about the TowerTalk mailing list