Hello Pete, I think this discussion is going is going in two directions. The
ones that have had no failures and the ones that have had them. I think if you
look at the average installation you will find that the wind conditions are
low. By that I mean the average wind for the year measured 24 hours a day for
365 days is probably below 10 mph. Most urban areas are built in low wind
locations. The problem arises when the average wind is high with day after day
of winds over 30 mph. We have had people make statements that Force 12 elements
don't vibrate and therefore don't need rope in them or will not fail from wind
induced vibration. I know this is false because if you take an element and
swing it around you will hear and feel the vibration from the element. We have
had comments from people that had failures and I suspect they are in high
average wind locations. The question is what level of vibration is acceptable
for the average installation and what is the life expectancy in that
environment. I don't think any manufacturer does wind tunnel testing or
software analysis to determine the vibrations at speeds from 0 to 120 mph and
what effect it will have on the structure. The aircraft industry does do these
analysis and designs the products to work in a specific range for a certain
period of time. The products the we are talking about are not in the price
range of aircraft components and it is a different market. With the amount of
time and money invested in putting up an antenna I would like it last as long
as possible and take every measure to keep it up in the air.
73 Steve
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