[TowerTalk] How many tower sections i can install??

[Alex Malyava]

since we are talking about 30' short "tower" on the building roof, why not
to use some sort of pipe instead of pretty heavy Rohn sections?
I don't think it is a big deal to find or weld 9-10-12m long tubular mast
that will be able to support a spiderbeam or some other lightweight
tribander.

On Wed, Aug 26, 2015 at 11:22 AM, TexasRF--- via TowerTalk <
towertalk at contesting.com> wrote:

> Hi Douglas, you can achieve a a greater guy point distance by using four
> guys instead of three. You would not want the guy to guy angle to exceed
> 120
> degrees in any case.
>
> Your roof dimensions would allow guy to guy angles of 120, 60, 120 and 60
> degrees. With the tower mounted in the center of the roof and assuming the
> anchors are at the edge of the roof, a guy to guy angle of 120 degrees,
> the
> distance would be 20.0 ft to the anchor. The distance between anchors
> would be 34.6 ft, 20 ft, 34.6 ft and 20 ft.
>
> So, in this case, you could guy the tower a couple of ft below the top and
> three 10ft sections would have a anchor/height ratio of 66.66%.
>
> We typically use an 80% ratio mainly because that is the number Rohn
> specifies for all of their tower models. It is a good compromise between
> load
> capacity and space required.
>
> Considering that these towers are used up to 180ft in height or more, it is
>  reasonable to move anchor points inward for reduced heights. The issue in
> doing  this is that Rohn has no published data for doing this. The wind
> load
> rating has  to be reduced and it takes engineering skills to properly do
> the calculations.  It is not rocket science however.
>
> I would be concerned about possible roof damage as much as the tower
> surviv
> al. It is conceivable that using the roof edge as a turning point for the
> guy and then a ground anchor would be stronger. Something else that would
> benefit from an engineers blessing.
>
> 73,
> Gerald K5GW
>
>
>
>
>
> In a message dated 8/25/2015 9:14:22 P.M. Central Daylight Time,
> co8dm at frcuba.co.cu writes:
>
> Hi,
>
> I would like read your ideas.
>
> I have few 10 ft  section of a tower (it is like a Rohn 25G).
>
> I would like install few  section over some part of my roof...The roof is
> concrete...as you know many  house in the Caribbean has concrete roof ...it
> is 24ft by 40ft...so, i have  calculating and the distance from the base to
> the guy anchors is 14 ft  !!!
>
> I know the distance from the base to anchor points is 70 % of the  tower
> height...so, 70% of 20 ft is 14ft, that´s mean 2 tower sections...right
> ??...Is it possible install 3 sections adding more guy´s set  ???
>
> Thanks,
>
> 73....Douglas,  CO8DM
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk  mailing  list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>