T. A. Russell wrote:
>
> See additional question at end - de N4KG
>
> On Tue, 7 Oct 1997 10:15:20 -0700 Ken Fisher <kfisher@inreach.com>
> writes:
> >> | >I have attached a url with a pic of my stacked beams klm 20m-6
> >with
> >> | >a klm 40m-4 over it. The mast is aluminum t-6061 3/8 wall 14'
> >sticking
> >> | >out of the tower. No problems Cost was appx $130 for the mast.
> >Ken
> >> | >W6FK
> >> |
> >> | If that is a 2" O.D. 6061-T6 mast, my calculations predict
> >> | failure at 55 miles per hour if the wind is in line with the
> >> | two antennas. You have been lucky so far.
> >> |
> >> | Dave Hachadorian, K6LL
> >> | K6LL@juno.com
> >> |
> > If you look real close you will see steel guys from
> >the boom ends on the 40mtr beam down to the mast
> >just above the 20mtr beam. This is my margin of safety
> >and with the top guying on the 40 gives a nice diamond
> >effect of guying. Ken
> >
> >--
>
> The maximum bending moment will be at the exit point of the tower.
> Please explain how guying the boom of the TOP antenna on the mast
> back to the mast provides any margin of safety.
>
> de Tom N4KG
>
> --
> FAQ on WWW: http://www.contesting.com/towertalkfaq.html
> Submissions: towertalk@contesting.com
> Administrative requests: towertalk-REQUEST@contesting.com
> Problems: owner-towertalk@contesting.com
> Search: http://www.contesting.com/km9p/search
My concern is the aluminum mast breaking half way between the
20 mtr beam and the top. Thats why the guys are used. I have no
fear that the mast will break just coming out of the thrust bearing
or even two feet up where the klm 20m6 resides. This would take
one hell of a wind I feel in excess of 55mph and we dont have forces
like that in central Ca. Ken
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search
|