[TowerTalk] Tower design question

[Roger (K8RI)]

Maybe that is why I've seen so many Aluminum towers up here in the frozen 
north that have split legs from water getting in and freezing. I never 
noticed them to have this type of joint though and can't imagine why they 
would do so.

It's near 1:30 AM, but I had to go out to the shop and check an old Aluminum 
tower I have stacked up near the north wall.  Sure enough it too is 
"backwards".  I never paid any attention to it as I'd never put it together. 
It's a single bolt type, but I have no idea as to who made it. It has solid 
aluminum rods/braces welded in place that look like the diagonal braces on a 
25G.  I have planned on putting it up as a 40 or possibly shortened 75 meter 
vertical. (some day?)  48' plus some aluminum tubing to get close to a 1/4 
wave on 75... maybe stuck out in the NW corner of the back yard  (out of 
sight). It should do a good job of loading up the trees and the nearest home 
in that direction has been empty for some time.

Learn something new every day including what I've had in he shop for the 
last two years. <:-))
I still can't imagine why they would build them that way though.  Any 
engineers who can think of a good structural reason for doing so?

73

Roger (K8RI)


>I know of two manufacturers that do it "upside down". Heights is one and
> there is another (can't recall the name)  that looks almost like it that 
> is
> also upside down. They are aluminum towers and each section is tapered (so
> you can't install them the wrong way) and the upper section joins the 
> lower
> section by fitting inside of the lower part. It makes a nice funnel for
> rain. I have one.
>
> 73
> Gary  K4FMX
>
>> -----Original Message-----
>> From: towertalk-bounces at contesting.com [mailto:towertalk-
>> bounces at contesting.com] On Behalf Of Roger (K8RI)
>> Sent: Friday, June 29, 2007 6:52 PM
>> To: K4SAV; towertalk at contesting.com
>> Subject: Re: [TowerTalk] Tower design question
>>
>>
>>
>>
>> >I thought this was an interesting question, but no one tackled it except
>> > for one guy who said that's the way it's done.  So is that really the
>> > reason?
>>
>> I saw one answer that said that is *not* the way it is done.
>> I have never seen a tower designed the way you describe. They are all the
>> other way around. The larger tube or bell on on the upper section and 
>> sets
>> down *over* the lower.  Small end should always point up with the next
>> section setting down *over* it.
>>
>> That will still not keep water out of the legs except for rain.
>> Atmospheric
>> pressure changes be they barometric changes or due to temperature changes
>> will cause water to condense inside the tower legs which is the reason 
>> for
>> the bottom section setting in pea gravel or sand below the frost level so
>> it
>> can drain.
>>
>> Roger (K8RI)
>>
>> >
>> > Floyd Rodgers wrote:
>> >
>> >>Something has been bothering me for a while. With all the discussion 
>> >>and
>> >>problems with tower leg corrosion, filling with water and splitting,
>> etc.
>> >>Why do almost ALL the manufacturers design the joints to telescope
>> inside
>> >>from above which leaves water able to run inside joints and fill tubes?
>> >>Why not simply invert the connection by telescoping over the bottom
>> >>section so water just runs outside not through the joint. I know there
>> is
>> >>no difference in joint strength or assembly difficulty, so why?
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