[TowerTalk] U Kno this ain't the last on Aluminum

[Bill Aycock]

Mr. Dimitry
I was an aerospace Engineer for many years , and, to my sorrow, I wrote a
lot of "proposals", so I know  how to spot a lack of Precision (a mild term
for it !) in product description. However, I have observed that, here on
TowerTalk, as on Antennas, statements like some of those you have made
about the differences between Steel and Aluminum will be challenged. And
properly so. Comparisons of apples and oranges, while calling the both
fruit just wont hack it. What is OK for Brochures is just bait for the
wolves on here.

I have picked out just a couple of examples from a recent posting of yours,
and put my questions or comments after.

At 03:39 PM 10/10/98 -0500, you wrote:
>
SNIP
--.  Specifically, this is probably the price difference
>between a moly-chrome mast less than 2" O.D. with less than .150 wall  and
>an aluminum 2" x 1/4" wall mast.  

Why not compare on the basis of the same OD, with the same load (bending
will do) at a level typical of the duty we expose these things to? Get
specific, then give the numbers of cost, FOB.

>  I know I can supply Hams
>with superior values in masts, measured in $ for strength, flexibility and
>longevity.  

Again- give a real comparison. (Flexibility? see below)


> One point I want to echo is that I think because
>of its elasticity and flexibility, I think an aluminum mast, in terms
>of tensile strength, may tend to bounce back and not completely fold or
>break like steel and stainless would under similar pressure.

In terms of semantics, this is nonsense. there is almost no meaning in this
statement. Flexibility is just another word for giving under load, and I
dont think that is a good criteria for a mast.
 In what way is the elasticity of Aluminum greater than that of steel? I
really feel the need for a definition, here.  If it's modulus of
Elasticity, Aluminum has a value about a third of steel.
In addition, "under similar pressure" is about as vague a comparison as I
have seen.  Which pressure are we talking about?
>
>
>.  Then take your tower apart
>every 3 to 5 years to check the joints. 

Are you serious? I just bought a tower erected in about 1978, and up since
then- it is hot-dipped galvanized, and was in great shape when the owner
became an SK and it was taken down . The joints on the tribander on its top
were not in very good shape, however. It was aluminum.
>
>
>Drake Dimitry
>Heights Tower Sys.


Bill- W4BSG

Bill Aycock   W4BSG
Jackson County, AL
EM64vr
W4BSG is "vanity" this time, but was 
earned by exam in 1954, the first time.

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