Bottom line, if the manufacturer can't, or won't, give you 90 mph data or at
least the projected tower area and, taking into account the materials used,
the maximum allowable restraining moment, then they probably know nothing
about things like section modulus and moment of inertia and never did the
calculations themselves, in which case I would have second thoughts about
buying their tower.
Gene / W2LU
----- Original Message -----
From: "Jim Thomson" <jim.thom@telus.net>
To: <towertalk@contesting.com>
Sent: Wednesday, December 07, 2011 7:24 AM
Subject: [TowerTalk] HDBX-48 figures for 90 mph zone
> Date: Wed, 07 Dec 2011 00:19:21 -0500
> From: K8RI <K8RI-on-TowerTalk@tm.net>
> Subject: Re: [TowerTalk] Fwd: HDBX-48 figures for 90 mph zone
> To: towertalk@contesting.com
> Message-ID: <4EDEF759.7040005@tm.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> On 12/6/2011 11:13 PM, HansLG@aol.com wrote:
>>
>> In a message dated 12/6/2011 4:43:51 P.M. Eastern Standard Time,
>> w2lu@rochester.rr.com writes:
>>
>> As I recall wind pressure "on a flat surface" at 70 mph is 20.6 lbs/sq
>> ft.,
>> so if the tower is rated for
>> 18 sq ft at 70 mph, would it be too much of a stretch to say to the
>> zoning
>> board that since wind pressure at 90 mph is 34 lbs/sq ft, by simple
>> math,
>> the tower should be good for 10.9 sq ft at 90 mph ?
>> Gene / W2LU
>
> Regardless of wind area isn't there a boom length limitation on both the
> BX and HDBX series?
>
> 73
>
> Roger (K8RI)
>
> ## yes, I think they reduced it to just 10' years ago..and sales
> plummeted.
> Just fudge the ant wind load a bit, and perhaps 'take out' one section on
> paper.
> Then when u install it, add the extra section back in. IF you ever did
> hit it with
> a 90 mph wind, and a big ant, ur gonna be in for an eye opener. That
> thing about
> 70 mph = 20.6 sq feet. That's from 1976. 222- REV-D. It's now REV G !
> A Trylon T-500, 72' tall..is good for 22 sq feet @ 70mph....but only 6 sq
> feet
> at 100 mph. The tower itself will eat up all the windload. Toss in any
> ice,and
> you can kiss it goodbye. I wonder if the factory will even give you a
> windload
> rating for 90 mph ?
>
> Jim VE7RF
> _______________________________________________
>
>
>
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