W7CE wrote:
>> One could look at the off-vertical situation by considering that
>> installing it non vertical puts a static side load on the whole thing.
>> The load would be sin(theta)*weight. Say the whole thing weighs 1000
>> pounds (I don't know if this is plausible.. it's just easy to calculate)
>> and you're 2 degrees off vertical (about 3.5 feet in 100). The side
>> load is about 35 pounds (distributed along the whole thing). That's
>> pretty small compared to the wind load (90 mi/hr = about 20 lb/sq ft,
>> and you know the tower has a lot more than 10 square feet of cross
>> sectional area)
>>
>
> Is 20 lb/sq ft correct for 90 mi/hr winds? I've run several of the
> published formulas in the past and seen other references that would
> indicated that 36 lb/sq ft is a good number to use at 90 mph. I realize
> that it is dependent on height above ground and other factors. Have I
> miscalculated or am I in the right ballpark?
>
36 lb/sf is more like 120 mi/hr...
lb/sqft = Vmph^2/391 is the equation.
8100/391 -> 8000/400 -> 20 approx
391 is the half the density of air in weird units (F = 1/2 * A * rho * V^2)
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