[TowerTalk] ma550 guying

[jim Jarvis]

Yes, you're right.  I hadn't considered guying just the lower section.

You could do that, but it wouldn't add capacity.

I'm a fan of these tubular crankups, except for the fact that their  
ratings
are relatively low.   So long as you don't have to meet a 90mph wind  
rating,
you can use them for small antennas.

N2EA




On May 7, 2008, at 10:32 PM, Jim Lux wrote:

> jim Jarvis wrote:
>> Ignoring, for the moment, the prime directive,  let's look at  
>> what  you're doing if you guy a crankup tower.
>> The lateral forces on the tower, which cause it to flex and shed   
>> load, are transferred to
>> the guys, and to the vertical structure itself.   With a crankup,   
>> that means to the hoist cable!
>> The cable is not specified for anything more than lifting the  
>> weight  of the tube, with some
>> safety margin.
>
> Except if you just guy the bottom section. I'm assuming that the  
> lowest tube has plenty of compression strength.  I'm not sure this  
> buys you much (I suppose you could get away with a smaller (or  
> almost no) base, since it doesn't have to take the overturning  
> moment)..
>
> I've seen this strategy used with things like tower trailers.   
> Solves the problem of keeping the whole thing reasonably upright,  
> without adding load to the hoist cable.
>
>
>
>
> Jim, W6RMK