[TowerTalk] hdbx rating

Jim Jarvis jimjarvis at verizon.net
Mon Mar 13 00:34:41 EST 2006

there are two issues here. (and some side comments)

1)  Will HBX support the array?

2)  Do you have to convince local zoning officials that
	it will support the array?

If the former...the answer is yes, for some time, but it isn't
recommended by the manufacturer.  If the latter, then forget
about it...the cost of providing engineering documentation
will exceed the structural costs by a substantial margin.

The HBX/HDBX towers were designed as self supporting towers,
not guyed.  And, liability issues forced them to restrict the
boom length to 10'.  Will they hold more than rated?  Undoubtedly.
For a long time?  Undoubtedly.  Are they OK guyed?  Undoubtedly,
but not by design.  Can you get a building permit for one, if you
plan to exceed the design specs?  Only if you fail to disclose some details.

If you put it where it won't hit a house, then it probably won't
matter, unless your local code officials say it does.  And that's
a different problem, entirely.

As for stories about how big and how much, and who else did what...
they simply don't matter.  Rohn under-specified their towers for
liability reasons, for a long time.  You can get away with quite a lot,
although you bear risk when you do.

The idea of using a torque tube and base mounted rotor is a good one,
if you can finesse the zoning folks. And as a final thought....they're
a bitch to climb, having no horizontal bracing elements.  Don't forget
that the foundation will cost as much or more than the tower itself.

jimjarvis at ieee.org
jimjarvis at verizon.net

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