[TowerTalk] hdbx48 failure

[Jim Jarvis]

Clearly, sheer winds from downbursts at leading edge
of Tstorms can be catastrophic, and Chuck's tower was
overloaded.  BUT...

If the guys had been connected using a triangular bracket,
such as Rohn uses for mounting their torque arms on 25g, 
and if there had been torque arms, along with the torque
tube to the low-mounted rotor...it's possible the stick would
have survived.  

As I reflect on the one hbdx48 I saw fail, it related to the
guys being looped around the legs.  Compressed leg structure 
and no resistance to torque loading crumpled the section.  

Ignoring, for the moment, the prime maxim of "following the
mfr instructions", I think this tower is viable for moderate
arrays, if the torque load is moved off the upper sections.

It STILL won't tolerate 20 sq. ft. in 100mph winds, without
guying...and only maybe then, if it's engineered.

(but PLEASE don't put 'em up next to a bloody powerline!)

n2ea
jimjarvis at ieee.org