[Towertalk] AB-577 Mast and Windloading

[Dan Hammill]

One of my AB-577's (full 50' height) had a top-mounted
G-1000SDX rotator with a 5-foot mast with a M2 6M7JHV at
the rotator and a M2 2M5WL at the top.  During a 4-day
windstorm that started at 35-40 MPH with 50-65 MPH gusts.
When the winds peaked at 75-80 MPH with 100+ gusts, the
upwind guy anchor jerked out, and the AB-577 came down.

The other AB-577 had only two sections inserted for a
rotator height of 13 feet.  Same azimuth rotator setup,
with a KR-500 elevation rotator, and a 4-bay of M2 2M9SSB.
It tumbled about the same time as the other when the
upwind anchor pulled loose.

I think the primary reason the anchors pulled loose was
from 4 days of continuous violent gusting.  The constant
jerking on the upwind guy anchors essentially liquified
the soil (very hard, dry decomposed granite) and out
they came.  I think that the AB-577's would have survived
had the anchors been concrete deadmen.

Hope this helps.

73,
Dan  KB5MY
Ramona, CA



> -----Original Message-----
> From: towertalk-admin@contesting.com
> [mailto:towertalk-admin@contesting.com]On Behalf Of Nat Heatwole
> Sent: Thursday, April 18, 2002 06:43
> To: towertalk@contesting.com
> Subject: [Towertalk] AB-577 Mast and Windloading
> 
> 
> Does anyone know how many square feet of antennas a AB-577 Rocket
> Launcher mast will support and at what wind speeds? What's the most
> antenna/mast/rotor weight that can be put on top of one? Any information
> is much appreciated.
> 
> 73, Nat, WZ3AR
> <nat@ajheatwole.com>
> 
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