[TowerTalk] Fwd: M2 40M3FS element tip problem

[donovanf at starpower.net]

Scott,

I've had a full size 3 element 40M beam in the air for the last 35 years, and a pair of them since 1986 in a very exposed location.  I've had no element failures, apart from several elements failures during a microburst in 1993 with winds estimated over 120 MPH (it severely damaged a dozen heavy duty Yagis).  I'm not sure if the failures was caused by the wind or by the aluminum siding hanging from the elements (torn from a house 1/2 mile upstream).

My 40M elements start at 2 inch o.d. tubing at the center, with six concentric layers of 0.058 inch wall tubing, gradually tapered to tips with 3/4 inch o.d. x 0.058 wall.  Each elements weighs approximately 75 pounds.

I can provide construction details for anyone interested in duplication this heavy duty, ice and wind resistant  construction.

73!
Frank
W3LPL

---- Original message ----
>Date: Wed, 9 Aug 2006 23:33:50 -0400
>From: "W3TX" <superberthaguy at adelphia.net>  
>Subject: [TowerTalk] M2 40M3FS element tip problem  
>To: <TowerTalk at contesting.com>
>
>I have a full sized M2 40M3 yagi at 120ft.  It's been up about 5 years.  The
>distal element taper is aggressive, ending with a 3/8 inch diameter tip on
>each of the six elements. Too small in hindsight!
>
>The 3/8 inch element tips are failing (it appears from a vibrational
>mechanism).  It's disconcerting tofind a 20 to 30cm section of aluminum with
>the mower blade :-)
>
>Q1). Has anyone else had this problem with the M2?
>
>Q2). Has anyone else modeled and/or implemented a less aggressive taper
>ending at 1/2 inch distal tips?
>
>Thanks in advance...
>
>73, Scott W3TX