[TowerTalk] sched 80 mast

[Jim Thomson]

VE9HF  indicates his  sched  80 mast is  .25" thick.     It's not. 

IF his mast is  typ 1.9" OD  sched 80  stuff... it's only  .200" thick.   His section modulus is only .412 

If the yield strength is  35 ksi.... his max  bending moment is  only     .412 x 35 ksi = 14,420  in lbs...[ 1200 ft lbs]

Lets say  7  sq feet @ 70 mph [20 lbs  per sq ft]   x  14'   .... =  1960 ft lbs  of  bending moment. 

1960> 1200  !     The mast will snap like a tooth pick.   The mast is maxed out  with 1200/140 =  8.57' 

This doesn't even factor in the  other TWO  proposed yagi's... nor the wind load of the mast itself !  

 It's NOT....." a serious  tower" .          It's made for TV ants'... and can be used with ham ant's,

provided you don't overload it...esp with tall masts.   Even if you guyed the tower,  the proposed  mast you 

are contemplating will fold over at a right angle.      That  Delhi  isn't CSA  approved, nor does it meet

the Canadian  S-37 tower specs.   Load it up with heavy wet snow + a tiny bit of ice  .....+  a 55 mph gust

.. and it's  bye-bye tower... plus 3 x ants'  trashed.  Removing a bent mast is a gong show in itself.. and

extremely dangerous.   If you want a   stronger, self support tower,  get a Trylon Titan..[with the 48" wide bottom section]...

... or better yet ..a  Trylon  Super Titan. The Trylon super Titan IS  a S-37  rated tower, and will handle  25 mm of radial ice  + high wind.

 It's the real deal.   The stock Delhi top bearing plate + mating thrust bearing is pure junk.   The rotor plate is worse.   You will end up

tearing up all the plates within months. 

Later.......... Jim  VE7RF