Steel tube mast

[Roman75]

Hi!
Newbie here. I am planning to build a 6 m (20 ft) tall 42.4 x 4,0 mm (1 1/4 x 5/32") steel tube mast for the Sirio Vector 4000 antenna (height 8480 mm (27.82 ft), weight 4.7 kg (10.36 lb), wind surface 0.29 m2 (3.122 ft2), wind load / resistance is 329 N at 130 km/h . The material is S355J (A572 Grade 50 equivalent).
Mast will be fixed to a solid construction at 1.2 m (4 ft).
Is there a calculation I can use?
Is it possible to use it without a guy?
Thank you.

 

[KB4MSZ]

I made a model in AutoCAD of that mast. That's quite thick. Based on a cubic foot of steel weighing 490 lbs., that mast alone will weigh 36.78 lbs. The mount point will need to be quite secure for sure. I'm not a PE by any means but I can't see the mast itself folding in any wind.

 

[Roman75]

Catalogue data says 3.79 kg/m, total weight per 6 m is 22.74 kg (50.13 lbs). Mast+antenna=27.44 kg (60.5 lbs).
Do you think it is too heavy?

 

[prcguy]

That mast is quite thick and from my seat of the pants experience I don't think it will have a problem with winds up to maybe 50mph. About 45yrs ago I had a similar setup but with a much thinner mast, about 1/16" (.0625") thick wall by 2" wide square high tensile strength steel tubing 20ft long with a 22.5ft long Hy-Gain Penetrator antenna on top. The mast was on a home made chimney mount with the base and upper securing point about 4ft apart.

That was up for several years until a 75mph wind came up and it buckled the mast just above the chimney. Your mast will only be 1.25" diameter but .156" thick wall, so it's close with maybe a little more strength than my old setup. Personally I would upsize the mast diameter to 2" keeping the same wall thickness and I suspect it will be fine with 75mph wind.

 

[Roman75]

Huh, at 2" the weight of mast will increase to 33.3 kg (73.4 lbs), that is almost 50% increase.