Tower guy wires

[halfcrazy]

I am constructing a 84 ft tilt up tower using 3 inch pipe for the tower and will guy every 21 ft. i have a guy radius of 42 ft and a gin pole 42 ft long. this tower will have a 10 ft homebrew turbine on it. should i do 1/4 inch 7*19 galvanized cable for the bottom 3 points and use 5/16 for the top wire? or is 1/4 sufficient all the way?

[wooferhound]

Your top guy wires will attach 6 feet below the turbine so the props don't hit them, that would make your guy wires attach every 19.5 feet. Are you sure that 3 inch pipe can go unsupported for that distance to hold up a 10 foot turbine. I am positive that 2 inch pipe isn't enough as this story shows...

http://www.fieldlines.com/story/2008/6/20/04423/6376

[halfcrazy]

ok i was basing my logic off of south wests tiltup kit for the whisper 100 or 200 it is a 80 ft tower with 2 1/2 shc 40 pipe i noticed they have 5 guy wire sets so i can do that if it is necessary but i will use 3 in shc 40 so it should be loads stronger then 2 1/2?

 so would you go with 1/4 inch guys all the way or bump to 5/16 at top? or should i sell the turbine and get more pv? seems like it is almost impossible to build a tower for these things? i am open to suggestions any help is appreciated.

[wpowokal]

I use 6mm for the cables except the top two on the pull up side which I use 10mm.

I don't know how strong the winds are in them there Adelaid hills but for me 42' radius is not enough for that height. It works for 64' but 84 was a disaster.

http://www.anotherpower.com/gallery/allans-place/$#|+_happens_small_001

Woof 21 feet is the length in the old measurements (we went metric in 1966) for pipe in OZ. Having the guys at the joins works for me, unless the joins are very ridgid it makes for a more stable.

allan down under

[wooferhound]

I was just pointing out that the guy wires can not be attached to the Top of the mast or the props will hit the wires. the wires should attach to the mast well below the turbine, at least a props length below the top. I was asking if the pipe can go unguyed for the last 6 feet, at the top where where the forces of the wind are.

[scorman]

you specifically asked about the guy wire sizing:

I see a rating of 1400lbs working load for 1/4" cable ...considering that a 10 footer will probably not even reach 125lbs trust on the tower at any time, considering that at 25mph, the total thrust on a 10 foot solid disk is only 127lbs, but then add in the geometry effects for the angle from 40 ft up to 79 ...I can't see why you would want to hang extra dead weight at the far end ...makes it even harder to gin pole the tower up

BTW "guy radius of 42 ft " is the correct ballpark for 84-5= 79foot tie point ...2:1 is typical ...about 60 degrees give or take

Stew Corman from sunny Endicott

[halfcrazy]

Thanks stew glad to get the input everything is ordered heres what i went with

3. inch inside diameter sch40 pipe for tower
   
2. 1/2 inch sch 40 for jin pole
   
5. /16 cable for top anchor point
   
1. /4 cable for the other 3 sets
   

[scorman]

three points:

1. that gin pole is a "long slender column" ...needs to be supported in several places along it's length or it will buckle under compressive load
   
2. always use a torque wrench ( click style is best) for all the cable clamps (rope clips) and three tweaks ...first, second, back to first ...too easy to tighten one side and the other can come off with your fingers
   
3. "South West's tiltup kit for the Whisper 100 or 200 it is a 80 ft tower with 2 1/2 sched 40 pipe I noticed they have 5 guy wire sets" and I have seen three of their setups and none use turnbuckles ...I like 1/2x6 jaw+ eye
   
   

source for hardware posted before:

http://www.baronsnaps.com/products_items.aspx?Category=Turnbuckles&Subcategory=Jaw+%26+Eye&P
age=1

check out malleable wire rope clips and HD thimbles too ...if someone has a better deal, then let me know about it

Stew Corman from sunny Endicott

[frackers]

I've just done the sizing calcs for my 12m tower with a 3m mill on it - its scary when you add in the 'once in 25 year' winds of 150km/hr we have here. The stresses shoot up to 950kgs and that is without considering angle of the guys.

I've decided to go with a wire rope that has a 300kg working load and breaking strain of 1.5 tonnes and if I end up with them stretched in a storm then so be it - at least I hope to still have something in the air and not cutting stock in half in the paddock!!

The most I've actually measured here on a 5 minute average is 68km/hr which is quite bad enough - hard to stand up in and that wasn't even during a storm!!

I'm looking forward to seeing what our average (I can't sleep with all the noise) spring winds get up to with my new anemometer :-) See here for a bit of background to our weather.