Troy:
My very conservative estimate has wind load at 660 lbsf. at a wind speed
that would have prompted me to lower the tower long ago…. The 7 x 7 wire
I’m using is rated for failure at 1400 lbs. load (consistent w/ your
comments). Assuming two of four guys are loaded, I appear to have a safety
factor of about 4.25 (or 2.12 if only one wire is taking the full load) and
recognizing the estimated load is likely much higher than will be realized.
I’ve written a procedure requiring the tower to be lowered if wind speed
exceeds 20 mph; so I think this issue is now covered. Says here….
Comments most welcome if anyone sees something I’ve missed, or just has
questions,
Bill
On Sun, Aug 29, 2021 at 5:53 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx>
wrote:
Wire (say stainless steel) will generally come with MBS (minimum breaking
strain in lbs or Kg or kN) and/or SWL/WWL which is MBS divided be a very
generous safety factor. Typically for 3.2mm (1/8”) wire, the MBS will often
range from 600 to 800ish Kg max load before failing. That’s for typical 316
austenitic grades used for rigging and architectural applications. Some low
strand count offerings can get beyond 800kgs but they’re not very flexible
and shouldn’t be exposed to any bending loads.
Troy
*From:* arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx]
*On Behalf Of *William Claybaugh
*Sent:* Sunday, 29 August 2021 11:15 PM
*To:* arocket@xxxxxxxxxxxxx
*Subject:* [AR] Re: Guy wire calculations
When I looked, I was I interested in how small the wires are for sailing.
As a test, I assumed the tower was a flat plate (18” wide, 24 feet long)
with a wind load at 60 mph (100 kph). That indicates 1/8” (3mm) diameter
stainless is sufficient for the load.
Bill
On Sun, Aug 29, 2021 at 3:08 AM Uwe Klein <uwe@xxxxxxxxxxxxxxxxxxx> wrote:
Am 25.08.21 um 01:05 schrieb William Claybaugh:
I’m in the final stretch of finishing an (initially) 24 foot tall launch
tower of triangular cross-section and fairly hell for stout.
The last (known) problem is setting up the guys to keep the front end
from whipping during launch and under wind loads.
I’ve worked out the geometry (four ground anchors on 24 foot centers) to
give a near 45 degree ground angle (52 degrees calculated). But I am
interested in the details of rigging:
What wire rope diameter is appropriate and how does one calculate that?
Does the sizing of the turnbuckles matter (12” of draw vs 6”?). Is
stainless preferable? What do experienced riggers know about this
problem that I do not yet know?
Bill
Whats used for sailboats
Metal: solid wire or low flexibility ( 1x19 ) wire
In recent times there is a wide range of rather stiff
synthetic fiber stuff around. (light, used for racing boats.)
I'd think about a set(quad?) of diamond stays from top to bottom
to curb whiplash effects.
Then attachment of the guy wires to ground from the middle of the rail.
