I don't know the weight of their cable yet, but the sales rep is
checking for me. A Corning ST drop is 20lb/1000ft, and I used their
weight figure for my guestimate since I didn't know the weight of FS's
cable yet.
I used this approximation formula:
https://www.engineeringtoolbox.com/cable-loads-d_1816.html
and I used the weight of the cable itself as the vertical load (q)
That gives me more conservative outcomes than the calculator you
linked. Your link tells me if I'm ok with 1% sag then I've only got
711N of tension. That's well under the 1200N they're saying. The other
figure put me just under 1200N.
I read the real method is something like integrate the cosine of the
tangent angle of the something somethings and I don't get it. I'm
content to rely on approximations for now LOL.
I guess the root of my question is whether it's even plausible that the
FS drop cable can take 3 times the tension of the Corning ST drop cable
or if it's clearly wrong.
-Adam
On 10/25/2018 12:53 PM, Chuck McCown wrote:
That is 269 lbs. Not a lot.
What is the weight per unit distance?
At .05 lbs per foot and with this much tension you will have 8' of sag
in the middle.
https://www.spaceagecontrol.com/calccabl.htm?F=269&a=600&q=.05&g=32.18503937&Submit+Button=Calculate
-----Original Message----- From: Adam Moffett
Sent: Thursday, October 25, 2018 10:46 AM
To: [email protected]
Subject: [AFMUG] Drop cable tensile strength
This cable at FS:
https://www.fs.com/index.php?main_page=product_info&products_id=31945
Their web page is saying long term tensile strength of 1200N.
Corning ST drop cable has a similar type of strength member and they say
400N.
At 1200N it would appear that I could hang that cable 600 feet with a 1%
sag and I'd still be within strength limits.
So is this a lie like the horsepower on a shop vac, or could they be
using some alternate but valid way of measuring tensile strength, or
could it actually be correct?
I sometimes pretend I'm an engineer, but I'm wondering if any of you
real engineers out there have any insight.
Thanks,
Adam
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