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Russ Kinne
Joined: 27 Jan 2006
Posts: 182
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 Posted: Sun Dec 17, 2006 8:00 am Post subject: q |
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In re recent talk about tie-down ropes -- this may be more academic than practical, but there have been recent MAJOR changes in cordage (ropes, strings, cables, whatever) that may interest the List.
I just researched this subject for a boating magazine, and found that the new synthetics are nothing short of amazing.
We all know nylon & dacron & polyester -- but the latter is very seriously weakened by UV; sunlight. Don’t trust it.
There are a lot of new fibers now, and some are FIFTEEN times stronger than steel. A half-inch rope will theoretically hold TEN TONS! (but don’t stand under it)
But they’re all different. Some are stretchy (we don’t want that) or very non-stretchy. Most are UV - sensitive and must be protected from sunlight by a woven cover of nylon or dacron. No big deal.
The fibers named SPECTRA or DYNEEMA are reportedly the strongest fibers ever created. Others are brait, vectran, lycra, twaron, PEN, PBO, zylon, technora and others. All with different specs.
The bottom line is that there are some VERY strong ropes available now. But of course there’s a price. As I’ve said, most of them are UV sensitive and should be protected. None of them like being knotted very much; use splices and fittings whenever possible. And of course they’re expensive -- but you won’t need a lot for your tie-down ropes. And an adequately=strong rope may be too thin to grab hold of and haul on.
The best place to find them is in marine stores like West Products, or if by any chance you have access to a local sailmaker, pay them a visit and ask some questions.
And bring your checkbook; something may be irrestible.
Russ K
[quote][b]
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ceengland(at)bellsouth.ne
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| Posted: Mon Dec 18, 2006 1:37 am Post subject: q |
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russ kinne wrote:
| Quote: | In re recent talk about tie-down ropes -- this may be more academic
than practical, but there have been recent MAJOR changes in cordage
(ropes, strings, cables, whatever) that may interest the List.
I just researched this subject for a boating magazine, and found that
the new synthetics are nothing short of amazing.
We all know nylon & dacron & polyester -- but the latter is very
seriously weakened by UV; sunlight. Don’t trust it.
There are a lot of new fibers now, and some are FIFTEEN times stronger
than steel. A half-inch rope will theoretically hold TEN TONS! (but
don’t stand under it)
But they’re all different. Some are stretchy (we don’t want that) or
very non-stretchy. Most are UV - sensitive and must be protected from
sunlight by a woven cover of nylon or dacron. No big deal.
The fibers named SPECTRA or DYNEEMA are reportedly the strongest
fibers ever created. Others are brait, vectran, lycra, twaron, PEN,
PBO, zylon, technora and others. All with different specs.
The bottom line is that there are some VERY strong ropes available
now. But of course there’s a price. As I’ve said, most of them are UV
sensitive and should be protected. None of them like being knotted
very much; use splices and fittings whenever possible. And of course
they’re expensive -- but you won’t need a lot for your tie-down ropes.
And an adequately=strong rope may be too thin to grab hold of and haul on.
The best place to find them is in marine stores like West Products, or
if by any chance you have access to a local sailmaker, pay them a
visit and ask some questions.
And bring your checkbook; something may be irrestible.
Russ K
|
Finding something that's uv-proof is a good idea, but super strength
isn't likely to do much good beyond regular ropes. I lost a Thorp T-18
to wind in Oklahoma about 14 years ago in a storm that destroyed over 20
other planes. Many of the certified planes (Cessnas, Pipers, etc) left
their ropes at the tiedowns when the tiedown rings ripped out of the
wing structures.
Charlie
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d-m-hague(at)comcast.net
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| Posted: Mon Dec 18, 2006 4:23 am Post subject: q |
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At 09:55 PM 12/17/2006, Charlie England wrote:
| Quote: |
russ kinne wrote:
>We all know nylon & dacron & polyester -- but the latter is very
>seriously weakened by UV; sunlight. Don't trust it.
>There are a lot of new fibers now, and some are FIFTEEN times stronger
>than steel...
>The fibers named SPECTRA or DYNEEMA are reportedly the strongest fibers
>ever created. Others are brait, vectran, lycra, twaron, PEN, PBO, zylon,
>technora and others. All with different specs....
|
FWIW, Dacron, Lycra and polyester are the same thing (Darcon and Lycra are
trade names). Spectra and Dyneema are two trade names for ultra high
molecular weight (UHMW) polyethylene. Kevlar, Twaron, and Technora are
aramids, with Technora being slightly stretchier than the other two. The
liquid crystal polymers include PBO and Zylon (same thing) and
Vectran. Most of these are available with a woven cover to protect the
core fibers from UV.
None are "15X stronger than steel" overall, but the strength to weight
ratio is much higher than steel.
You do want some stretch; an aircraft rocking against a rigid tiedown (e.g.
chain) can hammer itself to death.
| Quote: | Finding something that's uv-proof is a good idea, but super strength isn't
likely to do much good beyond regular ropes. I lost a Thorp T-18 to wind
in Oklahoma about 14 years ago in a storm that destroyed over 20 other
planes. Many of the certified planes (Cessnas, Pipers, etc) left their
ropes at the tiedowns when the tiedown rings ripped out of the wing structures.
|
When I had a T-Craft I wrapped the tiedown ropes around the wing strut,
using the ring only as a guide... and I bought good nylon rope, replacing
it every two years. I once had a girlfriend with her own T-Craft; some
years later she lost the plane in a windstorm when the ropes broke (cheap
rope, AND she hadn't bothered to replace them).
-Dana
--
--
I do not feel obliged to believe that the same God who endowed us with
sense, reason and intellect has intended us to forgo their use. -- Galileo
Galilei
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slyck(at)frontiernet.net
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| Posted: Mon Dec 18, 2006 6:30 am Post subject: q |
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Leaving an airplane outside, even tied down, makes me nervous, and
I did it myself a long time ago. A shelter also needs some protection.
I built my open front, steel pole shed 30 years ago for about $800.
The main winds hit at a rear quarter and have to encounter an earthern
berm first which helps ramp them up and over. The ramp is hidden
within a fencerow thicket.
On a windy day scarcely a breeze can be felt standing outside the open
front.
BB do not archive
On 17, Dec 2006, at 9:55 PM, Charlie England wrote:
| Quote: |
<ceengland(at)bellsouth.net>
russ kinne wrote:
> In re recent talk about tie-down ropes -- this may be more academic
> than practical, but there have been recent MAJOR changes in cordage
> (ropes, strings, cables, whatever) that may interest the List.
> I just researched this subject for a boating magazine, and found that
> the new synthetics are nothing short of amazing.
> We all know nylon & dacron & polyester -- but the latter is very
> seriously weakened by UV; sunlight. Don’t trust it.
> There are a lot of new fibers now, and some are FIFTEEN times
> stronger than steel. A half-inch rope will theoretically hold TEN
> TONS! (but don’t stand under it)
> But they’re all different. Some are stretchy (we don’t want that) or
> very non-stretchy. Most are UV - sensitive and must be protected from
> sunlight by a woven cover of nylon or dacron. No big deal.
> The fibers named SPECTRA or DYNEEMA are reportedly the strongest
> fibers ever created. Others are brait, vectran, lycra, twaron, PEN,
> PBO, zylon, technora and others. All with different specs.
> The bottom line is that there are some VERY strong ropes available
> now. But of course there’s a price. As I’ve said, most of them are UV
> sensitive and should be protected. None of them like being knotted
> very much; use splices and fittings whenever possible. And of course
> they’re expensive -- but you won’t need a lot for your tie-down
> ropes. And an adequately=strong rope may be too thin to grab hold of
> and haul on.
> The best place to find them is in marine stores like West Products,
> or if by any chance you have access to a local sailmaker, pay them a
> visit and ask some questions. And bring your checkbook; something may
> be irrestible.
> Russ K
Finding something that's uv-proof is a good idea, but super strength
isn't likely to do much good beyond regular ropes. I lost a Thorp T-18
to wind in Oklahoma about 14 years ago in a storm that destroyed over
20 other planes. Many of the certified planes (Cessnas, Pipers, etc)
left their ropes at the tiedowns when the tiedown rings ripped out of
the wing structures.
Charlie
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Russ Kinne
Joined: 27 Jan 2006
Posts: 182
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| Posted: Tue Dec 19, 2006 10:48 am Post subject: q |
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At the Cessna factory they always (used to, at least) use chains with
over- center levers to cinch the wings down TIGHT. No chance for any
give or play or stretch.
I assume they knew what they were doing -- but you never know.
I appreciate the comments in re lycra-dacron-polyester, but I do
disagree. And I believe the UHMW fibers ARE 15x as strong as steel --
but I haven't personally tested them, I'm not gonna argue, and if I'm
wrong I'm wrong
do not archive
On Dec 18, 2006, at 7:22 AM, Dana Hague wrote:
| Quote: |
At 09:55 PM 12/17/2006, Charlie England wrote:
>
> <ceengland(at)bellsouth.net>
>
> russ kinne wrote:
>> We all know nylon & dacron & polyester -- but the latter is very
>> seriously weakened by UV; sunlight. Don't trust it.
>> There are a lot of new fibers now, and some are FIFTEEN times
>> stronger than steel...
>> The fibers named SPECTRA or DYNEEMA are reportedly the strongest
>> fibers ever created. Others are brait, vectran, lycra, twaron,
>> PEN, PBO, zylon, technora and others. All with different specs....
FWIW, Dacron, Lycra and polyester are the same thing (Darcon and
Lycra are trade names). Spectra and Dyneema are two trade names
for ultra high molecular weight (UHMW) polyethylene. Kevlar,
Twaron, and Technora are aramids, with Technora being slightly
stretchier than the other two. The liquid crystal polymers include
PBO and Zylon (same thing) and Vectran. Most of these are
available with a woven cover to protect the core fibers from UV.
None are "15X stronger than steel" overall, but the strength to
weight ratio is much higher than steel.
You do want some stretch; an aircraft rocking against a rigid
tiedown (e.g. chain) can hammer itself to death.
> Finding something that's uv-proof is a good idea, but super
> strength isn't likely to do much good beyond regular ropes. I lost
> a Thorp T-18 to wind in Oklahoma about 14 years ago in a storm
> that destroyed over 20 other planes. Many of the certified planes
> (Cessnas, Pipers, etc) left their ropes at the tiedowns when the
> tiedown rings ripped out of the wing structures.
When I had a T-Craft I wrapped the tiedown ropes around the wing
strut, using the ring only as a guide... and I bought good nylon
rope, replacing it every two years. I once had a girlfriend with
her own T-Craft; some years later she lost the plane in a windstorm
when the ropes broke (cheap rope, AND she hadn't bothered to
replace them).
-Dana
--
--
I do not feel obliged to believe that the same God who endowed us
with sense, reason and intellect has intended us to forgo their
use. -- Galileo Galilei
|
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Russ Kinne
Joined: 27 Jan 2006
Posts: 182
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| Posted: Tue Dec 19, 2006 10:48 am Post subject: q |
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|
Yes, the tiedown rings are often the weak link. But a friend's Cessna
went on its back when the ring-weld broke. Since I heard that I put
the rope thru the ring, then over the strut, then tie it. Should be
doubly safe.
I have broken 1/2":poly tiedown ropes by hand -- they'd been in the
sun all summer. Good to check.
On Dec 17, 2006, at 9:55 PM, Charlie England wrote:
| Quote: |
<ceengland(at)bellsouth.net>
russ kinne wrote:
> In re recent talk about tie-down ropes -- this may be more
> academic than practical, but there have been recent MAJOR changes
> in cordage (ropes, strings, cables, whatever) that may interest
> the List.
> I just researched this subject for a boating magazine, and found
> that the new synthetics are nothing short of amazing.
> We all know nylon & dacron & polyester -- but the latter is very
> seriously weakened by UV; sunlight. Don’t trust it.
> There are a lot of new fibers now, and some are FIFTEEN times
> stronger than steel. A half-inch rope will theoretically hold TEN
> TONS! (but don’t stand under it)
> But they’re all different. Some are stretchy (we don’t want that)
> or very non-stretchy. Most are UV - sensitive and must be
> protected from sunlight by a woven cover of nylon or dacron. No
> big deal.
> The fibers named SPECTRA or DYNEEMA are reportedly the strongest
> fibers ever created. Others are brait, vectran, lycra, twaron,
> PEN, PBO, zylon, technora and others. All with different specs.
> The bottom line is that there are some VERY strong ropes available
> now. But of course there’s a price. As I’ve said, most of them are
> UV sensitive and should be protected. None of them like being
> knotted very much; use splices and fittings whenever possible. And
> of course they’re expensive -- but you won’t need a lot for your
> tie-down ropes. And an adequately=strong rope may be too thin to
> grab hold of and haul on.
> The best place to find them is in marine stores like West
> Products, or if by any chance you have access to a local
> sailmaker, pay them a visit and ask some questions. And bring your
> checkbook; something may be irrestible.
> Russ K
Finding something that's uv-proof is a good idea, but super
strength isn't likely to do much good beyond regular ropes. I lost
a Thorp T-18 to wind in Oklahoma about 14 years ago in a storm that
destroyed over 20 other planes. Many of the certified planes
(Cessnas, Pipers, etc) left their ropes at the tiedowns when the
tiedown rings ripped out of the wing structures.
Charlie
|
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http://www.matronics.com/Navigator?Kolb-List |
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