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Martin Roberts
Guest
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 Posted: Tue Jun 27, 2006 7:02 pm Post subject: Dyneema Cable |
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We have been using 1 Dyneema cable @ Bowland Forrest
for the
past 12 Months - on grass with rubble hardned tow out
track
After initial teathing troubles - Finding the most
durable cable
manufacturer and modifying linkages and shock ropes
etc it has
now settled down and we have converted both drums to
Dyneema.
The cable lifts free of the ground as soon as tension
is put on it
therefore wear and tear on the ground is minimal either
at cable
retrieve or launch
Launch hight are regularly 200ft higher than stranded
steel cable
and there are significantly less cable breaks.
Care has to be taken not to land across thc line of
cables as the
cable can stand above the surface of the grass especially
in dips
or hollows or when the cable is under any kind of
load - ie cable
retrieve - hand pulling of cable to obtain slack to
attach to a
glider etc. (This is potentially far more hazardous
than steel
which tends to bed into the grass.
Also worth noting is the potential for the cable to
fly in windy
conditions - so care must be taken on the retrieve
to make sure
cables do not cross and that a very large seperation
is used @
the departure point. |
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Frank Whiteley
Guest
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| Posted: Tue Jun 27, 2006 8:36 pm Post subject: Re: Dyneema Cable |
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Interesting comments about the rope resting on the grass and the snag
hazards.
What is the length of your launch run?
Frank Whiteley
Martin Roberts wrote:
| Quote: | We have been using 1 Dyneema cable @ Bowland Forrest
for the
past 12 Months - on grass with rubble hardned tow out
track
After initial teathing troubles - Finding the most
durable cable
manufacturer and modifying linkages and shock ropes
etc it has
now settled down and we have converted both drums to
Dyneema.
The cable lifts free of the ground as soon as tension
is put on it
therefore wear and tear on the ground is minimal either
at cable
retrieve or launch
Launch hight are regularly 200ft higher than stranded
steel cable
and there are significantly less cable breaks.
Care has to be taken not to land across thc line of
cables as the
cable can stand above the surface of the grass especially
in dips
or hollows or when the cable is under any kind of
load - ie cable
retrieve - hand pulling of cable to obtain slack to
attach to a
glider etc. (This is potentially far more hazardous
than steel
which tends to bed into the grass.
Also worth noting is the potential for the cable to
fly in windy
conditions - so care must be taken on the retrieve
to make sure
cables do not cross and that a very large seperation
is used @
the departure point. |
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Martin Gregorie
Guest
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| Posted: Wed Jun 28, 2006 2:21 am Post subject: Re: Dyneema Cable |
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Martin Roberts wrote:
| Quote: |
The cable lifts free of the ground as soon as tension
is put on it
therefore wear and tear on the ground is minimal either
at cable
retrieve or launch
Out of curiosity, have you tried any lowish level simulated power |
failures with it? My own observation is that during a power fail the
weight of steel cable keeps the drogue and shock cord well out of the
way below the glider, but I've wondered what happens with Dyneema.
The possibility of it not being heavy enough to keep the drogue etc.
clear of the glider is my only worry about taking a launch on it.
I don't remember this point being discussed here.
--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org | |
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Frank Whiteley
Guest
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| Posted: Wed Jun 28, 2006 6:11 am Post subject: Re: Dyneema Cable |
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Martin Gregorie wrote:
| Quote: | Martin Roberts wrote:
The cable lifts free of the ground as soon as tension
is put on it
therefore wear and tear on the ground is minimal either
at cable
retrieve or launch
Out of curiosity, have you tried any lowish level simulated power
failures with it? My own observation is that during a power fail the
weight of steel cable keeps the drogue and shock cord well out of the
way below the glider, but I've wondered what happens with Dyneema.
The possibility of it not being heavy enough to keep the drogue etc.
clear of the glider is my only worry about taking a launch on it.
I don't remember this point being discussed here.
I've posted here and on the winchdesign group about the 'float' we |
experienced. However, we also used our normal chute and strop
arrangement. Powered off, the strop falls first, causing the chute to
collapse and the rig falls out of the way taking the rope with it. The
remaining rope did fall rather slowly, but it would take, in my
estimation, quite an effort to get under it.
That being said, the new plastic disk design and other light weight
solutions might lead to longer hang times for the rope in the event of
the launch failure.
Frank Whiteley |
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