line cutting weight &time

[aerorigging 6]

Hi all, Im doing some round canopy work with MIL-C-5040-Type3 550 pounds, I remember some % rule to put tension on the line before cutting, any info will be apreciated.

Thanks 

 

nico

[mark 102]

Poynter's procedure comes in two parts.  First is tension for marking -- see Vol 1 para 7.25.H.4, on page 399: 10 pounds for Type-2, 20 pounds for Type-3, and mark within 30 seconds of applying tension.

Then there is pre-stretching, in 7.25.H.5:  "Pre-stretch the line by applying tension to the full line equal to 10% of its rated strength (55 lbs for Type-3 line and 40 lbs for Type -2 line) for 15 minutes.  Relax tension and remove the line from the [tension device]."

I have no idea why additional pre-stretching/tensioning would be required after marking the line.

[fcajump 153]

5 hours ago, mark said:

Poynter's procedure comes in two parts.  First is tension for marking -- see Vol 1 para 7.25.H.4, on page 399: 10 pounds for Type-2, 20 pounds for Type-3, and mark within 30 seconds of applying tension.

Then there is pre-stretching, in 7.25.H.5:  "Pre-stretch the line by applying tension to the full line equal to 10% of its rated strength (55 lbs for Type-3 line and 40 lbs for Type -2 line) for 15 minutes.  Relax tension and remove the line from the [tension device]."

I have no idea why additional pre-stretching/tensioning would be required after marking the line.

Or is it pre-stretch, let relax, then tension for marking/cutting?
(real question/speculation)

 

JW

 

[mark 102]

21 minutes ago, fcajump said:

Or is it pre-stretch, let relax, then tension for marking/cutting?
(real question/speculation)

 

JW

 

No.  The first 10-20 pound stretch is for marking.  

I didn't mention:  cutting must be done with a hot knife, not shears or scissors, so sheath and core are both tensioned the same to share the load.