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Blink

Closing loop material?

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you can also use cored type V suspension line as is generally used with racers. With Type V, you do not need a washer because of the thickness.
I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet.

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I use 725 microline, the lines left after canopy reline. It lasts 50+ jumps without any significant wear. Mine required change in 100+ jumps. But of course better use the type that container manufacturer recomends;)



I would recommend caution here...
Consider this:
1 - microline provides much less friction on the pin
2 - microline does not stretch like type IIa (550 cord sheath)
These two could easily lead to a pin that comes out too easy. Too much can be just as bad as too little. (I don't remember off the top of my head what the minimum bridle tension should be...)

Just my $.02
JW
Always remember that some clouds are harder than others...

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I always used gutted 550 line it works just fine . As far as the knot use a figure eight knot also known as a stopper knot .My pull up cord is the same if you break one in the field you can always make a new one with your hook knife. If you have seen the double loop on a RWS tandem , its flat and white other than the manufactures color code ,.It was from crown lines of a Paracommander.Hope this helps

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Is the sheath of gutted 550 cord actually equivalent to the Type IIa Coreless cord, that is the most common closing loop material?

The spec I see for Type IIa is 225 lbs.

But when I took my rigger's course in '91, my notes show "100 lbs" for Type II casing or Type III casing (where the former would be gutted 400lb cord, and the latter, gutted 550 cord) One old time jumper also always assured me the gutted cord is 100 lbs.

Why was I getting that information? Since it came from more than one source, I doubt it was a typo. Was it some sort of misinterpretation, old standards, a conservative rule of thumb, or what? I've never been able to figure it out.

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Is the sheath of gutted 550 cord actually equivalent to the Type IIa Coreless cord, that is the most common closing loop material?

The spec I see for Type IIa is 225 lbs.

But when I took my rigger's course in '91, my notes show "100 lbs" for Type II casing or Type III casing (where the former would be gutted 400lb cord, and the latter, gutted 550 cord) One old time jumper also always assured me the gutted cord is 100 lbs.

Why was I getting that information? Since it came from more than one source, I doubt it was a typo. Was it some sort of misinterpretation, old standards, a conservative rule of thumb, or what? I've never been able to figure it out.



A quick check of Paragear:
http://www.paragear.com/templates/parachutes.asp?group=32&level=2&parent=193

I don't see a spec on the IIa... but note that it is the sheath of type II. Don't know how different it is from type III sheath (I've also used type V sheath for a different use and noted that it is different.)

Did see that Type I is 100lbs...

But having used:
II sheath, IIa and IIIsheath... they've all worked for me. AND as IIa comes in different colors (red/green/white) I use them for different uses.

Blue ones,
JW
Always remember that some clouds are harder than others...

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Type III coreless is 100 lb. per Strong’s sample book. It is commercial not milspec.

Type IIA is 225 lb. per mil-C-5040H.

I keep a roll of Type IIA on hand for main closing loops and pull cords. Pull cords made of 3/4 inch Type III tape have a sharp edge for the looms and will cut or wear you loop out twice as fast.:)
My idea of a fair fight is clubbing baby seals

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Type III coreless is 100 lb. per Strong’s sample book. It is commercial not milspec.



Thanks!
Sparky, just to be absolutely sure:

The Type III coreless is actually the sheath of Type III MIL-C-5040, which is the 550 cord, not some other "Type III Coreless", right?

I now see Poynter's manuals do list III Coreless, but without a strength.

Since there's no actual milspec, I wonder if the 100 lbs is actually a conservative strength?? Type IIa and the type III sheath sure have a similar look and feel (other than the IIa being manufactured flat and having the dotted stripe).

Taking the numbers at face value:

If one guts old 550 cord for a closing loop, the material is only good for 100 lbs.
But if you use the similar looking Type IIa, that's good for 225 lbs.

(When formed in a finger trapped loop the strength is of course higher, I guess roughly doubled, minus a percentage for the knot.)

While both may be adequate in strength, I'd prefer not to use the gutted cord option unless necessary.

I've seen people confuse the two, calling them both 'sheathing', either thinking both were 100 lbs or both 225 lbs.

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The Type III coreless is actually the sheath of Type III MIL-C-5040, which is the 550 cord, not some other "Type III Coreless", right? ............................I now see Poynter's manuals do list III Coreless, but without a strength.



It is a commercial grade item and has no milspec. I don't think it is used for 550 sheath but do not know for sure.

The reason I use Type IIA is because by some strange twist of luck I ended up with a 3000 foot roll a few years ago and have yet to find any other use for it.
My idea of a fair fight is clubbing baby seals

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As for the sub-thread on different material strengths, it doesn't look like we have a definitive answer. To summarize:

Type IIa (normal closing loops) is 225 lbs.

Type III Coreless (no actual milspec) is 100 lbs but we don't quite know what it is used for.

Type III Cored is the old 550 cord parachute line, but may or may not be related to the Type III Coreles.

Gutted 550 cord (550 cord sheathing), which has sometimes been used instead of Type IIa in the past, could be either :

(a) 100 lbs (if the Type III Coreless is supposed to be like Type III Cored, minus the core) or

(b) 225 lbs (if it is like the Type IIa material that it resembles).

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