Nomex

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Fred

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I'm wanting to buy some bulk Nomex and cut my own chute protectors. What type, weights specs for the Nomex do I need to know, so I get the correct stuff? Thanks in advance!
 

RocketFeller

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I think that the most important factor is porosity. They measure air permeability in CFM, a low value would be less than ten. We recently got some 6oz clot wit a porosity of 2.5CFM from Sterns & Sterns. It is very nice stuff, much smoother than a lot of stuff I've seen.
 

emckee

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Most of those look like 60/40 nomex/cotton blends... any issue with that? (I'm not sure what the standard 'chute protector is made from)

-e
 

cwbullet

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Most of those look like 60/40 nomex/cotton blends... any issue with that? (I'm not sure what the standard 'chute protector is made from)

-e

No issue, but I will text a few over the weekend and let you know.
 

Peartree

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I don't know how much you want to buy in "bulk" but if it isn't a lot, this might be useful.

Some years ago, at the suggestion of someone here, I went on eBay and bought a pair of used forestry service uniform pants which are made of Nomex. I spent a little time with a seam ripper cutting them apart and have had more than enough Nomex squares (of all sizes) to use and give away for some time.

Total cost, including shipping, was about $10.
 

dhbarr

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I don't know how much you want to buy in "bulk" but if it isn't a lot, this might be useful.

Some years ago, at the suggestion of someone here, I went on eBay and bought a pair of used forestry service uniform pants which are made of Nomex. I spent a little time with a seam ripper cutting them apart and have had more than enough Nomex squares (of all sizes) to use and give away for some time.

Total cost, including shipping, was about $10.
+1, oilfield coveralls come in fairly large sizes as well.
 

Banzai88

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Most of those look like 60/40 nomex/cotton blends... any issue with that? (I'm not sure what the standard 'chute protector is made from)

-e
I have used the 6 oz cloth without issues with TF chutes. Just be aware that it's a more open weave than the 'rocketry' products. Use with 4F BP ejection charges only. 3F has larger grains that burn longer, and can cause issues with the lighter weave.

If you can get ahold of tighter weave/heavier, use it.
 

CZ Brat

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Don't forget, it's not just the quality of the Nomex, but how you use it. A direct hit can burn through rocketry specific chute protectors. I always use some dog barf to take the brunt of the hit.
 

H_Rocket

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Something to consider is that heavyweight Denim will work as well as Nomex for most of our uses and is a whole lot cheaper. Unless you really need the continuous fire resistance that an Aramid provides and, IMHO, an ejection charge does not merit it you will get the same protection for a fraction of the price.
 

emckee

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some good ideas on this thread... at least for someone (me) who continuously melts parachutes!
 

cwbullet

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My wife made a few to test this weekend. She made a test chute out of orange ripstop and chute protectors out of a cotton shirt, canvas, heavy twill, and several types of nomex. I will compare the results.
 

sunward

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Most of those look like 60/40 nomex/cotton blends... any issue with that? (I'm not sure what the standard 'chute protector is made from)

-e
NOMEX is a type of material that is manufactured. If it is a cotton blend, then the cotton is made flame proof with either the help of the NOMEX or a flame retardant is applied to the cotton fabric.

NOMEX's properties will not wash out or deteriorate with age (unless exposed to sun). Cotton's properties will degrade with use and will even wash out if cleaned.

The only way to tell the difference is through a chemical test. You can't tell the difference by feel.

You also need a thread to sew the edges or it will fray with use.

Sunward uses NOMEX only with NOMEX thread - both expensive stuff, especially the thread.
 

rharshberger

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I have used both the Ebay Nomex listed in an earlier post, and have made my own "flame retardant fabric" from cotton duck canvas available from JoAnns Fabrics. The flame retardant chemical is a solution of borax and boric acid in hot water. The borating liquid is easy to make, and to borate the fabric is all you have to do is soak the cloth in it until wet then let air dry. While the canvas protectors dont last as long as nomex ones they are much cheaper to make, and I have as many as 10 flights on some of mine, but they are definitely showing wear. Nomex is a better cloth for protectors, but the borated canvas is a lot cheaper (the chemicals used are borax and roachkiller powder).
 

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Ok guys,

I finished my testing this week.

Methods: I did a total on 30 tests. Each material was tested with 1 gm of 4F BP and 1 gram of BP meal. Interesting that the ejection charge was similar with homemade meal and 4F BP. The test was performed with homemade e-matches in a 3 inch x 18 inch mailing tube. I put bulk heads in it and made it function like an airframe. The airframe had a kevlar shock cords and a 36 inch parachute.

I used various chute protectors that my wife made. The fabric is readily available form eBay or JoAnn Fabric. Each was made of 9 inch squares of fabric with a button hole and nomex surged edges. Two pieces need different approaches: cotton t-shirt and sleeve material would not allow a botton hole to be stitched.

I tested chute protectors made with two types on nomex ripstop that contains kevlar thread, several types of nomex twill, double and single ply thin nomex, nomex from ACU Army uniforms, plain untreated canvas, plain untreated twill, cotton t-shirt material, and a nomex soft sleeve.

Results: All materials protected the chute. 30 ground tests with zero burns to the chute. I will wash the chute protectors tonight and post pictures an videos tomorrow.

This is not a scientific study, but I am surprised how well common fabrics that are not designed to protect against heat were able to protect a chute. If a plain cotton t-shirt works, it is cheap and sho cares if it last 3 flights. It lasted two ground test so far. Once I launder them, I will post if there are scorch marks.

Here is my "test stand":

IMG_0301.jpg
 

cwbullet

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Fabric #1

IMG_0299.jpg
The first test subject is above. It is a nomex sleeve material that is used to insulate round objects. The exact auction was for 5 years of Ballistic Aramid Twaron Sateen Ballistic Fabric Sleeve. It is loosely weaved and stretchy. I am utterly amazed that it did not result in a scorched chute.
Link: I got this on eBay for $2 a yard but it is no longer available. I will keep looking.

IMG_0300.jpg
Post 2 ground test photos. Some discoloring but there is no evidence of a burn.

It is hard to sew a button hole so I will likely use it for sleeves to protect my trackers.
 

RocketFeller

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When we tested the ejection charges for our Dragonfly we used a pillow case (thin, smooth cotton) with a sheet inside as a dummy chute. The pillowcase had some black spotting, but wasn't even close to burned through. We used four grams of 4F twice.
 

cwbullet

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The reason I used meal on a second charge is that it is notorious for not fulling burning. What I found out is that is is close to the same level of power and it still did not cause burns.

Questions I have:
1. Would a large tube make burn throughs more likely? I was extra careful to wrap the chute in a Taco of nomex and it was relatively tight in the tube.
2. Would extra large charges make scorches more likely? I used double the amount of recommended powder and it did provide a moderate report. I might do a few more tests with larger charges.
 

cwbullet

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cwbullet

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Material #5

IMG_0315.jpg
Before: Orange Nomex from eBay. It fold similar to #2. It does not have the ripstop appearance.
Link: I bought it on eBay but it is no longer sold. I will keep looking for it.

IMG_0316.jpg
After: Mild discoloration with no scorch marks.
 

Leo

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cwbullet

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Fabric #7

IMG_0320.jpg
Before: This is a 8 oz ACU pattern ripstop fabric: Nomex 31% / Nylon 29% / Cotton 40%. Very strong and is resists staying folded. It will open when it comes out of the tube on its own. It is also waterproof.
Link: https://www.ebay.com/itm/-/170950412174?ssPageName=ADME:L:OC:US:3160

I bought 10 yards from eBay clearance sale. No longer available but is similar to: https://www.ebay.com/itm/AGED-COPPE...152095?hash=item464f5c2edf:g:cogAAOSwxN5Wahpl

IMG_0321.jpg
After: No scorch or visible discoloration.
 

Oldschool77

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Also try your local electricians for worn out/ripped uniforms. My nephew gave me a jumpsuit and I'm still cutting squares out of it for my l/mpr. It's similar to mid-weight denim (Looks like post 25)and difficult to cut so I buy cheap throwaway scissors so my wife won't kill me.
 

cwbullet

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Fabric #8

image.jpg
Before: this is similar to the Tan fabric in # 4. It is think but was stitched single ply. 4.4 oz. It is a twill nomex.
Link: none. Purchased locally at surplus store. I have seen it for $2 a yard.

image.jpg
After: minimal discoloration. No scorch.
 

Screaminhelo

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Just a little thought to contribute.

I am drawing from my time as an Army crewchief and I would say that any natural fabric should work for at least a short time untreated. It seems to me that what we are dealing with here is a flash fire and the primary quality to look for is a non-melting fabric.
 
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