Material Strength vs. Weight

[Lawson Kline]

Which material do you think has the best strength to weight for each application. Lets say this is a pack that needs some durability but still needs to be semi-lightweight.

Pack bottom:
Pack sides:
Pack front:
Hip Belt:
Should Straps:

The weights are as follows:
70D Ripstop 2.5oz
200D Oxford 4.2oz
70D Ripstop VX07 XPAC 4.8oz
400D Packcloth 5.7oz
200D Oxford VX21 XPAC 6.0oz
400D Packcloth Ripstop 7.4oz
500D Cordura 7.5oz
500D Cordura Dyneema Ripstop 7.5oz
400D Packcloth VX42 XPAC 8.4oz
500D X 100D Cordura VX51 XPAC 10.4oz
1000D Cordura 11.1oz

[Lawson Kline]

My thoughts:

Pack bottom: 500D Cordura
Pack sides: VX21 XPAC
Pack front: 200D Oxford
Hip Belt: 400D Packcloth
Should Straps: 200D Oxford

[Jerry Adams]

My pack – 200d bottom and shoulder strap reinforcement, silnylon rest of pack

I've used it for a year with no problems – maybe 500 miles, 60 days

I'm thinking that's overly conservative – maybe just silnylon with doubled silnylon for shoulder strap reinforcement – maybe I'll do that on my next pack.

[Terry Trimble]

Lawson,
Why not make the whole pack out Vx21 X pac is the strongest of all the fabric in strength to weight ratio and water proof, Make your job easier. That's in less your going for a different color scheme.

I still back up all my shoulder straps,hip belt, stress points and bottom for strength water proof with X pac fabric when I make a all 210d dyeenma grid stop looking backpack.

But I am working on a pack now and I want a different color not offered in Xpac but Xpac will be used at stress point, bar tacks. Some may call it over building but I like a strong pack.
Terry

[Dustin Short]

This pretty much looks like standard pack materials. The design (few frills, frameless) is where you'll save the most weight compared to 'regular' packs. Just inherent when you're using the same materials.

Also what usage are we looking at, long days on alpine trails or bushwhacking through desert scrub? Makes a big difference on how durable you really need it. For most well maintained trails or alpine travel you really only need the bottom/back/straps to be durable, the pack should be ok with a non-careless owner. For bushwhacking obviously everything else will need to be buffed up as well.

With the CT5HBK.18 cuben you're looking at twice the threads (in twice the directions) and twice the thickness of film of the usual .74oz cuben. At only 1.3oz it's considerably lighter than any of your options and should work for a pack body in all but the harshest environments.

Strength alone isn't necessary too. The fabric surface can help a lot. Slippery fabrics will snag less and need less strength than rough surfaces that get caught up on brush. 1000D cordura is bomber, but has to be because it's highly textured surface finds every little thorn in a 20 mile radius (As does ANY meshing).

So yeah, using your fabrics and under the assumption this is just a backpacking pack:

VX21 XPAC for bottom and straps
VX07 XPAC for everything else

[Daryl and Daryl]

Lawson,

For about 10 years now I have made all portions of all my packs out of 1.9 ounce uncoated nylon ripstop.

I like uncoated because I can run the pack through the washer and dryer when it gets dirty. I rely on a trash compactor bag inside the pack to keep things dry.

I don't encounter anything while backpacking in the Pacific Northwest of the US that damages it.

If I was dragging it across granite rock or pulling it through thorn bushes then I'd have to reconsider things. So far so good, however.

Daryl

[Lawson Kline]

>>"Some may call it over building but I like a strong pack."<<
Well Said Terry. I couldn't agree with you more.

I have been working on a modular hybrid frame style backpack for over two years now. The hybrid frame is designed to carry everything from 5-50lbs and works with several different style packbags that range from a 20L day pack to an 85L expedition pack. The latest prototype hybrid frame weighed 30oz complete. That's the frame, shoulder straps, full wrap hip belt, buckles, webbing, and the removable 7075 aluminum stays.

So in its current configuration its pretty darn light but I would like to get it under 24oz without sacrificing the frames overall performance and durability. I have been looking into using different materials like woven Cuben Fiber and XPAC but I am really not sure they are worth it for this particular application but I really like both materials so its been really hard to decide. The VX21 Xpac is a nice balance of weight and strength with its 200D Oxford face. I have been thinking of using to this material throughout the entire frame including the back panel, front panel, outside of the shoulder straps and hip belt but when a 400D Packcloth weighs less then this material I almost wonder if its worth it to switch. I am having a hard time wrapping my head around how a 200D Oxford face VX21 XPAC would be more abrasion resistant then a 400D Packcloth. Any thoughts?

Oh and while I am thiking of it. I came up with a hypothetical woven cuben fiber. A 400D Packcloth with a CT5K.18 Laminate that weighs 6.0oz which is the exact same as a VX21 XPAC. Problem is cost. This material would be about 3 times as expensive as an XPAC and about 10 times as expensive as a 400D Packcloth but boy would it be burly. Might just be the perfect material :)

[Terry Trimble]

Lawson,
The VX 21 is part of the Xpac Expedition family of pack cloths they all have 0.25 mil PET film laminated to it with black polyester X ply laminated in between. Vx 21 weighs 6.2 oz a yard with a 200 d oxford nylon to help in abrasion basically it the laminate that makes it abrasion and tear resistant and easily available from rocky woods fabric.

But if you need a more abrasion resistant bottom you could order some VX 42 that has pack cloth laminated to or VX 51 that 500x 1000 d cordura laminated to it from Dimension Polyant they will direct you to CSR in charged of consumer sales selling over runs or 2nds he will email you a pdf of what cloth is available at what price. You will pay a cut fee and they will ship it to you on a rolled card board tube that about 6 foot long.
If they still have the program when he does send you the list check in to the tent fabric they have a Vx31 laminated to 40d nylon that weighs 2.3oz and is water proof and UV resistant. When you buy from Dimension Polyant stock up because the price are very affordable you only want to place one order because of the cut fee and shipping.
Phone number is 860-928-8300.

Or I have also thought about a less expensive way to buy Xpac if you need a small amount you could call Clio gear backpacks and see if they have remnants of the heavier Xpac. What's the worst they can say is no we will not sell you Xpac cloth.
Terry

[Lawson Kline]

Hi Terry,

Thanks for the info. I am very familiar with the Xpac materials and have quite a bit of different versions hanging out in my workshop but your information is very useful to those who are new to their materials.

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