Carbon fiber frame backpacks in the future

[Bunta Fujiwara]

Do you think big manufacturers will produce CFRP frame backpacks in the near future?
What is it going to take to make that happen?

Do you think they have not started R&D on such project,because they cant make a backpack at a price that will cover its costs and produce profit?

Will 3D printing open the door,for making cheaper CFRP frames?

This is all theoretical conversation ofcourse.

[Bob Gross]

What is CFRP?

–B.G.–

[Bunta Fujiwara]

Carbon Fiber Reinforced Polymer.
https://en.wikipedia.org/wiki/Carbon-fiber-reinforced_polymer

Carbon Fiber also means the fibers without the polymer/plastic,so to avoid confusion i say CFRP.

[David Drake]

Bunta,

Here's my own 'theoretical' speculation:

Big manufacturers make design decisions driven at least as much by form (i.e., fashion) as by function. And they want to sell the largest number of units to the biggest pool of consumers.

For example, why do big manufacturers make so few external frame packs? Not because they don't work for the on-trail hiking practiced by most casual backpackers. Rather, there's been a marketing decision to make packs that *look* suited to more 'hardcore' pursuits, like off-trail hiking, mountaineering, etc.

The Osprey Exos series is an exception, and uses what is basically a lightweight external frame. So, what would it take to make an Exos-like pack with carbon fiber?

You could use straight, easy-to-manufacture CF tubes, and get something similar to a ZPacks pack. Trouble is, I suspect those packs are too eccentric-looking to appeal to mainstream consumers.

Or you could spend a massive amount of money on tooling (and labor) to produce CF frames with curves. The trouble with that is very few mainstream consumers will pay the massively-increased cost for a few ounces weight savings.

As far as 3D printing goes: part of my job is working with 3D printers, and I can assure you there is nothing especially magic about them. 3D printing is a rapid *prototyping* technology, not a rapid *production* technology.

[Roger Caffin]

David makes excellent points. A lot of it is marketing trying to sell to the maximum number of the biggest part of the market – usually novices, street and casual. The smaller markets, like genuine serious hikers – not so financially attractive.

Been there, seen that – with my tents.

Cheers

[Bill Fornshell]

David Drake said:

"The Osprey Exos series is an exception, and uses what is basically a lightweight external frame. So, what would it take to make an Exos-like pack with carbon fiber?

You could use straight, easy-to-manufacture CF tubes, and get something similar to a ZPacks pack. Trouble is, I suspect those packs are too eccentric-looking to appeal to mainstream consumers."

============

I have wanted to see one of the new Osprey Exos packs since reading a review of it end of last year. I discovered one of my local Outdoors stuff stores has the Exos 48. I spent about an hour on Saturday checking out the pack. I really like how the mesh and frame is used to allow air to flow between the pack bag and your back.

My thoughts were to buy the pack and replace the pack bag with one I would make out of Cuben Fiber. I don't know how much the Osprey bag weighs but the total weight of the complete pack is maybe 2.5 pounds. A home made Cuben Fiber pack bag would not weigh very much and might bring the total weight down a pound or so.

[David Thomas]

>"Do you think big manufacturers will produce CFRP frame backpacks in the near future?
What is it going to take to make that happen?"

No. Alas.

I've tried my hand at a lot of sports equipment – kayaks, paddles, pack frames, pots, stoves, chairs – and compared to mass-produced items, it is very easy to use a few techniques and produce MUCH lighter gear. The biggest savings I achieve are from foam-core construction. The second-most bang-for-the-buck is to intelligently use wood (the original composite material). The third biggest is by minimizing the amount of epoxy in any lay-up (vacuum bagging being the most effective reduction in reducing the "plastic" of CFRP or FGRP items).

But all of those techniques are labor-intensive and not suited to mass-production, unless people will pay A LOT for incremental improvements as they do in golf and the America's Cup races.

Shorter answer: Gorilla glue rigid foam around 1/8" plywood and cover in vacuum-bagged CFRP or FGRP for your pack frame. The difference between CFRP and FGRP won't be detectable, while use of the wood insert and the foam core will vastly exceed the strength-to-weight of an aluminum or CF-only frame.

My 3-D printing home-fabrication wet dream is when we can deposit molten metal or perhaps metal ions through a vacuum where we wish. Then something akin to aerogels could be constructed from aluminum or we could model bird bones (with a solid skin around an inter-connected matrix of internal struts) in metal. The weight of golf club, pack frames and hiking poles could be reduced to 1/2 or 1/3 of what they are now.

[Alister R Barnes]

I made a CF frame, basically to compare with light weight aluminium in the same application. Both were shaped to fit me and designed to have a degree of flexing in two dimensions to allow lozenging, (but still stiff vertically).
I aimed at having similar stiffness in both, by using appropriate cross-section in the CF members
Very time intensive, and I don't think the weight saving was justified over the Al in terms of both time and cost. Haven't completed the bag yet, so cannot comment on performance.

[David Drake]

Interesting suggestions, David. I have a student who brought in some Sitka spruce veneers–beautiful stuff, with tight vertical grain. About 1/16" thick. These were the rejects(!) from a company that makes piano soundboards.

So, realizing Granite Gear just made a pack with a wood-core molded frame sheet, I started thinking about what could be done with the spruce. A little Wiki research during lunch break, and it turns out Sitka spruce has about the best stiffness-to-weight ratio of any wood (so why did Granite Gear use maple?)–in fact, for stiffness-to-weight, spruce is even a bit better than aluminum or titanium.

As it happens, my shop is set up for vacuum-bag lamination (although we've only used it for wood, not resin) and has a CNC router. So I'm thinking a CNC-carved two-piece mold, used to form a frame sheet with complex curvature. Maybe something like CFRP/spruce/thin foam/spruce/CFRP? Then when the sheet is cured, take another pass with the CNC to make some lightening holes (although I understand machining CF can be difficult).

When will I get to this? Oh, sometime when I've finished a bunch of other projects (including the ones they pay me for). But it's fun to think about.

[Christopher *]

For a couple years now KUIU has been producing a carbon fiber frame for their ICON series hunting packs. Apparently it is a single piece with molded vertical frame rails/stays and an integrated frame sheet comprised in the design. It is a hefty frame (13 ounces stripped bare) but it is somewhat over-built to accommodate a hefty bolt-on harness and thick padding … and of course the requisite gigantic hunting pack.

It always interested me as a design, but it is too pricey to purchase for the sole purpose of hacking down into something more weight conscious … at least for those of us of modest means. (About 300$ for frame & harness alone.)

[James Marco]

The biggest problem with CF frames is not the manufacture, it is the flexability both in use and in application. If it is a stiff frame, you might simply reproduce this with a simple piece of 1/4" plywood. If you cannot tayler it to meet individual needs, body shapes differ, then it won't fit most users that well.

In the past, a light weight aluminum frame has been used. Newer packs often make the mistake of using a bent rod. A tube is a bit stronger, but takes more technique to bend. Mostly such internal or external frames simply use padding to make up for the lack of forming to a body shape. Where CF tubes are used (arrow shafts) these are always followed by thick padding. The older Gossamer Gear packs (example: Miniposa) used a NightLite pad to dual purpose the padding.

You need flexability in basically three dimensions. 1) It needs to conform to a users back for good comfort. 2) It needs to folow the twisting motion (oposite shoulder and leg) of a normal gait. 3) It needs to flex with the user in response to ascents, descents, twisting around in a heavy forest, crawling over/under blowdows, and other trail movements.

CF is good at supporting loads, but not real great at flexibility. For example, my boats are covered with fiberglass cloth. Fiberglass is very flexible and conforms easily to the curves. Carbon fiber cloth does not. Special weaves and techniques are needed to lay this over a form. These same techniques would work for making light weight panels/frames for packs. But, they require the mould to be set up first. And they would fail to conform to another person, precluding mass production. The KUIU frame pictured shows this. It is a simple panel with attachments for a harness. They use heavy foam padding to make up the fit. Not the mould.

I can easily set up my old Kelty for hauling loads. (Again, padding is used to adjust the fit.) But it fails over a trail, primarily because of the lack of flexibility. You can set it up for straight trail walking, but it gets less comfortable when making an ascent.

Untill someone designs a rigid pack to carry a load with all three dimensions of flexibility, then they really cannot make a good UL frame. The rigid nature of fiberglass/carbon after polymerization means it will alway fail at least one of the degrees of flexibilty. Adding hardwear, panelization, has been tried (by Gregory) with limited success due to the heavy nature of such framing (4pounds plus.) I agree that a lightweight tube with padding will still yield the best overall results for light packs. Gossamer Gear sold the MiniPosa at 18oz, complete. You have to go some to get lighter. The Maripose of the same design was about 24oz as I remember, might be wrong about that though.

[Bunta Fujiwara]

That explains it.Thx

[ROBERT TANGEN]

Re: "Until someone designs a rigid pack to carry a load with all three dimensions of flexibility, then they really cannot make a good UL frame." Have you rested the Zpacks Arc Blast?

[James Marco]

No, I just got a Gorilla to use this year…maybe next year.

Anyway, the overall frame is still a couple arrow shafts with some mesh as padding. This will waste space and the pack itself is not extremely light. The 1 pound is only for around 2750ci. But it doesn't include any pad keeper so you waste that volume in the pack. For example my Murmur is about 2200ci, but adding a 2"x10"x20" pad to the outside adds about 400ci that is not figured into the size, for a total of 2600ci. And the pack weighs about 12oz. With the addition of a shoulder pocket, they are about same size and about the same weight. I get out for two weeks with the Murmur with zero issues carrying it. Not sure where this is better for me…I save about 4oz with the Murmur. We could debate about comfort all day long, it's totally subjective.

In the larger sizes it would be usefull for heavier loads. But, rather than using padding, he is simply using netting under tension, similar to Osprey. His CF frame is basically straight, a couple "arrow shafts" though I am not sure that is what he uses. Maybe in the larger sizes it would be better. Joe does a good job with all of his packs and especially his shelters. But cuben and CF don't automagically add up to lightest. The Zero's ae nice little packs, but lack a hip belt for stabilization. Almost necessary in the ADK's.

[ROBERT TANGEN]

You should take a closer look at the Arc Blast. His carbon elements are not straight or tubular like an arrow shaft. They are flat and flexible, a lot like hack saw blades. And there are 4 of them, 2 of them horizontal. The bottom of the pack itself rides on the butt / lower back of the user, and the mesh takes no weight.

[James Marco]

Could be. I don't have one. If the mesh doesn't carry any load, why does Joe use it? He would not add something that does not help support the pack somehoh. I would guess that it actually works in tension, but, what do I know. I can only see a picture.

[ROBERT TANGEN]

Joe is either crazy or a genius. The bend in his frame does not conform to the bends in the user's body, but JUST THE OPPOSITE! Crazy, huh? You crank down on the left side of the mesh, and it bends the left carbon "hacksaw blade" into a "C" shape, with the back of the "C" bending AWAY from the body. Ditto the right side. Apparently the point is to copy the arch in ancient Roman architecture, but turn it on it's side, so all the weight is concentrated on the hip? I'm just blathering there, but I own a 60 liter Arc, and it works well, and may be one of the lightest 60 L framed pack around.

[Bob Moulder]

As a recent convert to UL and having the Arc Blast 52 as my only UL pack experience, I am operating with a data point of exactly one.

However, I would have to agree with Robert that the design is rather ingenious. The suspended mesh prevents any slight packing discrepancies from causing a 'lumpy' spot in the back, and keeps the back cooler by permitting some airflow. Very clever in a pack that weighs barely a pound including a padded hip belt, very useful/functional back mesh storage area, very well thought-out side bottle pocket design, side compression cords and whose main compartment is essentially a big dry bag.

[Matt Dirksen]

+ 1 on Arc Blast design.

Clearly, Joe’s frame design was both about providing some rigidity the Zero & Blast didn’t have, and creating some breathing room between the back and the bag to keep the pokey stuff off the back- negating the need for a padding solution. In a nutshell, the Arc Blast has the “back breathability” of an external frame, while providing the “flexible agility” of most internal frame packs. All that while being substanially lighter than the next best thing, imho.

I've been using the Arc Blast now for close to a year, and am planning on bringing it to Philmont this summer w/ my son's scout troop. On day two of this past weekend’s shakedown trip, I decided to "reward" the boys after a rugged 12 mile trek by surprising them with a (seedless) watermelon I had hidden in the pack. Although my watermelon endowed packweight in the mid 30's, I never once noticed it. I believe the frame design was the primary contributor to that experience for me. No hot spots, no bruising, no sore trapezius, nothing. In my years of trying out scores of packs of various designs (and working in outdoor retail for quite a while), this pack design is one is a HUGE winner to me – at least for on-trail backpacking excursions.

Anyway, there are few things I was thinking of when reading this thread:

1) Professionally I design additions and whole house remodels as a living. The first thing I always do is analyze the existing conditions of a home before I would ever contemplate adding space to it. Likewise, (and especially in the spirit of UL): is it possible to design a way to store my gear on my body while making use of my existing structure, before I introduce any new structure? Obviously frameless packs take advantage of my existing structure, but I believe there are “gear storage solutions” out there which likely better distribute our gear over our body better than by simply throwing it all on one’s back. Perhaps what simply goes on the shoulders or upper back is not what goes tucked in the lumbar, or around the waist, hips, or even legs & arms. I believe the next advancements will come from this particular mindset.
2) If I need to add structure, Should it be rigid or flexible? And if flexible, how should it flex and will it ultimately benefit both the user, and it’s end use? These are all questions which are best answered by both what one is doing, and what they are bringing with them.
3) Can the “frame” be multi-use? If the structure of the pack can be taken apart and used to help with either the shelter or sleeping system, then +1. Perhaps a type of sleeping pad foam which can be strategically folded to become a packbag, or a few carbon stays which can be integral to a tent shelter setup.

[Anonymous]

A while back, i came up with a simple pack design which used carbon fiber arrow shafts, in a rectangular box shape. Dyneema cord was wrapped around somewhat tightly all around the outside in a up down VVV. Since the back went against the cord, it helped distribute the weight a bit and keep the tubes off the back some, while keeping the back cooler.

A simple, lightweight silynlon stuff sack went inside to hold contents and keep them dry. Since the silnylon will not be rubbing up against anything abrasive, would last a long time.

It's not a great design by any means (if you fell backwards on it, might break somewhat easily?), but it was easy, relatively cheap, and very light.

The main problem was connecting the carbon fiber tubes together. I used puddy epoxy and don't think that was ideal, as out on a trip, one of the corners where three rods meet came apart (on closer inspection i had used a lack of puddy in key areas on that corner). I recently found this stuff that is a fabric, that you wet and wrap around things and is supposed to be very strong. Will try that out after re puddying the area to initially hold it in shape. I originally looked for pre made connectors at kite shops and hardware stores but either didn't find anything that would take 3 tubes with 2 at a right angle at top and one at the bottom, or connectors that were light enough.

David, i think, suggested some kind of homemade wood connector, which i might still try (but haven't yet because i have very little wood working experience, knowledge, or tools). There wasn't much interest in the project at the original time of mention, not sure if it was because people thought it a stupid/impractical design, or because i was a pretty new member, or a combo.

Ideally, i would have two extra tubes of carbon fiber connect in a V (or inverted V) between the top and bottom tubes that are against the back and which are connected to the pack straps, if i wanted to carry more serious weight (but that was not the intention of pack, is for UL and SUL loads). That would be hard to do well.

Well, tangent over.

[Author]

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