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By faiq386
#402092
I want a little help about lower side wires. I have seen some hang gliders that have loose lower side wires,I did not understand that why it happend so ,is this common in all type of hang gliders ,what is the reason behind this?
Thanks in advance!
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By red
#402093
faiq386 wrote: Sun Jan 28, 2018 10:31 amI want a little help about lower side wires. I have seen some hang gliders that have loose lower side wires,I did not understand that why it happend so ,is this common in all type of hang gliders ,what is the reason behind this? Thanks in advance!
faiq386,

Many hang gliders are easier to turn with *some* slack in the side wires. The bottom side wires become taut in flight, of course; the slack is then in the upper side wires. Some HGs have too much slack in the side wires, IMHO.

Test fly any glider you may choose (if that design is recommended to you by your instructor and mentors). You may wish to avoid HGs with a lot of side-wire slack, for the glider you purchase. A little slack goes a long way, in turning ability.
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By klh
#402094
Hang gliders with Variable Geometry systems, where the crossbar can be pulled farther back in flight to spread the leading edges and reduce overall twist in the sail (improving glide performance while reducing roll response) often require slack in the side wire loop to accommodate the changes in geometry. Many pilots like to launch such gliders with the VG string pulled 1/4 tight or so to reduce the 'sloppy' feel when ground handling.
By Lazypilot
#402096
I'm sure that many here remember the UP Comet. It had a bunch of slack in the wires, and it's difficult to believe it helped the handling any, if it did I sure would have hated flying one with tight wires.

One thing about having loose upper wires that may have been beneficial is the extra anhedral present when ground handling in wind.

The extra anhedral should help prevent getting blown over in a cross wind, theoretically. It would be better to have the upwind wing get pushed down than up, in my estimation. In my considering the design and construction of a conventional layout 103 glider I gave thought to using dihedral coupled with rudder for steering, like the Quicksilver by Bob Lovejoy did, and in my imagineering I figured that having anhedral via loose rigging might benefit ground handling in wind. Just gonna have to try it I guess. Sometimes the simplest little thing can have unintended consequences, that's aeronautics for ya.

But I'm leaning evermore towards wing warping for roll, what the heck it worked for the Wrights.
By faiq386
#402109
red wrote: Sun Jan 28, 2018 11:20 am
faiq386 wrote: Sun Jan 28, 2018 10:31 amI want a little help about lower side wires. I have seen some hang gliders that have loose lower side wires,I did not understand that why it happend so ,is this common in all type of hang gliders ,what is the reason behind this? Thanks in advance!
faiq386,

Many hang gliders are easier to turn with *some* slack in the side wires. The bottom side wires become taut in flight, of course; the slack is then in the upper side wires. Some HGs have too much slack in the side wires, IMHO.

Test fly any glider you may choose (if that design is recommended to you by your instructor and mentors). You may wish to avoid HGs with a lot of side-wire slack, for the glider you purchase. A little slack goes a long way, in turning ability.
But how actually this slackness cause an ease in turning.can you please through some more light on this?
By Lazypilot
#402110
" But how actually this slackness cause an ease in turning.can you please through some more light on this?"

Hang gliders turn when one wing "billows", or twists trailing edge upwards, more than the other wing. This twist differential or "billow shift" occurs when you place more of your weight on one wing than the other one. This can only occur when the hang glider is elastic in nature, or Flexible. That's why we call them "flex wings", as opposed to "rigid wings", which don't flex and require a very complicated system consisting of a wire pulling up a spoiler, which is much too heavy compared to a VG.

Modern hang gliders have what is usually called a "floating keel", or it's sometimes called a "floating cross-bar". Same difference, it means that the cross spar and the keel spar are not rigidly connected together.

This disconnect adds flexibility to the glider, and since flex wing hang gliders depend on this flexibility to allow the wing to billow or twist differentially, it's considered a good thing. And having loose side rigging supposedly facilitates this flexibility. If they were tight they might inhibit the ability of the keel to move sideways relative to the cross spar, and the glider would be stiffer to turn, that is it wouldn't wing warp as much when you place more weight on one wing than the other, and you would sweat and swear and generally not enjoy the flying very much. Now the beginner kites are more flexible and easier to get turned around should you ever need to do so, so fly those and leave the good glide angle ones to the masochists that like a glider that resists their efforts to turn it around. That stiffness is a life saver, without it hang glider pilots would probably over control and hit the hill.

It's a ridiculously archaic system, but we got addicted to it and will continue to suffer until we can figure something out. It's 2018, I'm sure it won't take much more than another decade for us to see the folly of our ways. Keep your fingers crossed, and in the meanwhile maintain your VG system, you don't wanna get caught with one stuck on full while you're on approach on a turbulent day. Hang gliding is supposed to be fun, and with any luck it will be someday. Don't listen to crusty old curmudgeons, they don't have a clue what they're talking about. And for heaven's sake don't go paragliding, you might like it.
By blindrodie
#402111
..."rigid wings", ...and require a very complicated system ...
This mad me chuckle... Setting them up maybe, but the spoiler system is really not that complicated. YMMV

8)
By Lazypilot
#402112
My tongue got stuck in my cheek again, Blindrodie. I personally feel that if the weight, cost, and complexity of some VG's I've seen were invested instead into something not quite so laughable that actually did something useful, like maybe give that billow shift a good kick in the butt to motivate it some, then maybe we'd have a device that helps us turn the thing around when we need to. But I guess it's too much like rocket science to ask for, you know how complicated that cradle the Wrights laid in that directly converted body motion into wing warping must have been, why it would have put a VG system to shame, what with all those wires that twisted the wings and doubled up as bracing wires too, why who would be so foolish to try that today, after all that was 115 years ago. It must not have worked, I bet the government faked that famous photo and fed us a pile of lies about twisting the wings to turn. I know it would never work, who they tryin' to kid?
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By DAVE 858
#402114
My friend has a Gecko and there is a device in the king post that keeps the lower wires tight on the ground. Not sure how it works. I always found the slack in the wires annoying. Its like the yoke in a Cessna, there's some play in it before in engages, maybe only a 5mm or so, but its noticeable. I kind of wish I went with a Gecko instead of U2, the lighter weight alone is worth it.
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By kukailimoku2
#402115
Those slack side wires on my Comet served only two purposes:
1. It made steadying the glider for a windy lauch a real pain in the butt.
2. It was a turbulence meter. If they went slack in flight and then slammed tight again, it was turbulent.

Sure loved how the thing flew, though...

(Fer sher on the Cessna slop, it was just enough to be a distraction in the little ones and made the Cardinal feel like a tractor. The first time I flew a Cherokee it was like they'd invented power steering.)
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By hs
#402118
Had a ww Talon that used a different vg system that allowed the side wires to be tight on ground. useful when launching in light conditions.
By Lazypilot
#402119
"Had a ww Talon that used a different vg system that allowed the side wires to be tight on ground. useful when launching in light conditions."

We keep making these ground breaking advancements in aeronautical technology and someday we'll have something to brag about. :roflcat:

I'm gonna have me a fully cantilever glider, with a straight, not swept aft wing, and a tail assembly. Might have a canard as well, the more the merrier. I won't have slack wires to annoy me, there won't be any wires. Why do we have side wires? Because we're so lazy and dumb we buy our gliders from a factory that makes them for us, and they of course can't do that unless they make a profit, and they can't make the profit if they don't make the glider as inexpensively as they can. They accomplish that by making them using relatively skinny aluminum tubes, which aren't strong enough to do the job on their own and so must be wire braced.

The math that is used to create a wing spar shows that if you double the height of it you quadruple it's strength. Have you ever looked at how much room there is between the lower surface and the upper one? If you made a spar that tall, you wouldn't need no stinkin' wires.

Hang gliding continues to screw itself by remaining addicted to the highly refined Rogallo/Dickenson formula of two LE tubes, a keel tube, and a X-bar and control bar, arranged to create a swept-aft tail less monoplane, or more romantically a "flying wing", which due to it's habit of tying wing twist to it's pitch stability has to have a bunch of extra parts to provide torsional rigidity, when if we take a hint from God or Evolution or both we'll come to the same conclusion they did millions of years ago.

You see that conclusion practically every time you look up, or maybe down if you happen to be flying at the time. How come the Red Tail Hawk isn't a swept-aft flying wing? I mean, if that is the preferred arrangement for a minimum weight to performance ratio glider, how come the Ravens don't look like that? Do you think that maybe God or Evolution tried that out a few million years ago, we call 'em Pterodackles or something like that, and decided the cost/benefit ratio wasn't adding up to what was needed?

Well now, our Hg manufacturers aren't stupid, they have college degrees in aeronautical engineering and a lifetime of experience building our hang gliders, why they must be doing it right, after all there's no one competing with them using a design that resembles, in a fashion, the Red Tail Hawk. So I guess God and Evolution don't know what they are doing, Their designs have straight wings, that don't couple washout with pitch stability, no, they have a tail. Why, who ever heard of such nonsense! You can bet that if I pay off the right guy and get to Heaven I'm gonna have a talk about this travesty with the Big Guy hisself!

I'm having a lot of fun playing the role of Krusty the Kurmudgeon (you kids get off my lawn!) and poking fun at folks that are really good people but have found themselves, just like you and formerly me, addicted to a way of doing things, and along comes the paraglider and steals the show right out from under us. It was kind enough to put up all manner of signs, telling us well maybe just maybe, we oughta be looking for ways to make 'em lighter and slower, but the signs were in a language we weren't familiar with, so we ignored 'em and kept right on truckin', figuring that heavier and faster would be the route to success, blindly pursuing the dream of a foot-launched sailplane, ignoring for some reason the fact that the "sport" of sailplane soaring was not growing but diminishing. Oh well, maybe if we make 'em even faster and heavier things will get better.

Meanwhile, back at the Cross-Country Ranch, pilots were setting up on Crestline and the wind died down, so, unlike the pilots of the late 1970's, they broke down or didn't bother to unload the truck to begin with, and went home crying in their beer. You see, in the late'70's the gliders weren't so fast and not so heavy either. They didn't glide quite as flat as they do now, but they were generously equipped with gobs of wing area, and could be relatively easily launched in nil wind, and the pilots flew and partied in the LZ provided by the kindly Andy Jackson and his friendly wife Juanita.

The pilots didn't fly very far away and they for the most part all landed at Andy's place and built big bonfires and drank beer and smoked some things and once in awhile even had these toy balloons that a guy could take a hit off of and laugh and fall down, with pleasant memories of the dentist office and his cute helpers roaming around their brains.

But Man, in his eternal quest for more and faster and flatter kept on tinkering and we ended up with some really neat gliders. Many pilots couldn't deal with the ego-deflating whacks right in front of their friends, after all, they were the Sky Gods and it just won't do to be laughed at when they should have been applauded.

The ranks thinned a bit, and some guys were rumored to be launching off cliffs with sky diver ram air square parachutes. Not much attention was paid to that, why their glide angle was a paltry 4 to 1 on a good day, and who needs that? There were some with a crazy vision of very light gliders that all you had to do was wad 'em up and stuff 'em in the trunk and if the hang glider guys could improve the performance of the 4 to 1 Standard then why couldn't the square canopy's be boosted up with higher aspect ratios and made into something worthwhile?

So as we continued in our quest for Higher! Faster! Heavier! We plugged away, and the Europeans, with their tiny cars and trams to the top continued with Lighter! Slower! Easier!

The lesson was lost on us and our ranks shrunk, but no matter, we could go 200 miles in a day! We finally went 475, and gladly paid for the gas in the Suburban to get us home the next day.

In the meantime we were losing more participants than we were gaining, and there were all kinds of ideas floated around, but nobody stepped up to the plate and said "Wait a minute! Maybe we oughta look into Slower! Lighter! Tighter turning! Easier! Less intimidating! Fun like we used to have!"
And, Heaven forbid, something we can make at home, the way we used to, only using the safety lessons we learned the hard way.
But no one thought of any of that, and the lighter, slower, tighter turning, easier paraglider sneaked in and stole our thunder.
Now we all can be forgiven for that...but the definition of insanity, as I've been told, is doing the same thing over and over and expecting a different result every time. Well, maybe the next time it will work. We'll keep on trying, I'm totally convinced that adequate roll control of high performance gliders using only pure weight shift is possible, just gotta find a way to hook up this windshield wiper motor so I can use a lithium battery to run my VG. It would be foolish to figure out a way to put my sore muscles to work directly influencing wing billow shift, when using the middle man we've always used works so damn well. But hey, if we did that we would have to compete with the rigids at a contest, there's absolutely no way the governing bodies will hear our plea for a class 1.5, flex wings with a boosted billow shift to improve safety and enjoyment.

We can only hope that no one spills the beans and lets the rest of the aeronautical world know what we're doing, using a sailboat main sheet block and tackle stolen from a Hobie Cat to make our gliders either : 1. turn with some degree of confidence that yes, it will. Or: 2. Get a good glide angle.

I've been the laughingstock before, it don't hurt all that bad, the laughter from the rest of the flying world will eventually die away, and we'll be able to take pride in standing our ground and proving that...weight shift is a viable way to warp the wings of a flat-gliding glider, just so long as you don't mind using the main sheet pulley system to obtain what some aviators would describe as a pitiful rate of roll. And of course we won't tell them that we regularly fly in strong thermal conditions with an apparatus that is airworthy so long as it doesn't get flipped over, where it will almost certainly snap in two with a loud bang, and if it doesn't it won't matter because it can only be controlled when it is upright and experiencing a positive G load. But you see, that's Ok too, after all we all have an emergency parachute.

Out of beer. See ya all around the bend. Gotta take some time to finish restoring my Hobie Hawk, a glider with a tail and movable control surfaces. When did they think of doing it that way? In the meanwhile, enjoy the wonderful simplicity of weight-shift control. I did for 40 years.
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By kukailimoku2
#402120
Canard, heavy tubing, etc. etc. etc.

Aaaand...it's too heavy to footlaunch.
By Lazypilot
#402124
kukailimoku2 wrote: Tue Jan 30, 2018 7:28 pm Canard, heavy tubing, etc. etc. etc.

Aaaand...it's too heavy to footlaunch.

No, you're missing the point, my bad, I need to clarify but it will take me a few tries to get through. In the meantime if you're satisfied with the status quo don't waste your time reading my rants and tirades, it will only upset you and it's not my goal to upset, it's my goal to raise awareness and encourage sane behavior.

I just gotta decide which route I want to take. It's tempting to want a very light glider, but it's also a neat idea to just go ahead and take advantage of the maximum legal weight of 154 lbs. A guy could have a lot of glider that way, and if it was in 2 or 3 sections that's only a few trips from car to set up, not a bad deal here at my home site.

My glider is gonna be my glider. I'm not interested in creating something for you or anyone else. If I do go for it, and create something that others find desirable, well, when I land and go to town for a beer run and forget to take my tape measure and contour gauges and someone utilizes them to copy my glider, I won't care. But I'm leaning an awful lot towards something intended for wheeled launches and landings only, I simply don't have to have foot launchability, and if it's heavier than about 70 lbs I wouldn't want to do it anyway. With a bungee assist for light winds, a wheeled glider is likely a safer way to go, especially when my goal of the lowest possible stall speed is taken into consideration.

Powered ultralights can weigh as much as 254 lbs. So if I built a glider with a 5 hp "sustainer/glide booster" motor on it, which I wouldn't have to use, I could have a helluva lot of glider. Heated cockpit, stereo, an extra seat, maybe some fancy stuff like an airbag and an ice chest. So long as there's at least a Cox .049 on the nose it would be a legal powered ultralight.

In the early days of ultralights that were using HG construction methods, a Cessna engineer, Steve Woods, knew that a much better airplane could be built using more efficient construction. Aluminum tubing is the way to go if you're in production, but if you've got a garage and aren't in a big hurry, a method utilizing styrofoam and wood yields a lightweight plane that's fully cantilever. If you're curious, Google "Skypup". You're right, it looks just like the balsa wood models your dad made. It's just a lot bigger. I'm tempted to buy a set of plans for it, with an engineers help with moving the pilot forward and removing the motor it could be a viable glider. It supposedly got 12:1, and without the motor the thing could be streamlined quite a bit. It utilizes a pitch neutral Ercoupe airfoil, which is fine for what it was meant to be, but with some re-engineering of the wing structure a harder working and lower drag section could boost the L/D by a significant amount, a glider capable of flying as slow as a paraglider and still capable of 15 or 16 to 1 glide could be had for a couple grand and a winter's work time. Read up on it, one guy built his airframe for $700, in 1980 something dollars of course.

i'm only trying to open some eyes and minds here. I'm pointing out obvious stuff that has been simply overlooked. Our corner of the aeronautical arena got subverted into a "sport". Well, it may be a sport to you, but for me and a few others flying is an activity that doesn't have to be considered a sport. I like to call it a hobby, just like I do my model flying. It's primarily a matter of scale, a glider big enough to carry me is just a glider that's a few times larger than the Rc model.

But the glider I have in mind isn't a Skypup, although the construction technique used there is tempting, offering a better strength to weight deal and for less $. If you take a close look at what is being done in other corners of the aeronautical arena you'll soon see that if you aren't paying someone to build your glider ( $28K for a new Atos) you could easily have high performance for a fraction of the cost. If my friend back in Arkansas can build a 200 mph airplane in his garage over a winter, then surely any competent construction worker could build a 50 mph glider with no sweat.

The one I'm imagineering uses construction tech borrowed from both Hg and other forms of aircraft. I'd like to have an airframe that folds up, but is able to be semi-rigid and "warpable". No hinged control surfaces with actuating cables or pushrods. Hg development shows that a twistable airframe can work just as well, with less structural complexity and weight. It's just that if you aren't flying in a competition class that forbids you having any common sense you can warp your wings directly, rather than depend on your weight being able to overcome the resistance to flexing. When I put out a lot of effort to twist my wing, I can't help but believe I'm being screwed by someone's insane idea of how to steer a glider.

Weight shift means you get to choose which of three sizes of the glider you like. On light days you get to wish you could have had the biggest one, on strong days you want the smallest one. If we make a relatively minor alteration to the glider's construction we can have one size fits all conditions and all pilots. When you go to sign up for a pilots license course you aren't asked how much you weigh and then offered your choice of three sizes of Cessna 150. Why are we doing this crazy way of designing gliders? Why, after 40 years, are we still struggling to ground handle a glider with a bunch of up-elevator built right in on a windy day? Are we not capable of controlling an elevator?

Weight-shift hang gliders are a very dumbed-down form of aeronautics. Taking control authority away from you might be Ok for neophytes, but I know I outgrew it a long time ago, and I'll wager that most of the pilots reading these words are in the same boat, but with no readily available alternative to try out we don't know that we've outgrown it. There is no demo glider with real control- of- it's- attitude- at- all- times available for you to try so you can see that flying a real aircraft is within your comfort level. Such a glider could have springs installed to simulate the handling characteristics of an Hg, and once you find that it ain't rocket science after all you can reduce or just eliminate the spring tension, and discover the wonders of flying a glider that isn't dependent on being upright for controllability. A glider that, should it meet it's meteorological match and get tumbled or rolled over doesn't throw you out of it and let you slam back into it and snap it in half. Do you realize that we're still doing that, 40 years later? Oh yeah it's not nearly as common, but I ask you: Why in God's name do we put up with it? Are we crazy, as some would say we are? We're very intelligent, just ask any pilot. But intellectual capacity and ability won't guarantee sanity. Weight-shift and pilot pendulum is insane. You may not like being called crazy, but a good look at what we do, and in particular how we do it, will reveal some facts that you heretofore have overlooked.

You say the safety record shows I'm the one who's nuts? Yeah, and who's to say that the record might actually be even better if we had more control and lower stall speeds and the ability to put her down in a tiny field with no damage, and most importantly, no drama. Wouldn't the record be improved if stall speeds were so low, and control authority so great, that no wind launches would be taken for granted, not oohed and aahed over by those who wish THEY could do what they just saw Billy do.

Paraglider pilots might just take a second look at what we do, if what we did was worthy of their second look. And don't tell me about the Alpo,er,Alpha I mean. Just because I brought up the subject of flying Hg in the '70's doesn't mean we have to return to that level across the board, let's take back the good we left there but leave some things, such as a narrow speed range and mediocre glide angles.

Again I say: It's 2018, not 1896, when weight-shift control was first put on trial. If the Wrights could do without hinged surfaces and actuating linkages in 1903 but still twist their wings I see no reason to keep banging our heads against the wall and wondering why we have a headache.

Time for a beer. Flamers are invited to flame away, Pilots willing to at least consider it all objectively can line up on the left or right, there's room for everybody. I can't pull it off on my own, In fact, I'm just the lonely voice in the wilderness, sounding the alarm. I'm just a dumb hillbilly from the Ozarks that never finished high school, although I did graduate airplane mechanics school. The next time you see me you can thank me for not working on your airplane. :ahh:

P.S. If we quit thinking of it as being a "sport" we won't have to be athletes to participate in it. We can be old fat pharts, discovering the wheel, invented a few thousand years ago and only recently have given it any serious consideration. Hey, if it ain't dangerous it ain't macho. But I've outgrown macho, are you ready?
By Goonie
#402125
I believe in you, SC, and am willing to help. Draft up specs, a working mini model, and a list of materials needed for a full-sized model. You have the time. I have the funds. Give Yoda my regards.
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By DMarley
#402134
Sounds like we're talking about something like along the loose lines of a Goat, or a Super Floater, or even a VJ-23. But with wing warping, and perhaps cantilever spars. And a prone position... or not. A very simple fuselage fashioned from one stock carbon tube ala Dragonfly, Kolb and Carbon Dragon. Might as well throw in a control stick and a simple rudder bar. I would love to slip 'er into tight spots.
Lightweight doped fabric coverings always work, but lightweight taped mylar skins may work just as well.
A design I was working on last year had my feet as part of the undercarriage, with the rear wheel supporting most of the glider's weight. But then there would be the chance of messing things up if something silly happened.

https://www.youtube.com/watch?v=qpqlItC6Iek

https://www.youtube.com/watch?v=40bwvYd9S2U
https://www.youtube.com/watch?v=2kieHZsaPhQ
By Lazypilot
#402167
Goonie wrote: Wed Jan 31, 2018 4:27 am I believe in you, SC, and am willing to help. Draft up specs, a working mini model, and a list of materials needed for a full-sized model. You have the time. I have the funds. Give Yoda my regards.
Yoda is insatiable, the only peace I get is when he sleeps. But I love to play with him and pet him, so it's Ok.

Your vote of confidence is much appreciated. The inspiration netted a simple sheet foam joined-wing glider, another in a series. The layout has some structural advantages I'm sure, but it seems a bit cluttered. But if I don't compare it to a flying wing, which has the most design economy, it shines.

I raided the stack and have a lot of old battens that I'll use to simulate a structure based on tubes. More to follow.
By Lazypilot
#402168
DMarley wrote: Wed Jan 31, 2018 2:24 pm Sounds like we're talking about something like along the loose lines of a Goat, or a Super Floater, or even a VJ-23. But with wing warping, and perhaps cantilever spars. And a prone position... or not. A very simple fuselage fashioned from one stock carbon tube ala Dragonfly, Kolb and Carbon Dragon. Might as well throw in a control stick and a simple rudder bar. I would love to slip 'er into tight spots.
Lightweight doped fabric coverings always work, but lightweight taped mylar skins may work just as well.
A design I was working on last year had my feet as part of the undercarriage, with the rear wheel supporting most of the glider's weight. But then there would be the chance of messing things up if something silly happened.

https://www.youtube.com/watch?v=qpqlItC6Iek

https://www.youtube.com/watch?v=40bwvYd9S2U
https://www.youtube.com/watch?v=2kieHZsaPhQ
There will always be an opportunity to mess things up. "Aviation is inherently dangerous".

I like the idea of a wheel supporting most of the weight, but not all of it. I think that supporting some of the weight can help me to know what's going on with the glider, if the design is such to exploit that feature.

For a homebuilt glider I think that the Tyvek house wrap would be suitable as a covering. I took a piece and fastened it to a wooden frame about 2 feet square, I jumped on it and it held, with just a bit of stretch. It's been used to make sailboat sails. A glider with a 2 lb wing loading needs a material that can take 12 lbs if you need 6 G's. I think that the Tyvek can do it, and it's relatively cheap. It's reasonably light, and so could be doubled in places, just as sailcloth is today.
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By kukailimoku2
#402183
I wonder how Tyvek likes UV time?
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By TjW
#402189
The instructions for Tyvek house wrap say that you shouldn't leave it exposed for more than 90 days, IIRC. So my guess is they don't spend much money on UV protection on something that's supposed to go under sheathing anyway.
OTOH, for proof-of-concept type stuff, that sort of lifetime might be okay.
I've seen glider bags made out of it, but I don't know what kind of lifetime they got out of it.
As I understand it, the big issue is sewing it. Poking holes in it weakens it, because it's a non-woven material like paper, and so the fibers aren't as long as something woven. Typically it's held together with tape.