Shoulda been an "up" near the beginning of the previous post.
Spark,
That was a comment on the technology of the era - period.
Yeah, I might kill myself on my next flight at (or drive to) Ridgely but I've removed some of the more common facilitators from my equipment and procedures so it may take another two or three outings.
Bacil,
I'm not saying that everyone who doesn't rush out to the garage and remove his backup suspension immediately is an idiot.
I don't have any problem with disagreement as long as basic rules of civilized discourse and evidence are adhered to. Brian and I have had a few disagreements ALL of which have been resolved with one or the other of us conceding after having run the numbers.
When I'm dealing with an individual who can make as statement along the lines of "take all your equations and stuff them", no counting of sedimentary layers at the Grand Canyon will ever budge him from the certainty that the Earth is no more than six thousand years old. He can certainly be elected president (of this country anyway) but in any legitimate academic circles he's going to be drawn and quartered. I keep hoping, despite all previous experience, that these discussions and disagreements can be academic.
The current tack in this thread is mostly about the indisputable (though, of course, the dispute has been massive) fact that when you keep loading up any system - let's make it a chain - the weakest link will fail and you don't alter the point at which that happens one iota by ignoring that link and putting all of your attention and resources into one of the stronger ones. Somebody figured this out in the Bronze Age while trying to haul the Woolly Mammoth carcass back to the yurt - yet here we are.
Danny,
Thanks for the blast from the past stuff.
Yeah, I just hauled out my 1982 Robertson cocoon and it does indeed feature the comforting redundancy you mentioned.
I'm quite happy with the data you provided (don't bother with the camera) about webbing wear 'cause it supports my main point - that if it happens at one end of the carabiner it separately but equally happens at the other.
Also - if the people who were using cotton thread to stitch hang loops were also stitching harnesses...
Janni,
I am very sympathetic to your position appreciate the logic of your proposal to make the glider's backup system less irrelevant but...
Wills Wing (for example) knows how to make stuff right. Their gliders and harnesses don't fail. On my original equipment suspension they're using about six inches of stitching to support you - three per side on the primary, six continuous on the backup. It's designed for massive overkill.
Compare the stitching on your glider suspension to those overlap lengths and then compare that construction to what's on your harness. If the lengths, stitching patterns and densities, and rigidity of those bindings are all comparable - stop worrying about it (and quit smoking).
Keep your harness in the bag when you're not flying, protect the glider suspension from the sun, and have fun.
hook-in failures
Moderator: CHGPA BOD
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Flying Lobster
- Posts: 1042
- Joined: Fri Feb 25, 2005 4:17 pm
I decided to call Wills myself and find out what their "actual" position is on this matter.
I did not talk to Mike--but it appears that the single strap adequacy issue is related to single continuous loop type hang loops that used to predominate on keel-hang suspensions. However, once you introduce hardware interfaces such as rocker-arms and steel hardware, the idea of possible accelerated wear "does not make a back-up a bad idea."
Tad--I have to say I actually enjoy the way you write--your talents in written prose far exceeds your skills in either the flying or engineering world--I think you should seriously consider developing that talent.
I've rock-climbed cliffs and mountains for 3 decades around the US and Europe. I've seen first hand what can happen to nylon webbing when repeatedly loaded and ages. While Tad is correct in that a new strap far exceeds the breaking strength of any other component on a hang glider, the ultimate load-bearing capability does not remain constant and wear is a hard thing to judge.
The list of pilots I know of willing to fly without a back-up hang strap is very, very short. I'll give Tad the benfit of the doubt that he's right he can fly safely with just one hang strap so that we can exit this discussion gracefully.
marc
I did not talk to Mike--but it appears that the single strap adequacy issue is related to single continuous loop type hang loops that used to predominate on keel-hang suspensions. However, once you introduce hardware interfaces such as rocker-arms and steel hardware, the idea of possible accelerated wear "does not make a back-up a bad idea."
Tad--I have to say I actually enjoy the way you write--your talents in written prose far exceeds your skills in either the flying or engineering world--I think you should seriously consider developing that talent.
I've rock-climbed cliffs and mountains for 3 decades around the US and Europe. I've seen first hand what can happen to nylon webbing when repeatedly loaded and ages. While Tad is correct in that a new strap far exceeds the breaking strength of any other component on a hang glider, the ultimate load-bearing capability does not remain constant and wear is a hard thing to judge.
The list of pilots I know of willing to fly without a back-up hang strap is very, very short. I'll give Tad the benfit of the doubt that he's right he can fly safely with just one hang strap so that we can exit this discussion gracefully.
marc
Great Googly-moo!
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Tad Eareckson
- Posts: 304
- Joined: Wed Feb 09, 2005 8:50 am
Bacil,
To answer your first two questions and save some bandwidth:
http://www.chgpa.org/forums/viewtopic.php?p=4332
or, yeah, close to seven years AFTER publication of his Crestline induced epiphany.
I had read the article when it first appeared and it had made a permanent impression (and I just reread it). I had a similar, but less detailed, response to nearly getting killed in the afternoon solar oven conditions in the South Bowl of Jockeys Ridge on 1984/07/05. I landed smelling like a rose after being rolled beyond placard, falling downwind to far below ridge level, and rocketing back up and just over the spine - but I realized that flying there in similar conditions was a dice roll.
(I voluntarily terminated my then - 1992/02/09 - site record duration flight with a top landing several passes after a similar dump at the NE end of the Smithsburg ridge for the same reason.)
Marc,
I didn't want to drag Mike or Wills Wing back into this 'cause my feel is that he/they caught the kind of crap that I'm getting for committing hang gliding culture heresy and were smart enough to say fuckit and go with the flow... but thanks for checking.
Let's take a look at what you got.
-
...the idea of possible accelerated wear "does not make a back-up a bad idea."
...the IDEA of POSSIBLE accelerated wear "DOES NOT MAKE A BACK-UP A BAD IDEA."
-
How many C5s could you simultaneously fly through the wiggle room provided in that statement?
Eat you're heart out, Roberto Gonzales! The master has been revealed and you ain't it!
Gee, and I thought Danny's post was a treasure trove (more on that later).
With respect to my flying skills... Again, NOTHING I have posted in, probably, the past few years is legitimized or invalidated by my status as a pilot. A thirteen year old kid from a good school with an A on his science test who's never been near an aircraft of any kind in the course of his short life could evaluate and/or originate everything I've done. The theory is one thing and it's pretty simple. Piloting skills mostly belong in the PhysEd Department (not that there's anything wrong with that).
But you might want to check with Sunny for an evaluation of my flying skills. He's been nearby during nearly all of my flying over the course of the past nine seasons, was the USHGA's Hang Gliding Instructor of the Year in 2003, and I've heard some statements from and attributed to him which are in sharp contrast to what seem to be your impressions.
Your disparagement of my engineering ability makes me wonder just how dangerously low your oxygen to THC intake ratio has been lately. Here are some quotes off the wire - most of them from this forum...
-
I was too green to fully appreciate your system when you showed it to me a couple of years ago.
...but I've seen his work. His release mechanism is elegent in it's simplicity and effectiveness.
He's a pretty sharp guy and makes interesting stuff.
Your straight pin release is also far superior to the curved pin.
If I had known Tad was going to make one I would have just waited for his.
I've seen the photos, quite clever I might say!
Ironically, I've always admired Tad's creative way at looking at things, and I have seen the equipment he's made with his own hands--it is beautifully made stuff.
-
Two of those comments are yours! (You got a somewhat less evil twin?)
If you need some more opinions check with the aforementioned Sunny and/or make another call to Wills Wing and ask if Rob is well enough to be bothered (and I very much hope he is - he's in my thoughts a lot). Are those parties sufficiently qualified and disinterested enough to suit you?
I question whether Type 18 flat nylon webbing degrades when repeatedly loaded with the relatively minuscule percentage of its capacity to which our hang gliding demands subject it (and, obviously, I'm content with tubular for myself). And I'll give folk another opportunity to say, "Oh yeah, asshole?"...
No glider suspension undamaged by abrasion has ever failed at any location other than that of the stitching (or junction at which there was supposed to have been stitching).
And I totally disagree with the last part of your statement in that paragraph or, at least, its relevance.
If one doesn't have enough brains to be able to preflight a glider, one should not be flying it. If one does, worn webbing is a whole lot easier to detect than is a broken strand of a 3/32-7x19 stainless steel cable and a whole lot less critical. If you're comfortable with the degree of wear (and you legitimately can be) - fly it. If not - replace it. It's that simple.
What does scare the crap out of me, however, is ultraviolet radiation. The flavor of webbing is ratable, the quality of the stitching is eyeballable, and abrasion is blindingly obvious. I don't know how to evaluate the extent of UV damage to webbing and stitching so I'm extremely careful about that aspect. My glider suspension is well protected as I've described earlier, my harness goes into the bag shortly after I extract myself.
I take comfort in the fact that no problems manifest themselves in Highland Aerosports solo trainers which are staked out in the field all season long.
With respect to your final paragraph...
You're still not getting it. You're still not thinking about what's below the carabiner.
Everybody flies with backup suspension on the glider but NOBODY - save for people flying cocoons in the configuration Danny described (which, nowadays, is almost nobody) - is effectively backed up. They think they're backed up but they're not.
Janni ("...wouldn't the right logic be to think about how to back the harness suspension...") gets it.
Now the bad news - I ain't exiting this discussion for a while. There are a few issues that folk have raised that I haven't been able to address 'cause I've been buried by dealing with the volume of comments and responses. (Dan, thanks for the input, I hope I covered it adequately with my discussion of preflight inspection.)
I hope you stick around and reciprocate the courtesy I extend to you of always answering and addressing your questions and points.
To answer your first two questions and save some bandwidth:
http://www.chgpa.org/forums/viewtopic.php?p=4332
or, yeah, close to seven years AFTER publication of his Crestline induced epiphany.
I had read the article when it first appeared and it had made a permanent impression (and I just reread it). I had a similar, but less detailed, response to nearly getting killed in the afternoon solar oven conditions in the South Bowl of Jockeys Ridge on 1984/07/05. I landed smelling like a rose after being rolled beyond placard, falling downwind to far below ridge level, and rocketing back up and just over the spine - but I realized that flying there in similar conditions was a dice roll.
(I voluntarily terminated my then - 1992/02/09 - site record duration flight with a top landing several passes after a similar dump at the NE end of the Smithsburg ridge for the same reason.)
Marc,
I didn't want to drag Mike or Wills Wing back into this 'cause my feel is that he/they caught the kind of crap that I'm getting for committing hang gliding culture heresy and were smart enough to say fuckit and go with the flow... but thanks for checking.
Let's take a look at what you got.
-
...the idea of possible accelerated wear "does not make a back-up a bad idea."
...the IDEA of POSSIBLE accelerated wear "DOES NOT MAKE A BACK-UP A BAD IDEA."
-
How many C5s could you simultaneously fly through the wiggle room provided in that statement?
Eat you're heart out, Roberto Gonzales! The master has been revealed and you ain't it!
Gee, and I thought Danny's post was a treasure trove (more on that later).
With respect to my flying skills... Again, NOTHING I have posted in, probably, the past few years is legitimized or invalidated by my status as a pilot. A thirteen year old kid from a good school with an A on his science test who's never been near an aircraft of any kind in the course of his short life could evaluate and/or originate everything I've done. The theory is one thing and it's pretty simple. Piloting skills mostly belong in the PhysEd Department (not that there's anything wrong with that).
But you might want to check with Sunny for an evaluation of my flying skills. He's been nearby during nearly all of my flying over the course of the past nine seasons, was the USHGA's Hang Gliding Instructor of the Year in 2003, and I've heard some statements from and attributed to him which are in sharp contrast to what seem to be your impressions.
Your disparagement of my engineering ability makes me wonder just how dangerously low your oxygen to THC intake ratio has been lately. Here are some quotes off the wire - most of them from this forum...
-
I was too green to fully appreciate your system when you showed it to me a couple of years ago.
...but I've seen his work. His release mechanism is elegent in it's simplicity and effectiveness.
He's a pretty sharp guy and makes interesting stuff.
Your straight pin release is also far superior to the curved pin.
If I had known Tad was going to make one I would have just waited for his.
I've seen the photos, quite clever I might say!
Ironically, I've always admired Tad's creative way at looking at things, and I have seen the equipment he's made with his own hands--it is beautifully made stuff.
-
Two of those comments are yours! (You got a somewhat less evil twin?)
If you need some more opinions check with the aforementioned Sunny and/or make another call to Wills Wing and ask if Rob is well enough to be bothered (and I very much hope he is - he's in my thoughts a lot). Are those parties sufficiently qualified and disinterested enough to suit you?
I question whether Type 18 flat nylon webbing degrades when repeatedly loaded with the relatively minuscule percentage of its capacity to which our hang gliding demands subject it (and, obviously, I'm content with tubular for myself). And I'll give folk another opportunity to say, "Oh yeah, asshole?"...
No glider suspension undamaged by abrasion has ever failed at any location other than that of the stitching (or junction at which there was supposed to have been stitching).
And I totally disagree with the last part of your statement in that paragraph or, at least, its relevance.
If one doesn't have enough brains to be able to preflight a glider, one should not be flying it. If one does, worn webbing is a whole lot easier to detect than is a broken strand of a 3/32-7x19 stainless steel cable and a whole lot less critical. If you're comfortable with the degree of wear (and you legitimately can be) - fly it. If not - replace it. It's that simple.
What does scare the crap out of me, however, is ultraviolet radiation. The flavor of webbing is ratable, the quality of the stitching is eyeballable, and abrasion is blindingly obvious. I don't know how to evaluate the extent of UV damage to webbing and stitching so I'm extremely careful about that aspect. My glider suspension is well protected as I've described earlier, my harness goes into the bag shortly after I extract myself.
I take comfort in the fact that no problems manifest themselves in Highland Aerosports solo trainers which are staked out in the field all season long.
With respect to your final paragraph...
You're still not getting it. You're still not thinking about what's below the carabiner.
Everybody flies with backup suspension on the glider but NOBODY - save for people flying cocoons in the configuration Danny described (which, nowadays, is almost nobody) - is effectively backed up. They think they're backed up but they're not.
Janni ("...wouldn't the right logic be to think about how to back the harness suspension...") gets it.
Now the bad news - I ain't exiting this discussion for a while. There are a few issues that folk have raised that I haven't been able to address 'cause I've been buried by dealing with the volume of comments and responses. (Dan, thanks for the input, I hope I covered it adequately with my discussion of preflight inspection.)
I hope you stick around and reciprocate the courtesy I extend to you of always answering and addressing your questions and points.
Hahahahahaha!!!!!so that we can exit this discussion gracefully.
New here?
And I'm the one ignoring the manufacturer?I didn't want to drag Mike or Wills Wing back into this 'cause my feel is that he/they caught the kind of crap that I'm getting for committing hang gliding culture heresy and were smart enough to say fuckit and go with the flow... but thanks for checking.
Hello Kettle :)Jim's never gonna let a statement from the manufacturer interfere with his concept of why the manufacturer does something.
Yeah ya sarcastic prick... I meet up with Rob at various hang gliding functions throughout the year (along with plenty other "big names"). I'd say I'm pretty up on the ins and outs of the hang gliding world. Quit posing just cuz you pester someone. Namedropping went out in the 80s.I'm pretty sure you've met Rob Kells...
Jim
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Flying Lobster
- Posts: 1042
- Joined: Fri Feb 25, 2005 4:17 pm
Tad;
I think you were right about the weak link issue (should scale with pilot mass, and using light pilots as the scale is reasonable), and there is a measurable benefit to increasing the strength so that heavy pilots have the same breaking ratio as lighter pilots.
You are very likely right about the backup strap, but where's the benefit worth all this fuss? I think the drag is negligible. We intuitively feel that a fabric connection is weak, so if a backup strap helps us get our mind off it so we can fly more effectively, I'd call it a benefit.
-Brian.
I think you were right about the weak link issue (should scale with pilot mass, and using light pilots as the scale is reasonable), and there is a measurable benefit to increasing the strength so that heavy pilots have the same breaking ratio as lighter pilots.
You are very likely right about the backup strap, but where's the benefit worth all this fuss? I think the drag is negligible. We intuitively feel that a fabric connection is weak, so if a backup strap helps us get our mind off it so we can fly more effectively, I'd call it a benefit.
-Brian.
Brian Vant-Hull
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Flying Lobster
- Posts: 1042
- Joined: Fri Feb 25, 2005 4:17 pm
The accident I referred to I can't remember exactly the details--but I vaguely recall it was a pilot around Hood River in Oregon who freefell to his death after a hang strap failure. I could not find any report from searching on the net. OK--since I can't cite the source I'll concede it didn't happen.
A hang loop that remains relatively free of wear contact points and possible heat producing friction will almost certainly not fail. The effects of UV and sea air exposure can have weakening effects which are in fact hard to determine without a static load test.
From John Heiney on the UP site:
" The tangs that attach the hang strap to the king post can cut through the strap after hundreds of hours of flight. Some of these tangs were sewn into hang straps without proper deburring, causing damage to the strap much earlier than expected.
The king post “boot” should be detached from the sail and slid up to allow inspection of the hang strap during your annual. Also, slide the spreader tube to inspect the area of the strap that lives inside the spreader for possible damage by the rivets. You should always adjust the spreader so the rivets are on the top before flight to prevent this damage."
Although incredibly rare--failure of stitched loops under low loads has happened--and in fact claimed the life of one of America's most renowned climbers. Abraded or "fuzzy" webbing is also cited as having significant strength loss. http://www.thebmc.co.uk/News.aspx?id=1121
More common are incidents of failure where friction is produced from sudden loading over a sharp edge or movement of nylon upon nylon. As long as a strap remains free of movement or any contact with objects with sharp or abrasive surfaces, the probability of failure is near zero. Is this the situation with your own hang and harness suspension systems? You decide.
marc
A hang loop that remains relatively free of wear contact points and possible heat producing friction will almost certainly not fail. The effects of UV and sea air exposure can have weakening effects which are in fact hard to determine without a static load test.
From John Heiney on the UP site:
" The tangs that attach the hang strap to the king post can cut through the strap after hundreds of hours of flight. Some of these tangs were sewn into hang straps without proper deburring, causing damage to the strap much earlier than expected.
The king post “boot” should be detached from the sail and slid up to allow inspection of the hang strap during your annual. Also, slide the spreader tube to inspect the area of the strap that lives inside the spreader for possible damage by the rivets. You should always adjust the spreader so the rivets are on the top before flight to prevent this damage."
Although incredibly rare--failure of stitched loops under low loads has happened--and in fact claimed the life of one of America's most renowned climbers. Abraded or "fuzzy" webbing is also cited as having significant strength loss. http://www.thebmc.co.uk/News.aspx?id=1121
More common are incidents of failure where friction is produced from sudden loading over a sharp edge or movement of nylon upon nylon. As long as a strap remains free of movement or any contact with objects with sharp or abrasive surfaces, the probability of failure is near zero. Is this the situation with your own hang and harness suspension systems? You decide.
marc
Great Googly-moo!
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Flying Lobster
- Posts: 1042
- Joined: Fri Feb 25, 2005 4:17 pm
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Flying Lobster
- Posts: 1042
- Joined: Fri Feb 25, 2005 4:17 pm
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Tad Eareckson
- Posts: 304
- Joined: Wed Feb 09, 2005 8:50 am
Oops, somehow neglected to include one of my most cherished engineering endorsements...
-
You clearly have the physics down well enough (as good as anyone else in the world) to do so.
-
(Sorry 'bout that, Brian.)
Marc,
Thanks much for the research efforts.
There was some bizarre accident in that neck of the woods in which a Northwest Airlines pilot tried to reinvent towing - in this case boat. I can't find a reference either but here's my best shot. I believe he concocted a release system that simultaneously separated the glider from the tow line and the harness from the glider. He died upon impact with the surface of the Hood(?) River. I'm pretty sure that's the one your thinking about and I'm pretty sure it's not relevant.
Yeah, I take all those points. My partial response is yeah, whether one has backup suspension or not, one should properly preflight the glider every once in a while. If one finds a problem (sandpaper glued to the keel, burred hardware) one should remedy the problem (peel, file) and, if necessary, replace the damaged webbing.
I'm not sure the climbing accident for which you provided the link was terribly relevant. It referred to "tape" which, to my untrained ear, sounds like something a lot less robust than the material about which we're concerned.
You've got a couple of statements citing parameters in which one's suspension "will almost certainly not fail" and in which "the probability of failure is near zero". Yeah. I'm good. If our suspension systems are properly designed we're all good. Those two comments support my earlier assertion that "Fabric to metal connections do not wear."
I note in particular your reference to "movement of nylon upon nylon".
THE SUSPENSION DAMAGE CAUSED BY PEOPLE ABRADING THEIR STRAPS WHILE TIGHTENING AND TYING THEIR TIE-DOWN ROPES DWARFS ALL OTHER CAUSES TO THE POINT OF COMPLETE IRRELEVANCE.
Is anyone cutting through enough to convert the suspension to the weak link in the chain? No. Is everyone backed up anyway? Yeah? Does that make it a good practice?
But I digress a bit...
>
The effects of UV and sea air exposure can have weakening effects which are in fact hard to determine without a static load test.
<
You're still not addressing that factors such as THESE apply equally to the stuff at BOTH ends of the carabiner.
If you're otherwise properly caring for your equipment the harness suspension is gonna soak up MORE UV 'cause it's less in the shade while you're flying (and it's way less likely to get replaced in the course of annual maintenance.
If something is gonna fail because of UV exposure it WILL BE the harness suspension. And few of those are backed up.
The posts are getting ahead of me...
Yeah, the Viper reference is what I'm talking about. With the harness suspension backed up there is at least some logic to backing up that of the glider. (Sounds like it was NEVER preflighted though.)
The paragliding parachute bridle failure was not particularly relevant to this discussion. It happened because of an improper installation which was a FABRIC TO FABRIC - not metal - phenomenon.
Brian,
I AM, of course, right about the weak link issue - but it's not a point of ME being right. It's a point of understanding the physics or, failing that, looking at ANY text or set of guidelines, requirements, standards, or regulations that's ever been written. But hang gliding culture, not for the first time, has gotten away from or never even understood basic aviation principles and developed a religion along the lines of "This is the way it's done 'cause we've always done it this way."
(I'm not using light pilots as the gold standard - I'm using USHGA guidelines.)
I've been around long enough to have seen a lot of ridiculous, overbuilt, poorly designed crap disappear from our equipment and airflow. Today's competition topless gliders with their faired control frames and the state of the art harnesses and instrument pods that go with them are things of beauty.
When you've got a sky full of people who know how to get the most of those things flying a hundred mile task that's gonna be decided by a matter of seconds, a foot and a half of useless extra bulk in the airflow gets real significant.
Some of these same pilots intuitively know that their weak links are way understrength but, being unaware of those USHGA guidelines and the actual data on the systems being utilized, allow themselves to be bullied by the religious authorities into accepting less safe and less fair tow launch conditions.
I think it's a pretty safe bet that just about all of these pilots think that they MUST fly with backup suspension 'cause it's some sort of regulation or HGMA requirement.
But shaving a minute and a half off of a task time is not what I'm primarily concerned with here.
Yeah, people intuitively feel that a fabric connection is weak. I think our community owes our sport a better grip on reality.
Sometime back we had a forum discussion on the causes of launch dollies drifting from the desired track. Runway crown was suggested, differential tire pressure sounded good too. I'd have accepted it.
Chad let all the air out on the left tire and inflated the hell out of the right (or vice versa) and went for a tow. So much for that hypothesis.
I think it was about a year ago that Sunny fired up the Singer and punched out a loop. Ask him sometime about the experiment he then conducted with a seven ton hydraulic jack.
Marc's a very experienced climber, has done his homework on webbing, and knows "that a new strap far exceeds the breaking strength of any other component on a hang glider".
I can make an argument that, in one regard, a backup loop could actually make things MORE dangerous.
I can't find a reference but... Once upon a time a pilot brought a harness into Betty's shop for some reason. She noted that the suspension webbing looked faded/UVed and recommended its replacement. The pilot talked her down to stitching in some reinforcement. After the sewing machine needle had completed a few up/down cycles the webbing disintegrated - fell apart. She and her customer turned white. That's one of the scariest things I've ever heard that didn't involve a Great White Shark.
My feeling is that the backup gives one a false feeling of security, a perceived ticket to abuse the glider's suspension system, a diminished focus on the critical points and issues of the entire suspension system, and a tendency to breeze by some of the related preflight procedures.
Dumbo almost got himself killed - along with Timothy - because he was focused on the Magic Feather and didn't understand the stuff that was actually able to keep him safely aloft.
I've got a reasonably good understanding of the structure, materials, capacities, geometry, and construction of my equipment and I feel a lot better flying with the confidence that brings than I did with some of the baseless anxieties I maintained before I levered an outboard leading edge section back straight using a couple of closely spaced tree trunks.
-
You clearly have the physics down well enough (as good as anyone else in the world) to do so.
-
(Sorry 'bout that, Brian.)
Marc,
Thanks much for the research efforts.
There was some bizarre accident in that neck of the woods in which a Northwest Airlines pilot tried to reinvent towing - in this case boat. I can't find a reference either but here's my best shot. I believe he concocted a release system that simultaneously separated the glider from the tow line and the harness from the glider. He died upon impact with the surface of the Hood(?) River. I'm pretty sure that's the one your thinking about and I'm pretty sure it's not relevant.
Yeah, I take all those points. My partial response is yeah, whether one has backup suspension or not, one should properly preflight the glider every once in a while. If one finds a problem (sandpaper glued to the keel, burred hardware) one should remedy the problem (peel, file) and, if necessary, replace the damaged webbing.
I'm not sure the climbing accident for which you provided the link was terribly relevant. It referred to "tape" which, to my untrained ear, sounds like something a lot less robust than the material about which we're concerned.
You've got a couple of statements citing parameters in which one's suspension "will almost certainly not fail" and in which "the probability of failure is near zero". Yeah. I'm good. If our suspension systems are properly designed we're all good. Those two comments support my earlier assertion that "Fabric to metal connections do not wear."
I note in particular your reference to "movement of nylon upon nylon".
THE SUSPENSION DAMAGE CAUSED BY PEOPLE ABRADING THEIR STRAPS WHILE TIGHTENING AND TYING THEIR TIE-DOWN ROPES DWARFS ALL OTHER CAUSES TO THE POINT OF COMPLETE IRRELEVANCE.
Is anyone cutting through enough to convert the suspension to the weak link in the chain? No. Is everyone backed up anyway? Yeah? Does that make it a good practice?
But I digress a bit...
>
The effects of UV and sea air exposure can have weakening effects which are in fact hard to determine without a static load test.
<
You're still not addressing that factors such as THESE apply equally to the stuff at BOTH ends of the carabiner.
If you're otherwise properly caring for your equipment the harness suspension is gonna soak up MORE UV 'cause it's less in the shade while you're flying (and it's way less likely to get replaced in the course of annual maintenance.
If something is gonna fail because of UV exposure it WILL BE the harness suspension. And few of those are backed up.
The posts are getting ahead of me...
Yeah, the Viper reference is what I'm talking about. With the harness suspension backed up there is at least some logic to backing up that of the glider. (Sounds like it was NEVER preflighted though.)
The paragliding parachute bridle failure was not particularly relevant to this discussion. It happened because of an improper installation which was a FABRIC TO FABRIC - not metal - phenomenon.
Brian,
I AM, of course, right about the weak link issue - but it's not a point of ME being right. It's a point of understanding the physics or, failing that, looking at ANY text or set of guidelines, requirements, standards, or regulations that's ever been written. But hang gliding culture, not for the first time, has gotten away from or never even understood basic aviation principles and developed a religion along the lines of "This is the way it's done 'cause we've always done it this way."
(I'm not using light pilots as the gold standard - I'm using USHGA guidelines.)
I've been around long enough to have seen a lot of ridiculous, overbuilt, poorly designed crap disappear from our equipment and airflow. Today's competition topless gliders with their faired control frames and the state of the art harnesses and instrument pods that go with them are things of beauty.
When you've got a sky full of people who know how to get the most of those things flying a hundred mile task that's gonna be decided by a matter of seconds, a foot and a half of useless extra bulk in the airflow gets real significant.
Some of these same pilots intuitively know that their weak links are way understrength but, being unaware of those USHGA guidelines and the actual data on the systems being utilized, allow themselves to be bullied by the religious authorities into accepting less safe and less fair tow launch conditions.
I think it's a pretty safe bet that just about all of these pilots think that they MUST fly with backup suspension 'cause it's some sort of regulation or HGMA requirement.
But shaving a minute and a half off of a task time is not what I'm primarily concerned with here.
Yeah, people intuitively feel that a fabric connection is weak. I think our community owes our sport a better grip on reality.
Sometime back we had a forum discussion on the causes of launch dollies drifting from the desired track. Runway crown was suggested, differential tire pressure sounded good too. I'd have accepted it.
Chad let all the air out on the left tire and inflated the hell out of the right (or vice versa) and went for a tow. So much for that hypothesis.
I think it was about a year ago that Sunny fired up the Singer and punched out a loop. Ask him sometime about the experiment he then conducted with a seven ton hydraulic jack.
Marc's a very experienced climber, has done his homework on webbing, and knows "that a new strap far exceeds the breaking strength of any other component on a hang glider".
I can make an argument that, in one regard, a backup loop could actually make things MORE dangerous.
I can't find a reference but... Once upon a time a pilot brought a harness into Betty's shop for some reason. She noted that the suspension webbing looked faded/UVed and recommended its replacement. The pilot talked her down to stitching in some reinforcement. After the sewing machine needle had completed a few up/down cycles the webbing disintegrated - fell apart. She and her customer turned white. That's one of the scariest things I've ever heard that didn't involve a Great White Shark.
My feeling is that the backup gives one a false feeling of security, a perceived ticket to abuse the glider's suspension system, a diminished focus on the critical points and issues of the entire suspension system, and a tendency to breeze by some of the related preflight procedures.
Dumbo almost got himself killed - along with Timothy - because he was focused on the Magic Feather and didn't understand the stuff that was actually able to keep him safely aloft.
I've got a reasonably good understanding of the structure, materials, capacities, geometry, and construction of my equipment and I feel a lot better flying with the confidence that brings than I did with some of the baseless anxieties I maintained before I levered an outboard leading edge section back straight using a couple of closely spaced tree trunks.
Hello Kettle....
talk about a false sense of security?...
The stuff under the carabiner is not the same as the stuff above it. The stuff below connects to fabric (your harness), the stuff above connects to metal... the glider... a single bolt hole in many cases. NOT the same.
Argue all you like about what it is, but saying it's the same... hello kettle.
And where is this notion of the webbing being the strongest thing on a hang glider coming from? Granted, it's strong stuff, but... 8,000lb webbing vs 72kN carabiner? (14,000lb)
Webbing is far more suspect to wear than steel, which is the entire point here. False sense of security.
Hello Kettle
I know! Lets follow that logic... Parachutes just give you a false sense of security. They convince you that you can attempt crazy things without being in danger. Best not to fly with them. (HA! I've actually heard this in real life!)
Walks like a duck.
Talks like a duck.
(must be a witch)
talk about a false sense of security?...
The stuff under the carabiner is not the same as the stuff above it. The stuff below connects to fabric (your harness), the stuff above connects to metal... the glider... a single bolt hole in many cases. NOT the same.
Argue all you like about what it is, but saying it's the same... hello kettle.
And where is this notion of the webbing being the strongest thing on a hang glider coming from? Granted, it's strong stuff, but... 8,000lb webbing vs 72kN carabiner? (14,000lb)
Webbing is far more suspect to wear than steel, which is the entire point here. False sense of security.
Hello Kettle
I know! Lets follow that logic... Parachutes just give you a false sense of security. They convince you that you can attempt crazy things without being in danger. Best not to fly with them. (HA! I've actually heard this in real life!)
Walks like a duck.
Talks like a duck.
(must be a witch)
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Tad Eareckson
- Posts: 304
- Joined: Wed Feb 09, 2005 8:50 am
"The stuff AT BOTH ENDS OF THE CARABINER" IS the same. After one extends a bit in either direction variables start coming into play.
The doubled webbing of my harness suspension splits a short distance above the harness and each end is stitched to form an eye which engages another length of webbing with anchor points a short distance fore and aft of the CG on the side.
The connection allows free movement between two elements in a fabric to fabric connection and I wasn't happy when I first noted that construction but I'm guessing that in flight no movement actually occurs 'cause it doesn't seem to be a problem in the least.
But...
Let's have a race. You choose any stock Wills Wing hardware designed to engage suspension webbing you want, I'll take a section of webbing. Each of us gets a (nother, in my case) section of webbing. Let's see who can do the greatest amount of damage in the least amount of time.
And again... Unless your harness suspension is backed up you can't justify glider suspension backup with the wear (UV, dirt, salt) issue(s). In fact any harness suspension wear which may occur at the carabiner is concealed as well as or better than any suspension problem area on the glider. Preflight once in a while.
My glider suspension is, in fact, anchored by a single (quarter inch) bolt. Justifiably or not, that makes me a bit nervous and, as I've said before, I am backed up for that scenario.
This notion of the webbing being the strongest thing on a hang glider comes from Marc (note the quotation marks). But I'll save him the trouble of defending himself.
The carabiner is part of the harness.
OK, let's not nitpick and consider the entire system. My (steel) carabiner is 53 kN (11914 pounds) (you're a bit over a ton low on your conversion). Type 18 webbing is 6000 pounds. But it's doubled. You're not gonna get the full six tons 'cause of the bend so I'm guessing the carabiner still wins with a comfortable margin.
But so what? A long time ago you stopped hang gliding and started skydiving.
(Which segues neatly to...)
The difference between the backup suspension and the parachute is that one may require the latter through no fault of his own.
The doubled webbing of my harness suspension splits a short distance above the harness and each end is stitched to form an eye which engages another length of webbing with anchor points a short distance fore and aft of the CG on the side.
The connection allows free movement between two elements in a fabric to fabric connection and I wasn't happy when I first noted that construction but I'm guessing that in flight no movement actually occurs 'cause it doesn't seem to be a problem in the least.
But...
Let's have a race. You choose any stock Wills Wing hardware designed to engage suspension webbing you want, I'll take a section of webbing. Each of us gets a (nother, in my case) section of webbing. Let's see who can do the greatest amount of damage in the least amount of time.
And again... Unless your harness suspension is backed up you can't justify glider suspension backup with the wear (UV, dirt, salt) issue(s). In fact any harness suspension wear which may occur at the carabiner is concealed as well as or better than any suspension problem area on the glider. Preflight once in a while.
My glider suspension is, in fact, anchored by a single (quarter inch) bolt. Justifiably or not, that makes me a bit nervous and, as I've said before, I am backed up for that scenario.
This notion of the webbing being the strongest thing on a hang glider comes from Marc (note the quotation marks). But I'll save him the trouble of defending himself.
The carabiner is part of the harness.
OK, let's not nitpick and consider the entire system. My (steel) carabiner is 53 kN (11914 pounds) (you're a bit over a ton low on your conversion). Type 18 webbing is 6000 pounds. But it's doubled. You're not gonna get the full six tons 'cause of the bend so I'm guessing the carabiner still wins with a comfortable margin.
But so what? A long time ago you stopped hang gliding and started skydiving.
(Which segues neatly to...)
The difference between the backup suspension and the parachute is that one may require the latter through no fault of his own.
I like to think of Tad's posts like a jehovah witness telemarketer.
Jehovah witness (insert any crazy religious cult for that matter) for their blind devotion to bent logic. Telemarketers because they aren't allowed to hang up on you and they read from a script (including the same sort of circular logic).
They can be quite amusing to play with... you wind them up and see what contorted path they squirm around to keep their "logic" house in tact. Try it sometime... they can't hang up on you (I don't think the Jehovah guys can't leave either). Hours of good clean American-family-values fun.
I like the Jazz/Blues one better though.
:)
Jim
Jehovah witness (insert any crazy religious cult for that matter) for their blind devotion to bent logic. Telemarketers because they aren't allowed to hang up on you and they read from a script (including the same sort of circular logic).
They can be quite amusing to play with... you wind them up and see what contorted path they squirm around to keep their "logic" house in tact. Try it sometime... they can't hang up on you (I don't think the Jehovah guys can't leave either). Hours of good clean American-family-values fun.
I like the Jazz/Blues one better though.
:)
Jim
Where's the Love?
Come on people. Where's the love????
As someone previously pointed out, there's no need for insults.
Matthew
As someone previously pointed out, there's no need for insults.
Matthew
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Flying Lobster
- Posts: 1042
- Joined: Fri Feb 25, 2005 4:17 pm
Re: Where's the Love?
of course, tastes in voyeurism (as well as stimulants) vary greatly.Matthew wrote:Come on people. Where's the love????
As someone previously pointed out, there's no need for insults.
Matthew
". . . oh, sorry waiter, just our check. the other couple will be staying for desert."
since my impulsiveness got the better of me, i'll attempt a different 'note' before i duck back out. i got no business here anyways.
there are definitely nuggets and things to be learned by following these threads, but . . . well, i'd always thought that being a forensic pathologist would be fascinating also. it's just that, " golly gee batman! digging through all the gory stuff - it gets so darn messy! it's hard to keep track of things ".
there are definitely nuggets and things to be learned by following these threads, but . . . well, i'd always thought that being a forensic pathologist would be fascinating also. it's just that, " golly gee batman! digging through all the gory stuff - it gets so darn messy! it's hard to keep track of things ".
garyDevan
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Danny Brotto
- Posts: 709
- Joined: Mon Feb 14, 2005 9:29 pm
Carabiniers do fail...
Carabiner failures while rare, are not unheard of... just google "carabiner failure" or see:
http://www.hypernews.org/HyperNews/get/ ... R/112.html
Danny Brotto
http://www.hypernews.org/HyperNews/get/ ... R/112.html
Danny Brotto
I have been following this post for a while …
I never tie down my glider by the hang strap. I run the tie down over the keel and tie it back to itself. If the tie down isn't long enough I find another. I think Jim Rooney taught me this.
I do not like how the backup on most integrated hangloops is routed inside the main where the carbineer will wears on it first. The backup should be stitched to the outside of the main loop. It just occurred to me that I should check my "Single Point" harness hang strap for the same situation. The harness does have a mainstrap to the slider and a backup to the shoulder straps stitched together.
I was concerned about hangstrap redundancy of my first harness, a HES I-Tracer ... if say one side broke. The hangstrap has a second loop of webbing stitched into the apex so if one side broke it was impossible for the broken end to run through the carbineer. Yes you would be hanging from one hip but you would be still attached. The second loop also doubles the thickness of the hangstrap at the carbineer.
So Tad, if your harness hangstrap has any of the same configurations, consider it backed up. So your argument about not having a backup hang loop is "what's under the carbineer is the same as was above" does not hold up.
Tad … back it up!! Or at least stitch a piece of webbing from one side of your homemade kingpost hangloop to the other just below the keel. So, when the webbing fails at one of the metal tabs bolted to the kingpost … we can just hope that the other side is not as worn as the first. Or that single piece of 1/4 inch piece of hardware, the bolt you have been swinging back and fourth on for 16 years, hasn’t been worn nearly through.
With regards to the failure of a Hang strap on a Viper/Myth harnesses. The same situation was present on my Rotor harness. When I rocked up the, the hang strap jammed itself between the slider bar and the backplate causing wear. I placed a 1/2 inch thick stop, like the ones used to control drill depths, on the slider bar so the hangstrap slider stopped before the jam spot. Yes I considered the consequences of having the load of the hangstrap a total of 1 inch from the support, but in the rocked up position most of the load is axial and not beam loaded so little bending moments are placed on the slider bar.
JD
I never tie down my glider by the hang strap. I run the tie down over the keel and tie it back to itself. If the tie down isn't long enough I find another. I think Jim Rooney taught me this.
I do not like how the backup on most integrated hangloops is routed inside the main where the carbineer will wears on it first. The backup should be stitched to the outside of the main loop. It just occurred to me that I should check my "Single Point" harness hang strap for the same situation. The harness does have a mainstrap to the slider and a backup to the shoulder straps stitched together.
I was concerned about hangstrap redundancy of my first harness, a HES I-Tracer ... if say one side broke. The hangstrap has a second loop of webbing stitched into the apex so if one side broke it was impossible for the broken end to run through the carbineer. Yes you would be hanging from one hip but you would be still attached. The second loop also doubles the thickness of the hangstrap at the carbineer.
So Tad, if your harness hangstrap has any of the same configurations, consider it backed up. So your argument about not having a backup hang loop is "what's under the carbineer is the same as was above" does not hold up.
Tad … back it up!! Or at least stitch a piece of webbing from one side of your homemade kingpost hangloop to the other just below the keel. So, when the webbing fails at one of the metal tabs bolted to the kingpost … we can just hope that the other side is not as worn as the first. Or that single piece of 1/4 inch piece of hardware, the bolt you have been swinging back and fourth on for 16 years, hasn’t been worn nearly through.
With regards to the failure of a Hang strap on a Viper/Myth harnesses. The same situation was present on my Rotor harness. When I rocked up the, the hang strap jammed itself between the slider bar and the backplate causing wear. I placed a 1/2 inch thick stop, like the ones used to control drill depths, on the slider bar so the hangstrap slider stopped before the jam spot. Yes I considered the consequences of having the load of the hangstrap a total of 1 inch from the support, but in the rocked up position most of the load is axial and not beam loaded so little bending moments are placed on the slider bar.
JD
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Tad Eareckson
- Posts: 304
- Joined: Wed Feb 09, 2005 8:50 am
Shawn,
Late in the day during my last excursion to Ridgely - 2007/10/21 - I noticed Sunny taking wraps to give a student proper basetube clearance. If I had said, by way of critiquing the practice, something on the order of "FUCK THAT!!!" I imagine he'd have taken a bit of umbrage.
I also imagine I'm not the only person on the forum to have taken same with respect to your first comment following this most recent accident. If you lack the competence to safely effect this common and perfectly acceptable adjustment then, by all means, stay on the ground if that's your only other option but please don't judge most of the rest of us too harshly.
Regarding your two contributions to this topic...
It appears to me that you're far on one side or the other of the bell curve of knowledge and understanding of suspension systems and materials. I'll suppress all of my gut instincts and assume you're on the right.
So I hereby absolve you of the requirement to keep reading this "shit" and grant you permission to go puke in some other thread. That way you won't distract those of us who don't know everything already (list includes Brian, Steve, Marc, Janni, Bacil, JD, and me - at least).
Danny,
I was a bit unhappy at first upon reading the referenced advisory 'cause I'm got an Omega Pacific steel auto locking modified D carabiner of which I'm quite fond - but then I noted that the date takes it back over a decade. I'm guessing those problems have since been rectified.
Despite the fact that the prospect of failing carabiners also bolsters Wills Wing's (noticed how I phrased that) position that backup webbing is there purely for show, that ammunition is only good for cheap shots.
I did google:
carabiner failure
and a quick scan of the leading results just didn't reveal anything more pertinent to our situation.
Steel hang gliding carabiners lead lives more pampered than anything that's not in a museum exhibit.
At about the point my glider fails the carabiner is feeling about a seventh of its rating. We just never load these things significantly, we don't arrest falls, bang them around on scaffolding, drag them through caves, or drop them on rocks.
OK, with respect to the harness...
High Energy cocoon flown circa 1988 to circa 2004. Let's knock it down to fifteen years to allow for the circas.
Can we safely assume that Danny represents an upper airtime limit for us mere mortals? Good.
Now let's multiply him by 1.5 to approximate Janni's hook in weight and thus penalize the harness by reducing its lifespan by a third to yield a decade.
Let's make the harness more dangerous by turning it into a pod with no redundancy built into the suspension.
We're starting with three ton webbing.
It's doubled at the carabiner but let's penalize it fifty percent 'cause of the 7/32 inch radius U-turn it's gotta make, so we're still at three tons.
Let's cut the strength in half to allow for UV damage. 3000 pounds.
Now let's say Danny waits until the abrasion has eaten a third of the way through the webbing before he gets back on the horn to Betty. 2000 pounds - 8 Gs. The skydivers are still happy. (And the degrees of those degradation adjustments were extremely generous.)
So what all this means is that if you check for wear in your harness suspension once every five years or so (as opposed to the before-each-flight requirement) you're probably gonna be in real good shape.
From the description of the wear I'm guessing that the carabiner probably looked like:
http://www.buckscountyoutfitters.com/st ... Carabiner/
which, I believe, is what came with my High Energy pod.
That is a rather poorly suited piece of hardware to be included in our suspension systems - it's made for ropes. Since it does not support the webbing evenly you end up with a wear pattern such as Danny described and your suspension lasts only ten years (worst case scenario) - instead of forever. (The Wills Wing raised suspension hardware is designed properly and those interfaces do impart the gift of eternal life.
The other downside of using a carabiner shaped as such is that you're sacrificing a significant percentage of the webbing's capacity. If the rest of a combined raised suspension system is designed properly the harness webbing's interface with the carabiner is the weak point of the system, even if the webbing is new and undamaged.
A carabiner such as:
http://www.omegapac.com/op_climbing_oval.html
(forget the material and strength - I'm just talking shape) will provide for a better load distribution and reduce (probably to negligible) the wear issue.
My current carabiner:
http://www.omegapac.com/op76s38q.html
is also reasonably webbing friendly - especially at the top - but I'm thinking about replacing it with:
http://www.para-gear.com/templates/para ... &parent=34
1" Speed Link - 101735
Of course, if I ever need to get away from my glider quickly I'll have to use the hook knife but in a situation in which things are that critical the hook knife would probably be the better option anyway.
Janni,
Take a look at:
http://www.highenergysports.com/articles/trouble.htm
Betty also addresses some of the concerns you expressed about the esoteric issue of fabric and stitching inspection.
Late in the day during my last excursion to Ridgely - 2007/10/21 - I noticed Sunny taking wraps to give a student proper basetube clearance. If I had said, by way of critiquing the practice, something on the order of "FUCK THAT!!!" I imagine he'd have taken a bit of umbrage.
I also imagine I'm not the only person on the forum to have taken same with respect to your first comment following this most recent accident. If you lack the competence to safely effect this common and perfectly acceptable adjustment then, by all means, stay on the ground if that's your only other option but please don't judge most of the rest of us too harshly.
Regarding your two contributions to this topic...
It appears to me that you're far on one side or the other of the bell curve of knowledge and understanding of suspension systems and materials. I'll suppress all of my gut instincts and assume you're on the right.
So I hereby absolve you of the requirement to keep reading this "shit" and grant you permission to go puke in some other thread. That way you won't distract those of us who don't know everything already (list includes Brian, Steve, Marc, Janni, Bacil, JD, and me - at least).
Danny,
I was a bit unhappy at first upon reading the referenced advisory 'cause I'm got an Omega Pacific steel auto locking modified D carabiner of which I'm quite fond - but then I noted that the date takes it back over a decade. I'm guessing those problems have since been rectified.
Despite the fact that the prospect of failing carabiners also bolsters Wills Wing's (noticed how I phrased that) position that backup webbing is there purely for show, that ammunition is only good for cheap shots.
I did google:
carabiner failure
and a quick scan of the leading results just didn't reveal anything more pertinent to our situation.
Steel hang gliding carabiners lead lives more pampered than anything that's not in a museum exhibit.
At about the point my glider fails the carabiner is feeling about a seventh of its rating. We just never load these things significantly, we don't arrest falls, bang them around on scaffolding, drag them through caves, or drop them on rocks.
OK, with respect to the harness...
High Energy cocoon flown circa 1988 to circa 2004. Let's knock it down to fifteen years to allow for the circas.
Can we safely assume that Danny represents an upper airtime limit for us mere mortals? Good.
Now let's multiply him by 1.5 to approximate Janni's hook in weight and thus penalize the harness by reducing its lifespan by a third to yield a decade.
Let's make the harness more dangerous by turning it into a pod with no redundancy built into the suspension.
We're starting with three ton webbing.
It's doubled at the carabiner but let's penalize it fifty percent 'cause of the 7/32 inch radius U-turn it's gotta make, so we're still at three tons.
Let's cut the strength in half to allow for UV damage. 3000 pounds.
Now let's say Danny waits until the abrasion has eaten a third of the way through the webbing before he gets back on the horn to Betty. 2000 pounds - 8 Gs. The skydivers are still happy. (And the degrees of those degradation adjustments were extremely generous.)
So what all this means is that if you check for wear in your harness suspension once every five years or so (as opposed to the before-each-flight requirement) you're probably gonna be in real good shape.
From the description of the wear I'm guessing that the carabiner probably looked like:
http://www.buckscountyoutfitters.com/st ... Carabiner/
which, I believe, is what came with my High Energy pod.
That is a rather poorly suited piece of hardware to be included in our suspension systems - it's made for ropes. Since it does not support the webbing evenly you end up with a wear pattern such as Danny described and your suspension lasts only ten years (worst case scenario) - instead of forever. (The Wills Wing raised suspension hardware is designed properly and those interfaces do impart the gift of eternal life.
The other downside of using a carabiner shaped as such is that you're sacrificing a significant percentage of the webbing's capacity. If the rest of a combined raised suspension system is designed properly the harness webbing's interface with the carabiner is the weak point of the system, even if the webbing is new and undamaged.
A carabiner such as:
http://www.omegapac.com/op_climbing_oval.html
(forget the material and strength - I'm just talking shape) will provide for a better load distribution and reduce (probably to negligible) the wear issue.
My current carabiner:
http://www.omegapac.com/op76s38q.html
is also reasonably webbing friendly - especially at the top - but I'm thinking about replacing it with:
http://www.para-gear.com/templates/para ... &parent=34
1" Speed Link - 101735
Of course, if I ever need to get away from my glider quickly I'll have to use the hook knife but in a situation in which things are that critical the hook knife would probably be the better option anyway.
Janni,
Take a look at:
http://www.highenergysports.com/articles/trouble.htm
Betty also addresses some of the concerns you expressed about the esoteric issue of fabric and stitching inspection.
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hepcat1989
- Posts: 684
- Joined: Thu Jan 06, 2005 11:15 pm
-
Danny Brotto
- Posts: 709
- Joined: Mon Feb 14, 2005 9:29 pm
Done...
"that ammunition is only good for cheap shots."
Huh? I'm out.
Danny Brotto
Huh? I'm out.
Danny Brotto