That becomes noticeable in some cases from as little as five millimeters of change in individual lines, it's noticeable for the lines too, and if it isn't noticed, then it's simply that the changes, the accompanying changes, just happen way too slowly. The pilot just gets used to the fact that it's already flying poorly. Podz
-Glidz, the Lu-Glidz podcast. Stories from the cosmos of paragliding. Today with Der
Ralf, Ralf Ahns is here.
And Lucian Haas on the mic.
At the heart of Podz-Glidz are always people and their personal stories surrounding paragliding. That is also the case this time, although the actual topic behind it is one that affects and should interest every pilot. Our gliders have long lines, and they are only more or less shape-stable. This means that over the course of using a paraglider, they can become longer or shrink. Since our gliders are obviously made of soft fabric, stretched lines cause the entire glider to change. The profile might get a slight kink. The angle of attack increases or decreases, possibly differently on the outer wing than in the middle. In any case, the distorted glider then no longer sits in the airflow as the designer originally intended.
It flies differently, maybe hangs at the start, collapses more often, doesn't pull as cleanly into turns, stays in the deep stall phase longer after a front collapse, and so on and so forth. Under certain circumstances, that is the case. This is even safety-relevant. Ralf Ahns has been campaigning for years to sensitize the paragliding scene to this topic. As a flight instructor and paraglider checker, he has seen hundreds of examples and had them brought into his workshop, which showed that even slight trim changes—occurring even within the usual tolerances of plus or minus 15 millimeters for the line lengths—can give a glider a completely different flight character. And some older gliders fly almost like new once they are correctly adjusted again.
Ralf is convinced that during a glider check, the line lengths must not only be checked for their absolute dimensions according to the tolerance specifications, but must also always be readjusted relative to one another. Specifically, so that the final trim of the glider comes as close as possible to the ideal intended by the manufacturer. In the podcast, Ralf Ahns explains, among other things, how relative trimming works. What difficulties it involves and how a computer program he developed can help automate trim optimization. However, he also reports how even the DHV and many manufacturers still struggle to take these findings into account. This includes, among other things, the problem that as a pilot and even as a check center, it is sometimes difficult to access the correct data sets for the line lengths.
Ralf also gives tips on what pilots should look out for to detect possible trim changes in their glider. In the end, the conversation jumps to a completely different, but no less interesting topic: singleskins. Specifically, why these gliders without undersails could represent the future of paraglider training.
Ralf, why do lines actually shorten?
That's basically exactly the same as with a side instrument. If I have a violin or a guitar, then thermal influences and material aren't that great for me. With a paraglider, the material factor comes into play even more. Of course, they can't stay the same length. Everyone knows that materials expand in heat and contract in the cold. And moisture and cold, snow, change the lines to such an extent that you eventually have to ask yourself, does that have an impact, yes or no. But that they change should be immediately clear to everyone. What exactly happens there, I don't think you can say that via audio. You can't convey that. It's not possible. But they change, and that's immediately clear to everyone.
What do they actually do? Do they lengthen or shorten? What is it that you see more often in practice?
Shorten. Clearly shorten. People always go around saying, my paraglider was on a winch tow, so surely everything got longer because of the higher load. I always say, relatively, that's correct. But actually, something shortened less because of the load. So most lines, the vast majority of lines, shorten.
But are there also lines that can actually lengthen? Or is that just temporary because they were under load for a bit, so they stretch a little but then return to their original state later?
You can't say what happens later. I can only say that we always only have snapshots when we test gliders. And what's noticeable is essentially the picture that certain lines actually lengthen. Although that is really the exception. The vast majority of lines shorten. And quite dramatically so.
What do you mean by dramatic? I mean, if I say my line is now seven meters long, how much does it usually shorten over the course of a normal glider's lifespan?
Over the life of a glider, you have to assume that it will be well over one percent. In exceptional cases, the highest value I've ever been able to prove was 3.7 percent. Which, on an eight-meter line, is already several centimeters. In that case, we're already in the double-digit range. That was just under 20 centimeters. And that's almost unbelievable. But I was able to prove it because we've been tracking the history of this glider over eight years. And we were able to prove that lines have shortened by up to 20 centimeters.
If you imagine a normal speed bar now, it might have a travel distance of 14 centimeters or something like that. Then 20 is much more than what a normal speed bar even provides.
No, you can't see that just like that. You have to see what angle changes are happening on the glider. And if we're flying with about an eight-degree angle of attack and push the speed bar all the way through, we have an angle change that goes to approximately four degrees. That means the speed bar changes the angle of attack by four degrees. And the changes in the lines account for about one degree, half a degree, one degree, 1.5 degrees. It stays roughly within that range. And that's about like 20, 25 percent of the speed bar travel in terms of glider behavior. And then you get a very good idea. Of the fact that the glider really changes. Significantly, so that you notice it.
When gliders come out of a factory brand new, people always say, "Yeah, that's the new condition." With a car, you'd say, "That's how it's supposed to be." Is a glider actually like that with the lines as it's rigged and how you receive it? Is that what you'd have to say is truly the ideal trim you get?
We all hope that's the case, of course. No one can say for sure. You'd have to measure every new glider to know. And of course, nobody is going to do that work. I did it myself for some gliders just to figure out how much variance there is in production. I had one very dramatic case. We don't want to name names. Dramatic cases where a new glider actually wouldn't meet its own check criteria. That means we got a glider from production, measured it, and unfortunately had to find that this glider would have failed the two-year check because of the trim.
Stupid, right? But it's a fact. And my collaboration with this company ended at that point. Because it obviously caused more problems than it could solve. For me, it was another point where I'd say, that's a piece of reality that maybe isn't seen that much. But I also have to say, I believe the production of the gliders has reached a good standard by now.
What does "good standing" mean? What kind of variance can one expect? For instance, in what range can the line lengths still differ significantly from what one might call the optimum, or what would actually be expected of an ideal glider?
I think it would be presumptuous of me to claim that generally. I can't do that. It also depends on the glider type, of course. And as for production accuracy, I can't say who produces better or worse. I can't. I can only say that there are measurement errors, production errors, measurement errors that would be factored in. I can really only say to what extent a change in lines becomes significant for the glider's behavior. There are plenty of statements from test pilots. There are my personal experiences in measuring, but also, since I'm a pilot myself, while flying. And there I can only say that it becomes noticeable in some cases from a change of just five millimeters in individual lines, even for a single line. And if it's not noticed, then it's simply that these changes, the accompanying changes, are just happening far too slowly.
The pilot just gets used to the glider flying poorly. And if it flies poorly enough, they usually try out a new model and get excited about the sensational development in paragliding, how great it has become. And I have this slight suspicion, which is confirmed time and again, that if you were to properly adjust the old clunker, most pilots would be amazed at how much potential even old gliders have. Yes, that's true. And that's what always blows my mind. I experience that over and over again. But of course, it's easier—and also for sellers, for schools, for manufacturers. The pilot also enjoys a new glider. Yes, and actually, nobody really wants to mess with it. Or at least very few people want to.
Let's go back to the glider that just came out of the factory. Let's say it has a decent set of lines that are really well trimmed from the factory. Now I go out and fly with it. So, my weight comes in. I weigh about 72 kilos, it hits the glider, and then it pulls quite a bit on the lines. And I fly and maybe do some wing-overs for fun at first and stuff like that. So something stretches, the knots seat, and so on. After a few hours of flying, the glider is probably different in terms of trim. How noticeable would that be if you were to measure it?
I don't find the question entirely relevant because a glider has been tested, received a classification, and is now going to market. And the manufacturer knows exactly how they produced this tested glider. Since the test result only comes after the flight maneuvers, all those settling processes of the rigging are already included. That's why the question of how much it settles, or within what range, is actually irrelevant for the pilot, because the glider was checked in flight operation with the knots already settled. And the manufacturer really only has to produce the glider exactly like the tested model. That's what they should do. And then everything should be in the green.
I'd have to guess here, because you'd have to test a new glider and then re-check it after several flight hours. I don't think it's as much as people assume. It should be in the 10 to 15 millimeter range, if at all. But that's just an estimate, and I don't think it's relevant.
But it's still always said on the market that you should maybe do a first trim of a glider after 20 flights, 20 flight hours, or something like that. Why is that so important?
Yes,
Basically, it doesn't hurt at all to re-trim a glider. And if I'm being mean, I'd say that very, very good re-trimming would iron out production inaccuracies. That's a pretty bold claim, of course. But if you look at it objectively, the complexity of manufacturing simply cannot achieve one hundred percent accuracy. If I were making a violin, I wouldn't have to, well, I'd have to turn the pegs a bit; they don't come out of production perfectly accurate either. And of course, any trim is better than production. Because if I re-trim in the right places, I can obviously adjust the glider much, much more precisely. To what extent that's useful and how large the margins are that a glider can handle depends largely on the glider itself.
There are gliders that can handle very, very large—I'll say it this way—production inaccuracies, trim changes over time; they are reasonably stable. You hardly notice anything when you change something. And then there are gliders where small changes are very significant. Basically, my personal goal would be that post-trimming a paraglider should be done just as regularly as packing the reserve, and probably more regularly than people think. I will post-trim the glider at the latest after 100 flight hours. It might actually be sensible to do it once a year. But I don't think we'll manage that.
Maybe we'll go into the fine-tuning in a bit more detail later. What interests me is, you're an expert now, you've been trimming—or rather, checking—gliders for almost 20 years, and you've even developed your own trimming procedure and such. How did you even get into getting so involved with this topic of line changes, glider trim, and so on? What originally led you to say, hey, something needs to happen here, I'm going to really dive into this?
Well, that actually started over 30 years ago, when I had my first flight season as a teacher and unfortunately had to observe how some students from another school—thank God—constantly tumbled into a deep stall next to me. I asked myself, that shouldn't be happening. There's a student who has no idea, gets equipment, and crashes with the thing. Then the ambulance comes, picks him up, and somehow that was completely normal in the early days, and it can't be normal. Then I tumbled down myself with a glider, and actually crashed with one too. Thankfully, nothing happened to me. And then I saw test pilots handling prototypes and went over out of curiosity and asked, what are you actually doing there? And then they said, ah, the collapse behavior isn't good, we have to change something.
And then I asked, "Yeah, what are you changing on your glider? Yeah, I'm going to make the outermost A-line ten millimeters higher and here at the stabilizer, I'm going to make it ten millimeters less." And then I had a question mark. I thought, okay. And then the test pilot flew it, landed again, and he was really happy. I say, "Yeah, and did what you just did actually achieve anything?" Then he says, "Yeah, yeah, the collapsing behavior, great. And now we can certify it for type testing." And I said, "Okay. So ten millimeters caused those changes, I found that very astonishing." And when we started with the first checks and they had that tolerance range, which unfortunately is still common today, of 30 millimeters, I said, "That actually can't be right." A test pilot told me that ten millimeters were significant now for the certification process.
and two years later, I'm checking the same glider with a 30-millimeter tolerance. Something is wrong. Something isn't right here. And because I come from a mathematics background, I said, okay, let's visualize a measurement like that and see what the profile looks like. Then I talked to manufacturers, especially of course with Hannes Pappisch, who was immediately all ears, and I presented the first results to him. He came all the way to Germany specifically for that, we stood in front of the computer together, and then he said, great idea, keep going. Yeah, that's how it started.
You said you come from a mathematics background. Did you study mathematics? Yes. But did you become a paragliding instructor later? Did you not want to do anything with mathematics?
Well, but somehow they wouldn't let me go. I studied mathematics for teaching. I actually wanted to become a teacher.
And when I was gaining my first experiences in teaching, I realized that school isn't my world. And then a professor of mine passed away, who had supervised my work, my thesis. So I took some time off first. I thought, as a kite flyer—I had flown kites before—I thought, okay, I'll try out these "stubborn heads" [paragliders]. I did my first paraglider course here in Rieden, at the school that I now own 50 percent of. Yes, and then I just got stuck. In the truest sense of the word.
Then you got hooked, but you still have the mathematician in you, and you started thinking, "Now I want to mathematically understand this line trimming of paragliders better." You even wrote your own computer program that helps you with trimming gliders. What does this program actually do?
Well, first of all, it's a modular procedure. I wouldn't even define it as a program. There are a huge, huge number of programs running, I don't even know how many. These are Excel macros; it's based on Excel. The whole procedure is what Hannes Sann once called a visualization procedure for all the measured values. All parameters are related to one another, the result is visualized, and I can simulate changes. So I can simulate exactly what happens if I change something at this or that point, and I always see the big picture. I see all the parameters, how they change and how they relate to each other, and that's the huge advantage of the thing, because I can simulate a trim.
In the beginning, I kept re-measuring them because I didn't trust my own work. Then I said, let's see if everything I'm doing there is actually correct. And gradually I stopped because the simulations worked perfectly. So, a second re-measurement is generally not necessary.
So if you check it now, just conceptually, you first measure all the lines, probably in terms of length. Yes. You save them all in your Excel sheet. Yes. Then your Excel program, or rather the individual macros, can access this data and can then say, okay, I have certain values that a line should normally have as the target value, and then I have the actual values, what you measured, and then this program probably calculates the differences and stuff like that. And what do I get displayed then?
You get displayed a huge amount of information, and that's what distinguishes this work from many other jobs that just produce a listing. Target value, actual value, deviation, and then, as a rule, the symmetry on the left and right is checked in these listings, displayed by red, green, and orange fields. That's what pretty much all the Excel-based programs I know do. Mine goes much, much further. It has a visualized representation. That's that Excel graphic that I think everyone knows, but that's only a small part of the whole story. That's what I publish. That's only a fraction of what my Excel sheet actually does. I've never published the whole thing.
I don't do that either. It's just funny that there weren't a few workers, people who had to do with my program, who thought they could copy it and then very quickly hit limits and realized that it's significantly more work than they thought, and significantly more problems pop up, and they then very quickly dropped it again. There are a whole lot of things here that you have to be very interested in. Data is processed with all sorts of cross-references. The profile sections are displayed, the symmetry is displayed, the total length shrinkage is displayed—how much a glider has changed in total—and of course, for the trim, the profile sections are interesting. So if I now go from the leading edge to the trailing edge in the center wing, I have A1, B1, C1, D1, and then I just look at how the profile stands, whether it has a kink and whether it's homogeneous, whether the angle of attack is rather higher or rather lower.
And you then try to adjust it again so that it's how the manufacturer intended. The name Trim Tuning is also misleading, because I don't tune gliders. I just put them back the way the manufacturer wanted them, not the way I want them. That is a very, very important aspect that I believe has been misunderstood by the public. I don't make gliders better; I make them the way the manufacturer wanted them. And that should be the optimal way. That should be the optimal trim.
Well, the manufacturer does provide certain lengths if you look at the line lengths. But what you're doing isn't saying, "I'm bringing this line back to the exact length—the absolute length—that the manufacturer wrote down somewhere." Instead, what you're doing is a so-called relative trim. How much can your relative trim actually deviate from the manufacturer's target value when you look at the absolute lengths?
It depends on the lines, of course. Basically, we have two different types of lines. Some tend to snap or break more easily, and the others don't have as much dimensional stability.
So you're talking about Dyneema on the one hand, and Aramid on the other.
Yes. And
both change.
I already said, 3.7 percent was the most earlier, and we were at about one or two centimeters per line. That adds up all the way to the downline over the life of a glider. Over the life of a glider, that can definitely add up to three to six, seven centimeters on Dyneema lines. That means the gliders generally get shorter overall.
Let's say, very roughly, five centimeters would be a value by which a glider is eventually decommissioned; if the Dyneema is stretched out, it becomes five centimeters shorter. That means the pilot gets closer to his sail over the course of its life. And that's why this absolute trim makes no sense at all. I can't get the lines back to their original length. It's not possible. The glider shortens, and I have to make sure that the different shortening of the line levels is put back into the correct relation to one another. That's what it's about. This whole discussion of absolute and relative trim is completely pointless in my eyes, because absolute trim simply cannot exist. I would very likely have to replace all the lines at every check. It's not possible.
Now, if you look at the LTF and the rules provided there, it would actually be a relative. Relative trimming, at least legally in Germany, isn't possible at all, or is it?
That's the problem. That's exactly the problem. It became clear in the forum that the manufacturers are now naming names. And of course, they don't like doing that. And if I recall one of the numerous discussions I had with Guido Reusch, the head of the EHPR approval body, he had a very clear assessment of this situation and said that a prototype I checked didn't have those weird loops in the line lock. And if a glider gets shorter, it no longer corresponds to the prototype. Consequently, it loses its approval. And then I said, well, then you'd have to phase out many Dynamo-equipped gliders after two years because they wouldn't pass the check at all. He said very clearly that as the head of an approval body, that doesn't matter to him.
Then the gliders just have to get new lines. From his perspective, I can understand that assessment. From my perspective, of course, I say it's not practical, not customer-friendly, and above all, not necessary. And the officials were asked to provide a solution here. Manufacturers who might have a bit of balls—and Nova is one of them—then said, okay, we allow this relative trim in our check instructions and overrule the type certification authority. Of course, it's questionable whether it's that simple. Nova just wrote it into the check instructions, very explicitly, because they use my procedure and thus naturally allow it.
Yes, and that's also a legal safeguard for a checker. He has to do it. If a conflict ever arises, Nova has to take the fall. However, I wouldn't know why. Because a properly trimmed glider that is safe in the air is a legal liability. And a poorly trimmed glider that falls within some absolute tolerances is legally fine, but flies dangerously in the air. It's so absurd that there's actually a need for action. I've been trying to point that out for years, but too little is happening.
You've mentioned Nova several times now, partly because Nova does the so-called Nova Trim Tuning. And basically, they apply your program, your procedure, and say, we'll just give that out as a check instruction. And they say, people who do a trim of our Nova glider in our sense should just use this procedure accordingly. If your trim procedure with this automatic trim optimization—the program you have behind it, or these instructions, Excel and so on—works so well and provides so much in your eyes, why hasn't it actually caught on in the industry with the other manufacturers yet?
You can't really say that. I was probably the first one to start with it. Of course, that was well over ten years ago. But others followed suit. That means the manufacturers didn't just sit around—most of them, at least—but they developed their own procedures. I was at Skywalk and presented the NTT procedure many years ago. All the key people were there. Manfred Küstler, they developed the Check-R afterwards based on, let's say, the information I provided there and the reasoning I shared. The Check-R came into being. UPI was at my house. I instructed them, which means instructed in the sense of informed them.
I didn't give them lessons. I informed them how NTT works. My interest was never to make a fortune here; I wanted to make the sport safer, or I still do. I've crashed with gliders. I still see students with training issues, and actually, one fell out last autumn. The boy couldn't have done anything about it. They told him he pulled the brake lines too far. So I pulled the instructor aside and said, "Look, you know exactly what's going on here. The glider is shit." And then he says, "Yeah, it was checked five months ago, what am I supposed to do now?" Then I say, "Well, we both know exactly that the glider is shit. It's not being inspected. The student stops flying, he got lucky, nothing happened to him."
It probably went like that, and then I asked for the money because the glider was totally damaged afterwards. And I just think that kind of stuff is shitty. And that makes me angry. And my sense of justice is really offended by it. And I get mad at myself because I should have rebelled and said, people, you're not doing this here while I'm watching. But I kept my mouth shut. And it's actually not right. And in the scene, but I often hear, I'm still getting deaf ears after ten years. Not enough is happening, but something is happening. The manufacturers are catching up. And I don't want to stand there and say Nova is now the miracle-working manufacturer that's the only one doing this. That's not the case. Nova started it because Hannes Papisch maybe recognized it first. But others have caught up and the procedures are working.
And I don't want to say anything about the quality. They're catching up. And they're going to come under increasing pressure to catch up. And that's a good development in the scene.
There have also been many discussions about this in the paraglider Drachenforum over the last few months. But there was primarily one pilot who got involved and wrote to many manufacturers, and apparently managed to get many of them to agree to change their check instructions so that they explicitly include this relative trim as permitted, making it quasi legally possible in Germany. One thing is what might be legally possible, at least from the manufacturers' perspective. The other thing is, what do the checkers actually do—do they do it accordingly? One thing is that it's permitted or allowed by the manufacturers. And the other is, do the checkers actually do it? From your experience, how many check operations are actually working with this underlying thought and with the knowledge of how to actually perform a proper relative trim?
I can't say for sure. But I do see it occasionally; pilots call me and report that a glider just came back from a check and is flying completely weird since the check, always pulling to one side. And I had another case like that right here on-site recently where a pilot contacted me. She had a glider at a check and complained that it was pulling to the side. A week later, another pilot came to this region reporting the same thing. And on both gliders, lines were torn. That's normal, that's what you're supposed to do. And they were replaced with lines in original lengths. Pre-assembled, probably provided by the manufacturer, in original length.
And if you factor in that lines change and a main line can certainly become one, two, or three centimeters shorter, and if I then throw in a line of original length, it doesn't even take ten seconds. I rigged both risers, did a quick symmetry check, and found that the newly installed line was two and a half centimeters longer than on the opposite side. And if that's the case, if I think about the customer going to a check and getting their glider back with that as the result, I'm going to lose my mind, because I'd say the checker didn't understand their homework at all. How can I deliver a glider with this asymmetry? It's obvious that it will pull to one side. I then took out the line I had just installed, and I did what I call re-trimming—I trimmed the new line that I had then manufactured.
I checked and adjusted the trim for symmetry again, and both pilots here in the region said, yeah, the glider doesn't break out anymore and starts straight and true again. As a side note on the flight behavior, the female pilot also said the glider flies differently. Yeah, at first it flew a bit too aggressively because the trim was just a tiny bit faster. You usually do that with old gliders. With this glider, it turned out that it might have had a negative effect. I then changed the wing camber a bit, really in the millimeter range. And she was very satisfied afterwards, said again that the glider was more stable and she feels comfortable again. And that's why I don't know what checkers do. I can only say I keep getting checks here where the checkers just don't do it.
And why should they? There isn't just one paraglider manufacturer; the trim issue still interests very few, if any, of them.
And what is a checker supposed to do if there's no trim system prescribed by the manufacturer? What's he supposed to do? He's got plus or minus 15 millimeters. We're back to those old tolerances where nobody knows exactly how they even came about in the first place. It says "DHV tested" on the stamp, and DHV says they've actually never had anything to do with 15 millimeters. But those 15 millimeters have become so established. And it's still checked that way. And I can only say that the results are sometimes catastrophic.
You just said there are some manufacturers who actually work in this way, who probably have all the data available that a checker would actually need, where you'd say, oh, which target values should I specify for the line lengths? But how easy is it actually to get the correct target values? Could I, as a pilot, write to my manufacturer and say, look, I need the target values for my glider for a check. What lengths do I have to specify?
This is perhaps one of the biggest embarrassments in paragliding. We've been around for over 30 years and it starts with the fact that the lines don't have a uniform designation. I don't know of any sport where the users of a piece of sports equipment don't know what their components are called. So, if I define a line, it's called A-A1 once, then 11A or A11 or something, but there's no uniform designation. I find that embarrassing. That means if I have a line with its length now, I have to see how the manufacturer defines their line. It's very different. I think that could be changed, a uniform designation. And then with the target values. Yes, the DHV publishes the values in their data sheets on the website for years, and that was the basis and is still the basis today for two-year checks.
I then put the DHV on the spot quite firmly and said, guys, this isn't working. The data you're publishing in the German Hang Gliding Association's data sheets differ so significantly from the data the manufacturers provide. We're not talking about millimeters here; we're talking about several centimeters. This is unacceptable. Checks are being done with incorrect data. Please take this data down from the website and tell the checkers they're useless, or at least provide them with the appropriate disclaimer. That's what's happened in the meantime, and I don't quite understand why they haven't completely disappeared from the website. They're wrong. They're still being used as the basis for checks.
For incorrect checks, for critical checks, for negligent checks. And in my eyes, the DHV is being a bit too indifferent about it. They are still on the website. They are still being used. I know this firsthand. And pilots who have their gliders checked are being checked with incorrect target values. I consider that negligent.
Just for clarification. Why is it that what the DHV has listed as the data sheet—those are probably the line lengths the DHV measured on their test gliders—why are they, or why can they be so different from what a manufacturer says, for example, that we think is the target value?
Well, basically, they have to be wrong. They can't be correct at all because they include production errors. Every glider has production errors. I can't manufacture a line to 100 percent.
They contain production errors. They contain measurement errors. A single glider is measured, two lines—so left and right—meaning production errors, measurement errors from the device, measurement errors from the person doing the measuring, and of course the condition of the glider are all being explained as the target value here. And errors just love to accumulate. And if I now have production errors and just the measurement errors from the device, which the manufacturer specifies as already 1 or 2 millimeters, then I have positioning errors from the person measuring. Those are also in the range of 1 or 2 millimeters. Production errors that are naturally in the glider. If I take all of that plus or minus,
then I might end up with a value that's already in the double-digit millimeter range. I cannot explain that as the target value. Basically, in theory, that's not allowed. And then, of course, this glider has been flown and stressed with extreme maneuvers. It's already lost its shape. I'm taking a deformed glider with all these aforementioned measurement errors and calling it the target value. That's impossible. That's complete nonsense. And no glider should be cross-checked using these incorrect target values. That's rubbish.
That means I actually really need the target values from the manufacturer, the designer, who says that would be the ideal glider for me, as I imagine it. And then it's possible that if it's been flown a lot, it might eventually end up at these values that the DHV also measured. That can happen in practice. But actually, we want a different glider, or rather, the glider is built differently from the start.
He used to be different.
And if I take out all the measurement errors from the device and the people, I'm already getting closer to the target values. But ultimately, the manufacturer has to say it, and if the instructions or any regulations state that the manufacturer provides the values, then it says that very clearly. The manufacturer determines the values, not the DHV. There are manufacturers who say, to be on the safe side legally, they take the values from the DHV. That's the manufacturers' policy. That's fine, because they're saying, then I can't be legally attacked. That's okay. But they also implicitly accept that all the errors are being explained away as part of the target value. I'm not getting involved in that now. That's a manufacturer's matter. Then there are various methods for how to get to the target values at all. There are inductive and deductive methods.
I don't want to dwell on that now. I did it myself for years, calculated the target values myself. Because at some point—and I'm saying this personally—I was so fed up with how poorly it was being done that I went in myself and calculated the target values. I then compared them with theirs. That was with NOVA. Then we reconciled them and eliminated errors. It was a hell of a job, until there was a consensus. And we also found that the target values that came out worked quite well. Yes, there are different procedures. But it can't be that the measurement of a single glider is declared as the target. That's not possible. That is definitely wrong. At the moment, by the way, this leads to this grotesque situation where, I believe, the record currently stands at five different sets of target data that I've had for one glider, where I then asked the pilot, "Okay, which one are we using today?"
Do we take the one that fits best? Or do we take the one from the DHV? Do we take the one from the manufacturer? Or did the test pilot himself have another set of target values to contribute? He said that one works best. And data security during the check was not guaranteed in 2020 either. That's a very clear statement. There are brand-new gliders that have just hit the market where I, for example, compared DHV data with the manufacturer's data and found discrepancies in the range of several centimeters. Most, admittedly, in the millimeter range, the 10 to 15 millimeter range, the 5 millimeter range. But if we assume that even a few millimeters of change—now I'm back to the test pilot and my own experience—I can only say that for some gliders, and these aren't competition rigs, these are definitely A-gliders, where changes in the sub-ten millimeter range, so the 5 to 10 millimeter range, if I modify the gliders, they have significantly different properties.
You notice it most during ground handling, during launch, and during inflation. And if the target values deviate by more than that, they don't make any sense. My demand to all manufacturers, but also to our associations, is to establish data security so that an independent database is set up somewhere for all gliders, where every pilot and especially every check center can access the correct data. The manufacturers, of course, like to keep this data under wraps; you can't get to it at all. And the checkers, who have the glider right there at their feet, have to check it, they have to earn money, the pilot wants the glider back, and they can't get to the target values. So, they just take the ones from the DHV, because the DHV is the umbrella organization. And if they publish the data, then we'll just take those; they have to be correct.
And now there's this funny little sentence, and every checker should be aware of it; it explicitly states for some time now that these datasets may not be used for the check. And I once approached a checker about this, explicitly, who didn't know that. And then he looks at me and says, "Yeah, what am I supposed to do now? My boss gives me these data and I work for this check operation. And yeah, that's my assignment. And am I supposed to..." Yeah, I say, "You have to. You put your name under this check. Not your boss, but you sign with your name knowing that you're checking with incorrect data. If you can live with that, that's your business. I couldn't."
From your experience or from your conversations in the industry, are there any manufacturers who say, "Oh, we would support having an independent database where you can simply retrieve the respective target value datasets for all gliders and the corresponding glider sizes"?
There was a checker summit at the DHV recently. It was a bit sad. I actually initiated it, but in the end, I wasn't there. For reasons—now, for private reasons—that were really fundamental for me. Unfortunately, I couldn't participate. It was stupid because I'm the one who initiates all this shit, and then the shit happens. Sorry, the whole meeting, and then I can't come myself and don't come. I blamed myself for that. But I don't know what they discussed there. One of the focus points should have been this database; I would have demanded it, and demanded it vehemently. I didn't get to it. I don't know if anyone else did. But everything else leads to this whole discussion falling asleep again.
and everyone is happy again in the end. And every manufacturer says their process is better than their competitor's anyway. One has NTT, my process, Nova—the company FEE has taken that over now. Advance has their process, the name of which I don't know, which I've been trying to get access to for over a year but am being denied. CheckAir also keeps its process under wraps for only selected check stations. I find that also acceptable somewhere. If you want a high-quality check, you have to do that or train checkers. But the basis is that everyone is cooking their own soup and is of the opinion that our gliders have the best check process. And no matter what, I think that's all. Everyone does their job wonderfully.
But the basis must be reasonable target values. And we don't have that basis. We don't even have a uniform definition of the lines yet. That's the basis of the basis. That's not given either.
Would that be a task from your perspective, maybe for the PMA or, if we're being honest, the DAV shouldn't make it a national story, maybe the EHPU, the European Paragliding Union, and so on?
Yeah, I have little hope there. If the pressure doesn't come from the pilots through actions like this, an interview, where the pilots stand up and say, we demand this, we demand this, and anyone who doesn't participate, we'll boycott them, then nothing happens. I've been trying, for I don't know how many years, decades, to implement this line color scheme for gliders. We have it now, BMA. The PMA pushed that through. Principally, it's a great thing that they finally want to make uniform colors, also in terms of inventory management for the manufacturers. That's obviously a step that is really good. But nobody asked us again. As teachers. Now they're making the stabilizer lines dark green.
So you're trying to identify a dark green line on a meadow to see if there's a knot in it. The D-line at the back, lying on the grass, is dark blue or blue—it looks just as shitty. This means they're not thinking about it properly at all, and we as the front-line people dealing with students aren't being asked at all. Let me put it bluntly. I spent ten years trying to push through a decent color scheme at Nova. It started with the steering line, which was dark red and then became dark blue, completely invisible. That's a safety issue. The fact that a student and also a teacher can't recognize from a meter away whether there's a knot in the steering line hasn't been realized to this day. If these simple things don't work, if even our umbrella organization allows incorrect target values to be on the website, if the PMA as an expert body finally makes uniform colors, but then makes them so shitty that they're unsuitable for a training operation,
what can I expect? I mean, I don't expect much. It's been falling asleep for ten years now. Unless the pilots demand it. And that first step—I don't care who that anonymous person in the forum was—they did it exactly right. They didn't let up. They bit down. More than I ever did. But let me be honest, I'm a bit tired.
But from what you're saying, you sound a bit like Don Quixote fighting against the windmills or something. Do you ever feel that way?
Yes, I do. But I keep fighting anyway. Don Quixote didn't stop either. But I want to wake people up and say, stop believing that a few millimeters of change in the lines don't matter. That's not right. And nobody, I've said it before, nobody probably has any interest in it. Schools have no interest, manufacturers have no interest. Of course, everyone always thinks about how great the new products fly. Of course, they fly great. And the manufacturers do a good job. The paragliders are really fun, you really have to say that. It's great. Our sport is developing beautifully. But the old gliders don't fly that badly. If I have a glider that's five, six, seven, ten years old that's properly in trim, then it definitely holds up for a sports glider, for a hobby pilot,
if it's not completely worn out, but still in very good condition, then it can still keep up quite easily. We see this on every flight, that gliders that are sometimes ten years old and haven't been used much, can still keep up quite easily in the thermals. Keep up in cross-country flight. Yes.
A bit, you keep saying that the pilots have to put pressure on it. But as a pilot, you first have to be sensitized to this topic, be able to recognize for yourself, okay, I need a proper trim on my glider. Now let's make it very simple. I'm a pilot now, I'm sitting at home and thinking, okay, I'm listening to this podcast and I'm wondering, say, is my glider actually in proper trim? I don't want to send it to the next checker right away, is there a way for me to find out relatively easily for myself if my glider is still somewhat properly trimmed or if it really already shows some deviations where I would say, you should do something there? What can I do to test the same thing?
Two things, actually three things, that I advise every pilot to do, and which are also very simple. The first is, if a glider comes back from a two-year check and lines were torn. One, two, five, or even none at all. First of all, if no lines were torn, that's not a sign that the checker was asleep, but maybe he was actually very vigilant, because every torn line brings a potential trim problem for the glider's lifespan. And in recent years, I don't know, we've had kilometers of dynamic lines torn for no reason, for nothing. Some of them are for life, they hold the glider, it makes no sense at all to tear them, but that's a topic in itself, let's not start on that now.
If lines are torn, have your friend hold the riser or put a screwdriver between the carabiner attachment points on the riser below and do a very, very simple symmetry check to see if the torn lines the checker installed are at least symmetrical to the opposite side. A very simple check that can be done quickly at the launch site, and for one or another, their hair will stand on end because they'll realize they have pre-assembled lines, as I described earlier. The second thing is, every pilot—and now we get to the serious topic, which is very easy to check—is the steering line length. The steering lines have that funny marking, and I know that many checkers don't check the steering plane at all because they say, well, that's up to each pilot how they adjust their steering line.
In my eyes, that's a very lame excuse; the steering line has to be adjusted relative to the load line plane. They shrink differently. And if it leads to the steering line shrinking more than the load lines, it means the gliders are already braking when the steering lines are up, so when I'm not braking. And that, in turn, naturally leads to the fact that in the event of a canopy collapse—if they are in a sack flow, or B-line stall, or after a collapse—they might not be able to accelerate properly anymore because they already had a pre-brake. Everyone listening right now, you can compare this; the DHV published a safety notice regarding this about half a year ago, it's still there, you can read it, stating that corresponding attention must be paid to this.
Every pilot should regularly look up at their glider while flying, whenever they don't have anything else to do, and check how much slack they have in their control line.
And if he sees that the trailing edge has no slack, then he urgently needs to lengthen the control line a bit. It's somehow part of the culture among pilots to always shorten their control lines because they think the handling will get better. Of course, that can certainly be true sometimes, but if I cut out the slack completely, it becomes dangerous. And a pilot has to check that himself after the check, again and again. We need about, let's say, 10 cm of slack; if it's 8, that's also okay, but if there's none left, it's bad. And any pilot can check that themselves. So, to summarize: do a simple symmetry check, especially with the torn lines. Check the control line for slack. And of course, again and again, if a glider starts to hang at the back during inflation, just a little bit, if it hangs at 80, 85 degrees during backward inflation and has a tendency to want to fall back down, if it doesn't go over the zenith during ground handling and it should voluntarily go over this zenith to 95 degrees and want to accelerate on its own—if it no longer does that, then
it's the first sign that the trim is off. Even a layman can notice that. You don't need an expert for that.
And if gliders collapse relatively often, that's already next level, then it could be because the washout, which also changes over the life of a glider, is too steep in the outer wing, and maybe it should be corrected a bit. If I notice the glider is becoming more sensitive than it usually is, that the wings no longer have stability at the end, then you could suspect the problem lies in the washout, and then maybe you should also have a professional take a look. But if he then does something with plus or minus 15 mm again, then we're back at the beginning, he won't find anything at all and the glider stays shitty.
So, as a pilot, if you're saying that nothing happens if he only works with plus or minus 15 mm, how can I know which checker might actually do a proper check? What would you recommend asking the checker to find out something like that—to get them to say, "I'll get you a proper relative trim" or whatever?
Yes, good question. I get asked that often.
Basically, it's about this: if I were a pilot right now and I was feeling uncertain, I would fundamentally look at the manufacturer's homepage, ask the manufacturer who is qualified to check my glider? That's certainly not the person offering something for 99 euros on eBay; they obviously have to have the official checking procedure. I've already said, Advance has their own procedure, UP has their own procedure; I don't want to list every manufacturer, but I don't have the UP procedure, quite simply, I don't have it. Why am I not authorized to check a UP glider? Because I don't have the procedure at all, I have no access to it. That means, first and foremost, I need a checking center that has access to the company's internal checking procedure.
First. And if I don't know that, then I contact the manufacturer and ask who is qualified to check it on your behalf according to the manufacturer's specifications? That's very, very important. And not just, oh, I have a check center around the corner, I'll just drop the glider off there. That doesn't mean they don't work properly. They might even work better; it's like with a backyard workshop for a car, they can be better than an official VW workshop. I don't want to dispute that at all, but I have to start somewhere. Yes, and then I naturally have to see, further on, which manufacturer even has such a procedure and do they make it transparent. For example, the NTT procedure from Nova, my procedure, has been communicated very transparently. CheckAir from Skywalk, for instance.
Everyone knows that it exists, and everyone knows a little bit about who's interested in how it works, since it's online-based.
Can you also assume that they know what they're doing? If someone says, well, we check that, clearly. If I get an answer like, yeah, we've been doing that for 30 years. That's not a badge of honor.
Do you know the ads for Bett 1, the best-selling mattress? You can't conclude from that it's the best mattress. The best-selling hamburger is the one from McDonald's. That's not the best hamburger in the world just because it sells the most. But I have to start. That means the manufacturer should make that transparent. And I would recommend the manufacturer—I don't care, it was prompted in the forum now. Where is this whitelist? I think that's a bit of an exaggeration, but he put on some pressure. People, dear manufacturers, disclose your checking process. Disclose what you do in terms of this relative trim. And train your checkers. I've trained so many checkers by now, and even trained trained checkers. Those were people who had been doing this for years, they came to me and realized,
that they... that they hadn't considered a few things at all and what they learned. And I would wish for us to get a uniform standard. But that's not going to work. We're a long way off from that. That might be somewhere after I retire.
A uniform standard would mean there's basically a certificate from DRV or someone else where you could say, after that, I'm a certified checker, or even a DAX-certified checker.
Yes, I remember a time when I was doing civil service. Back then, paramedic wasn't a profession, for example. They just helped people and it wasn't a profession. Now it is a profession. I wish they would create standards that... I can't just call myself a TÜV inspector. If I'm checking a car's technical functionality, I have to have completed some training. Checkers, I can teach my daughter, who just walked in, how to do this today, and then the Morgenschirme certify it. That can't be right, can it? That's the reality. And a lot of knowledge gets lost in the process. A trained checker trains his colleague. Then he leaves the company and the trained colleague B trains C, C trains D, D trains E. Yes, it's like Chinese whispers.
There's not much left. I keep experiencing that checkers who were trained through this chain don't actually know my procedure at all. They say, "Oh, I didn't even know that function was in the checksheets." They weren't trained on that at all. "Oh, that works too." Yeah, they had no idea. "Oh, there's a program behind the image that runs." They had no idea about that either. Yeah, it's actually sad.
Let's talk briefly again about trim in practice. Just what you actually do there. You're saying, okay, you've checked, measured the lines, and said they might be too long or too short. And then you loop these lines at the harness buckle. And then there are different looping options. If you look at a checksheet, it says things like single loop, double loop, figure-eight, figure-eight plus, and so on. To what extent can you actually change a line length just by using these different looping methods?
Well, of course I don't have pegs like a violin that I can tune continuously. I can tune a violin, but I can only trim a paraglider in steps.
Ideally, 5 mm increments would be enough. Anything more precise exceeds the measurement accuracy. And 5 mm is already an increment where I'd say you can notice a significant difference, and I can trim it reasonably well to the original—or even better than the original.
Yes, and that's naturally guaranteed by a few things. I have a shortening from the single loop to the double loop, depending on the line lock thickness and line thickness. That's in the range of 7 to 12 mm; usually, it's about 8 to 9 mm, maybe 10 mm at most. Then I have the anchor stitch, which brings another 3 to 6 mm of shortening, usually 4 to 5 mm. Then I have the additional loop, which brings another 8 to 10 mm depending on the line lock. But of course, it can also loop in the galleries, which is a lot of work. Checkers might not enjoy doing that work very much because then you're really getting into the nitty-gritty. That takes a lot of time. But these steps are sufficient to definitely provide a significantly noticeable improvement.
And the customer feedback is always quite surprised by what a difference it makes. I can only say, on my computer, I get so many emails from customers saying, "Hey, the glider flies completely differently, much better, it's never even flown as well as it does now." And I have another Mentor 3 pilot who has a very old wing. He had a very old Mentor 3 with me that was actually so slow at the end of its lifespan; it's been properly trimmed again. He recently emailed me saying that with his cross-country flights, he could currently keep up with the club and even at one point made the longest, best, most beautiful flight. And he was thrilled that this new trim had such a noticeable effect.
If you look at it this way, you said, okay, a double loop gives you 8 millimeters or something. A knot gives you maybe up to 17, and so on. The knot plus gives you up to around 17 or something. Then you can still loop at the top of the gallery. But that means, at most, I'll probably get somewhere around 20 to 30 millimeters that I can shorten a line in a reasonable way. Am I seeing that correctly?
Yes, it's about three and a half centimeters total, all in one line, what comes out. I once had a glider—can't remember the name, a competition glider even. There was a trim change there. It required four and a half centimeters. And the trim went all the way to the bottom sail. That's where the line starts, at the bottom sail in the sail loop. And you can also double loop that. With that, you already have a shortening of the gallery line of over a centimeter. And then, of course, you can shorten it further over all the galleries. And then restore the relation between levels A and B, which were two lines again. That was a hell of a job. That took several hours until the glider—I'm never doing that again. That was a job for someone who's had it up to their neck. When you have to take the whole glider apart.
But that was four and a half centimeters. Usually, we trim whenever possible. Trim changes are only necessary in a magnitude of maybe a maximum of 15, 20 millimeters.
What would you do if looping in all the different places you can do it isn't enough for the trim? Do you tell a customer, "Man, you need a completely new set of lines"? Or what do you do in that case?
No, I've actually never reached that limit. I've never had a glider where I'd say, "I'm running out of powder." I've never failed to manage it.
Sometimes it's happened that the stabilizer lines, which of course don't carry any load at all, they only stabilize as the name suggests, they shrink down very significantly due to the low load. In those cases, they're only looped in a single loop by the manufacturer. Now I have two options. I can hammer the whole glider down to these two lines. You know what I mean? I can adjust all the lines so they fit the stabilizer again. That's a lot of work and it doesn't look nice either. Or I can say, to hell with it, I'll just throw in two new stabilizer lines. They've shrunk, so I'll extend them back to the original measurement. And then it fits again. Then, of course, you choose the path of replacing the lines.
Wouldn't it make sense from a checker's perspective to also work with other options? There were ideas like saying, maybe you use longer line locks, and then after a certain amount of time you say, okay, the C-line has shrunk by a total of 15 mm. So I don't mess around with the loops that much, but simply say, I'll just put in line locks that are already 15 mm longer.
Since the trim is also different within a line plane, that wouldn't help much. You know what I mean? That is, if I have a C1, a C2, and I still have a hybrid lining, then one has shrunk and is too long, the other is too short, then the line lock doesn't help either. It just shifts the problem. But it's funny that you mention it, because a few years ago I worked on a patent—it's actually patent-ready, I even submitted it as a utility model. I even presented it internally, but I was shot down with the comment that development is moving towards ever smaller line locks and mine would have been a bit more massive. It would have actually allowed this trim or would allow it. Without loops, and the utility model—I never published it, it still isn't.
That would mean that a pilot team would also want acceptance for slightly larger components at the end of a riser, but the trend is moving more towards those unfortunate softlinks that save about 50 grams, and I've stepped back from actually communicating that idea. And from pursuing it further, but maybe I'll pick it up again. The market just isn't ready to embrace this idea.
You just mentioned those unspeakable softlinks—are they a nightmare for checkers?
Yeah. Why? Have you ever taken those things apart? No. Try it then. Yeah, you can take them apart, but the trim steps are usually way too large. That means I can't do the necessary fine-tuning. If the first step already means a change of 12 to 15 millimeters, then it's not worth it. It's too coarse. It's too coarse, and the effort for eight risers—let's say we're talking classic 2a, then b, c, 4 on each side—if I have to take out the softlinks on every riser and then put the other loop in and put it back together. I've actually tried to trim several softlink gliders properly.
That was a job that took several hours. I was on one glider for five or six hours. The customer actually can't pay for that at all. And then the checker comes along and says, "No, you know what, I'm not doing that work. There were those funny plus or minus 15 millimeters again. Let's just take those instead." I don't know what I mean. I highly doubt whether a checker will develop the ambition to actually do it properly. I clearly doubt that. The checker says, "Oh, come on, Schirau, but I'm off the clock, I want to go home." That's way too much work for the money.
That means, in terms of proper trim, it would also make sense for a pilot to say, I don't need to save these 50 grams. Please deliver a glider with proper line locks and not those weird rope locks.
I don't get it either. The weight saving is maybe 50 grams. I always say, guys, before you head up the mountain, go pee against a tree one more time. Sorry, just between us. We're among ourselves here. Better go pee against a tree, you'll get more of it there. Or think about whether you absolutely have to take the jacket with you. If you have to carry 50 grams extra, then you'll get more of it. And if 50 grams are really decisive in whether you can do this hike and fly or not, then maybe go to the gym for another hour for those 50 extra grams. But if you value a well-trimmed glider, then you give up the softlinks. And if you don't care and the 50 grams are more important than a well-trimmed glider, then in my eyes, something hasn't been understood correctly. Lately, I've also had some X-Alps—let's just say Omega X-Alps gliders, I think three of them—I've taken the softlinks out of those again.
and I installed regular carabiners. You're actually not supposed to do that, because the operating permit technically expires. The pilots didn't care. They said, I don't care if I'm allowed to or not, I want them in there now. Then you tell the pilot, yeah, but it's not the standard model anymore. And if you commission me, I can do it, but I have to point out that you won't get an official two-year check. Yeah, I don't care. I want a glider that is properly trimmed. Then I say, bravo, the pilot understood; legally, it's questionable, but I always say, whoever is right owns the majority of the vote.
Let's do one more complete jump in topics at the end. You haven't just been dealing with the trim that you've really been doing there for 20 years,
let's say 15, 17,
15 years of serious success. You don't just have a bit of a special status there, even if it might be slowly fading now, but in the industry. You also have a bit of a special status with your paragliding school. You are the only paragliding school, or you lead as the only paragliding school in Germany, that trains with singleskins. Why?
I don't know if I'm the only one who does it consistently. But I think so, because there's only one single in the A-segment. That's the
Grashopper by Independence. That is
It's good that you're saying that, you're allowed to. That's the Grashopper from Independence. We've had it for two years now, first as a trial and then exclusively last season. And yes, I won't be changing this strategy anymore because it only offers advantages.
Where exactly do the advantages lie for you?
A whole lot of advantages. The glider—or singleskins, I'll make it more general now—I think anyone who has ever flown one, set it up, or handled it on the ground would have a grin spread from ear to ear, because these gliders have such amazing cross-axis stability. That means they don't lunge forward, and they don't hang. These are the gliders that invented the Siemens air-hook. The gliders just fly over the pilot. And if the pilot is so far off-center that the stabilizer is hanging on the ground and the glider still doesn't want to give up at 45 degrees, the pilot just takes half a step toward the glider and then, like by magic, it pulls itself back over the pilot. That means it's extremely unproblematic in terms of overall handling.
The success sets in very early. The new pilots gain confidence in this new sport very quickly. Yes, and it's just fun. The error rate drops dramatically. Yes, and then comes the judgment from colleagues who say they aren't learning it properly at all. They have to learn how to do the under-run and how to set the cross-axis brake so that the glider doesn't shoot forward, that it gets braked. Then I always ask back, how many times have you done such a retraining in your career? Yes, we haven't even done that yet, but that's not real flying. Then I always say, yeah, I've probably done that a few hundred times by now, or at least 200 times.
I can only tell people that there is no problem. People take a normal glider after the singleskin training, after ten flights, and in most cases, they handle it immediately. The feeling has kicked in by then, and the reflexes usually work quite well. It doesn't require any elaborate retraining.
Mine is a judgment, and calling it "not learning it properly" is a prejudice.
That means, just to understand this correctly, you don't do the entire training with the singleskin, but you're saying people start with a singleskin, do the first inflation exercises with it, the first jumps on the practice slope, maybe the first easier flights—not very high ones. And when it actually comes to high-altitude flights, you switch over and say, people, now you have to be able to fly with a double—doubleskin, well, it's not a doubleskin by name, but simply a normal paraglider with a double wing.
Yes, although they do do the first flights in the basic course with the singleskin as well. There are no problems at all. But the school's task is, of course, also to prepare them for normal flying life, and normal isn't flying a singleskin, but normal is eventually flying a double-celled glider, which they'll also buy later. And that's what we have to teach. We have to prepare people for normal flying life. Tendency-wise, nothing is against doing the entire training on the single, but that might happen in the future if it becomes more established. At the moment, the singleskin thing hasn't established itself at all. Unfortunately. But there are promising concepts in the works. We'll see one or two new singles in 2020. And the performance increase of the single will come too.
And I can also imagine that this has a lot, a lot of potential for the coming years. And as for the training, I can basically only recommend that every, every paragliding school try it out. Plus, of course, students who are on a single learn very, very easily—Kröhe will kill me if he hears this—they are introduced very easily to the backward start or to the backward inflation. That means the same thing. And they just learn it much more easily.
With the singleskin, if you pull it up backwards and there's a bit of wind, you don't actually have to do anything. You basically just have to put a bit of weight into it and then the glider does most of the work on its own. I mean, you could already say that from there to the next step, pulling up a normal dual-sail glider. Backwards, that involves significantly more fine motor skills—adjustments and all that—and maybe catching it and other things. But you're saying that this transition from one glider to the other is relatively easy.
Yes, because with the Singleskin, the turning out is practiced. The moment of turning, the motor skills are learned in a playful way, and they work very quickly too. And once that's mastered, then comes the part where I'm actually only holding the risers in my hands. That depends of course on which technique I'm using to do something. But that's another topic. Which technique do you use for a beginner? Which technique do you use for an advanced flyer, for a performance flyer? If we also use a favored technique from the DHV, the parallel arm position, then besides the motor skills of turning out, it's actually just a matter of me taking my paddles, my two hands, to the risers for a parallel hand position. And then I can build on the methodology already learned and have immediately grasped the first backward inflation technique in a playful way.
And people are thrilled. They know they can do it. And then I can build on other techniques. You don't have to believe that there's only one sensible backward pull technique. And I also warn against reducing it to that. There are several sensible backward pull techniques. And you shouldn't get the idea that this is now the only one that works.
Do singleskins actually have such a strong, so to speak, trim issue? Or is it somewhat dampened with them because the profile works a bit differently anyway?
I can't say for sure, of course. I completely lack the experience. I can say that we have now... we've checked the trim on all our training singles, just as we do with all gliders annually. At the latest annually, but usually semi-annually.
They behave similarly to doubles. I have a bit of a feeling that they are less susceptible. But that's just an impression. When I have the first training days again, which are coming up immediately, and I'm on the practice run, I'm always surprised myself. When our newly trimmed gliders are in the air for the first time, there's always a bit of an "aha" effect. Wow! So they do fly significantly differently than in the autumn.
You notice time and again that they fly significantly better, even in terms of performance. Flying isn't just about a trim making the launch better; the performance is increased too. And I'm curious about the singles now. We have the first basic course on Monday. But I have the feeling that they aren't as susceptible. They were actually very, very consistent, even though they changed in the trim, as the check shows. I don't get the feeling that they flew poorly in any way. So we were satisfied until the last training day.
Ralf, I'd leave it at that. I think we've covered a lot of ground. And I find it super interesting what all has to do with trim—what you really have to pay attention to in the details to keep a glider in proper trim. I hope that your initiative, even though you say you're getting tired of it, continues to fight for it to keep filtering into the entire paragliding industry, so that people understand better how important good trim is for the safety of the gliders and also for the performance of the gliders in the end. And that the work you've been doing for 15 years might still find even broader, truly fertile ground. I thank you for that regardless, and thank you for your selection.
Thank you very much for the opportunity to lay this out so broadly to a large audience again. And the hope is indeed that something should change, something has to change. And if this contribution, your contribution to it, helps with that, then all the better.
Well, it's your contribution too. Definitely. Thanks to you. All the best.
Thanks.
That was Ralf Arntz in conversation with Lucian Haas. In the show notes for this podcast episode on the Gleitschirm-Blog Lu-Glidz, I've put together some additional links on the topic of trim tuning. I also want to clarify one detail here. A term or name came up several times in the conversation. Ist mir egal. That is the pseudonym of an anonymous pilot in the Gleitschirm-Drachen-Forum. And the German paragliding scene can certainly be grateful to him. Because Ist mir egal was... contrary to his pseudonym, not indifferent about one thing at all: the legal situation surrounding trimming a paraglider. Until now, the instructions for most manufacturers only stated that the line lengths during measurement had to be within the specified tolerance. There was no mention of relative trimming.
Strictly speaking, a relative trim would not be permitted in Germany under the current LTF, at least. Or rather, it should be viewed as a very dark gray area. Ist mir egal has repeatedly written to various paraglider manufacturers over the past months and, with his persistence and convincing arguments, managed to get many of them to change their check instructions. Specifically, so that they now allow relative trimming while observing certain limits. Which manufacturers have done this so far can be found in a list in the Gleitschirm-Drachen-Forum, which Ist mir egal updates regularly. The link to it can also be found in the shownotes on Fluglites. By the way, if you enjoy Podz-Glidz and the associated Gleitschirm-Blog Fluglites, then why not become a supporter of my work?
How much you want to give as a contribution is entirely up to you. For those who are unsure, I recommend one euro per podcast episode and two euros per reading month on Fluglites as a non-binding guideline. Payments are easily possible via PayPal or bank transfer. You can find the relevant details on the Fluglites website, specifically on the "Fördern" page. I say thanks, stay trimmed, and feel free to recommend Podz-Glidz and Lu-Glidz. See you soon, ciao.