TRACK THE xTc CLIENTS 'LIVE' Which wing? How to choose?
by Toby Colombé of Passion Paragliding
How to choose the right wing for you
Wing reviews rave about this wing and that wing. The paragliding forum is full of punters raving about their recent purchase. Your local dealer raves about his favourite brand. Pilots in your area tend to fly a certain brand and on it goes. How do you read between the lines? How do you make an informed choice? And when the information is either overwhelmingly positive, or worse, conflicting, which wing do you choose? And just what is it that you should be considering when it comes to choosing your ideal wing anyway?
In this article we’ll touch on all the factors you should consider. We’ll look behind the fluff, and get to what’s really important. Just how important is wing category? Where should you be on the weight range? We’ll explore the idea of “useable performance” versus quoted performance? We’ll also have a detailed look at the subject of “handling”, the different wing “flavours” on offer and the questions you should be asking before buying.
The right level of wing for you
There are two types of classification systems, namely the LTF (formally referred to as DHV) and the EN system. Broadly speaking an EN-A wing is similar to an LTF1, B to 1-2, C to 2 and D to 2-3. (Note that the LTF has now adopted A,B,C,D though their testing procedures are still different from the EN). There are some specific differences between EN testing and LTF testing and in particular it seems that some manufacturers can tease more performance out of the EN system than the LTF system, hence a lot of the top EN-D wings could potentially fail the LTF2/3. Without going into too much detail, traditionally pilots learn on a 1 (A), buy a 1-2(B) and occasionally progress on to a 2 and beyond. So which is safer and what are the main differences in handling and performance and which wing category should you be flying? First of all we’ll take a look at passive safety and dispel 3 of the more common misconceptions…
“My wing is tested so it’ll be ok”
Whether EN or LTF, wings are tested mainly for passive recovery characteristics – that is how they behave or recover from very specifically defined collapses in benign still air conditions with no pilot input. Although this is arguably the only quantitative way a wing can be tested, the limits of these testing procedures cannot be overstated. THEY DO NOT quantify a wing’s propensity to collapse in the first place; nor do hint at how much active piloting a wing will require to avoid the collapse in the first place; nor do they tell you much about how a wing will recover in turbulent air; nor do they tell you how a wing will recover from more severe collapses (asymetrics are of a limited size during testing for example); nor do they tell you how likely or otherwise a wing is to cravat and so on and so on. A wing’s rating is therefore only half the story. Later on in this article we’ll look at some other factors you should consider. For now, let’s look at another common misconception.
“My wing is bullet proof”
Although some lower-end wings are very solid and collapse resistant (and you might even liken some models to flying a truck(!?)), it’s still a piece of material that if put in the right (or wrong(!) place) can lead to unrecoverable scenarios. Every now and then, having briefed clients for a particular site and the danger areas to avoid, someone will pipe up, “Oh, I’ll be ok: I’m only flying a “1” and it doesn’t collapse, or even if it does it pops out again immediately”. Whilst that might be true in most situations including mild turbulence, put any wing in the wrong place – strong turbulence such as rotor and it can crumple into little ball never to re-inflate. Remember that keeping safe is more about where you put your wing than which wing you choose to hang underneath. No wing is bullet proof.
“It’s a “2”, but only in accelerated asymmetrics so it’s really a 1-2 until you use bar”
This (very false statement), or something similar, is something I hear disturbingly often. Pilots are often tempted into a higher wing category by this thinking more than any other factor save perhaps peer pressure. Please remember that the vast majority of higher end wings have very few higher end ratings. For example, to be a 1-2, a wing only has to respond as a 1-2 in one testing configuration. It is then classified according to its highest rating, i.e. in this case 1-2. Likewise, most 2 s score only a few 2s and often only one. YOUR WING IS NOT a 1-2 if it scores a 2 in just one test. It’s a 2!! For example, the Gin GTO, Gin’s highest certified wing scores only 2 Ds, but ask anyone who flies one. It’s a proper full on D / 2-3. The passive recovery testing categories, although limited, give us the best “on-paper” idea of how a wing behaves. A 2 is a 2 is a 2. Kid yourself at your peril!
So how do you choose the right wing rating for you?
In my opinion about half the pilots flying ENC (LTF2/LTFC) wings shouldn’t be. They move up for supposed higher performance, but with the reduced passive safety they leave themselves far more vulnerable than they’ll hopefully(!) ever realise. To move up from the 1-2 category, pilots should be flying regularly, should be flying at least 70hours per year and should have excellent wing handling and wing control skills. Then and only then, (ie with excellent wing control skills), a 2 might even be considered safer than a 1-2: its increased sensitivity, manoeuvrability, speed and glide could be considered safety features – IN THE RIGHT HANDS.
Here’s a few things to consider if you’re thinking of changing wing class:
1. Have a look at the manufacturers (not the dealers!) website. Who are they aiming their wing at? They have a reputation to look after and that involves not selling wings to pilots that aren’t yet ready. Plenty of pilots have flown 100km or more on a 1 for example. Upgrading a wing rarely by itself results in bigger xc distances. Experience does.
2. Consider the aspect ratio. In the last 3 years the aspect ratio of some wings have been increasing in certain categories. Increased aspect ratios help a wing’s performance, but a high aspect ratio requires more “management” from the pilot. Compare aspect ratio for a hint as to how it handles! The Gradient XC2 for example, scored an ENC and thus attracted a lot of pilots onto a very high aspect wing (6.4!)The XC2 is a “safe” wing, but it’s aspect ratio is still 6.4 and despite it’s EN-C rating it was clearly aiming it at EN-D and LTF2/3 pilots.
3. Talk to an experienced pilot who can give you an honest opinion – remember this is probably not your flying “peers” and might not even be your local dealer. Consider the performance points in the rest of this article. Performance starts with where you are on the weight range.
Where to be on the weight range
Wings are sold in different sizes depending on the all up weight (pilot plus wing harness and everything else) of the assemblage. Since the recommended flying weights (to which the wings are subject to passive safety tests) usually overlap this can often leave pilots with a choice of where to be on the “weight-range”. Being near the top of the weight range will mean that a wing is more highly “loaded”.
The more highly loaded a given wing, the faster it will fly, and the more collapse resistant it will be. A higher loaded wing will also behave more dynamically, that is it will respond to inputs more directly. Collapse recovery will tend to be faster. The glide angle is little affected (assuming low porosity ie a wing in good condition) by a wing’s loading. A more highly loaded wing will also generally be easier to launch in strong conditions or higher winds, easier for YOU to collapse (ie big-ears and B-line, stalls in air or on the ground) and most importantly, the handling will feel more direct and responsive making highly loaded wings much more fun to fly.
So what of the disadvantages of flying “heavy”? First of all, collapses. Although less likely in the first place, if a highly loaded wing does collapse it will potentially turn more and dive more on recovery for example. That is, everything is more dynamic. In my experience whilst it’s important to be aware of the potentially more dynamic nature of the collapse, the increased turn is only slightly more than a lightly loaded wing because the collapse opening is usually faster. Add to that, the fact that a highly loaded wing is less likely to collapse in the first place and flying heavy really isn’t any more dangerous than flying light. Indeed in many ways it’s safer. The difference in speed between top of the weight range and bottom of the weight range is about 5km/h! This is a huge difference and a factor that highly favours being heavy on your wing.
The second perceived disadvantage to being heavy on a wing is to performance. The increased speed as a result of higher loading will lead to a slightly increased sink rate. However, since glide is not affected, when it comes to xc flying the slight increase in sink rate is of little consequence except in very light scratchy conditions. In normal or even light XC conditions (ie thermals of +1m/s or more) the increased speed and loading will improve your “speed to fly” making it easier to fly further particularly if there is likely to be any into wind gliding or sink to fly through.
Being light on your wing is old-school thinking from 20 years ago when wings could barely soar let-along fly XC. All in all, it’s worth being as close to the top of the weight range as possible. Given the choice between being light on your wing or heavy, I’d choose heavy every-time. Welcome to easier more dynamic flying, increased performance, less dragging on launch and more fun in the air.
Performance
No discussion on choosing a wing would be complete without discussing performance. What do we mean by performance? There are two important aspects to a wing’s performance that need to be discussed. These are speed and glide (angle). The sink rate of a wing is by definition a function of the other two (or vice-a versa if you like). Speed is useful to get places quickly and glide lets you arrive there higher (or just get there as opposed to not quite making it).
Performance is almost impossible to measure accurately. This is because paragliders fly so slowly, are so susceptible to even the smallest air flow changes and because totally still air is almost impossible to find (even on still days the air is usually sinking or rising slowly). It is easier to measure the relative performance of a wing – that is by comparing its performance with another wing – swapping pilots and so on several times to obtain a statistically valid picture. Whilst the performance differences between classes are very apparent, within a class (ie between brands) the differences are usually very small indeed. Also bear in mind that manufacturers performance claims should be treated with plenty of scepticism. For most pilots flying LTF1-2 or even LTF 2 wings assuming the wing is of a modern design and in good condition then performance shouldn’t even be considered. Any noticeable performance differences at this level of wing are most easily influenced by wing loading (where you are on the weight range) and perhaps even harness profile than any other factor. Where performance differences become more noticeable is where the speed bar is used. In fact there is very little performance difference between a 1-2 and a 2 until the speed bar is used! On lower end wings, applying speed bar (particularly lots of it) will, in still air, greatly reduce your glide angle. The higher the wing rating then generally your speed bar will give lots of speed without reducing your sink rate too much. Unfortunately manufacturers rarely if ever publish glide angle on bar (and even if they did the difficulty in measuring it would leave the data open to doubt)
So given that published performance data is hardly worth bothering with, what do we mean by “useable performance”? Increased speed or increased glide is not worth having if a wing can’t turn or if a wing collapses all the time. There are three factors to consider when it comes to useable performance.
1) Thermalling: Given that, when it comes to xc flying, a significant amount of time is spent thermalling, one question you should ask yourself is how easy it is to thermal with a wing? How does it turn? How does it bite into thermals? How easy is it to manage in thermals of different types?
2) On bar: If a wing cannot be flown on full bar in anything but the smoothest of conditions because of its propensity to collapse for example, then what use is the so called top-speed? How well does it deal with turbulence on bar?
3) Thermic air: Similarly, when it comes to normal flying conditions, can you let the wing fly hand’s up or does it always need reining in? Again the manufacturers claims are made even less significant if the wing needs so much managing that its claimed performance can only be reached in still air. Turbulence no matter how light will always reduce a wing’s glide, because none of them are (even close to) 100% efficient. How a wing performance changes with turbulence is even harder to measure!
So when it comes to performance, I would suggest you give it little attention at all, unless that is you have hundreds of hours and regularly fly big distances or fly in competitions. Consider instead the factors surrounding a wing’s useable performance and consider most importantly of all, how a wing handles:
How a wing handles
A high performing wing is of no use at all if it won’t turn, if it collapses all the time, behaves like a beast and leaves your nerves frayed. Flying is all about having fun and being safe. Indeed, having fun and being safe are also the two most important factors that will influence how you improve and develop as a pilot. So pick a wing whose “handling” you like. When it comes to choosing a car for example, whilst you might prefer how a certain car drives, your friend might prefer another. There’s not necessarily a right or wrong answer. There’s room for taste. The same is true when it comes to choosing a wing. However, the challenge when it comes to choosing a wing is how to appreciate handling differences especially if you lack experience. If you want to develop your skills as a wine taster, be critical, aware, and drink lots of it! And so it is when it comes to critiquing wings. As a starting point though, once you’ve more or less decided on which category to aim for, what are the handling characteristics that you should be considering? These might then lead you to at least start asking the right questions. Here’s a look at some wing characteristics worth considering:
Wing weight: lightness vs. heavy?
Some wings are heavier than others. This is not just a result of the type of cloth with which they are made but also how much internal construction there is and of course the amount of line used, risers and so on. Recently there has been a move to heavier construction in the leading edge, but thankfully the heavier Gelvnor cloths are now rarely used. A light wing will tend to be easier to launch and have a crisper more dynamic less “sluggish” feel to it than some of the weightier wings. So what about the very light weight wings. Wings less than 5kg tend to fall into two categories: the “travel” wings (4- 5 kg) and the “mountain” wings (less than 4kg). Be careful about going too light – these wings tend to be made from material that is so light that the life expectancy and durability is very noticeably compromised.
Brake pressure
Some pilots like brake pressure that is light and others heavy. Heavy brake pressure can make a wing feel more reassuring, but can also be tiring if you spend a long time in the air. Heavy brake pressure is a particular feature that can be found more often in lower end wings, but is often also found in higher end wings. Some manufactures have heavier handling than others. Some have a direct feel where you feel very much “in touch” with your wing and others a more damped feel.
Brake travel
The higher end wings generally have shorter brake travel. Indeed there is a strong correlation between brake travel and rating which is also inherent in the rating systems. The shorter brake travel common in higher end wings means that corrections and piloting requires only small inputs which can be less tiring. It also means that is a wing is easier to stall either inadvertently (!) or on landing when you need to collapse a wing. The long brake travel common to EN-A and LTF1 wings can make them cumbersome and difficult to “kill” in stronger winds.
As well as length of travel some wings have very progressive “pressure” and others feel more on or off. Most pilots prefer a more progressive feel.
Pitch stability
A very stable wing is very difficult to manoeuvre. A completely unstable wing would be a nightmare to try and keep in the air. The question then is how stable should your wing be? Stability in pitch usually means its more efficient and smoother to fly, but some instability will allow for more manoeuvrability and playfulness.
Roll stabililty
Most lower end wings are quite pitch stable, but suffer from more roll instability. Roll is more difficult to pilot, but it can render a wing more playful and “wangy”.
Launch characteristics
How a wing launches is also a factor to consider when making a purchase. Whereas most low end wings do not have a tendency to overshoot, some of the less pitch stable wings will require a more polished launch technique.
The turn
How a wing turns is surprisingly complicated. It is a function of its pitch, roll, yaw, and responsiveness to brake inputs. Although some wings tend to dive more on turning than others, none of them turn totally flat. If a wing tends to dive on turn, how it recovers (and climbs) on exiting a turn is the real question to ask. In the end, this is a complicated area of dynamics. There are different ways to turn different wings. Experiment safely. Enjoy and never stop learning.
Final word
In conclusion, if you want the best wing, pick one that’s not going to scare you. Be honest about your current level. Maybe the wing you currently own is just fine and your money would be better spent on some decent training? Don’t be tempted to think too much about performance. Instead focus on where you’ll be on the weight range and how the wing handles. By all means test fly 3 or 4 wings (not more or you’ll probably confuse yourself) or if you lack the experience and time consider the opinions of trusted pilots (more than those reviews!) All that’s left, is to choose a snazzy colour, make sure you’ve got swivel brakes (or whatever other little features you need!?) and enjoy! Best of luck and happy landings.
February 2011
Toby Colombé (Current Tandem FAI O&R World Record holder)
