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​The EN classification system​

The EN classification system

There's a worryingly common misconception around the EN rating system and its purpose. So, I thought I'd attempt to clarify the truths and bust the myths around the issue. This isn't to say "ignore EN ratings" or that "everyone should be flying an EN-A certified glider". But hopefully it'll shed some light on the complexity of glider selection and the certification system.

We first need to understand just what EN-926.2 is. The certification process involves launching, flying and landing a wing in a strictly controlled environment while inducing a number of scenarios such as stalls, spirals and collapses, and observing how the wing recovers from each scenario with (mostly) no pilot input. All while measuring deviation from original course and the time taken to return to normal flight. It's the paragliding world's version of a car crash test. And - in the same way a car crash test does not reflect top speed, braking distance, manoeuvrability, general performance or the likelihood of being involved in a crash - the EN 926.2 test does not directly reflect a gliders performance (remember that).

So why aren't all wings EN-A rated? This is where things get a little complex… we now need to look at where a wing's performance comes from. When we perceive one wing as being higher performance than another, we are generally referring to it having a superior glide ratio, higher top speed, and being more efficient in a turn. For simplicities sake we're just going to look at straight line performance for now. A paragliders performance in a straight line depends on its lift to drag (L/D) ratio. While the end result is a nice clean figure we refer to as a glide ratio, the process of optimising it requires some seriously sophisticated number crunching. A wing which produces maximal lift with minimal drag flies more efficiently. This can be achieved by increasing the aspect ratio as a higher aspect ratio results in lower induced drag for the same surface area (for new pilots the aspect ratio of a wing is the ratio of its span to chord, the higher the aspect ratio the skinnier the wing appears), or by creating a clean lifting surface with the optimal aerofoil, or by reducing parasitic drag (lines, risers etc). Traditionally, aspect ratio has been the go to tool for designers to increase performance across their glider range, however an increase in aspect ratio comes at a cost. Passive recovery deteriorates as internal pressure decreases and dynamic behaviour becomes less forgiving. And, as we now know, the EN test measures the time taken for a passive recovery to take place, so these gliders traditionally obtain ratings further along the EN scale.

Hopefully the next question that comes to mind is "then why don't we choose gliders based on aspect ratio?" And quite simply, we should. As aspect ratio increases, so does workload. Competitions are also starting to use aspect ratio to divide gliders into classes instead of the EN rating, and manufacturers are specifically defining what type of pilot a glider is suited to in the same manner. You'll know by now that flying is incredibly mentally demanding. In time, many of the processes involved in the air will become second nature, but for now everything is a deliberate and considered mental effort. So if we add the task of managing a demanding wing, something has to give - either performance or safety. You're far better off flying a wing that you feel secure on so that you can concentrate on where real performance comes from - the pilots decisions.

So, what's changing in glider design? Recently, advances in glider design are allowing manufacturers to improve performance without resorting to a higher aspect ratio. Do these new developments mean that I can safely fly a high performance glider provided it's got a low EN rating? In short, no. As we touched on earlier, the EN test is like a car crash test, it doesn’t consider the likelihood of the induced events occurring in normal flight. While many still retain high passive safety, others are considerably more demanding in the air than their EN certification would suggest. EN926.1 (now superseded by 926.2) stated that A and B certified gliders were "Designed for all pilots including pilots under all levels of training." 926.2 consequently separated the two classes and their respective pilot requirements. We are now seeing certification classes expanding. For example Gin Gliders at the time of writing produce 6 different gliders within the EN-B class, covering a considerable range of pilots.

The performance paradox: The Boomerang's, Enzo's and other high performance gliders flown by the worlds best pilots are hard work. Only a very, very small percentage of pilots have the skills required to exploit their performance gains. Internal pressure is low, tip pressure even lower, feedback is violent, stall speeds are high, and flying them efficiently requires considerable effort. The trade off is an exceptional glide ratio and accelerated glide. Without this skill, the workload is overwhelming and less of our mental capacity can be spent thinking about the air and planning our next move so more mistakes are made. While this is an extreme example, the same comparison works across the glider spectrum. Less workload = better decision making. As a new pilot, you need to understand that you're suspended in a completely foreign environment which (no matter how gifted you may be) you do not yet understand. Fully understanding the air across the paragliding world would take far more than a single lifetime. So, it's vital that throughout your flying career you always leave yourself a margin for error - for when those surprises jump out and 'educate' you. The more experienced you become, the less surprises you're likely to encounter and so you can start pushing performance barriers that would be too risky for inexperienced pilots. As you gain experience, you'll gain the ability to fly progressively higher performance wings and exploit their benefits without the risk of finding yourself in an overwhelming situation. Until then, your EN-A certified glider will have more than enough performance to get you through the early learning stages of a long flying career and progressing onto a higher performance wing too quickly will slow your learning.

In summary:

Choosing a glider is a complicated affair. Weight, handling, performance, safety, price and brand all play a role in the end decision. The EN system is just one facet of this selection process. It’s an important consideration, however it needs to be applied in the right way. Gone are the times when all gliders within an EN class could be compared - and it’s a great thing for pilots. Safety and performance are better than ever.

-Guy Bolton.

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