EN-C 2-liners, really ? Just as in Formula 1, technological advances reserved for the world of competition are eventually democratised and everyday car drivers end up benefiting from them too, both in terms of safety and performance: tyres, composite materials, engines, and so on. It's about the same in paragliding.
In paragliding, we can talk about the "sharknose", introduced in 2011 on Ozone's performance wing, the R11. The idea was to modify the shape of the leading edge to make it more efficient (better scooping during inflation or reopening in case of bulk, less accelerated drag...).
Although invented by Ozone, the brand did not object to its use by competitors, and today it is found throughout the range of different manufacturers, even if they sometimes use a different name.
What are the two lines?
Initially, a paraglider looked like a big spider's web: there were 4 rows of lines (sometimes even 5 at the beginning!) in addition to the brake lines. Some designers started to prune the lines, proposing ramifications by levels (crow's feet): the idea was to reduce the drag.
For the same reason, we then went to three lines, adding some reinforcements (diagonal partitions, rushes inside the sail itself) and even transverse crow's feet, in the direction of the rope...
It is logical that the race for performance should lead to the removal of this third line.
This is how the 2 lines.
The Brazilian manufacturer SOL even offered a "one-line" prototype in 2011.
This change is not without consequences. Less drag, more performance, but also more demands.
The older among us remember the "Mantra 10", released in 2010, which existed in two versions: Mantra R 10: 3 lines ("child model" as a friend said) and Mantra R 10.2 in 2 lines for competition.
Initially reserved for competition models, this modification is soon to be found on almost all "performance" gliders (EN-D).
The removal of a line (the C's) effectively moved the anchor point of the A-line back from the leading edge. The result was that it is very difficult to induce a closure during certification tests without the addition of "C" lines.folding lines".
It is sometimes said that some 2-line D wings (Omega X-alps 3, Wild, Klimber...) could have been converted to a 'C' without this device, if we stick to the other results of the homologation tests.
At the end of 2021, the regulations will become more flexible, and it will now be possible to homologate a 2-line in C, provided that it passes the tests of course.
Airdesign is the first designer to homologate a two-line C in February 2022: the Volt 4.
This sail is quite successful. In 2023, almost all new C models will come out in 2 lines to follow the trend and not lose market share.
- AirDesign Volt 4
- Soil LT-2
- Gin bonanza 3
- Skywalk Mint
- Ozone Photon
- Niviuk Artik R (breed),
and the list is not exhaustive...
In short, this is a basic trend.
Advantages of a "2-line" system
Removing a line means an average of 70 metres less line.
This is a significant advantage in terms of drag.
The sail therefore performs better in light conditions, gains maximum speed, and of course glide (Glide = Lift / Drag). In windy conditions, the difference is clear!
If you're flying next to a friend with a "two-line", it's likely to make you want to change wing. It's a good bet that he'll leave you behind (better speed), and that he'll also give you the impression that he's climbing: it's an illusion, he's just descending less quickly than you (better sink rate, therefore better glide). This type of glider is more typically cross-country.
Disadvantages of a "2-line" system
As there is more pressure on the remaining lines, this can result in a false sense of security. The sail closes less ... up to a certain point.
A bit like the fable "the oak and the reed"(the latter, I recall, bends but does not break), a 3-line sail will resemble the reed, a "2-line" the oak. The reed bends more often, but at the end of the storm, it straightens up.
On the other hand, this type of canopy allows accelerated speeds greater than a 3-line canopy. As a result, an accelerated 2-line closure is inevitably impressive, and reopening more hazardous, requiring more time and control. Not to mention possible tie problems (due to a more pruned line). But one can also say that the sail closes less often, if one sees the glass as half full.
Finally, this type of sail requires more maintenance: there are fewer rows of lines, and the lines are more stressed. As a result, the rigging has to be monitored more closely, and probably more often. This is the price of performance. On the Mint, Skywalk recommends checking the trim after the first 25 hours of flight.
Piloting a 2-line
It is imperative to learn to fly at the back (active steering at B), especially when the accelerator is pushed.
On a classic C glider, this is already a good habit, on a two-line glider, this piloting mode takes all its sense and even becomes compulsory. It allows you to feel the pressure in the canopy, to correct the incidence and to prevent a surge.
The increased sensitivity when flying actively at B's makes it possible to better anticipate closures and thus avoid them more safely, and to fly faster and more efficiently.
In accelerated flight, if the air becomes a little turbulent, put some traction on the B-risers; when the turbulence stops, this traction can be reduced (or cancelled) to increase speed. Flying fast in normal air conditions requires constant attention, combining B-riser control with speed bar adjustment to keep the canopy open and pressurized. This way of controlling the wing is suitable for "normal" air, but in strong turbulence it must be replaced by appropriate active control (brakes). Remember to release the accelerator before using the controls (handles).
Getting used to this type of flying takes time, so don't go too fast in any sense of the word. That said, it is perhaps this B-riding, the feeling of being connected to the reactions of your glider, that will make you want to change to a C-category glider.
Furthermore, it is wise to have experienced the consequences of an asymmetric collapse, and the piloting necessary to counter an autorotation departure during a SIVThis is not a problem for a "classic" sail. As we have seen, it is difficult to reproduce this type of behaviour on a two-line, but some manufacturers offer "folding line kits". Finally, it is not so much on asymmetrics that the problems arise for two lines, but rather the generalized frontal, which will require appropriate piloting, as explained by Russell Ogden and Martin Orlik :
This video is a bit dated (2012), but most of what they say is still true.
Feedback on the 2 lines
As I flew all winter in the MexicoI share my experience here:
I saw quite a few new EN-C in 2 lines (not to say Volt 4) ...
I have also seen a lot of emergency openings, especially under some Volt 4s.
Of course, not ONLY the Volt 4 and not ALL the Volt 4, so don't let me be accused of criticising this wing, which I almost fell for! I have to say that I am even envious of the flights made during my Mexican stay by pilots under this same wing, and it suits me to believe that it is due to the wing, rather than the pilot 😉 Besides, the feedback in SIV indicates that it is a wing well within its category. As it happens, it was the only EN-C in 2 lines. And the facts are stubborn.
Most of these pilots were long-toothed "young wolves", for whom it was their first C, intoxicated by the perceived safety of the glider, who were probably flying above their level, accelerated near the terrain, and/or in a muscular aerology without being aware of it. In short, an explosive cocktail.
In short, as Uncle Ben says to Peter Parker in Spiderman:
Conclusion
These two-line EN-Cs tend to become more widespread in 2023. Some designers have already taken the lead, while others are more of a wait-and-see attitude. Who is right? The future will tell. It's a safe bet that all manufacturers will eventually get on board.
Performance oriented, they are globally more demanding than a classic EN-C (3 lines). They are more suitable for experienced pilots with good piloting skills.
If you are already in C, and often fly accelerated, and feel limited by the performance of your wing, then this type of wing is probably for you.
Some of them are for sale (and for trial) at the paragliding shop of Grands Espaces. This is still the best way to form an opinion.
Find out more about 2-line EN C comparison and Robin's impressions.
