The Return of the Black Sheep

This article was first published at Lucian’s blog at
Translated from German by Judith Mole

Ozone plans to test the new Delta 3 with folding lines. Although it was designed as an EN C, folding lines mean that it will automatically be certified as EN D. Will they set a new precedent? 

Delta 3 = EN D?

Years ago Ozone was ahead of the pack with its BBHPP open class competition wing. The wing was fitted with carbon rods and the subsequent heated industry-wide discussion centred on whether a paraglider should be permitted to have rigid elements; and if so, which ones. In the end, a compromise was reached which included a bending radius, so carbon rods were not permitted while nylon rods were. Since that time, Ozone have been going it alone and encouraged people’s view that they are innovative outsiders.  In their marketing, they make reference to this status by calling what they do “Black Sheep Technology”.

Ozone is soon to step into the role of the black sheep again. During certification testing for the Delta 3, the manufacturer seems determined to have the accelerated collapse tests performed with folding lines. An indication of this was given at the Thermik trade fair and this information has now been confirmed on the Ozone website. This means that Ozone accepts that although the Delta 3 was designed as a traditional EN C wing, it will automatically be certified as EN D. Under the current EN 926-2 rules, EN A, B or C may only be awarded if all collapse tests are performed without a folding line.

Ozone claim that its predecessor, the Delta 2, has been the best-selling EN C ever. Generally pilots viewed the Delta 2 as a good wing that didn’t push the limits of its class, especially when considering safety aspects. Interestingly, the Delta 2 was also certified using folding lines. At the time, EN rules permitted the wing to be certified in the EN C class.

The Delta 3 is a further development of the Delta 2 design, with nearly identical technical data like the aspect ratio, etc.  One distinguishing feature: the A-lines have been situated far back along the profile, which Ozone says increases the wing’s stability in turbulence. It has to be noted that because of a pre-acceleration effect, these “induced” collapses can escalate more than they would in normal flying conditions. The Ozone development team are so convinced by the safety gains of this design that they wish to keep it. In order to be able to perform the EN test collapses, folding lines that are attached at the front of the leading edge are necessary. But this means a guaranteed certification class: using folding lines forces the Delta 3 into the EN D class, even though the flying characteristics and safety behaviour are nearly identical to the EN C certified Delta 2. 

The Ozone development team had to think long and hard whether they wanted to take this step. This would buck the current trend: despite high aspect ratios or other performance characteristics, manufacturers usually trim and test gliders in order to achieve a lower certification class. The Delta 3 would be the first glider where the manufacturer consciously accepted the risk that the glider’s certification class would be higher. This means that Ozone is once again testing the waters; being, as they describe themselves, “Black Sheep”. The real test will be whether pilots completely rely on the EN classification or to what extent pilots trust the manufacturer’s safety claims. Because of course Ozone would say that the Delta 3 is only an EN D on paper, but really it is a traditional EN C.

The outcome of this marketing experiment is still unclear. Given the huge success of the Delta 2, one would expect many satisfied customers to stay loyal to Ozone, especially as they are already flying a wing that was tested using folding lines. For the industry as a whole this could have a big impact. If the Delta 3 is certified as an EN D and sells well, this would set a real precedent.

As a consequence, other innovations may gain momentum – it has become increasingly clear that the A, B, C and D certification classes only represent test conformity; they indicate less about the actual performance and safety level of the glider. Having the various competition classes in cross-country leagues makes less and less sense. Instead, other factors like aspect ratio and wing-loading are becoming more important.

If there is a further blurring of the boundaries between C and D (actually these days between B, C and D), the industry might consider a general overhaul of the certification rules. Ozone is not alone in considering having just two classes: school wings and advanced wings. The description of the advanced wing’s characteristics would be the responsibility of the manufacturer. In conjunction with safety tests á la DHV for verification, at least for the mass market lower aspect-ratio wings, this information would be more useful to experienced pilots than the current fluidity of the EN classes. 

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