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  • Фото автораAlexander Vashlyaev

One Year with the Ozone Edge 7m and Some Discoveries

It has been a year since I started using the Ozone Edge V11 7m kite for all my twintip sessions. I weigh 80 kg and am 44 years old, with 20 years of kiteboarding experience. I have ridden in various conditions ranging from 7 to 25 m/s in Hurghada, Egypt. This has been the most unique kite season of my life.




Originally, I purchased the Ozone Edge 7m as a birthday present for my wife. Since she is light, weighing only 52 kg, I wanted a kite that could cover her in a wide range of wind conditions. Being a long-time fan of Ozone, I decided to go for their newest small size, the Edge V11 7m. To my surprise, it turned out to be a perfect match not only for my wife but also for me! After just a week of trying it out, I fell in love with this beast and decided to sell my previous quiver, which consisted of a 10m Enduro V2 and an 8m C4 V6.

The Edge 7m proved to have the wind range of both those kites combined. I first discovered this when I was out with my 10m Enduro while my wife was riding the Edge. The wind was a sweet 9m/s, and out of curiosity, I decided to compare both kites by doing "mickey mouse" looping with my WOO to register the real data. To my astonishment, I was able to jump higher with the 7m than with my 10m. It was truly incredible as I had never considered it as a kite in my quiver!



With the Enduro and C4 kites, it was safe to fly and loop but quite challenging to go above 10m in kite loop on the choppy surface of a stormy Red Sea. However, with the Edge, I can easily reach 11-12m high loops in 11-12 m/s wind speeds and loop at heights of 5-7m during sessions in 8-9m/s wind. The real excitement starts at 13m/s and beyond! The Edge 7m is always quick enough to be where you need it, even in 20m/s winds. 25m/s was nearly the limit for me—I didn't want more. Then I tried it in very light wind of 7m/s and was still able to go upwind and make some small jumps with the same 136cm twintip. People around me were on twelves and seventeens. Totally beyond any expectations!



This led me to start exploring and trying to understand why the 7m kite was able to pull my 80 kilograms in such light wind. The logic is simple. Let's find out what is the maximum power a kite can extract from the wind! We will need to know the exact mass of the air in kilograms that passes through our kite in one second and pushes it. To find the mass, I need to know its volume and density. How do we calculate the volume? We need to determine the exact surface area of the kite that directly extracts power from the wind and then multiply it by the kiter’s speed and apparent wind speed to get the volume.

The interesting thing is that Ozone is the only company in the market that mentions the exact projected area of their kites. When I tried to apply my calculations to other brands, nobody else provided this data! You just can’t find it on their websites. Proof: Duotone - https://www.duotonesports.com/kiteboarding/kites/rebel-sls/, Core - https://ridecore.com/us/kite/kites/xr8, North - https://northkb.com/products/orbit-2023?variant=41894805897388#specifications, Cabrinha - https://www.cabrinha.com/products/switchblade, F-One - https://www.f-one.world/product/bandit-xvi/, Naish - https://www.naishkites.com/product/pivot-le/, Airush - https://airush.com/kites/lift-kite/, Eleveight - https://www.eleveightkites.com/kites/xs-v4#technical-details, Ocean Rodeo - https://oceanrodeo.com/products/rise-a-series?variant=37399248765082#, Crazyfly - https://www.crazyflykites.com/kites/hyper, Slingshot - https://slingshotsports.com/collections/kites/products/rpx-v1#dev-specs, Vantage - https://www.vantagekites.com/products/vulture/, Reedin - https://reedin.com/supermodel-3/.

It's strange when we're talking about flying things. Or maybe they don't know! LOL. This information turned out to be quite valuable because it is a real parameter of the kite, not just marketing descriptions and "style or size selectors."


According to the Ozone website, the Edge 7m V11 has a projected area of 5.1 square meters. And it explains why it behaves so well in both light and strong conditions, as it has a great ratio of real area to projected area. More than 2/3 of its surface is working, which reduces the resistance caused by extra canopy in the air. I would love to have this data on all the other kites.

The density of the air (source: https://en.wikipedia.org/wiki/Density_of_air) is approximately 1.2-1.3 kg per cubic meter.


Next, we need to consider Betz's law, which indicates the maximum power that can be extracted from the wind (source: https://en.wikipedia.org/wiki/Betz%27s_law). I had never heard of it before starting this little research. Unfortunately, the news was not great. In short, according to Betz’s Law, we can only harness 59.3 percent of the power carried by the wind (a bit less than two-thirds). Anything beyond that limit means there is no wind, and it doesn’t matter what you improve in your wing, you just can’t get anything more out of it.


The easiest approximate calculation I made was as follows: assuming a kiter is going 90 degrees to the wind at a speed of 7m/s, with a wind speed of 7m/s, and using a 7m Ozone Edge kite. The apparent wind in this situation would be 10m/s (this is another calculation that can be obtained from an IKO course).


The volume of air passing the kite in one second would be the product of the kiter's speed (7m/s), the projected area of the kite (5.1m), and the actual air flow speed (10m/s): 7 * 5.1 * 10 cubic meters. This gives us 357 cubic meters of air passing through our kite per second in this situation. To determine the weight of all this air, we multiply the volume by the density (1.2 kg per cubic meter), resulting in 428.4 kg, or nearly half a ton of air mass pushing our kite! Now, it's time to apply the Betz limit to find out what is left for a poor little kiter. Multiplying this by 0.593 gives us 254 kg, and that's a tremendous amount of pull!





Oops, I forgot that the kite is not perfect yet, so we can't get all the possible power out of the wind just yet. That's the trickiest question for me now. How far are we from perfection? How do a kiter's skills affect the efficiency of the kite (which I'm sure they do)? Even if we're only halfway there (which I expect to be the case already), my 7m would still generate a pull of 122 kg at a wind speed of 7m/s! Can you imagine how powerful it can be in 15-20 m/s winds!

This explains why, as an 80kg rider, I'm able to ride the 7m kite at 7m/s with a 136 cm twintip, overcoming all the resistances like water friction, waves, and gravity. It also explains why some people say that a 9m kite, for instance, pulls like a 12m. All kites have different parameters that are real, such as aspect ratio, projected area, etc. Different kite shapes have different ratios of the actual size to the "working" size. So why do the majority of kite companies still not provide this data to their customers? I don't understand.



Come on, guys. Please stop with this nonsense. Don't treat us like idiots; give us real data!


I have firm plans to stick with the 7m Edge for the next season and continue my exploration. If it were a bit lighter and stiffer, it could potentially become even more efficient. A narrow 5-strut kite crafted with Aluula would undoubtedly capture my attention. I'm particularly hopeful that Duotone Rebel or the new OR Rise will lead the way in adopting this revolutionary material, and I also hope that one day they will share the genuine data of their kites with us. If Ozone were to create a 7m Edge using Aluula, it would be an absolute dream come true for me.



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3 comentarios


Кирилл Семёнов
Кирилл Семёнов
03 jul 2023

Саша, ты мне рассказывал про этот расчёт тяги пару недель назад!) Уже тогда начал писать статью?)

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Jyrki Tikka
Jyrki Tikka
03 jul 2023

"So why do the majority of kite companies still not provide this data to their customers?" - flysurfer do provide the data also! How is it so hard to others to give the data they have.. weight especially. I'm a fan of ozone edge, using v11 11m. br, Jyrki

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Sergej Rusakov
Sergej Rusakov
03 jul 2023

It’s amazing interesting. Thank you for sharing information

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