From the sky to the sea and back.

From the sky to the sea and back.

How aircraft technologies are used in the shipbuilding industry, and why is it beneficial for both industries?
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The exchange of experience between the shipbuilding and aviation industries in aerodynamic technology and design is increasing, and both industries benefit from this.

Remember the USA 17 racing trimaran, where Oracle Team USA won the 33rd «America»'s Cup in 2010. Its rigid sailing wing was and still is the largest in the history of sailing. Its wing height (67.97 m) is more than twice the size of the Boeing 747 - it was often compared at the time.

Seven years later, the AC class catamarans that fought for the Auld Mug in June 2017, the 15-meter long hull and 23.77-meter sailing wing. They were the smallest multihulls ever to compete for the world's oldest sports trophy. But here, too, the analogy with planes remains relevant.

«The size of the Oracle wing sails was the same as that of the Airbus A320»," says Pierre-Marie Belleau, Airbus Business Development Manager, who collaborated with Oracle's American team on the AC50 catamaran.

However, the size is not the only thing that unites the AC50 sail and wing. They have a very similar structure.

«In aviation, the airflow creates more pressure on one side of the wing than on the other. This creates a lifting force," Bello explains. - As with an airplane, the shape of the sail-wing-wing is important for the boat, because the speed»depends on it.

The speed also depends on the design of the hydrodynamic foils, thanks to which the 14.93-meter catamaran rises out of the water and flies over it four times faster than the wind.

«On a conventional yacht at speeds below 20 knots, the main challenge is to overcome water resistance, so aerodynamics is not such a concern," he continues, "but when you go 40-45 knots, aerodynamic resistance becomes a priority».

That's why the foyles have an L-shape that replicates the sharklets - the raised ends of the wings of Airbus planes. This is a patented development of the company to reduce fuel consumption and increase range.

Work on the AC50 project lasted about three years. Some 30 Airbus aviation engineers contributed to its creation. Some of them worked full time.

The cooperation between Airbus and Oracle Team USA started in 2012. Then, at a meeting with Fabrice Brégier, President and CEO of Airbus, the attendees compared the performance of AC boats and Airbus aircraft and concluded that they had much in common.

If the keel of a boat is the tail fin of an airplane, it is clear that both designs are not so far apart.

That the aircraft construction, that the shipbuilding is constantly trying to reduce the weight of its products. It is a kind «of quest» to develop lighter and stronger materials.

In pursuit of this goal, the aviation industry has promoted the use of carbon fibre, now actively used in the construction of racing yachts. The A320 and its own brother, the ACJ320 business jet, which was developed in the 1980s and 1990s respectively, initially consisted of 100% aluminium. Now they contain around 60% carbon.

The latest Airbus private jet, the fully custom-built ACJ350 XWB, is probably the most advanced VIP aircraft in the world, with a range of 10,800 miles or 22 hours. It is 53% carbon-fiber. Everything goes to the point where, over time, the carbon content will reach 72%, like in AC catamarans.

Another key point in the weight reduction race was 3D printing. It allowed Airbus to produce elements with a much more complex geometry while retaining the strength of titanium.

«In such difficult details, as foils, it is possible to reduce to 40 percent of weight», - marks advantage of the 3D-press Bello.

The hydrofoil is a really difficult element - it consists of 16,000 parts and weighs around 80kg and has to withstand a 2.4 ton boat when it comes out of the water.

The 3D printing speeds up the production process of a part of this complexity considerably.

Manufacturing the rudder or foil using traditional means of production can take about a month, and with 3D printing it takes only two days.

Laurent Chatillon, one of Airbus engineers who worked on the project in Bermuda, believes that in terms of innovation, yacht design is about 30-40 years behind «aviation technology, so the potential for new technology and collaboration is huge and this is just the beginning».

The catamarans that competed for the America's Cup «last» summer used the power of the wind and the hand-powered winch (or in the case of the Emirates Team New Zealand - with a pedal). The drives generated 5000 psi - enough pressure to hydraulically control the sail-wing, jib, foyles and rudders.

The same pound-per-square inch pressure was used in the ACJ350 XWB, so the know-how of the Airbus flight control system was actually transferred to the AC cockpit, which was an absolute innovation in yacht design.

Or take the new generation of pressure sensors, a technology similar to that used in smartphone touchscreens, known as MEMS (or microelectromechanical systems). These sensors can be found on the new A350-1000 and its sister aircraft, the ACJ350 XWB. They are also inherited from the AC50 boats.

Positioned in small strips at equal intervals along the wing's sails, they act as micro anemometers to measure wind speed and atmospheric pressure, continuously providing detailed data on airflow around the wing.

«I wouldn't be surprised if this technology becomes the standard for the yachting industry in the future," says Bello. - Most weather forecasts are completely inaccurate and also do not take into account all local aspects, such as sea»temperature.

These sensors are truly another useful development for sailors and pilots.

The benefits of working with Airbus for Oracle Team USA are clear: The «America»'s Cup has long been renowned for the technological sophistication of boats and, as a result, the virtuoso skills of the crews.

«There are great similarities between piloting and sailing. It's all about aerodynamics. A well-appointed boat is like a well-adjusted plane»," said Oracle Team USA skipper Jimmy Spithill. Spithill has a private pilot's license, so he knows what he's talking about.

The benefits to Airbus from working with Oracle Team USA are not so obvious. Working with Oracle Team USA has given Airbus the opportunity «to go beyond». Working together on racing yachts has allowed Airbus to do far more daring experiments than it could afford when designing aircraft where safety and durability requirements are many times stricter.

«What I want to preserve at all costs is a spirit of innovation," says Brezhi. - The ability to experiment and evolve by testing ideas and materials and simulating situations in real life is expensive. We used something to create the boat, something had to be abandoned. But failure is also part of the way».

That's why we can't say that Airbus exaggerates by positioning its business jets as «the most modern family of corporate aircraft».

This article was written by Claire Wrathall and published in March 2018 in Boat International magazine.

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