Luna Rossa and the boats participating in the America's Cup use the physical principles of airplanes, in fact… a technical jewel that takes off on the water.
They are Formula 1 racing cars at sea, known as AC75, and they participated in the America's Cup, the oldest sailing competition in the world.
However, if in the first edition of 1851 we challenged each other on boats of very different shapes and weights (even 200 tons), today the technology has developed to the point that these modern boats can even fly! how can it be? “All thanks to the foils”, explains Davide Tagliapietra, aeronautical engineer of the Italian team Luna Rossa, who contributed to the futuristic design of the appendages of the AC75.
“We are talking about two movable carbon fiber robotic arms, which are located on the side of the ship with two aluminum fins or wings at the end. They act downwind at some distance from the hull. At a given speed, they produce a load that balances the inclination of the boat, resulting in a force called "righting moment" that lifts the hull out of the water ».
These racing cars at sea follow the same principles as airplane flight. In fact, the various parts of the foil are "teardrop" because they follow the aerodynamic properties of the aircraft wing. Tagliapietra continues: “Hovering on the waves, the relatively weak wind is sufficient to manage it, about 8-10 knots on average, it can trigger the exchange of forces, allowing the passage from the state of classic navigation to that of“ flight ”.
In fact, we pass from the hydrostatic force that regulates the buoyancy of any object immersed in water to the hydrodynamic force that characterizes the flight phase.
However, the maximum speed of the AC75 is reached with 15-20 knots of wind remaining above 40-45 knots (75-85 km / h) and the theoretical peak is 55 knots (100 km / h or more). h). To fly, the rudder is of fundamental importance: “It has a horizontal attachment called an elevator, which can balance the vertical force and stabilize the navigation, a bit like the tail of an airplane”.
