Home > Technical Terms Kitefoil and Windfoil

Technical Terms Kitefoil and Windfoil

Jargon arround Windfoil - Kitefoil

We shall not go into technical details, but only on the role of each different parts of the foil.

The box will connect the foil to the board via one or more screws. There are different types of boxes with each of the advantages and disadvantages that you will find in this article.

The Mast is one of the most important parts of the foil, in fact many of its characteristics will influence the foil's behavior. In summary there are 3 sizes of mat:

- short mast (- 60 cm) intended only for schools, their low height greatly reduces falls and promotes learning. After 1 to 2 hours of training, this length of matt is no longer interesting.

- medium mast (- 90 cm) this mast length is the most used because it corresponds to a versatile use - Freeride.

- long mast (more than 100 cm) intended only for the race, the masts of more than 100 cm, even to 115 cm for some, make it easier to cross the waves and allow a better upwind angle.

The fins of a foil function exactly as the wings of an airplane, they serve for the lift and maneuverability of the foil.

The explanation of the phenomenon of hydrodynamic lift can be partially given, by the variation of velocities of the fluid, between the intrados and the extrados. This variation in velocity (the particles traveling on the extrados go faster than those on the intrados due to the greater distance) causes a pressure variation which generates the lift.

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Roll, pitch and yaw

Pitch
This axis of rotation is directly related to the general stability of the foil, if the foil is not stable, it will spend its time pricking the nose. This imbalance is however the easiest to manage because it is corrected by pressing on the front legs to go down or on the back leg to go up. Note however that navigation will be much more tiring due to the constant search for a good balance.
Yaw
Yaw is a left-right movement from the front to the board, this may be a good or a bad thing, it all depends on the style of navigation sought. A foiler looking for a freeride, wave foil will be delighted because it will be more manageable. At high speed this will make the foil very uncontrollable and will increase the risk of falls.
Roll
This axis is for sur  the most constraining, if the foil has roll it can causes an imbalance of your supports between the heels and the points of your feet. This imbalance comes from the profile of the wings or also the curved bridges of certain boards.

Technical terms related to the hydrodynamism of a hydrofoil

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Lifting
The more a wing offers lift more it will take off early in the lightwind. The surface of the wing and its profile are the two factors to be taken for the lift. The deflection of the air flow downwards by the wing creates an upward force: lift. (Wikipedia)
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Drag
Drag is the force of resistance that a fluid exerts on an object when the fluid or object is moving relative to each other. The drag resistance is parallel to the path of the fluid, it is directed in the direction of the fluid and it is opposed to the advancement of the object if it is moving in a fluid. (Source mecaflux.com)
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Cavitation
Cavitation results by the creation and the oscillation of gas and vapor bubbles in a liquid subjected to depression. The problem caused by cavitation is that small bubbles (or cavitations) implode in a few milliseconds. This causes severe nuisance such as material erosion, noise and falling performance.
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Ventilation
Ventilation is a poorly known phenomenon which often appears on hydrofoils and is very difficult to study. It results in a sudden drop in lift when the foil is too close to the surface (the air is sucked into the vacuum zone).