Hydrofoil Control: How Stable Flight Is Achieved

The lift produced by hydrofoils must be precisely regulated to keep the vessel flying at the desired height above the water. To achieve this, modern hydrofoil systems use active control technology that monitor flight conditions in real time and adjust the lift generated by the foils many times per second. Thanks to advanced onboard software, the system compensates automatically for changes in speed, wave conditions, vessel loading and turning radius. As a result, active control enables hydrofoils to operate safely and efficiently across a wide range of weather and sea states.

To adjust lift, a control system needs sensors, an onboard controller, and a way to change the water flow over the foil. This can be achieved through two primary methods:

1. Flap Control

Flap-based systems work similarly to the flaps on an aircraft wing. A small, adjustable surface on the trailing edge of the hydrofoil changes its lift characteristics when deflected.
By continuously fine-tuning the flap angle in response to speed and sea conditions, the system maintains an optimal ride height and stable flight.

‍Benefits:

• Lightweight
• Energy-efficient
• Precise lift control with minimal added drag

2. Full-Wing Lift Control

In a full-wing system, the entire foil is adjusted to change its angle of attack. This approach removes the need for small underwater mechanisms but typically requires more power and can introduce additional drag.

‍Benefits:

• No exposed flap hardware
• Simple mechanical layout
• High range of lift forces possible

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Considerations:

• Higher energy use
• Generally more drag than flap systems

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Control Expertise at Flying Fish

At Flying Fish, we apply advanced control system engineering to ensure hydrofoils remain stable and balanced by dynamically adjusting lift across the wings. To develop and validate our systems, we use an in-house hydrofoil flight simulator that allows us to test different foil configurations, control strategies, and sea states before implementation.
This approach ensures reliable performance, maximum safety, and an optimized flight experience for every hydrofoil design.

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