Stability analysis and prediction of performance for a hydrofoil sailing boat

Masuyama, Yutaka

doi:10.3233/isp-1987-3439001

Cited by 3 publications

(2 citation statements)

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“…It is possible to check the flight stability of the boat in different modes through stability derivatives without fully solving the non-linear Equations of Motion (EOM). The EOM are linearized around an equilibrium point and motions are treated as small disturbances (Masuyama, 1987). The stability derivatives in each DOF are calculated and the eigenvalues of the resulting stability matrix provide details on the dynamic stability of the system in different modes.…”

Section: Dvpps Versus Linearized Approachesmentioning

confidence: 99%

“…The stability derivatives in each DOF are calculated and the eigenvalues of the resulting stability matrix provide details on the dynamic stability of the system in different modes. Masuyama (1987) provided a detailed study on the methods to compute the stability derivatives for a foiling sailboat and has stated the differences between the stability derivative approach and solving the non-linear EOM. During calculations of the stability derivatives, several assumptions were made to reduce the order of the equations, thereby reducing the accuracy of the method.…”

Section: Dvpps Versus Linearized Approachesmentioning

confidence: 99%

See 1 more Smart Citation

Split-Flaps – a Way to Improve the Heel Stability of T-Foil Supported Craft

Prabahar

Persson

Larsson

2021

Journal of Sailing Technology

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Horizontal T-foils allow for maximum lift generation within a given span. However, the lift force on a T-foil acts on the symmetry plane of the hull, thereby producing no righting moment. It results in a lack of transverse stability during foil-borne sailing. In this paper, we propose a system, where the height-regulating flap on the trailing edge of the foil is split into a port and a starboard part, whose deflection angles are adjusted to shift the centre of effort of the lift force. Similar to the ailerons which help in steering aircraft, the split-flaps produce an additional righting moment for stabilizing the boat. The improved stability comes, however, at a cost of additional induced resistance. To investigate the performance of the split-flap system a new Dynamic Velocity Prediction Program (DVPP) is developed. Since it is very important for the performance evaluation of the proposed system it is described in some detail in the paper. A complicated effect to model in the DVPP is the flow in the slot between the two flaps and the induced resistance due to the generated vorticity. Therefore, a detailed CFD investigation is carried out to validate a model for the resistance due to the slot effect. Two applications of the split-flap system: an Automated Heel Stability System (AHSS) and a manual offset system for performance increase are studied using a DVPP for a custom-made double-handed skiff. It is shown that the AHSS system can assist the sailors while stabilizing the boat during unsteady wind conditions. The manual offset enables the sailors to adjust the difference between the deflection angles of the two flaps while sailing, thus creating a righting moment whenever required. Such a system would be an advantage whilst sailing with a windward heel. Due to the additional righting moment from the manual offset system, the sails could be less depowered by the sailors resulting in a faster boat despite the additional induced resistance. It is shown in the paper that the control systems for the ride height and the heel stability need to be decoupled. The paper ends with a description of a mechanical system that satisfies this requirement.

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Section: Dvpps Versus Linearized Approachesmentioning

confidence: 99%

Section: Dvpps Versus Linearized Approachesmentioning

confidence: 99%