# Development of a calculation model for planing seaplane equipped with automatically operated interceptors

### Аuthors

Ovdienko M. A.

Company «TrimSystems», 81, Dekabristov str., Kazan, 420034, Russia

e-mail: m.a.ovdienko@gmail.com

### Abstract

The presented work is dedicated to the development of high-speed vessels equipped with automatically controlled hydrodynamic interceptors to improve their hydrodynamic characteristics and seaworthiness.

The hydrodynamic interceptor is a small plate, being mounted transversely to the flow, near the aft cut or planing step of the gliding vessel. Due to the flow deceleration afore them, the area of increased pressure formed created, which leads to the total lift force increase and the displacement of its application point towards the interceptor. Thus, the interceptor can operate as a hydrodynamic mechanization to control the trim and roll angles. The interceptor minimal effort is required to move the due to the orthogonal position of the plates’ direction extension and the forces acting on it. It allows developing high-frequency control systems based on interceptors.

The author proposes to install controlled hydrodynamic interceptors on stern of seaplane forebody hull. It is possible to achieve optimum trim angles, which ensure minimum resistance, by controlling interceptors. It is also possible to fend off the oscillations and overloads acting on the seaplane during the planing on waves by controlling interceptors in the automatic mode. To verify this proposal, a mathematical model of the seaplane planing in conditions of smooth water, as well as regular and irregular waves was developed. The mathematical model is based on the plane cross sections method and accounts for the presence of hydrodynamic interceptors. Besides, this model allows simulating the operation of an aerodynamic pitch-rate damper, which is used as an elevator.

Computations were performed for a seaplane with a take-off mass of 37 tons, the of forebody width near the stern of 2.1 m, and a take-off speed of 52 m/s. Computations of planing on calm water confirmed the assumption on the possibility of the effective trim angle control, and thus ensure a minimum drag force. It was found that uncontrolled interceptor could lead to self-oscillations, but the automatic control system introduction completely eliminated the possible instability. Thus, the automatically controlled hydrodynamic interceptors can be considered as a tool of the seaplane steady planing boundaries expansion.

The seaplane planing dynamics in conditions of regular waves were simulated at the wavelength of 50 m and a wave height of 0.8 m. The computation results revealed that the hydrodynamic interceptors control system allowed reducing by several times the amplitude of the seaplane oscillations in the trim angle and in the vertical plane. Automatically controlled interceptors are most effective while joint operation with aerodynamic pitch dampener.

The performed studies confirmed the assumption put forward. Automatically controlled hydrodynamic interceptors application can be recommended for hydrodynamic and seaworthiness characteristics enhancing of the conventional and prospective seaplanes.

### Keywords:

hydroplane, hydrodynamic interceptors, hydrodynamic tests, towing tank, seaworthiness

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