An assessment of the relative speeds and payload capacities of airborne and waterborne vehicles accentuates a gap that can be usefully filled by a new vehicle concept, making use of both hydrodynamic and aerodynamic forces. A high speed marine vehicle equipped with aerodynamic surfaces (called an AAMV, 'aerodynamically alleviated marine vehicle') is one such concept. There are three major modes of motion in the operation of an AAMV including take-off, cruising and landing. However, during take-off, hydrodynamic and aerodynamic problems of an AAMV interact with each other in a coupled manner, which make the evaluation of this phase much more difficult. In this article, at first aerodynamic characteristics such as lift and drag coefficients, were calculated, using theoretical relations in extreme ground effect, and then a relationship was made between total aerodynamic lift force and effective weight force in the hydrodynamic performance. Then, taking into account the aerodynamic, hydrostatic and hydrodynamic forces acting on the AAMV, equations of equilibrium were derived and solved. The developed method was well-validated against experimental data, and finally, influence of different hydrodynamic and aerodynamic parameters on the performance of the AAMV was investigated. Time-and costsaving in the preliminary design stage of an AAMV are some of the superiorities of the developed method over the numerical and experimental approaches.

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Purpose – The purpose of this paper is to present a fast, economical and practical method for mathematical modeling of aerodynamic characteristics of rectangular wing in ground (WIG) effect. Design/methodology/approach – Reynolds averaged Navier–Stokes (RANS) equations were converted to Bernoulli equation by reasonable assumptions. Also, Helmbold’s equation has been developed for calculation of the slope of wing lift coefficient in ground effect by defining equivalent aspect ratio (ARe). Comparison of present work results against the experimental results has shown good agreement. Findings – A practical mathematical modeling with lower computational time and higher accuracy was presented for calculating aerodynamic characteristics of rectangular WIG effect. The relative error between the present work results and the experimental results was less than 8 per cent. Also, the accuracy of the proposed method was checked by comparing with the numerical methods. The comparison showed fairly good accuracy. Research limitations/implications – Aerodynamic surfaces in ground effect were used for reducing wetted surface and increasing speed in high-speed marine and novel aeronautical vehicles. Practical implications – The proposed method is useful for investigation of aerodynamic performance of WIG vehicles and racing boats with aerodynamic surfaces in ground effect. Originality/value – The proposed method has reduced the computational time significantly as compared to numerical simulation that allows conceptual design of the WIG crafts and is also economical.

Hydro-aerodynamic mathematical model and multi-objective optimization of a popular wing-in-ground effect craft are presented in this research using a hydro-aerodynamic practical method and the genetic algorithm. The primary components of the wing-in-ground effect craft configuration include a compound wing, catamaran hull form and a poweraugmented ram platform. The hydro-aerodynamic practical method with low computational time and high accuracy is performed by coupling hydrodynamic and aerodynamic considerations using the potential flow theory in ground effect and the semi-empirical equations proposed for high-speed marine vehicles. The trade-off between hydrodynamic and aerodynamic characteristics makes it difficult to simultaneously satisfy the design requirements of high hydroaerodynamic performance. In this article, three goals-reduced hump resistance, increased compound wing lift-to-drag ratio and reduced takeoff speed-are selected as the objective functions. The longitudinal position of center of gravity, position of outer wing with respect to main wing, power augmented ram platform angle to horizontal and flap angle are also adopted as design variables. Static height stability and the location of the center of gravity with respect to the aerodynamics centers are considered as constraints for the stable flight in ground effect. The optimal solutions of the multiobjective optimization were not unique, rather a set of non-dominated optima, called the Pareto sets, are obtained. As a result of the multi-objective optimization, 25 Pareto individuals are obtained that the naval architects can use in designing wing-in-ground crafts.

Aerodynamically alleviated marine vehicle (AAMV) is a high speed craft equipped with aerodynamic surfaces that operating in ground effect zone provides this craft with the ability to achieve much higher cruising speeds. Reducing the take-off mode of an AAMV is highly desirable. Additionally, it is seen where there is a considerable reserve thrust take-off can occur in the lower get-away speeds that shorten the take-off run and, therefore, is favourable. Accordingly, in this study an attempt has been made to develop a nonlinear mathematical model for an AAMV to simulate accelerations in take-off and landing phases, using semi-empirical equations mainly proposed for mono-hull high-speed craft, which concurrently take into account the hydrostatic, hydrodynamic, aerodynamic and thrust forces. The developed model of dynamics has been well validated against the existing experimental data of an AAMV model test calm water resistance. Finally, the effects of various hydrodynamic and aerodynamic parameters on accelerations and thus total resistance and get-away speed of an AAMV in take-off phase have been investigated. This model has the ability to provide the designers with the valuable data on influence of various hydrodynamic and aerodynamic factors on accelerations of an AAMV in take-off phase, which can be usefully employed to lessen the get-away speed and take-off run.