• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.8
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• pp.37-46
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• 2004

Several notes on ground effects drawn from Navier-Stokes analyses and their aerodynamic interpretations were addressed here; For two-dimensional ground effect, the change of surface pressure due to image vortex, the venturi effect due to thickness and the primary inviscid flow phenomena of ground effect, and for three-dimensional ground effect, strengthened wing tip vortices, increased effective span and the outward drift of trailing vortices. Irodov's criteria were evaluated to investigate the static longitudinal stability of conventional NACA 6409 and DHMTU 8-30 airfoils. The analysis results demonstrated superior static longitudinal stability of DHMTU 8-30 airfoil. The DHMTU airfoil has quite lower value of lrodov's criterion than the conventional NACA airfoil, which require much smaller tail volume to stabilize the whole WIG-craft at its design stage.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.911-916
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• 2012

The purpose of this study is to review and suggest coastal shipping policies for introduction of WIG craft into domenstic passenger shipping market. Two Korean companies are leading in the development of WIG craft as an innovative sea transportation vehicle, and it is awaiting for commercialization. WIG craft is expected to be commercialized from coastal passenger market and we used AHP method to investigate the major factors and its' priority for smooth market entry. The results shows that priorities are on the WIG craft legislation, dock installation and operation, port state control, and pilot hiring and training, craft maintenance, and ship's certification in order.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.810-812
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• 2008

Previously study on structural design of the main wing of the twenty-seat class WIG(Wing in Ground Effect) craft. In the final design, three spars construction was selected for safety in the critical flight load, and the Carbon-Epoxy material was selected for lightness and structural stability. In this study, the forced vibration analysis was performed on the composite main wing structure of the twenty-seat class WIG craft with two-stroke pusher type reciprocating engine. The vibration analysis based on the finite element method was performed using a commercial FEM code, MSC/NASTRAN. Excitations for the frequency response analysis were assumed as the H-mode(horizontal mode), the V-mode(vertical mode) and the X-mode(twisted mode) which are typical main vibration modes of engine. And excitations for the transient response analysis were assumed as the L-mode(longitudinal mode) with the oscillating propeller thrust which occurs in operation. According to the result of forced vibration analysis, structural design was modified to reduce the vibrations.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.5
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• pp.381-389
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• 2011

In this study, we are focusing our attention on lift characteristics of the low aspect wings for Wing-In Ground effect crafts (WIG). Experimental measurements at an open-type wind tunnel are carried out and results are comparatively presented. In order to simulate the realistic ground condition in where the WIG craft is flying, moving ground is implemented by a conveyor belt rotating with the same velocity of the inflow. We consider two different wings (NACA0012 and DHMTU section) which have four different aspect ratios (0.5, 1.0, 1.5 and 2.0). Forces acting on the wings are measured and lift characteristics are elaborately investigated for various different conditions. In addition, end-plate effects are estimated. Results are validated by comparing with theoretic solutions of the symmetric airfoil. Present results show that ground effects are differently generated in moving or fixed ground conditions, and hence left characteristics are affected by the ground condition. Consequently, accurate aerodynamic forces acting on the WIG craft are guaranteed in a realistic moving ground condition.

• Journal of Aerospace System Engineering
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• v.1 no.1
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• pp.36-44
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• 2007

This study was performed on preliminary structural design of a small scale WIG craft which has been developed as a next generation high speed maritime transportation system in Korea. A composite structure design using the foam-sandwich for main wing and tail fins and the honeycomb sandwich and skin-stringer-ring frame for fuselage was applied for weight reduction as well as structural stability. A commercial FEM code, NASTRAN for was utilized to confirm the structural safety for the reiterate design modifications to meet design requirements including the target weight. Each main wing was jointed with the fuselage by eight high strength insert bolts for easy assembling and disassembling as well as for assuring the required 20 years service life. For control surface structural design, the channel type spar, the foam sandwich skin and the lug joint were adopted.

• International Journal of Aerospace System Engineering
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• v.6 no.1
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• pp.1-7
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• 2019

In the present study, structural safety and stability on the main wing and tail planes of the 1.2 ton WIG(Wing in Ground Effect) flight vehicle, which will be a high speed maritime transportation system for the next generation, was performed. The carbon-epoxy composite material was used in design of wing structure. The skin-spar with skin-stressed structural type was adopted for improvement of lightness and structural stability. As a design procedure for this study, the design load was estimated with maximum flight load. From static strength analysis results using finite element method of the commercial codes. From the stress analysis results of the main wing, it was confirmed that the upper skin structure between the second rib and the third rib was unstable for the buckling load. Therefore in order to solve this problem, three stiffeners at the buckled region were added. After design modification, even though the weight of the wing was a little bit heavier than the target weight, the structural safety and stability was satisfied for design requirements.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.2
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• pp.209-217
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• 2016

Unlike conventional airplane, a WIG craft experiences righting moment and adverse yaw moment in banked turning in ground effect. Numerical simulations are carried out to study the aerodynamics of banked wing in ground effect. Configurations of rectangular wing and delta wing are considered, and performance of endplates and ailerons during banking are also studied. The study shows that righting moment increase nonlinearly with heeling angle, and endplates enhance the righting. The asymmetric aerodynamic distribution along span of wing with heeling angle introduces adverse yaw moment. Heeling in ground effect with small ground clearance increases the vertical aerodynamic force and makes WIG craft climb. Deflections of ailerons introduce lift decrease and a light pitching motion. Delta wing shows advantage in banked turning for smaller righting moment and adverse yaw moment during banking.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.1
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• pp.60-67
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• 1997

This paper presents the results of 3rd wind tunnel test for the wings of WIG R/C test models, 'Hanjin-1' & 'Hanjin-2'. We made 'Hanjin-1' in last May 1995 and had a success in test flight. And in order to grasp the aerodynamic characteristics of wings in ground effect, the measurements of lift and drag were carried out for the various kinds of wing. It was shown that lift and lift-drag ratio increase with decrease of the clearance, but the feature was considerably depended on the shape of wing section. In this case we select the three kind of wing. section, and then compare their characteristics especially for a stability in longitudinal motion. They are NACA6409 for 'Hanjin-1' and the two kinds of DHMTU for ekranoplans of Russia. Experimental results show that the pitching moments of DHMTU wing sections are smaller than NACA6409.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.282-296
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• 2014

In this paper, an iterative boundary element method (IBEM) was proposed to solve for a wing-in-ground (WIG) effect. IBEM is a fast and accurate method used in many different fields of engineering and in this work; it is applied to a fluid flow problem assessing a wing in ground proximity. The theory and the developed code are validated first with other methods and the obtained results with the proposed method are found to be encouraging. Then, time consumptions of the direct and iterative methods were contrasted to evaluate the efficiency of IBEM. It is found out that IBEM dominates direct BEM in terms of time consumption in all trials. The iterative method seems very useful for quick assessment of a wing in ground proximity condition. After all, a NACA6409 wing section in ground vicinity is solved with IBEM to evaluate the WIG effect.

• International Journal of Aeronautical and Space Sciences
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• v.1 no.1
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• pp.29-35
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• 2000

A numerical method to simulate Wing-In-Ground(WIG) effects for the wings moving near ground is developed. The aerodynamic analysis scheme for the wings is based on a compressible non-planar lifting surface panel method and the WIG effect is included by images. The thickness-induced effect is implemented into the lifting surface panel method by using the teardrop theory. The numerical simulation is done for the rectangular wings by varying the ground proximity. The present method is validated by comparing the calculated aerodynamic coefficients with other numerical results and measured data, showing good agreements.