# Conceptual Model of "Lapwing" Amphibious Aircraft

Iftikhar B Abbasov, V'iacheslav V Orekhov

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Iftikhar B Abbasov, V'iacheslav V Orekhov. Conceptual Model of "Lapwing" Amphibious Aircraft. Mechanics, Materials Science & Engineering Journal, 2017, 7, 10.13140/RG.2.2.12856.14081. hal-01508613

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# Conceptual Model of “Lapwing” Amphibious Aircraft

Iftikhar B. Abbasov¹, V'iacheslav V. Orekhov¹

1 – Southern Federal University, Nekrasovskyi lane, 44, Taganrog, Russia

<figure><img src="image_2.png" /></figure>

DOI 10.13140/RG.2.2.12856.14081

**Keywords:** conceptual model, amphibious aircraft, bionics, 3D model, method of polygonal extrude, shading and rendering.

**ABSTRACT.** The paper is dedicated to computational modelling of conceptually new amphibious aircraft. Based on the analysis of bionical forms of operational medium there provided are the visual and graphical solutions of the developed model. Sketch drawings considering the requirements of ergonomics are provided, sketch of amphibious aircraft 3D model is created. Based on sketch projects the stage-by-stage 3D modelling of amphibious aircraft structural parts was performed. Modelling has been provided by methods of polygonal extrude. Materials shading and rendering provided at sub-object level. There provided are the scenes of rendering of shaded 3D model of amphibious aircraft.

**Introduction.** Today hydroaviation is actively used in different fields, starting from fire-fighting and effective-rescue operations up to passenger traffic. The issues of applying modern technologies of modelling for aircraft designing are challenging. The most important stage is the development of preliminary concept of transportation means. Let us review some of the modern literary sources in this field. The article [15] is dedicated to conceptual designing of aircraft, where aerodynamic properties of bird wings are considered. The works [14], [18] study the issues of designing economical passenger aircraft.

The article [7] is dedicated to conceptual designing of passenger aircraft of “flying wing” type. There provided and analysed are the different variants of aerodynamic configurations. The work [8] contains the peculiarities of conceptual designing of new generation of supersonic aircraft with original arrangement of landing gear and fuel tank. Article [9] describes the peculiarities of implementing modern program tools for the purposes of designing. There described are the possibilities of new program for aircraft structure development. The issues of conceptual designing initial stage are described in detail in book [13]. There provided is the methodological base of idea generation stages, determination of initial requirements for future structure. The book [23] contains the peculiarities of preliminary and conceptual designing of aircraft. Modern systems of automated designing are described in detail.

This work is dedicated to three-dimensional computer-aided modelling of new concept of amphibious aircraft. It is supposed that the developed model will be in the middle segment of hydroaviation market. In the result of amphibious aircraft market review we can remark the following aircraft of low passenger capacity up to 25 persons: Be-103 produced by Beriev Aircraft Company [21], flying amphibious boat Airmaster Avalon-680 produced in the USA, amphibious aircraft Do-24 produced by German company Dornier Seastar [20]. For the developed model the crew will consist of 2 persons, the passenger compartment can contain up to 24 passengers.

It is necessary to note, that the issues of computer-aided modelling of aircraft were studied by the authors in the works [3-4]. The work [3] provides conceptual visual and graphical solutions of new aircraft based on bionical forms analysis.
**Concept development.** In every field of our life, everything in our environment is the product of human thought. The manufacturing of these subjects and objects starts from concept development, creation of prototype of future item [11], [12]. If earlier rather large expenses and materials were required for this purpose, then today in the era of computer-aided technologies this task is simplified, there is no limit for the designers' ideas and imagination.

The process of conceptual development and modelling of transportation means takes several stages. At the first stage the sketch was created, the general view of future model is drawn: compositional solution; proportion of component parts relatively each other; main style solutions [17], [10]. Based on the analysis of natural shapes rendering the concept of future prototype is selected.

In the course of concept development a method of designing based on bionical forms was used. Mammals, fish and birds can provide the designer with interesting visual solutions. At that aircraft fuselage, and mainly flying boat one, shall meet the requirements of aero- and hydrodynamics at the same time. That is why the designers have the task of searching for a compromise. In the course of creative search of aircraft outlines, some visual and graphical solutions were found, the base of which became natural biological forms living in this environment (Fig.1-4).

<figure><img src="image_3.png" /><figcaption>Fig. 1. Blue whale and sketch of amphibious aircraft fuselage.</figcaption></figure>
<figure><img src="image_4.png" /><figcaption>Fig. 2. Finback whale and sketch of amphibious aircraft fuselage.</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>Fig. 3. Mackerel and sketch of amphibious aircraft fuselage.</figcaption></figure>
<figure><img src="image_6.png" /><figcaption>Fig. 4. "Flying fish" in natural living conditions and sketch of amphibious aircraft fuselage.</figcaption></figure>

Based on the analysis of natural forms rendering of off-shore strips the bird lapwing (northern lapwing) has been selected. Northern lapwing (vanellus vanellus - in Latin) is a small bird of dotterel family, it lives in water ponds, has good flying properties, during mating season the males attract the females by air games (Fig.5) [22]. Black-and-white colour of its coat will be used for three-dimensional model shading in future. Fig.6 provides preliminary design, sketches of the future item forms.

<figure><img src="image_7.png" /><figcaption>Fig. 5. Lapwing bird.</figcaption></figure>
<figure><img src="image_8.png" /><figcaption>Fig. 6. Preliminary sketch.</figcaption></figure>

Then the model is drawn in detail with reference to medium dimensions, in which the item is planned for operation, biometric parameters of a man considering the requirements of ergonomics (Fig.7, 8) [19], [2].

<figure><img src="image_9.png" /><figcaption>Fig. 7. Left board view of prototype.</figcaption></figure>

<figure><img src="image_10.png" /><figcaption>Fig. 8. Prototype reference to anthropometric and ergonomic requirements.</figcaption></figure>

The base of future hydro-aircraft “Lapwing” concept is water-borne wing capable of glissading on three points (step, left and right rear edges of centre wing). Such scheme is very advantageous for stable movement on the water at taking-off and landing regimes and increase of seaworthiness. Low location of the wing relatively the boat creates increase of elevating force due to ground effect at taking-off and landing, allows simplifying and lightening the structure of aircraft (Fig.9).
<figure><img src="image_11.png" /><figcaption>Fig. 9. Front view and top view of amphibious aircraft prototype.</figcaption></figure>

The dimensions of prototype body shall consider the requirements of future interior and tasks on cargo containers arrangement. Wing span is 18.5 m, aircraft length is 16.9 m, and height is 4.87 m.

Fuselage structure can be done from aluminium alloys with the application of composite materials. In the top part of fuselage there are power elements on the base of solar batteries for partial power supply to aircraft on board network. Aircraft wing has all-metal structure, it has trapezoidal shape with root extensions; it consists of centre wing and two removable panels. On the wing end there are winglets and tips that are designed for increasing effective wing span and lifting force. For the provision of resistance to flooding the wing is separated by water-proof partitions to sections.

Vertical tail fins are single-fin, cantilever. In the top part of the fin there is controllable stabilizing fin. Landing gear is three-leg type, the diameter of rear leg tires is larger than the front one. Power unit consists of two turbojet engines located on the pylons close to fuselage tail part.

For cargo-carrying variant, the increase of fuselage length by 1 m is provided with the help of insert. It aims to locate cargo door with dimension 1700x1700 mm along the right board. The crew consists of 2 persons (as for business class variant one steward is added). The passenger compartment can contain up to 26 passengers, in cargo-carrying variant 4 LD2 containers are provided.

Fig.10 provides shaded sketch of three-dimensional model of amphibious aircraft. The aircraft is designed for use at short-distance lines in different regions of the world, in regions with large number
of rivers, lakes, shallow water ponds that are hard-to-reach for other types of transport. It can be used for transportation of passengers, cargos, fire-fighting supervision, patrolling, ecological control of water areas, provision of emergency medical care, rendering emergency-rescue works, rest and tourism.

<figure><img src="image_12.png" /><figcaption>Fig. 10. Shaded sketch of three-dimensional model of amphibious aircraft.</figcaption></figure>

## 3D modelling of amphibious aircraft “Lapwing”

Modelling of amphibious aircraft structure shall be done with the help of graphic system of three-dimensional modelling – 3ds Max. The graphic system 3ds Max allows working with drawings made in other graphic packages, thus extending the possibilities of the designer [1]. Three-dimensional model of amphibious aircraft can be created by different methods, one of which is the method of polygonal extrude. For this method, the modelling starts from creating three perpendicular planes with aircraft projections located on them.

For fuselage modelling created using the polygon based on Plane primitive element with the number of segments at X and Y axes equal to 1. Later this primitive element shall be transferred into Editable Poly object. According to fuselage projection the object surface is created by sequential duplication of one of polygon planes (Fig.11). At that body half is created for construction convenience with consideration of model longitudinal symmetry.
<figure><img src="image_13.png" /><figcaption>Fig. 11. Sequential extrude of fuselage polygons.</figcaption></figure>

In the course of planes extruding it is necessary to maintain constant number of polygons along the whole fuselage in order to prevent problems with geometry and further modification of model. Then the aircraft body is created by method of sequential extrusion of group of polygons followed by projects adjustment (Fig.12).

<figure><img src="image_14.png" /><figcaption>Fig. 12. Model control in front view.</figcaption></figure>

The received result is the base for fuselage, the other structural parts of the aircraft are extruded by similar method: tail fins, wing, engine pylon, engine body, lifting propeller (Fig.13, 14, 15) [24], [16]. The wing has complicated profile, because it plays the lifting role for the aircraft in glissading mode and works as the screen increasing the lifting force in the moment of taking-off from water surface.

At the next stage the model geometry is modified. Fuselage modification supposes modelling of transparency and side windows. The wing together with steering control and horizontal stabilizer is also designed in detail.
<figure><img src="image_15.png" /><figcaption>Fig. 13. Fuselage body blank.</figcaption></figure>

<figure><img src="image_16.png" /><figcaption>Fig. 14. Creation of tail fins.</figcaption></figure>

<figure><img src="image_17.png" /><figcaption>Fig. 15. Engine body with carrying pylon.</figcaption></figure>

Initially all model component parts are faceted. The capabilities of 3ds Max graphic system allow smoothing faceted objects by different methods. One of the variants is the application of smoothing method NURMS (Non Uniform Rational Mesh Smooth). When surfaces are smoothed the second mirror-like longitudinal half of the aircraft is constructed (Fig. 16).
<figure><img src="image_18.png" /><figcaption>Fig. 16. Assembly of aircraft body half.</figcaption></figure>

Shading and rendering of 3D model of “Lapwing” amphibious aircraft

The next step of designing is shading and rendering of constructed model. The process of materials rendering to fuselage separate parts is done at the level of polygons.

After all performed operations we can obtain finished model for further rendering with the help of realistic models of lighting (Fig.17). Integrated V-Ray module is used for scene rendering. Fig.18 a, b, c, shows final rendering scene of shaded model of “Lapwing” amphibious aircraft.
<figure><img src="image_19.png" /><figcaption>Fig. 17. Assembled three-dimensional model with rendered materials.</figcaption></figure>

As a result, we can note that the developed three-dimensional conceptual model of amphibious aircraft is performed from creative idea to photorealistic rendering.

<figure><img src="image_20.png" /><figcaption>Fig. 18, a</figcaption></figure>
<figure><img src="image_21.png" /><figcaption>Fig.18, b</figcaption></figure>

<figure><img src="image_22.png" /><figcaption>Fig.18, c. Rendering of “Lapwing” amphibious aircraft conceptual model.</figcaption></figure>

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