Reverse Engineering of Micro Light Aircraft Systems and Design

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REVERSE ENGINEERING OF MICRO LIGHT AIRCRAFT SYSTEMS AND DESIGN

WAN AZIZURRAHMAN BIN WAN HASSAN

A thesis submitted in

fulfillment of the requirement for the award of the

Degree of Master of Mechanical Engineering

FACULTY OF MECHANICAL AND MANUFACTURING ENGINEERING

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

JUNE 2014

ABSTRACT

Microlight industry has become popular nowadays and has its own fan in Malaysia. In western side of the world, the microlight boom which started in late 1970s and 1980s was driven by a number of factors that permitted practical flying machines to be produced at lower cost than ever before. Here in Malaysia, most of the aircraft were imported from European and US as the manufacturer are from there. To reduce the cost of manufacturing an aircraft, this paper had tried to study the construction of an aircraft by using proposed reverse engineering process. A microlight aircraft model Quicksilver GT500 has become a subject of study and Autodesk Inventor software is selected as preferred software to remodel the aircraft structure. Remodelling process of the aircraft started with taking actual measurement on the site aircraft guided with manual book of aircraft assembly and maintenance as reference. The CAD model of the aircraft then imposed stress load analysis to study the effect of proposed material to the structure reliability. Maximum take-off weight of aircraft of 1000lbs (454 kg) was used as maximum load on the aircraft while in cruise mode. Three types of aluminium alloy of Al2024, Al6061, and Al7075 have been studied on their influences to the wing structure design. The influence of Center of Gravity to the aircraft balancing is discussed. Wing structural design of joints between tubes is also discussed. Manufacturing process and techniques of the aircraft parts and components are identified. Lastly, the aircraft control system has been studied.

ABSTRAK

Industri penerbangan pesawat mikro menjadi semakin popular di kalangan rakyat Malaysia sejak akhir-akhir ini. Namun, di Negara-negara barat, populariti pesawat mikro telah lama meletus sejak dari tahun 1970-an hingga 1980-an lagi sehingga membolehkan penghasilan pesawat tersebut pada kos yang murah dan pelbagai rekabentuk. Industri penghasilan pesawat mikro di Malaysia tidaklah sehebat negara barat menyebabkan kebanyakan pesawat adalah diimport dari negara asal pengeluar dan pada kos yang tinggi. Namun permintaannya yang semakin meningkat di Malaysia telah mendorong beberapa pereka amatur untuk cuba menghasilkan sendiri pesawat berpandukan rekabentuk pesawat sedia ada. Kaedah yang digunakan adakalanya tidak sistematik dan sekadar menggunakan pengalaman dan pengetahuan peribadi dalam bidang fabrikasi untuk menghasilkan pesawat sendiri. Projek ini dijalankan bertujuan untuk mengkaji binaan rekabentuk pesawat untuk membolehkan ia dihasilkan semula menggunakan teknologi sedia ada pada kos yang lebih murah.Teknik kejuruteraan balikan digunakan bagi tujuan ini dan pesawat yang dikaji adalah jenis Quicksilver GT500 Microlight. Perisian yang digunakan untuk tujuan pemodelan adalah Autodesk Inventor versi 2012. Proses pemodelan dimulakan dengan kerja-kerja pengukuran pada pesawat sebenar dan dibantu oleh dokumen manual pemasangan dan penyelenggaraan pesawat tersebut. Model CAD pesawat tersebut kemudian dilakukan analisis beban tegasan menggunakan fungsi CAE yang tersedia pada perisian tersebut. Nilai beban maksimum pesawat iaitu 1000 lb (454 kg) digunakan sebagai beban maksimum yang dikenakan ke atas struktur pesawat dan pusat beban adalah pada pusat graviti pesawat tersebut. Tiga jenis aluminium iaitu Al2024, Al6061, and Al7075 digunakan sebagai bahan binaan sayap pesawat dan dikaji pengaruhnya terhadap keupayaan struktur menampung beban yang dikenakan. Pengaruh pusat graviti ke atas keseimbangan pesawat dibincangkan. Pengaruh rekabentuk sayap pesawat ke atas kekuatan sayap turut dibincangkan. Selain itu, proses dan teknik pembuatan yang terlibat telah dikenalpasti. Akhir sekali, sistem kawalan pesawat telah dikaji.

CONTENTS

TITLE i DECLARATION ii DEDICATION iii ACKNOWLEDGEMENT iv ABSTRACT v ABSTRAK vi CONTENTS vii LIST OF FIGURES xi LIST OF TABLES xvi LIST OF SYMBOLS AND ABBREVIATIONS xvii CHAPTER 1 INTRODUCTION 1 1.1 Research background 1 1.2 Problems Statement 1 1.3 Research Objective 2 1.4 Scope of Study 2 1.5 Expected Outcome 3 1.6 Significant of Research 3

CHAPTER 2 THEORETICAL AND LITERATURE REVIEW 5 2.1 Reverse Engineering 5 2.1.1 Types of Reverse Engineering 7 Techniques 2.1.2 Computer Aided Design (CAD) and 10 Computer Aided Engineering (CAE) 2.2 Microlight Aircraft 11 2.2.1 History of Microlight Aircraft 12 2.2.2 Types of Microlight Aircraft 12 2.3 Quicksilver GT500 Microlight Aircraft 14

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2.3.1 Main Aircraft Component 16 2.3.2 The Wings – Structure 16 2.3.3 Fuselage 18 2.3.4 Empennage 19 2.3.5 Ailerons & Flaps 20 2.4 Materials 21 2.4.1 Aluminium 21 2.4.1 Aluminium Alloy 2024 23 2.4.2 Aluminium Alloy 6061 23 2.4.3 Aluminium Alloy 7075 23 2.4.2 Steel 24 2.4.3 Composite 25 2.4.4 Tubes 26 2.4.5 Bracing Cables 28 2.4.6 Bolts and Nuts 29 2.5 Manufacturing Process and Assembly Techniques 31 2.5.1 Bending 31 2.5.2 Hole Drilling 32 2.6 Structural Analysis 33 2.6.1 Engineering Stress 34 2.6.2 Engineering Strain 35 2.6.3 Young's Modulus - Modulus of Elasticity (or Tensile Modulus) - Hooke's Law 35 2.6.4 Shear Modulus 36 2.6.5 Von Mises Stress 36 2.6.5.1 Distortion energy Theory 36 2.6.6 Principal Stress 38 2.7 Air-load Distributions 39 2.7.1 Schrenk’s Approximation Methods 40

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CHAPTER 3 METHODOLOGY 42 3.1 Assumptions 43 3.2 Specification of Quicksilver GT500 Microlight 43 Aircraft 3.3 Data Acquisitions 44 3.4 Image Modelling 45 3.5 CAE Analysis 46 3.5.1 Selection of Material 48 3.5.2 Simplification of Analysis 48 3.5.3 Distributed Load on Aircraft Wing 49 3.5.4 Wing Loading Calculation 51 3.5.5 Determination of Constrain 52 3.5.6 Evaluation on Analysis 53 3.6 Selection of Material 53

CHAPTER 4 RESULTS AND DISCUSSIONS 54 4.1 Stress Load Analysis 55 4.1.1. Loads on the Aircraft 56 4.1.2. Determination of Center of Gravity 58 4.1.3. CADCAE Analysis 59 4.1.3.1. Stress Analysis for Wing Base 60 Structure Using Aluminium 2024 4.1.3.2. Stress Analysis for Wing Base 64 Structure Using Aluminium 6061 4.1.3.3. Stress Analysis for Wing Base 68 Structure Using Aluminium 7050 4.2 Built up Material 72

4.2.1. Aluminium Alloy 75 4.2.2. Steel Alloy 77 4.2.3. Polymer 78 4.2.4. Composite 79 4.2.5. Fabric 80 4.3 Fasteners and Structural Joints 81 4.3.1. Aircraft Bolts and Nuts 82 4.3.2. Rivet 83 4.3.3. Weld Joints and Adhesive Bonding 85 4.4 Manufacturing Process 86 4.4.1. Bending 86 4.4.2. Drilling 87 4.5 Aircraft Control System 88 4.5.1. Flight Controls 89 4.5.2. Ground Control 90 4.5.3. Landing Gear 91 4.5.4. Fuel System 91 4.5.5. Brake System 92 4.5.6. Instrument Panel 93 4.5.7. Powerplant 94

CHAPTER 5 CONCLUSSION AND RECOMMENDATION 95 5.1 Conclusion 95 5.2 Suggestion for Improvement 96

REFERENCES APPENDICES

LIST OF FIGURES

Figure no. Title Page 1.1 Example of the sequences of the reverse engineering 2 (RE) process.

2.1 Basic flow of reverse engineering processes 6 2.2 Types of reverse engineering technique 7 2.3 Traditional reverse engineering process according to 9 QingJin Peng et. al. (1998) 2.4 The reverse engineering process based on vision 9 information 2.5 An example of point cloud from 3D scanning 9 2.6 Fixed wing aircraft 13 2.7 Flexwing aircraft 13 2.8 A Quicksilver GT500 microlight aircraft 16 2.9 Three types of aircraft wings 17 2.10 Dihedral angle for aircraft wing 17 2.11 Wing frame main components of Quicksilver GT500 18 aircraft 2.12 The built up components of an aircraft wings 18 2.13 Fuselage of GT500 aircraft 19 2.14 An example of fuselage frame of microlight aircraft 19 2.15 Empennage structure 20 2.16 Location of aileron (red area) and flap (yellow area) on 20 aircraft wing. 2.17 An example of landing gear for microlight aircraft 25 2.18 Modern ultralight airplanes use aluminium tubes as 27 both spars and wing leading edges 2.19 A single-tube frame structure of Maxair Hummer 28

ultralight 2.20 Cable construction is defined by number of strands and 29 the number of wires per strand 2.21 Basics of bolts installation 30 2.22 The position of hole that can be drill on the aluminium 32 tube of wing spar 2.23 Types of load acting on aircraft. 34 2.24 Condition of engineering stress in solid objects. 35 2.25 Representation of a pure distortion case. 37 Stress boundary conditions on a 2 dimensional element. 2.26 Stress boundary conditions in a 3 dimensional body 38 and normal stress values induced in it. 2.27 Span-wise and chord-wise loadings on aircraft wing. 39 2.28 Types of planform wing by aircraft manufacturers. 40 2.29 Plan-form geometry for Schrenk’s method. 41

3.1 Reverse Engineering procedure for the project 42 3.2 Quicksilver GT500 microlight aircraft. 44 3.3 GT500 mainframe structure. 44 3.4 The division of subsystem for Quicksilver GT500 45 microlight aircraft. 3.5 An example of CAD design performs using Autodesk 46 Inventor 2012. 3.6 An example of stress analysis on aircraft structure that 47 has been done by CAE software. 3.7 Flowchart diagram on engineering analysis for 48 determination of material. 3.8 Load distribution on wing. 52 3.9 Location of constrain at (a) landing gear carry thru, (b) 53 root tube

xii

4.1 (a) Top view of CAD design for Quicksilver GT500 55 microlight aircraft structure. (b) Front view of CAD design for Quicksilver GT500 microlight aircraft structure. (c) Side view of CAD design for Quicksilver GT500 microlight aircraft structure. 4.2 Total lift force, Ls distribution on the aircraft wing 55 structure. 4.3 Wing spanwise lift distribution. 57 4.4 The CG location of Quicksilver aircraft wing 58 determined by using CADCAE software. 4.5 Assembly of main wing structure and the loads acting 59 on the structure. 4.6 Parts and components of wing structure that being 60 replaced by 3 types of material for stress analysis. 4.7 Result of stress analysis on wing structure using 62 Aluminium 2024 material. 4.8 Displacement of structure using Aluminium 2024. 63 4.9 Safety Factor of structure using Aluminium 2024. 63 4.10 Result of stress analysis on wing structure using 66 Aluminium 6061 material. 4.11 Displacement of structure using Aluminium 6061. 67 4.12 Safety Factor of structure using Aluminium 6061 67 4.13 Result of stress analysis on wing structure using 70 Aluminium 7050 material. 4.14 Displacement of structure using Aluminium 7050. 71 4.15 Safety factor of structure using Aluminium 7050. 71 4.16 Landing gear of GT500 model aircraft are made from 78 high strength steel material. 4.17 The use of polymer material on aircraft bodyskin is 78 more on windshield and safety door application.

xiii

4.18 (a) Seat bucket for pilot are made from composite 79 materials. (b) Body skin of GT500 aircraft model are made from fibre glass material. 4.19 Wing skins of the aircraft are made from lightweight 81 but high strength fabric material like Dacron. 4.20 The use of bolts and nuts are being applied on main 83 structure joining for safety purpose. (a) An eyebolt is use to joint vertical stabilizer trailing edge and rudder leading edge assembly. (b) and (c) AN type hexagonal bolts and nuts are use to firmly joint the main structures of the aircraft and received large amount of shear loading from the aircraft body weight. (d) Bolt loaded in double shear with associated bending due to load offset. 4.21 Riveting techniques are applied to join non-structural 83 components of the aircraft. (a) Rivet joining on tail boom structure to hold empennage control parts. (b) Rivet is used to hold seat bracket in position on forward fuselage. (c) Rivet is used to assemble body skin to the tail boom tube. 4.22 An example of weld joint application on GT500 86 Quicksilver airplane as can be seen on rudder shaft joining. 4.23 Radius of tubing bending. 87 4.24 Location of the drilled holes must be at the centre of 88 the tube structure. 4.25 GT500 aircraft surface control system. 89 4.26 A simple mechanical cable operated system found on 90 Quicksilver GT500 aircraft. The cables in this aircraft sometimes are replaced by rods. The control column can be moved by raising and lowering the elevator.

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4.27 Location of (A) aileron and (B) wing flap as can be 90 seen on figure above. 4.28 Two main wheels and tail skid are playing important 91 role in landing situation while nose wheel give little support. 4.29 (a) The location of hand brake lever (inside yellow 92 circle) which is on the right side of the pilots give confident to the pilot while landing the aircraft. (b) Mainwheel construction are made from reliable material to give extra safety to the pilot. The mainwheel braking systems are using disc and hydraulic clamping system. 4.30 An overview of pilot cockpit of GT500 aircraft. Basic 93 controller indicator is as displayed on dashboard. 4.31 Instrument panel layout for GT500. 94 4.32 A Rotax 582/40 rotary valve engine that powered the 94 GT500 aircraft.

LIST OF TABLES

Table no. Title Page 2.1 Specification of GT 500 Quicksilver for two type of 15 engine. 2.2 Wrought alloy aluminium series 22 2.3 Mechanical properties of selected Aluminium alloys 24 2.4 Comparison of properties for thermoset resins 26 2.5 Comparison of the wire strength between sizes, 29 material, and number of strands

3.1 Detail specification of Quicksilver GT500 microlight 43 aircraft

4.1 Calculated lift distribution value of aircraft wing. 56 4.2 Coordination of CG as determined using Autodesk 58 Inventor 2012 software. 4.3 Results summary of stress analysis for Aluminium 61 2024 material. 4.4 Results summary of stress analysis for Aluminium 64 6061 material. 4.5 Results summary of stress analysis for Aluminium 68 7050 material. 4.6 Types of material using on wing’s structure of 72 Quicksilver GT500 aircraft. 4.7 Non-heat treatable alloys applications on aircraft. 76 4.8 Heat treatable alloys applications on aircraft. 76 4.9 Selection of fabric types by breaking strength criteria. 80

xvi

LIST OF SYMBOLS AND ABBREVIATIONS

CAD Computer Aided Design CAE Computer Aided Engineering AoA angle of attack MPa mega Pascals ksi kilopounds persquare inches CG center of gravity CP center of pressure CAS calibrated airspeed

Vso calibrated stall or minimum flying speed in the landing configuration at maximum take-off mass

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CHAPTER 1

INTRODUCTION

Reverse Engineering (RE) refers to the process of creating engineering design data from existing parts. It recreates or clones an existing part by acquiring the surface data of an existing part using a scanning or measurement device. It is useful in recreating the CAD model of an existing part when the engineering design is lost or when the model has gone through many design changes.

The application field of reverse engineering techniques are very wide. Many tools and methods had been introduced by researchers and engineers in order to propose the most economical ways of using reverse engineering techniques to the industry. In related mechanical areas like automotives and machineries, the used of reverse engineering become popular since it cost minimums and produce the results at shortest period of time compared to conventional R&D method.

Sokovic and Kopac (2006) have discussed in their publication about the importance of reverse engineering application on rapid product development in automotive industry. To upgrade the whole parts of a car may take a lot of time. However, by applying reverse engineering on certain parts, the new or facelift model can be introduced to the market at quicker time. Figure 1.1 explain the whole process of reverse engineering techniques in manufacturing industries start from digitizing the data, converting into standard computer language and lastly produce the product using CADCAM machining process. 2

Figure 1.1: Example of the sequences of the reverse engineering (RE) process. (Sokovic and Kopac, 2006)

Another popular application of RE besides of engineering fields is in medical fields. The needs of reconstructing the bones of patients requires the doctors to do RE on the patient’s damage bones by using conventional and new technologies. Lin et al (2005) have discuss about the RE technique use in reconstructing the artificial joint for the patients with arthritis types problems. The application of CADCAM technologies not only focus on manufacturing industries as explain by them. The needs of designing the customized prostheses that best matches the human anatomy, according to different patients’ requirement, is gaining more attention 3 nowadays. Various kinds of requirement indirectly had boosted the introduction of new technologies in the market to fulfil them.

RE application in aircraft industries are very similar to automotives industry. The techniques and methods are same as both of them apply general engineering knowledge during the whole development of the product. Further explanations are as in Chapter 2 of this report.

1.1 Research Background

This research will focus on determining the possibility of using RE methods to identify the types of material and manufacturing process involved in fabricating a microlight aircraft. For this research, one model of microlight aircraft will be use as reference upon completing the RE processes. The comparative study will be carry out in terms of the cost of manufacture, time to produce and dimensioning accuracy of both existing and redesign aircraft models.

1.2 Problem Statement

Currently in Malaysia, aircraft industry is developing quite slow due to the high cost of producing aircraft and also limited acquisition of manufacturing technology. These constraints cause a lack of interest from investors to invest in the aeronautics industry. However, in other countries especially Europe, there are a lot of investor and small scale manufacturers who actively involve in producing microlight aircraft to fulfil the demands. To produce an aircraft, a lot of money needs to be invested and very time consuming. Besides, lack of knowledge and limited facilities are the main factors of inability to produce an aircraft in Malaysia.

Reverse engineering (RE) is the best way to be applied by designers in order to produce their product at short time and at relatively lower cost. By applying RE into aircraft design, the designers are able to concentrate on small modification and upgrading the current product instead of spending a lot of time to built a new one. Most of the manufacturer just selling their products, but not the entire information about the product. Therefore, RE technique is appropriate to identify the 4 material specifications, manufacturing and assembly process, and also the alternative design for the product.

1.3 Objectives

The objectives of this research are as follows: 1. To model aircraft mainframe using CAD software. 2. To determine the materials used for structural and skin. 3. To identify the manufacturing methods/ techniques to produce the structural frame.

1.4 Scope of Study

The research is limited according to the scopes below: 1. The study of microlight aircraft subsystems is to understand the critical loads effect on structural beam. 2. The reference microlight aircraft is Quicksilver GT500. 3. The structural analysis is implemented by using Autodesk Inventor 2012. 4. The CAD model of the aircraft is developed by using Autodesk Inventor 2012.

1.5 Research Contribution

This research has able to accumulate a comprehensive information on the reference microlight aircraft into CAD modelling, acquire information on built up materials, and related manufacturing process to produce the aircraft.

1.6 Significant of Research

This project is being carried out to prove that reverse engineering techniques is able to reproduce the microlight aircraft with the help of available CAD software in the market. Besides, this project also hopefully will help to boost the manufacturing industry of microlight aircraft in Malaysia by producing it at lower cost. 5

CHAPTER 2

THEORETRICAL AND LITERATURE REVIEW

Reverse Engineering (RE) refers to the process of creating engineering design data from existing parts. It recreates or clones an existing part by acquiring the surface data of an existing part using a scanning or measurement device. According to Peng and Loftus (1998), RE is useful in recreating the CAD model of an existing part when the engineering design is lost or when the model has gone through many design changes.

2.1 Reverse Engineering

Reverse engineering and rapid prototyping of objects with complex surfaces have received significant attention from both research and industrial communities nowadays. This is happening mainly because of growing global competition that requires manufacturers to deliver more competitive products with better quality and lower prices. Reducing the product development time had become a challenging tasks faced by manufacturing industry. The demanding and competition exist all over the world since most of countries had practice open-air economic system.

Lin et al. (2005) stated that reverse engineering (RE) is an important branch of the mechanical design and manufacture application field. This technique has been widely recognized as a crucial step in the product design cycle. According to Lin et al. (2005), reverse engineering is the process of 6 engineering backward to build a CAD model geometrically identical to an existing product. As shown in Figure 2.1, Lee and Yoo (2000) define the reverse engineering as the backward process used to recover higher level conceptual elements from physical systems.

In normal automated manufacturing environment, the operation sequence usually starts from product design via computer-aided design (CAD) techniques, and ends with generation of machining instructions required to convert raw material into a finished product. In contrast to this conventional manufacturing sequence, reverse engineering represents an approach for the new design of a product that lacks an existing CAD model.

In the process of the product design and research, the use of RE will largely reduced the production period and costs. Unlike the traditional manufacturing philosophy of designs being transposed into products, reverse engineering measures, analyses, modifies, and produces the products based on existing artifacts (Vergeest and Horvath, 2009). Using 3D point data collected by contact or non-contact method, a CAD model can be created and employed in subsequent manufacturing processes.

Data Physical acquisition Image Engineering prototype using modelling Existing Parts analysis using using Rapid scanning or using CAD CAE software Prototyping measurement software Machine device

Figure 2.1: Basic flow of reverse engineering processes. (Lee and Yoo, 2000)

Yang and Chen (2005) had presented a new reverse engineering methodology based on haptic volume removing. By using a haptic device, the number of view changes could also be reduced and operating time be shortened. However, the limitation of the workpiece size to be measure makes it impossible to be applied on large size objects. The accuracy of the mirror image still considers low since it is dependent on the voxel resolutions.

The success of reverse engineering is that it not only generates accurate mathematical computer-aided design (CAD) models for design and manufacturing purposes, but can significantly reduce product design lead time.

Reverse engineering always come together with rapid prototyping (RP) technology. Jain and Kuthe (2013) in their publication had mention about a dominant technology for producing physical models for testing and evaluation purposes has been RP. The rapid prototyping processes can be broadly classified into processes that uses laser and ones which does not. RP in other word is a tool or medium to complete the reverse engineering process (Kumar and Kruth, 2010)

2.1.1 Types of Reverse Engineering Technique

The acquisition, analysis and transfer of technical data are the key elements of reverse engineering. Figure 2.2 shows the hierarchy of reverse engineering techniques which can be divided into two major groups; non-contact and contact method. Many researchers had published their works about the method of RE. Xinming et al. (2001) mentioned about applying a vision-sensor technique to gain data or digitizing on free-form surface before transferring them into CAD software. Dubravcik and Kender (2012) stressed the importance of 3D scanning techniques for reverse engineering process in automotives industries and can save a lot of time in design development.

Reverse Engineering Techniques

Contact Non-Contact Methods Methods

Manual Probe-touch Laser Scanning Optical Measurement Measuring

Figure 2.2: Types of reverse engineering technique. 8

Contact methods consist of using electro-mechanical equipment such as force- sensitive touch probes to mapping the coordinate of the objects surface. One of many popular devices from this category is Coordinate Measuring Machines (CMM). CMM is used for data acquisition of products, especially in the aeronautical and automotive industries where complex surfaces are frequently encountered. Peng and Loftus (1998) mentioned about the important of CMM as the key provider for dimensional inspection (see Figure 2.3). However, high cost of the co-ordinate measuring equipment, supporting software and the time to recover surface details by the measurement process are disadvantages of this technology. In addition, the use of touch-trigger probe technology on the current generation of CMMs may have the following drawbacks:  Damaging the product surface.  Misleading readings owing to the deflection of the probe and/or part.  Erroneous calculation of probe tip compensation.

These disadvantages can be overcome with a non-contact vision system. Vision is the most powerful sense. It provides human with a remarkable amount of information about the surroundings and enables us to interact intelligently with the environment, all without direct physical contact. Through it, the positions and identities of objects and the relationships between them can be identified. In a manufacturing process, the noncontact characteristic of the vision measurement enables the measurement to be taken without suffering from the drawbacks of contact measurement. There is no surface damage to the part, no deflection of the probe or part since there is no contact between the probe and part. Also, a calculation of the probe tip compensation is unnecessary because there is no probe tip in the vision system. Peng and Loftus (1998) also introduce a laser technology that has been used as a non-contact measurement method to replace the conventional technique. Its high energy limits its application in some areas, for example, in medicine (see Figure 2.4). The laser technique using 3D scanning device and the output is the points cloud. For further utilization it is required to customize the points cloud via CAD software into solid part or planes. This points cloud is mostly too large, so for best output data it is necessary to do some editing. (see Figure 2.5)

Figure 2.3: Traditional reverse engineering process according to Peng and Loftus (1998)

Figure 2.4: The reverse engineering process based on vision information according to Peng and Loftus (1998)

Li et al. (2002) in their report explained about new scanning technologies that have potential to further enhance the quality of 3D object scans. One such development is non-contact scanning systems employing white light rather than a single laser tracking line. This kind of laser technology generates dense volumetric scans where the detailed scans can be generated quickly, and the wide scanning volume reduces the importance of the angle at which the tracking light hits the target object. Fastest and in machine industry most used are laser and optical 3D scan devices. (Dubravcik and Kender, 2012). These devices allow us to scan shapes of the real parts with machine industry precision demands.

Figure 2.5: An example of point cloud from 3D scanning. 10

2.1.2 Computer Aided Design (CAD) and Computer Aided Engineering (CAE) Software

Complex CAD designs like a whole aircraft cannot be designed as one part. A huge amount of data, components and parts have to be organised in a smart way. Basically these designs can be split into parts and assemblies where assemblies are built of several parts. If a value changes in one part, this can have an impact to other parts. For example, if the position of the wings should be modified, it is not sufficient to send this information to the electronic assembly of the wings since the fuselage section with the wing box also needs to move, and depending on the level of detail that is reached, it might be necessary to move a lot of reinforcing elements. An associative model allows interrelating different geometric objects. If the position of the wings changes, also the wing box, the fuselage, and the fairing are automatically adapted to the new situation.

Redesign the large component like aircraft need powerful CAD software to support the thousands of parts to be assembled. Not many CAD software are able to provide the large amount of memory capacity to run the hundreds of 3D component at same time. Barbero (2009) had mentioned about an alternative method for recovering a damage product by using CAD software instead of applying complex mathematical algorithms. Besides, the designers need to use a powerful and high performance computer to do design task of this kind of project. Just to name a few, CAD software like CATIA, SOLIDWorks, Unigraphics, and ProE are among top medium to be use by designer in heavy industries like automotives.

According to Park and Dang (2010), previously engineering designers and analysts tend to use specific CAD software for design and other CAE software for analysis although most CAE tools have built-in modeling features. CAD and CAE tools are supposed to have the ability of integration or co-operation. By integrating the function of CAE into CAD software, a lot of time can be saving during design stage. CAE is stand for Computer Aided Engineering which the function is to do various engineering analysis and simulation virtually. This kind of application will help the designer to reduce design time. Ledermann et al (2005) however describing the important of CAE application that will help the design team to simulate the 11 movement of the product, assembly the product, and even analysis the physical limit of the product. Engineering analysis like stress analysis, flow analysis, impact analysis, and heat transfer analysis plays a vital role in determining the most suitable design of the product. Besides, this kind of analysis also will help the designer to develop safety procedure of their product simultaneously.

2.2 Micro Light Aircraft

According to Gratton (1999), microlight aircraft are defined as aeroplanes having no more than two seats, minimum flying speed in the landing configuration at maximum take-off mass (VSO) not exceeding 35 knots CAS (calibrated air speed) and a maximum take-off mass of no more than: i. 300 kg for a landplane, single seater, or ii. 450 kg for a landplane, two-seater, or iii. 330 kg for an amphibian or floatplane, single seater, or iv. 495 kg for an amphibian or floatplane, two seater.

There are three control systems used in this class of aircraft: these are three axis controlled (conventional aeroplane controls); weight shift controlled and powered parachutes (the last of these using an enlarged paraglide-style wing). The weightshift-controlled microlight aeroplane also referred to in the UK as the ‗flexwing‘ or in the USA as the ‗trike‘, is the most numerous type of microlight aircraft ever manufacture.

This class of aircraft is controlled by direct application of pitching or rolling moments to the wing through a control bar, with the mass of the ‗trike‘ unit suspended below the wing providing the necessary reaction. This means that, from the pilot‘s perspective, the bar is pushed to starboard to roll to port, and forwards to pitch upwards—the opposite sense to that required for a conventional aeroplane. For this reason pilots not initially trained on this class of aircraft are strongly recommended (although not legally required) to complete conversion training and then to pass an alternative control systems test before flying as pilot in command of a weightshift microlight.

2.2.1 History of Microlight Aircraft

In the 1960s, a NASA research scientist name Francis Rogallo had designed a collapsible delta wing which would deploy from within the hull of the shuttle after re-entry. His design proposal had been rejected by the NASA and the idea stopped at the moment. However, some of aviation enthuasiasts in USA saw the Rogallo‘s wing idea as a potential for leisure flying. So, they developed his design into the first delta wing glider, and the sport of hang glider had been born. This kind of aircraft later becomes quickly popular to the extreme sportsman around the world.

Almost immediately, some of the early hang gliding pioneers tried various ways of attaching power units to their wings so they could take off without first having to climb to the top of a hill. After all kinds of experimentation, the forerunners of the modern flexwing microlight took to the skies in the early 1970s. Since that time, wing and airframe/engine technology has moved on rapidly. Today's factory-manufactured microlights, powered by a choice of reliable two-stroke and four-stroke engines, are the result of years of design improvements within a framework of strict safety regulations.

In the last few years microlights have circumnavigated the globe and set new world records. Despite their fragile appearance, modern microlight aircraft are incredibly strong and have one of the best safety records in leisure aviation.

2.2.2 Types of Microlight Aircraft

There are basically two types of microlight which are the fixed wing (3 axis) and the flexwing (weightshift) aircraft (see Figure 2.6 and 2.7). Both types come in single or two seat form. The fixed wing is effectively a small conventional aircraft. The wing is fixed to the aircraft and has ailerons to control the roll and and elevator to control the pitch, the 3rd control being the rudder that controls the yaw, hence the term '3 axis'. These control surfaces are controlled by a control column (stick) and two rudder pedals requiring the coordination of the hands and feet.

The fixed wing market is divided into home built and kit built aircraft, regulated by the Popular Flying Association (PFA) and factory built planes which are regulated by the British Microlight Aircraft Association (BMAA). The price difference between the kit built and factory aircraft are not great such as kit plane may take some 500 hours to build. Some fixed wing aircraft are difficult to rig and are therefore best kept in a hangar or on some sort of trailer.

Figure 2.6: Fixed wing aircraft. (http://www.somersetmicrolights.org.uk/aircraft_text.htm)

Figure 2.7: Flexwing aircraft. (www.ultralightflying.com)

The flexwing (also known as a weightshift) has a wing reminiscent of a hang- glider with a trike unit containing the engine, seats and landing gear suspended below. The flexwing microlight is derived from the hang glider and although flexwing technology has progressed far and very quickly, it still has that increasingly rare pioneering feel about it. The aircraft consists of a moveable wing that pivots on 14 the 'trike' unit so that wherever the weight of the trike is put, the aircraft will roll or pitch in that direction. These inputs are made via a single horizontal bar in front of the pilot. The flexwing has a more 'open to the elements' feel than a fixed wing and is much simpler in construction. This allows it to be easily dismantled by one person to fit on a small trailer in around half an hour. Although it is possible to build a flexwing yourself, it is very rarely done as there very few kits currently on the UK market, so almost all flexwings are factory built and regulated by the BMAA.

The flexwing has no rudder therefore has no yaw control which makes it a little more difficult to land in a crosswind. The fixed wing aircraft has a rudder so can be kicked straight when landing, however the flexwing's lack of rudder and tail means it cannot spin.

2.3 Quicksilver GT 500 Microlight Aircraft

The Quicksilver GT500 (Figure 2.8) is a family of strut-braced, with high wing, pusher configuration, tricycle gear aircraft built by Quicksilver Manufacturing of Temecula, California. The aircraft is available as a kit for amateur construction or as a completed ready-to-fly. The GT500 was developed specifically for the Sportplane class of the primary aircraft category (Part 21.24 of the Federal Aviation Regulations), and on 26 July 1994 became the first aircraft certified in that category. The aircraft's nomenclature is unclear as the manufacturer variously refers to it as the GT500, GT 500 and the GT-500. The FAA certification officially calls it the GT500 (Cliche et al., 2001).

The GT500 is constructed from aluminium tubing, which is bolted together. The aircraft is covered in pre-sewn Dacron envelopes, with the forward fuselage made from fiberglass. The wing features half-span ailerons and half-span flaps. The GT500 has two seats in tandem, with dual controls featuring control columns with yokes.A 1991 upgrade included optional doors that are zippered into place adding 10 kn (19 km/h) of cruise speed, steel landing gear legs with dual brakes and an electric starter (Thompson, 1991). The GT500 model comes with two variant of engine horsepower and the specification given by the manufacturer can be refer to Table 2.1.

Table 2.1: Specification of GT 500 Quicksilver for two type of engine. (http://www.fpna.com/gt500.htm)

Specifications Rotax 582 Rotax R912UL Powerplant Model Rotax-582/40 Dual CDI Rotax-R912UL No. Cylinders 2 4 Displacement 580.7 cc 1211 cc Horsepower 65 hp 80 hp Recommended TBO 250 hrs 1000 hrs Propeller Rotax 582 Rotax R912UL Type 3 Blade, Carbon Fiber 3 Blade, Carbon Fiber Diameter 72 inches 72 inches Pitch 17 to 19 degrees-LH 17 to 19 degrees-LH General Rotax 582 Rotax R912UL Length 20' 5" 20' 5" Height 6' 6" 6' 6" Wingspan 30' 0" 30' 0" Wing area 155 sg. ft. 155 sg. ft. Wing loading 6.45 lb./sq.ft. 7.09 lb./sq.ft. Power loading 15.38 lb./hp. 13.75 lb./hp. Seats 2 2 Minimum flight crew 1 1 Empty Weight 575 lbs. 638 lbs. Useful load 425 lbs. 462 lbs. Payload w/full fuel 329 lbs. 366 lbs. Max takeoff weight 1000 lbs. 1100 lbs. Fuel capacity 16 U.S. gal. 16 U.S. gal. Performance Rotax 582 Rotax R912UL Takeoff distance, ground roll 220 ft. 244 ft. Takeoff distance, 50 ft obstacle 689 ft. 621 ft. Rate of climb 650 fpm. 655 fpm. Max level speed, sea level with Doors 88 mph. 91 mph. w/out Doors 81 mph. 88 mph. Landing distance, 50 ft obstacle 580 ft. 905 ft. Landing distance, ground roll 260 ft. 390 ft. Glide Ratio with Doors 7.0:1 6.5:1 w/out Doors 7.5:1 7.0:1 Minimum sink rate with Doors 540 ft/min 555 ft/mi w/out Doors 570 ft/min 584 ft/mi Service Ceiling 12,500 ft. 12,500 ft. Air Speeds Rotax 582 Rotax R912UL Vx (Best angle of climb) 47mph 50mph Vy (Best rate of climb) 55 mph 58 mph Va (Design maneuvering) 90 mph 94 mph Vne (Never exceed) 103 mph 103 mph Vs1 (Stall, flaps up, power off) 45 mph 47 mph Vs0 (Stall, flaps down, power off) 39 mph 42 mph Landing approach speed 51 mph 55 mph

2.3.1 Main Aircraft Component

An aircraft is conceived as a complete structure, but for manufacturing purposes must be divided into sections, or main components, which are in turn split into sub- assemblies of decreasing size that are finally resolved into individual detail parts. Each main component is planned, tooled and built as a separate unit and joined with the others in the intermediate and final assembly stages. In design stages, six subsystem of aircraft normally being set up which are fuselage, empennage, wings, landing gear, engine, and aileron and flaps division.

Figure 2.8 shows a typical weightshift microlight aircraft (a Quicksilver GT500). The aircraft comprises two distinct parts, the fuselage and the wing. While the interaction between them is essential to the characteristics of the aircraft, it is convenient initially to consider them separately.

Figure 2.8: Quicksilver GT 500 microlight aircraft.

2.3.2 The Wing – Structure

The wings are the most important lift-producing part of the aircraft. As can be seen in Figure 2.9, wings vary in design depending upon the aircraft type and its purpose. Most airplanes are designed so that the outer tips of the wings are higher than where the wings are attached to the fuselage. This upward angle is called the dihedral and helps keep the airplane from rolling unexpectedly during flight (Fig. 2.10). Wings also carry the fuel for the most airplane especially large size aeroplane. 17

Figure 2.9: Three types of aircraft wings.

Figure 2.10: Dihedral angle for aircraft wing.

The wing structure of a fixed-wing microlight (see Fig. 2.11) is complex and somewhat unlike that of a conventional wing. The primary parts of the structure are the leading edges two segmented tubes typically 4.5–5.0 m long, which are joined at the nose to the keel tube which runs the length of the wing and can be seen protruding from the trailing edge in Figure 2.8. Stretched over these is the sail manufactured from a high strength synthetic non-porous fabric such as polyester Dacron. The whole structure is put under considerable internal loads during rigging, rigidity and form being ensured by cross-tubes, which are hinged at approximately half-span to the leading edges and hinged to each other above the keel tube.

The structures of aircraft wing were built by ribs and spar that support the entire body of the wing. Refer to Figure 2.12, spar is the main tube that expands across the wings and become the backbone of the construction. While the ribs are the pieces of aluminium plates/ frame that hold the wing skins. Most of the material being use in the construction are high flexibility and light material especially aluminium and Dacron. 18

Figure 2.11: Wing frame main components of Quicksilver GT500 aircraft.

Figure 2.12: The built up components for an aircraft wing.

2.3.3 Fuselage

The fuselage is the main body structure to which all other components are attached. The fuselage contains the cockpit or flight deck, passenger compartment and cargo compartment. While wings produce most of the lift, the fuselage also produces a little lift. A bulky fuselage can also produce a lot of drag. For this reason, a fuselage is streamlined to decrease the drag. Most of us usually think of a streamlined sports car as being sleek and compact - it does not present a bulky obstacle to the oncoming wind. A streamlined fuselage has the same attributes. It has a sharp or rounded nose with sleek, tapered body so that the air can flow smoothly around it.

GT500 microlight aircraft is simple construction aircraft where the fuselage structure were built base on a single aluminium tube (Figure 2.13). The cockpit 19 frame structure are the combination of aluminium tube, rectangular shape tube, and also some pieces of aluminium plates that joint together by bolts and nuts. The simple design of the fuselage can assure the lightness of the aircraft weight without compromising the safety level. Figure 2.14 shows the example of fuselage structure for microlight aircraft which is built by using aluminium tubes.

Figure 2.13: Fuselage of GT500 Quicksilver aircraft.

Figure 2.14: An example of fuselage frame of microlight aircraft. (http://www.ultralightnews.com/)

2.3.4 Empennage

The empennage, commonly called the tail assembly (see Figure 2.15), is the rear section of the body of the airplane. Its main purpose is to give stability to the aircraft. The fixed parts are the horizontal stabilizer and the vertical stabilizer or fin. The front, fixed section is called the horizontal stabilizer and is used to prevent the airplane from pitching up or down. The rear section is called the elevator and is usually hinged to the horizontal stabilizer. The elevator is a movable airfoil that controls the up-and-down motion of the aircraft's nose. 20

Figure 2.15: Empennage structure

The vertical tail structure is divided into the vertical stabilizer and the rudder. The front section is called the vertical stabilizer and is used to prevent the aircraft from yawing back and forth. The principle behind its operation is much like the principle of a deep keel on a sailboat. In light, single-engine aircraft, it also serves to offset the tendency of the aircraft to roll in the opposite direction in which the propeller is rotating. The rear section of the vertical structure is the rudder. It is a movable airfoil that is used to turn the aircraft.

2.3.5 Ailerons & Flaps

Ailerons are hinged control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll. The two ailerons are typically interconnected so that one goes down when the other goes up: the downgoing aileron increases the lift on its wing while the upgoing aileron reduces the lift on its wing, producing a rolling moment about the aircraft's longitudinal axis. The word aileron is French for ‗little wing‘. While flaps are an aerodynamic devices found at the trailing edges of aircraft wings, used to augment lift at a lower speed during takeoff and landing. (refer to Figure 2.16)

Figure 2.16: Location of aileron (red area) and flap (yellow area) on aircraft wing. 21

2.4 Materials

Historically, one of the most thorough evaluations of the competition between materials was performed by the aerospace industry. It is not uncommon for commercial grade materials and components to be used in this class of aeroplane. For the aerospace industry, aluminium airplanes proved to be much lighter than steel airplanes. (Patton et al., 2004). The fuselage structure of most modern aircraft comprises curved aluminium alloy skin panels, which are fixed to stiffening members called frames and stringers, which provide radial and longitudinal stiffness, respectively. Previous technique in joining the structure was by riveting the steel to the mainframe. However, after the introduction of aluminium welding, there has been growing interest in the welding of aerospace aluminium alloys (Simmons and Schleyer, 2006). Aluminium, steel, and titanium will probably continue to be the principal material in airframe design for a while. All these material however, will have to be improved (Chun-Yung, 1999).

2.4.1 Aluminium

Aluminium alloy are the most commonly used airframe material because of their low densities, excellent range of properties which can be matched to particular requirements, experience of manufacturing techniques and the known in service behaviour (Howe, 2004). According to Mouritz (2012), series of aluminium alloys of 2xxx, 3xxx, 5xxx, 6xxx, and 7xxx are widely used in aviation. The 2xxx series is recommended for operation at high working temperatures and with high destruction viscosity rates. 7xxx series alloys – for operation at lower temperatures of highly- loaded parts and for parts with high resistance to corrosion under stress. For less loaded components, 3xxx, 5xxx, and 6xxx series alloys are used.

6000 series (magnesium and silicon) aluminium alloys are the most commonly used for microlight type of structure. They are medium strength aluminium alloys, which can be precipitation (age) hardened to an ultimate tensile strength of around 300 MPa. At this strength 6000 series alloys are not as strong as the traditional aerospace 2000 and 7000 series alloys. However, 6000 series alloys 22 have the significant advantages for this application of better corrosion resistance and reduced cost. 6000 series alloys can be used simply anodised. High strength alloys are occasionally used to save weight in high stress areas (such as wing spars).

6000 series alloys are most commonly used in the T6 temper: solution heat- treated and artificially aged. 6061-T6 is the traditional North American specification with a minimum ultimate tensile strength of 290MPa. 6082-T6 (formerly HT30TF) is the traditional British specification with a minimum ultimate tensile strength of 310MPa. (Syson, 2011). The summary of aluminium alloys are given in Table 2.2. The main alloying element(s) is used to determine into which one of the eight series an alloy is allocated.

Table 2.2: Wrought alloy aluminium series. (Mouritz, 2012) Alloy series Main alloying Temper process Application(s) element (s) Unsuaitable to used as structural materials 1000 Commercially pure Not-age on aircraft, sometimes used as sircraft fuel Al (>99% Al) hardenable tanks, fairings, oil tanks, repair material of wing tips and tanks 2000 Copper Age-hardenable Used in many structural and semistructural components in aircraft. Also used in damage-tolerant applications such as lower wing skins and fuselage structure of commercial aircraft which require high fatigue resistance. 3000 Manganese Not-age Rarely used in aircraft, sometimes used as hardenable nonconstructural material in fairing, fillets, tanks, wheel pants, nose bowls and cowlings 4000 Silicon Age-hardenable Limited due to brittle silicon phase that can (if magnesium form in the aluminium matrix which reduces present) the ductility and fracture toughness. 5000 Magnesium Not-age Used occasionally in nonconstructural hardenable aircraft parts such as wing ribs, wing tips, stiffeners, tanks, ducting, and frameworks. 6000 Magnesium and Age-hardenable Used in wide range of non-aerospace silicon components, such as buildings, rail cars, boat hulls, ship superstructures and in automotive components. Rarely used in aircraft component. 7000 Zinc Age-hardenable most common aluminium alloys used in aircraft for structure building due to carry higher stress than 2000 series alloy. 8000 Other (including Mostly age- mainly used in military fighter aircraft where lithium) hardenable cost is secondary to structural performance. Also used in super lightweight tanks for the space shuttle.

2.4.1.1 Aluminium Alloy 2024

Known as the ―aircraft alloy‖ in machining rod, this alloy has properties higher than 2017 and 2014. Even though its form ability is generally considered only fair in the cold state, Al2024 is one of the most popular alloys for cold heading and roll threading applications. This alloy can be machined to a high finish and corrosion resistance is fair. Among popular applications include Phillips head screws, wood screws, hydraulic fittings and small parts in clocks and meters. It is also the basic alloy for cold finished rectangular bar where strength and machinability are essential for precision fittings and parts.

2.4.1.2 Aluminium Alloy 6061

Al6061 is generally selected where welding or brazing is required, or for its particularly high corrosion resistance in all tempers. It is one of the most common alloys of aluminium for general purpose use. Even though it performs low in machining process, its weight is lighter than Al2024. Among popular applications from this material include railway car components, bridge components, pipe fittings, wheels and various transportation end uses. This alloy is generally use in construction of aircraft structures, such as wings and fuselages, and more commonly in homebuilt aircraft than commercial or military aircraft.

2.4.1.3 Aluminium Alloy 7075

Aluminum 7075 has been the strongest and hardest alloy sold commercially for decades. Though Al7175 is more pure, this kind of alloy may not be suitable for fracture toughness applications. The high value of stress corrosion resistance of the T73 and T7351 tempers of 7075 rolled or cold finished rod have made them a logical replacement for alloys 2014, 2017 and 2024 in many of the most critical applications. In machined parts and forgings it is used primarily in aircraft, ordinance, highly stressed structural applications, keys, small gears, etc. This kind of alloy is more difficult to forge than other alloys, but it often selected because of its properties. Al7075 perform well in machining process; produce excellent finishing characteristics, and also corrosion resistance fair. 24

Table 2.3: Mechanical properties of selected Aluminium alloys. (http://asm.matweb.com/) Mechanical Al2024 Al6061 Al7075 Properties Hardness, Brinell 120 95 150 Ultimate Tensile 469 MPa 310 MPa 572 MPa Strength Tensile Yield Strength 324 MPa 276 MPa 503 MPa Elongation at Break 19 % 12 % 11 % Modulus of Elasticity 73.1 GPa 68.9 GPa 71.7 GPa Poisson's Ratio 0.33 0.33 0.33 Fatigue Strength 138 MPa 96.5 MPa 159 MPa Shear Modulus 28 GPa 26 GPa 26.9 GPa Shear Strength 283 MPa 207 MPa 331 MPa Machinability 70 % 50 % 70 % Density 2.78 g/cc 2.7 g/cc 2.81 g/cc

2.4.2 Steel

Steel has several advantages over aluminium where it is three times as strong and can be welded easily into complex shapes that are far more durable than a bolted or riveted aluminium structure. Like aluminium, steel alloys are identified by a four- digit code that specifies the alloying components.

The used of steel in aircraft is usually confined to safety-critical structural components that require very high strength and where space is limited. In other words, steel is used when high specific strength is the most important criterion in materials selection. Steels used in aircraft have yield strength above 1500-2000 MPa, which is higher than high strength aluminium (500-650 MPa), titanium (830-1300 MPa) or quasi-isotropic carbon epoxy composite (750-1000 MPa). In addition to high strength, steels used in aircraft have high elastic modulus, fatigue resistance and fracture toughness, and retain their mechanical performance at high temperature (up to 300-450 °C). This combination of properties makes steel a material of choices for heavily loaded aircraft structures.

Aircraft structural components made using high-strength steel include undercarriage landing gear, wing-root attachments, engine pylons and slat track components. The greatest usage of steel is in landing gear where it is important to minimise the volume of the undercarriage while having high load capacity (see REFERENCES

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http://www.beliteaircraft.com/ultralight-aircrafts/Superlite-WoW-Belte.php http://www.fpna.com/gt500.htm http://www.lightsportaircraftpilot.com/ http://www.somersetmicrolights.org.uk/aircraft_text.htm http://www.somersetmicrolights.org.uk/aircraft_text.htm http://www.ultralightnews.com/ www.avidflyeraircraft.com www.ultralightflying.com