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i 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

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i

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

v

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.

vi

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.

vii

CONTENTS

TITLE

DECLARATION

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

ABSTRAK

CONTENTS

LIST OF FIGURES

LIST OF TABLES

LIST OF SYMBOLS AND ABBREVIATIONS

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CHAPTER 1 INTRODUCTION

1.1 Research background

1.2 Problems Statement

1.3 Research Objective

1.4 Scope of Study

1.5 Expected Outcome

1.6 Significant of Research

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CHAPTER 2 THEORETICAL AND LITERATURE REVIEW

2.1 Reverse Engineering

2.1.1 Types of Reverse Engineering

Techniques

2.1.2 Computer Aided Design (CAD) and

Computer Aided Engineering (CAE)

2.2 Microlight Aircraft

2.2.1 History of Microlight Aircraft

2.2.2 Types of Microlight Aircraft

2.3 Quicksilver GT500 Microlight Aircraft

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2.3.1 Main Aircraft Component

2.3.2 The Wings – Structure

2.3.3 Fuselage

2.3.4 Empennage

2.3.5 Ailerons & Flaps

2.4 Materials

2.4.1 Aluminium

2.4.1 Aluminium Alloy 2024

2.4.2 Aluminium Alloy 6061

2.4.3 Aluminium Alloy 7075

2.4.2 Steel

2.4.3 Composite

2.4.4 Tubes

2.4.5 Bracing Cables

2.4.6 Bolts and Nuts

2.5 Manufacturing Process and Assembly

Techniques

2.5.1 Bending

2.5.2 Hole Drilling

2.6 Structural Analysis

2.6.1 Engineering Stress

2.6.2 Engineering Strain

2.6.3 Young's Modulus - Modulus of

Elasticity (or Tensile Modulus) -

Hooke's Law

2.6.4 Shear Modulus

2.6.5 Von Mises Stress

2.6.5.1 Distortion energy Theory

2.6.6 Principal Stress

2.7 Air-load Distributions

2.7.1 Schrenk’s Approximation Methods

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CHAPTER 3 METHODOLOGY

3.1 Assumptions

3.2 Specification of Quicksilver GT500 Microlight

Aircraft

3.3 Data Acquisitions

3.4 Image Modelling

3.5 CAE Analysis

3.5.1 Selection of Material

3.5.2 Simplification of Analysis

3.5.3 Distributed Load on Aircraft Wing

3.5.4 Wing Loading Calculation

3.5.5 Determination of Constrain

3.5.6 Evaluation on Analysis

3.6 Selection of Material

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CHAPTER 4

RESULTS AND DISCUSSIONS

4.1 Stress Load Analysis

4.1.1. Loads on the Aircraft

4.1.2. Determination of Center of Gravity

4.1.3. CADCAE Analysis

4.1.3.1. Stress Analysis for Wing Base

Structure Using Aluminium

2024

4.1.3.2. Stress Analysis for Wing Base

Structure Using Aluminium

6061

4.1.3.3. Stress Analysis for Wing Base

Structure Using Aluminium

7050

4.2 Built up Material

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4.2.1. Aluminium Alloy

4.2.2. Steel Alloy

4.2.3. Polymer

4.2.4. Composite

4.2.5. Fabric

4.3 Fasteners and Structural Joints

4.3.1. Aircraft Bolts and Nuts

4.3.2. Rivet

4.3.3. Weld Joints and Adhesive Bonding

4.4 Manufacturing Process

4.4.1. Bending

4.4.2. Drilling

4.5 Aircraft Control System

4.5.1. Flight Controls

4.5.2. Ground Control

4.5.3. Landing Gear

4.5.4. Fuel System

4.5.5. Brake System

4.5.6. Instrument Panel

4.5.7. Powerplant

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CHAPTER 5 CONCLUSSION AND RECOMMENDATION

5.1 Conclusion

5.2 Suggestion for Improvement

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REFERENCES

APPENDICES

xi

LIST OF FIGURES

Figure no. Title Page

1.1

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

2.10

2.11

2.12

2.13

2.14

2.15

2.16

2.17

2.18

2.19

Example of the sequences of the reverse engineering

(RE) process.

Basic flow of reverse engineering processes

Types of reverse engineering technique

Traditional reverse engineering process according to

QingJin Peng et. al. (1998)

The reverse engineering process based on vision

information

An example of point cloud from 3D scanning

Fixed wing aircraft

Flexwing aircraft

A Quicksilver GT500 microlight aircraft

Three types of aircraft wings

Dihedral angle for aircraft wing

Wing frame main components of Quicksilver GT500

aircraft

The built up components of an aircraft wings

Fuselage of GT500 aircraft

An example of fuselage frame of microlight aircraft

Empennage structure

Location of aileron (red area) and flap (yellow area) on

aircraft wing.

An example of landing gear for microlight aircraft

Modern ultralight airplanes use aluminium tubes as

both spars and wing leading edges

A single-tube frame structure of Maxair Hummer

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xii

2.20

2.21

2.22

2.23

2.24

2.25

2.26

2.27

2.28

2.29

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

ultralight

Cable construction is defined by number of strands and

the number of wires per strand

Basics of bolts installation

The position of hole that can be drill on the aluminium

tube of wing spar

Types of load acting on aircraft.

Condition of engineering stress in solid objects.

Representation of a pure distortion case.

Stress boundary conditions on a 2 dimensional

element.

Stress boundary conditions in a 3 dimensional body

and normal stress values induced in it.

Span-wise and chord-wise loadings on aircraft wing.

Types of planform wing by aircraft manufacturers.

Plan-form geometry for Schrenk’s method.

Reverse Engineering procedure for the project

Quicksilver GT500 microlight aircraft.

GT500 mainframe structure.

The division of subsystem for Quicksilver GT500

microlight aircraft.

An example of CAD design performs using Autodesk

Inventor 2012.

An example of stress analysis on aircraft structure that

has been done by CAE software.

Flowchart diagram on engineering analysis for

determination of material.

Load distribution on wing.

Location of constrain at (a) landing gear carry thru, (b)

root tube

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4.1

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

4.10

4.11

4.12

4.13

4.14

4.15

4.16

4.17

(a) Top view of CAD design for Quicksilver GT500

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.

Total lift force, Ls distribution on the aircraft wing

structure.

Wing spanwise lift distribution.

The CG location of Quicksilver aircraft wing

determined by using CADCAE software.

Assembly of main wing structure and the loads acting

on the structure.

Parts and components of wing structure that being

replaced by 3 types of material for stress analysis.

Result of stress analysis on wing structure using

Aluminium 2024 material.

Displacement of structure using Aluminium 2024.

Safety Factor of structure using Aluminium 2024.

Result of stress analysis on wing structure using

Aluminium 6061 material.

Displacement of structure using Aluminium 6061.

Safety Factor of structure using Aluminium 6061

Result of stress analysis on wing structure using

Aluminium 7050 material.

Displacement of structure using Aluminium 7050.

Safety factor of structure using Aluminium 7050.

Landing gear of GT500 model aircraft are made from

high strength steel material.

The use of polymer material on aircraft bodyskin is

more on windshield and safety door application.

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4.18

4.19

4.20

4.21

4.22

4.23

4.24

4.25

4.26

(a) Seat bucket for pilot are made from composite

materials. (b) Body skin of GT500 aircraft model are

made from fibre glass material.

Wing skins of the aircraft are made from lightweight

but high strength fabric material like Dacron.

The use of bolts and nuts are being applied on main

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.

Riveting techniques are applied to join non-structural

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.

An example of weld joint application on GT500

Quicksilver airplane as can be seen on rudder shaft

joining.

Radius of tubing bending.

Location of the drilled holes must be at the centre of

the tube structure.

GT500 aircraft surface control system.

A simple mechanical cable operated system found on

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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xv

4.27

4.28

4.29

4.30

4.31

4.32

Location of (A) aileron and (B) wing flap as can be

seen on figure above.

Two main wheels and tail skid are playing important

role in landing situation while nose wheel give little

support.

(a) The location of hand brake lever (inside yellow

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.

An overview of pilot cockpit of GT500 aircraft. Basic

controller indicator is as displayed on dashboard.

Instrument panel layout for GT500.

A Rotax 582/40 rotary valve engine that powered the

GT500 aircraft.

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LIST OF TABLES

Table no. Title Page

2.1

2.2

2.3

2.4

2.5

3.1

4.1

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

Specification of GT 500 Quicksilver for two type of

engine.

Wrought alloy aluminium series

Mechanical properties of selected Aluminium alloys

Comparison of properties for thermoset resins

Comparison of the wire strength between sizes,

material, and number of strands

Detail specification of Quicksilver GT500 microlight

aircraft

Calculated lift distribution value of aircraft wing.

Coordination of CG as determined using Autodesk

Inventor 2012 software.

Results summary of stress analysis for Aluminium

2024 material.

Results summary of stress analysis for Aluminium

6061 material.

Results summary of stress analysis for Aluminium

7050 material.

Types of material using on wing’s structure of

Quicksilver GT500 aircraft.

Non-heat treatable alloys applications on aircraft.

Heat treatable alloys applications on aircraft.

Selection of fabric types by breaking strength criteria.

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xvii

LIST OF SYMBOLS AND ABBREVIATIONS

CAD Computer Aided Design

CAE Computer Aided Engineering

AoA angle of attack

MPa

ksi

mega Pascals

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

1

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

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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.

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.

Existing Parts

Data acquisition

using scanning or

measurement device

Image modelling using CAD software

Engineering analysis using CAE software

Physical prototype

using Rapid Prototyping

Machine

7

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.

Figure 2.2: Types of reverse engineering technique.

Reverse Engineering Techniques

Contact Methods

Manual Measurement

Probe-touch Measuring

Non-Contact Methods

Laser Scanning Optical

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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)

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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.

12

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.

13

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.

15

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

No. Cylinders

Displacement

Horsepower

Recommended TBO

Rotax-582/40 Dual CDI

2

580.7 cc

65 hp

250 hrs

Rotax-R912UL

4

1211 cc

80 hp

1000 hrs

Propeller Rotax 582 Rotax R912UL

Type

Diameter

Pitch

3 Blade, Carbon Fiber

72 inches

17 to 19 degrees-LH

3 Blade, Carbon Fiber

72 inches

17 to 19 degrees-LH

General Rotax 582 Rotax R912UL

Length

Height

Wingspan

Wing area

Wing loading

Power loading

Seats

Minimum flight crew

Empty Weight

Useful load

Payload w/full fuel

Max takeoff weight

Fuel capacity

20' 5"

6' 6"

30' 0"

155 sg. ft.

6.45 lb./sq.ft.

15.38 lb./hp.

2

1

575 lbs.

425 lbs.

329 lbs.

1000 lbs.

16 U.S. gal.

20' 5"

6' 6"

30' 0"

155 sg. ft.

7.09 lb./sq.ft.

13.75 lb./hp.

2

1

638 lbs.

462 lbs.

366 lbs.

1100 lbs.

16 U.S. gal.

Performance Rotax 582 Rotax R912UL

Takeoff distance, ground roll

Takeoff distance, 50 ft obstacle

Rate of climb

Max level speed, sea level with Doors

w/out Doors

Landing distance, 50 ft obstacle

Landing distance, ground roll

Glide Ratio with Doors

w/out Doors

Minimum sink rate with Doors

w/out Doors

Service Ceiling

220 ft.

689 ft.

650 fpm.

88 mph.

81 mph.

580 ft.

260 ft.

7.0:1

7.5:1

540 ft/min

570 ft/min

12,500 ft.

244 ft.

621 ft.

655 fpm.

91 mph.

88 mph.

905 ft.

390 ft.

6.5:1

7.0:1

555 ft/mi

584 ft/mi

12,500 ft.

Air Speeds Rotax 582 Rotax R912UL

Vx (Best angle of climb)

Vy (Best rate of climb)

Va (Design maneuvering)

Vne (Never exceed)

Vs1 (Stall, flaps up, power off)

Vs0 (Stall, flaps down, power off)

Landing approach speed

47mph

55 mph

90 mph

103 mph

45 mph

39 mph

51 mph

50mph

58 mph

94 mph

103 mph

47 mph

42 mph

55 mph

16

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

element (s)

Temper process Application(s)

1000

Commercially pure

Al (>99% Al)

Not-age

hardenable

Unsuaitable to used as structural materials

on aircraft, sometimes used as sircraft fuel

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

hardenable

Rarely used in aircraft, sometimes used as

nonconstructural material in fairing, fillets,

tanks, wheel pants, nose bowls and cowlings

4000 Silicon Age-hardenable

(if magnesium

present)

Limited due to brittle silicon phase that can

form in the aluminium matrix which reduces

the ductility and fracture toughness.

5000 Magnesium Not-age

hardenable

Used occasionally in nonconstructural

aircraft parts such as wing ribs, wing tips,

stiffeners, tanks, ducting, and frameworks.

6000 Magnesium and

silicon

Age-hardenable Used in wide range of non-aerospace

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

lithium)

Mostly age-

hardenable

mainly used in military fighter aircraft where

cost is secondary to structural performance.

Also used in super lightweight tanks for the

space shuttle.

23

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

Properties

Al2024 Al6061 Al7075

Hardness, Brinell 120 95 150

Ultimate Tensile

Strength

469 MPa 310 MPa 572 MPa

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

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