designing and analyzing preliminary parts of an...

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DESIGNING AND ANALYZING PRELIMINARY PARTS OF AN AEROSTAT

MOHD. EZUWAN BIN KASSIM

This report is to be present as criteria to fulfill a part of bestowal stipulation for

Bachelor’s Degree in Mechanical Engineering (Design & Innovation)

Faculty of Mechanical Engineering

Universiti Teknikal Malaysia Melaka

MARCH 2008

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I/we* admit that have read this work and in opinion of mine/ours* this work was

adequate from the aspect of scope and quality significantly to be awarded Bachelor

Degree of Mechanical Engineering (Design & Innovation)

Signature:………………………

Supervisor Name:………………

Date:……………………………

Signature:………………………

Supervisor Name:………………

Date:……………………………

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“I declare that this report is done by my own unless the citation with the mentioned

references for each.”

Signature:…………………….

Author: MOHD EZUWAN BIN KASSIM

Date: 27 MARCH 2008

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PREFACE

If you take a moment to observe your surroundings, you will see examples of

technological creativity. The physical objects you see, whether they are telephones,

automobiles, or even high end engineering equipments, all came into being through the

creative application of technology. These everyday inventions did not miraculously

appear but originated in the minds of human beings and took time to develop. This

project is somehow considered another step forward in gaining better designs and

solutions. The project is about creating and analyzing an aerostat and the main method

are; software simulation and calculation based on derived equation. The usage of

software such as CAD, ANSYS, COSMOSWORK is practically crucial for engineering

designs. In this project, the initial step is about determining a suitable design for an

aerostat. Due to the main goals, a research was conducted (internets and journals) in

order to claim this project as a success. However, the author consider this project as a

surface-orientated suggestions and not as detailed as a complete published journals. The

lack of knowledge and experiences are the main factor to what-so-called unrefined piece

of works. After all, we cannot determine a solution just by observing to the input without

any guidance and self-thought articulations.

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ABSTRACT

Aerostats are lighter-than-air vehicles tethered to the ground by a cable and used

for broadcasting, communications, surveillance, and drug interdiction. The dynamic

response of tethered aerostats subject to extreme atmospheric turbulence often dictates

survivability. This report develops a theoretical model that predicts the planar response

of a tethered aerostat subject to atmospheric turbulence and simulates the response any

other aspects that occurred due to pressure, temperature, and etc. The aerostat dynamic

model assumes the aerostat hull to be a rigid body with non-linear fluid loading,

instantaneous weathervane for planar response, and a continuous tether. The hull needs a

simple yet reliable design in order to estimate steady state effectiveness while floating

on air. Bachelor’s Final Project is perhaps achieving the objective of choosing the best

conceptual sketches in order to minor the spaciousness of aerostat’s engineer analyzing

method. A methodology that was used in order to expand the analysis method is

predominantly explained by the skills of gaining the interconnected information and

software usage. The result for this project in the initial phase is the champion concept

for aerostat design. The consequential stage in this report is the results that consists main

analysis constituent such as pressure, streamline and any other aspects to be shown and

translated in engineering point of view.

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ABSTRAK

Aerostat adalah sejenis pengangkutan terapung yang lebih ringan dari

udara, dipaksi pada tanah menggunakan kabel dan berfungsi untuk penyebaran

maklumat, pemerhati (tinjauan) dan pengawasan sempadan. Responsif dinamik aerostat

yang mempunyai kabel, bergantung pada keadaan dan keseimbangan atmosfera dan

kemampuan untuk bertahan lebih lama diudara merupakan suatu objektif yang

dikehendaki. Laporan ini akan mengemukakan model aerostat secara simulasi dan teori

serta akan dianalisis menggunakan grafik berbantu computer (CAD). Antara analisis

yang dilakukan ialah tindak balas tekanan, daya, suhu dan pergerakan kelajuan angin

yag menerjah pada bentuk aerodinamik aerostat tersebut. Walaupun terdapat pelbagai

elemen luaran yang penting, dalam repot ini, sebahagian pemboleh ubah akan dianggap

tidak berkaitan secara terus. Model dinamik ini akan dianggap mempunyai keupayaan

apungan yang berterusan, tidak berkaitan secara terus dengan pelancar dan beban yang

sekata. Projek Sarjana Muda ini diharap akan memenuhi kriteria yang dikehendaki iaitu

memilih rekabentuk konsep yang bersesuaian. Metodologi yang diguna untuk

memastikan kelancaran projek diterangkan melalui kajian ilmiah yang kemudiannya

diterjemah kepada kepada pengunaan perisian analisis yang terlibat. Keputusan yang

akan dicapai ialah analisis utama pada elemen-elemen yang terlibat dan perspektif

kejuruteraan mengenainya.

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ACKNOWLEDGEMENT

I would like to express an immense gratitude to the God All-Mighty Allah s.w.t and the

true idol of ours; Rasulullah s.a.w. who gave me the will to pursue this report until it

finished, the courage to hold on to my thoughts, and the astuteness to think wisely

whenever I need it the most. I also want to dedicate a special appreciation to my parents

whose always stand by my side and keep encouraging me until the end of whatever I am

doing. Special thanks also to my respected lecturer and supervisor, Mr. Faiz Redza bin

Ramli for his ideas and willpower of making this report as something can be touched

and observed physically, not just being articulated by words and speeches. His guidance,

experiences and the method of teaching were really useful for me in the future and I

undeniably think that it will somehow affect my opinion in a very positive way, indeed. I

also want to say thanks to all my friends for their helps and opinions because all of it

was functional to me in many kind of way. Hope fully this report is a piece of written-

work that meets the decisive factor and worth to be observed by others because

somehow, the endeavor to finish this task was something I wish it to be worth my effort.

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TABLE OF CONTENTS

TITLE PAGES

PREFACE ii

ABSTRACT iii

ACKNOWLEDGEMENT iv

LIST OF FIGURES xi

LIST OF TABLES xiii

CHAPTER 1: INTRODUCTION 1

1.0 Background of the Project 1

1.1 The Significance of the Project 2

1.2 Objective 3

1.3 Scopes of the Project 4

CHAPTER 2: LITERATURE REVIEW 5

2.0 What is Aerostat? 5

2.1 The Function of Aerostats 7

2.2 How Does Aerostats Fly 7

2.3 The Examples of Aerostats 8

2.4 The Component of Aerostats 10

2.4.1 An Aerostat System 10

2.4.2 Primary Components 11

2.4.3 Tether Definition 13

2.4.4 Mooring System 13

2.4.5 Types of Payloads 15

2.4.6 The Hull 15

2.4.7 The Windscreen 16

2.4.8 The Rigging 16

2.4.9 The Radar Platform 17

2.5 Product Review 18

2.6 Requirements 20

2.7 Expected Load 21

2.8 Atmospheric Condition 22

2.9 Aerostats Restriction 22

2.10 Designs with Mass Production in Mind 23

2.11 Gas Balloon 24

2.12 Helium 25

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CHAPTER 3: METHODOLOGY 26

3.0 Research Method 26

3.1 Usage of Software 28

3.2 Conceptual Designs 30

CHAPTER 4: CONCEPTUAL DESIGNS 32

4.0 Conceptual Sketches Selection 32

4.1 Part’s Design Option 34

4.2 Final Concepts 36

4.3 General Description 39

4.4 Concept Sketches Analysis 40

4.5 Concept Champion 41

CHAPTER 5: CALCULATIONS OF MAJOR AND 42

PRELIMINARY PART

5.0 Explanation of chapter 42

5.1 Technical Overview 43

5.2 Formula for Calculating Volume and Stress 45

5.2.0 Volume 45

5.2.1 Surface Area 46

5.2.2 Maximum Take-Off Weight 46

5.3 Calculations for Fin of an Aerostat 49

5.3.0 Tail Area Ratio 49

5.3.1 Fin location ratio 50

5.3.2 Fin aspect ratio 50

5.3.3 Fin taper ratio 50

5.4 Design of Fin 51

CHAPTER 6: ANALYSIS USING ANSYS CFX AND 52

COSMOSWORK DESIGNER

6.0 Explanation of chapter 52

6.1 Analysis Using Ansys CFX) 53

6.1.0 Parameters for the Envelope of an Aerostat 53

6.1.1 Steps of Using Ansys CFX 54

6.2 Analysis using Cosmosworks Designer 63

6.2.0 Parameters the fin of aerostat 63

6.2.1 Steps of using Cosmoswork Designer 64

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CHAPTER 7: RESULTS AND DISCUSSIONS 66

7.0 Explanations of chapter 67

7.1 Results for Hull and Envelope Analysis (Ansys CFX) 67

7.1.0 Pressure 67

7.1.1 Temperature 67

7.1.2 Density 68

7.1.3 Velocity 68

7.1.4 Mach Number 69

7.1.5 Streamline Velocity 69

7.1.6 Constant Values 70

7.1.7 Graphical Results for Ansys CFX 71

7.2 Results for Analysis of Fin (Cosmosworks Designer) 74

7.2.0 Von Mises Stress analysis 74

7.2.1 Strain Analysis 75

7.2.2 Displacement Analysis 76

7.2.3 Type and Deformations 77

7.3 Final Aerostat Design 78

CONCLUSION 79

RECOMMENDATIONS 79

REFERENCES 81

APPENDICES 82

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LISTS OF FIGURES

TITLE PAGES

1. Figure 1.1: Aerostat’s major parts 3

2. Figure 2.1: Aerostats “The Modern 64K”

(Source: www.blimpinfo.com) 5

3. Figure 2.2: Rapid aerostat deployment

(Source: www.defenseindustrydaily.com) 7

4. Figure 2.3: Water platform (Source: www.ilcdover.com) 9

5. Figure 2.4: Manufacturing an aerostat (Source: www.ilcdover.com) 9

6. Figure 2.5: Specifications (Source: www.ilcdover.com) 9

7. Figure 2.6: Components of tethered aerostat

(Source: rosaerosystems.pbo.ru) 10

8. Figure 2.7: The aerostats inflated (Source: www.hia-iha.nrc-cnrc.gc.ca) 11

9. Figure 2.8: Platforms and ground mobilised (Source: www.colmp.com) 14

10. Figure 3.1: Steps of planning and design process 26

11. Figure 3.2: Basic applications of aerostat 27

12. Figure 3.3: Requirement structure of development and design 30

13. Figure 4.1: Conceptual sketch (Idea #3) 40

14. Figure 5.1: Hull and Envelope dimensions 45

15. Figure 5.2: The fin dimensions 49

16. Figure 5.3: Example of Fin Design and Dimensions 51

17. Figure 6.1: Shape of the Hull and Envelope 54

18. Figure 6.2: Generating the shape 55

19. Figure 6.3: Determining solid body material 55

20. Figure 6.4: Projecting the CFX Mesh 56

21. Figure 6.5: Inlet Region 56

22. Figure 6.6: Outlet Region 57

23. Figure 6.7: Body Region 57

24. Figure 6.8: Free Slip Region 58

25. Figure 6.9: Generating Surface Mesh 58

26. Figure 6.10: Generating Volume Mesh 59

27. Figure 6.11: Inner Isometric View 60

28. Figure 6.12: Determining the speed of 20 km/h 60

29. Figure 6.13: Selecting the boundary details 61

30. Figure 6.14: Repeated Action for Free Slip 61

31. Figure 6.15: Repeated Action for Body and Wall 62

32. Figure 6.16: Fin designs 63

33. Figure 6.17: Material Descriptions 64

34. Figure 6.18: Determining the related values 64

35. Figure 6.19: Meshing Phase for the Fins 65

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36. Figure 7.1: Pressure Observations 67

37. Figure 7.2: Temperature Observations 67

38. Figure 7.3: Density Observations 68

39. Figure 7.4: Velocity Observations 68

40. Figure 7.5: Mach number Observations 69

41. Figure 7.6: Streamline Velocity Observations 69

42. Figure 7.7: Graph of Momentum and Mass Result 71

43. Figure 7.8: Graph of Turbulences Quantities 71

44. Figure 7.9: Von Mises Stress Analysis for Fin 1 74

45. Figure 7.10: Von Mises Stress Analysis for Fin 2 74

46. Figure 7.11: Strain Analysis for Fin 1 75

47. Figure 7.12: Strain Analysis for Fin 2 75

48. Figure 7.13: Displacement Analysis for Fin 1 76

49. Figure 7.14: Displacement Analysis for Fin 2 76

50. Figure 7.15: The selected fin 77

51. Figure 7.16: Aerostat design (isometric, front and side view) 78

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LISTS OF TABLES

TITLE PAGES

1. Table 2.1: Type and specification of aerostats (part 1 of 2) 18

2. Table 2.2: Type and specification of aerostats (part 2 of 2) 19

3. Table 2.3: Requirement list for aerostat 20

4. Table 4.1: Major part’s design concepts 34

5. Table 4.2: Concept sketches analysis 40

6. Table 5.1: Standard Parameter for Aerostat 44

7. Table 5.2: MTOW Calculation Results 48

8. Table 5.3: Standard Parameter Formula 49

9. Table 6.1: Material Basic Properties 53

10. Table 6.2: Material Basic Properties 63

11. Table 7.1: The constant values 70

12. Table 7.2: Table of Categories 70

13. Table 7.3: Table of Summarize values 72

14. Table 7.4: Table of Specific Heat Capacity 72

15. Table 7.5: Average Scale Information 73

16. Table 7.6: Fin 1 table of values 77

17. Table 7.7: Fin 2 table of values 77

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Bachelor’s Final Project II

CHAPTER 1

INTRODUCTION

1.0 Background of the project

Aerostat is a ship which can fly like an airship. Since the duration of its flight is

considered long, it is not suitable for any crew to control it. The aerostat, in the other

words, is known for its un-manned functionality and work independently once the

generator that pumps in the helium completed its task. Helium is practically the best

choice possible to make the so called ‘airship’ floating in the air since it is the lightest

gas that is not flammable. Even though the aerostat invention is useful and compulsory

by certain parties, there are still certain parts that need to be modified and upgraded.

This thesis will somehow explain my general ideas on creating better solutions. The

major problems that can be detected are;

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i. Aerostats sometimes do not emerge to its equilibrium condition when it reached

to certain height. This is due to the air pressure that will raise proportion to the

level of atmosphere. The wind movement has also brought consequences where

the steady states of aerostat will somehow being effected because of the

aerodynamics design do not considered the environment capability.

ii. Aerostat steady state depends on how the flow movement, pressure, stress and

any other factor thus the disability to understand the basic principal to fly an air

ship will cause failure in many ways.

1.1 The significances of the project

This project was initially conducted to understand the preliminary design of

aerostat and analyzing it in the aspect of temperature, pressure, and the state of any

exchange that occurred in the hull or the other parts. However, the ideas have developed

into more advance thinking-thanks to the internet observations and the will of creating

things better, invention after invention. This project will include the literature review

about the aerostats, the enhancement for tether in order to create better on-air stability, to

create equilibrium state between payload and hull, and redesign the preliminary parts.

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1.2 Objectives

1. Conduct preliminary designs for aerostat. The preliminary designs are the

envelope (hull) and the fin. The design will be consider roughly according to

the writer’s common sense in the initial stage. There will be a few design

concepts to be chosen and will taken further ton analyzed it using computer

aided software

2. To study and understand the aspects that involves with the major part of hull

and envelope such as the pressure, air flow, temperature, aerodynamics, and

the other aspect that will be reveal in detail in the ‘result chapter’. The design

will be analyze by calculations and software simulations.

3. To choose the best reliable design that has been successfully accomplished

through software simulations. The fin shape will be determined by

conducting an analysis regarding to stress, displacement and strain that

occurred due to force while on the air.

Figure 1.1: Aerostat’s major parts

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1.3 Scopes of the projects

The project can only be held in general point of view since the writer himself is

considered lack of knowledge or even experiences. The related scopes are;

i. The analysis will only relate to the mathematical equation without any certain

sum. In the other words, this proposal only acquired the assume value regarding

to the writer’s assumption and logical self-thought.

ii. The simulation of analysis will be accomplish using software (Ansys CFX,

Cosmos) including the experiment of finding the pressure values, temperature

values, and other aspects that relates to it. The environmental influences will be

neglected and considered not important.

iii. The designs are limit to two ways of sketching; hand-sketching and software

(Catia VSR, Solidwork).

iv. The design only include the aerostat itself without considering the point of

launching platform, generator to pump in the helium, and also the consideration

of any electrical or electronic devices.

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CHAPTER 2

LITERATURE REVIEW

2.0 What is aerostat?

Figure 2.1: Aerostats “The Modern 64K” (Source: www.blimpinfo.com)

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Aerostat is a ship which is can fly like airship. The aerostat is not used the crew

to do any task. Aerostat can carry instruments and sensors for long durations that are

impractical for humans and other aircraft. The aerostat is a large fabric envelope filled

with helium. It can rise up to 15,000 feet while tethered by a single cable, which has a

maximum breaking strength of 26,000 pounds. The aerostat network consists of three

sizes of aerostats and three varieties of radar. The smallest aerostat is about twice the

size of the Goodyear Blimp. The 275,000 cubic foot, aerodynamically shaped balloon

measures 175 feet long by 58 feet across the hull, with a tip-to-tip tail span of 81 feet.

The aerostat system lifts a 1,200 pound payload to operating altitude for low-level radar

coverage.

The term “aerostat” has two meanings. In the first, broader sense, it includes all

lighter than air aircraft. The expression lighter than air refers to objects that are buoyant

in air because they have an average density that is less than that of air (usually because

they contain gases that have a density that is lower than that of air). The opposite

expression, heavier than air, refers to aircraft, such as aero planes and helicopter that

have a greater density than air.

The term “aerostat” comes from the fact that buoyancy is technically said to

provide aerostatic lift in that the force upwards arises without movement through the

surrounding air mass. This contrasts with aerodynamic lift which requires the movement

of at least some part of the aircraft through the surrounding air mass. The second,

narrower and more technical usage refers only to moored balloons. This article focuses

on the narrower use of the term. Thus, in the narrower sense, an aerostat is a tethered or

moored balloon often shaped like an airship and usually filled with helium. Aerostats

differ from airships and balloons in that airship and balloons are both free flying

whereas aerostats are tied to the ground.

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2.1 The function of aerostat

Aerostats are commonly used to carry instruments and sensors for long durations

that are impractical for humans and other aircraft. Surveillance aerostats have also been

used in the 2004 American occupation of Iraq. Utilizing a high tech optics system to

detect and observe enemies from miles away and have been used accompanying foot

patrols in Baghdad.

2.2 How the aerostats fly?

How do aerostats fly is explained by the Principle of Archimedes:

"Bodies submerged into a fluid receive from it a lifting force which is equal to the mass

of the displaced fluid." (This is the same principle that explains why boats float on

water.) The aerostat is filled with a lifting gas (Hydrogen, Helium, hot air or natural

gas). The air in which the aerostat finds itself has a higher specific weight than the lifting

gas. The envelope filled with the light gas generates a lift that is equal to the weight of

the displaced air. Like a (light) kork floating in (heavier) water, a helium or hydrogen

filled balloon floats in the heavier air. (Clark-Maxwell J., 1961)

Figure 2.2: Rapid aerostat deployment (Source: www.defenseindustrydaily.com)

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2.3 The examples of aerostats

Aerostat system can be configured for many different uses including detection

and tracking of small aircraft, small ships, and ground vehicles. They can also be

outfitted for communications relay and broadcasting.

The aerostat is a large fabric envelope filled with helium. It can rise up to 15,000

feet while tethered by a single cable, which has a maximum breaking strength of 26,000

pounds. Normal operating height is 12,000 feet mean sea level.

The current aerostat network consists of two sizes of aerostats (275,000 cubic

feet and 420,000 cubic feet) and two varieties of radars. The average aerostat is about

two times the size of the Goodyear Blimp, i.e., the 420,000 cubic foot, aerodynamically

shaped balloon measures 208 feet long by 65 feet across the hull, with a tip-to-tip tail

span of 100 feet.

The aerostat system lifts a 1,200 pound or larger payload to operating altitude for

low-level radar coverage. The aerostat consists of four major parts or assemblies: the

hull, the windscreen and radar platform, the airborne power generator, and the rigging

and tether assembly.

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Examples of products

Used for Sea-Based Border Patrol, Drug Interdiction

• Volume: 56,000 cf.

• Major Diameter: 36.5 ft

• Length: 109.5 ft

• Payload/Altitude: 800 lb. to 3000 ft

• Fabricated to date: 14 ea. w/two on contract

Used for Border Patrol, Drug Interdiction, TV Marti (Television to Cuba)

• Volume: 275,000 cf.



• Payload/Altitude: 1000 lb. to 12,000 ft

• Fabricated to date: 12 ea. with two on contract

Used for Border Patrol, Drug Interdiction

• Volume: 420,000 cf.,



• Payload/Altitude: 2000 lb. to 15,000 ft

• Fabricated to date: 8 ea.

Figure 2.3: Water platform (Source: www.ilcdover.com)

Figure 2.4: Manufacturing an aerostat (Source: www.ilcdover.com)

Figure 2.5: Specifications (Source: www.ilcdover.com)

56K Aerostat

420K Aerostat

275K Aerostat

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2.4 The components of Aerostats

2.4.1 An Aerostat System

Basically tethered blimps, aerostats are non-rigid aerodynamic structures

manufactured of composite laminates and high-tech materials in combinations that have

been refined over years of testing. The aerostat and its ground support equipment have

evolved into the present state-of-the-art system over two decades of on-station

operations. Aerostats have demonstrated an overall availability unmatched by any other

aircraft in the history of aviation.

AIRBONE POWER GENERATOR

HULL

RIGGING AND TETHER

CAMERA

PORTABLE GCS

Figure 2.6: components of tethered aerostat (Source: rosaerosystems.pbo.ru)

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2.4.2 Primary components

� Aerostat

� Tether

� Mooring System

� Payload

The aerostat consists of a flexible structure hull filled with helium (an inert,

lighter-than-air gas that is safe and non-burning) and air (in an internal compartment

called a ballonet) and associated power and control equipment. The hull is an

aerodynamically-shaped balloon up to 71 meters in length, fabricated from a high-

strength multi-layer fabric and designed for long term use in all types of environments.

Thermally bonded together, the completed flexible structure exhibits an exceptionally

low helium loss rate. The multi-layer laminate provides significant resistance to

ultraviolet radiation, chemicals and oxidation, while offering a field-proven life

expectancy of 10 plus years with minimum maintenance. An automatic system of

sensors, switches, blowers and valves controls the super-pressure within the hull to

maintain the external aerodynamic shape.

During the aerostat ascent to altitude, expanding helium forces air from the

ballonet chamber to the atmosphere through automatic valves. As the aerostat is

retrieved from altitude, the helium contracts will reduce hull pressure. This triggers an

Figure 2.7: The aerostats inflated (Source: www.hia-iha.nrc-cnrc.gc.ca)

designing and analyzing preliminary parts of an...

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