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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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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.
• Major Diameter: 62.5 ft
• Length: 187.0 ft
• 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.,
• Major Diameter: 69.5 ft
• Length: 208.5 ft
• 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)