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Effects of Perception, Attention and Arousal on Aviation Incidents

How might our understanding of perception, different categories of attention, and arousal help us understand common causes of aviation incidents?
Human error plays a pivotal role in aviation incidents, it accounts for over 70 percent of aircrafts damaged beyond economic repair. Within the Human Information Processing (HIP) system perception, attention and arousal (P.A.A) all require a sophisticated cognitive process in order to comprehend and take action to distinct and contrasting stimuli a pilot encounters everyday. On a normal flight the pilots have a set checklist of workload that needs to be carried out and are trained meticulously, so performance tends to be very high because it’s a task that is carried out vey often. As the difficulty of the task increases, as such in an emergency situation the workload and task difficulty is increased unexpectedly but the time taken to deal with it is decreased.
Perception, attention and arousal (P.A.A) all play a crucial role in the way we understand the world around us and our understanding of HIP can help us how to prevent future incidents, however within this essay the breakdown within the HIP system is going to be examined and further investigation on how HIP played a catastrophic role within British Midland flight 072.
Flight BD 072 (G0BME) was operated by British Midland and flew from London Heathrow (LHR) to Belfast International Airport (BFS). In this particular incident the flight took of from LHR with 126 passengers onboard, as the aircraft proceeded to climb through 28,300ft the aircraft began to shake.
While ascending the cabin began filling with smoke, from previous training the pilots knew that the most probable cause was an engine fire.
Air Traffic Control instructed the pilots to divert to the closest airport, which was East Midlands, to deal with the contaminated air being pumped through the cabin the pilot shut down the starboard engine. The shaking and the fumes stopped temporally but on final approach a higher power setting was required and in an attempt to land the Boeing 737 the aircraft plummeted out of control crashing into the embankment.
Within this accident there were numerous failures by the aircrew, passengers and the airline itself which all accounted towards the crash.
All complex systems have barriers and safeguards in place, but all have a latent weakness. This model is known as the Swiss cheese model, the way in which the model works is the events that cause you from getting from where you are to hazardous risk accruing is blocked, the layers of cheese don’t line up. So at any point one of the barriers would be effective and prevents a hazardous situation from happening.

(, 2018)
The problem then arises when all of the layers/weaknesses line up causing an accident; within the G0BME accident there were a number of latent weaknesses that were highlighted within the accident report:
Aircraft Design

Human Information Processing
Information processing model proposes that our brain is similar to that of a computer in that we get:
Input – Environment
Process – Cognitive Process
Output – Decision
We are not able to attend to every stimulus that our senses receive because we have a limited cognitive resource so the HIP system filters through our senses and depending on what activity is being carried out focuses our senses on those signals. An important element of HIP is that you don’t have to have a memory of every situation in order for your brain to predict the outcome of an activity; we can use previous experiences and assumptions in order to forecast situations.
Perception is the operation where the brain can organize and interpret stimuli from the sensory registry in order for us to understand the environment around and put it into context.

Perception played a vital role within flight BD 072 crash, on the older models of the Boeing 737 the compressor on the right hand engine was used for Environmental Control System (ECS), this system controls the aircraft pressurization air-conditioning and air supply to the cabin, using pervious knowledge of this aircraft type the first officer came to the conclusion that the right engine was at fault and as a result shut it down.
The top down approach to perception can be used to explain how this fatal error was made, Gregory claims “the visual information available to us is not always of a high enough quality and therefore the brain needs to fill in the gaps by using prior knowledge, memories and similar experiences to understand what is around us” (Gibson,J). This top-down theory is hypothesized as a primitive reflex when it came to hunting food and is incredible when put within a situation in which you need to improvise, but when in a emergency situation where the workload is elevated and your not particularly familiar with the upgraded aircraft model can lead to flight BD 072.

You can only attend to a small of the sensations around us and only a small part of what we attend to can be remembered; in essence attention can be thought of as a filtering process. Attention is a limited resource and a pilot cannot focus on everything within the cockpit at once, but how he filters out the unimportant information and decides when to shift his attention to something new is fundamental. .
Within the cockpit of flight BD 072 the pilot and first officer had numerous things to attend to, but there primary task was to stop the smoke entering the cockpit and rerouting to East Midlands airport.
Selective attention – It concerns with signals we choose to focus on rather than others, so the pilot would be focused on altimeter and his speed. In an attempt to reroute and land the aircraft as quick as possible, only the essential tasks would get attending to.
Focused attention – Knowing that the aircraft is incapable of continuing the route and having to reroute the pilot would no longer be focused on fuel levels and instead thrust, so ignoring some stimuli and instead choosing to pay attention to others.
Divided attention – The pilots attention would have been divided between the flashing lights and aural cautions on the instrument panel and the smoke within the cockpit, while manually flying the aircraft in an attempt to land it.
Sustained Attention – Before the emergency occurred the attention o f the pilot would have been sustained on the Head Up Display (HUD), which gives the pilot all critical flight information.
Attention helps us understand how this accident could of occurred because from the flight deck the pilots could not see the engine and had to rely on an engine vibration gauge, but from previous experience the pilots believed the readings were unreliable and consequently disregarded it. If their selective attention attended to this gauge the accident would have been avoided.

Arousal leads to a release of adrenaline within the brain, an increased blood pressure/heart rate and a condition of sensory alertness. It is essentially apart of our primitive state in which we are ready to (fight or flight) when we feel threatened or in danger, it’s our readiness to respond.
The aircraft encountered a emergency situation, the pilots onboard would have been overwhelm attempting to deal with the issues at hand, the arousal system would have been important element because that release of adrenaline is needed when your in a emergency situation and scared.
Arousal and attention are closely associated because if your bored and lose attention your arousal decreases, inversely in an emergency situation both would be heightened, an optimum level of arousal for performance exists, and too little or too much arousal can adversely affect task performance.
Bystander Effect
Shortly after terminating thrust the captain of the aircraft made an announcement on the public announcement system stating that there was an engine fire and the right hand engine was shut down.
There were 118 passengers and 3 crewmembers that heard the announcement and could clearly see flames ravaging the left hand engine yet no one decided to tell the flight deck that they had turned off the wrong engine.
An individual is less inclined to take action because of the presence of others; there are a number of examples of why no one said anything:
Experience of the pilot
Passengers would think the cabin crew would have said something
The pilot simply misspoke
The pilot would have known
Diffusion of responsibility theory, when individuals are in the presence of others they feel less personal responsibility and are less likely to take action, the bystander affect is amplified by the number of people in a group, so because there are 121 people the less inclined each passenger felt to take action.
The P.A.A systems play a vital role within aviation incidents, having an understanding of these key contributors can help to minimize accidents reoccurring.
The air disaster of flight 072 has cemented how important P.A.A. is with the industry a number of regulatory changes have been made to ensure
Crew Training
It is now mandatory for crewmembers to report any findings to the pilot that may affect the flight.
Retraining pilots in order to have knowledge of the upgraded senser on this new model of aircraft.
Engine Testing
The CAA in conjunction with the engine manufacturer increased the frequency of engine inspections and health monitoring on the Boeing 737-400.
Gibson, J. (n.d.) Perception Psychology – How We Understand Our World [online]available from [12 November 2018] (2018). ESCM – Extended Swiss Cheese Model. [online] Available at: [Accessed 8 Nov. 2018].
Gibson, J. J. (1966). The senses considered as perceptual systems. Oxford, England: Houghton Mifflin

Analysis of UAV Manoeuvrability

Table of contents
1. Literature review
2. Designs and configurations
3. Aerostatic Principles
4. Lifting Gases
Similar projects
Aerodynamics and Stability
5. Manufacturing and materials
List of figures
Figure 1‑1: Pilatre de Rozier crossing the English Channel. (Pozdravish , 2011)
Figure 1‑2: Hindenburg disaster. (Syon G., Time, 2017)
Figure 2‑1: Traditional airship configurations. (Khoury et al. 1999)
Figure 2‑2: Megalifter winged airship. (Livejournal, 2016)
Figure 2‑3: Propellled airship configuration. (Khoury et al. 1999)
Figure 4‑1: Lifting capacity of different gases. (Goodyear Aerospace Corp)
Figure 5‑1: V-shaped hybrid airship. (Liu et al. 2011)
Figure 5‑2: Rotation angle variation with gondola position change. (Haque et al. 2014)
Figure 5‑3: Naca 6322 70% chord length. (Adamczyk G., (2017)
Figure 5‑4: Winged and wingless mesh models. (Adan et al. 2012)
Figure 5‑5: Wing vortex at different angles of attack. (Adan et al. 2012).
Figure 5‑6: Airship pressure contoursat at different empenage configurations. (Haque et al. 2014)
Figure 6‑1: NACA 6322 80% chord. (Adamczyk G., 2017)
Introduction Airships represent an attractive and promising solution to missions that can involve transportation, surveillance, recognition and monitoring, and so on. The many potential benefits that they can provide compared with UAV’s (Unmanned Aerial Vehicles), helicopters or drones in many practical applications have been proved, in terms of their high endurance capability with a lower investment, as they require much less power due to the lift generated through buoyancy force. Most of the traditional lighter than air airships are at the mercy of the surrounding air as the majority are used with advertising purposes (Haque et al. (2014)) Nevertheless, it must be taken into account for transportation missions heavy dusty winds will cause a great difficulty in handling, especially in the lateral stability of the vehicle. Taking this in mind, in the recent years there has been experienced an increased interest on the design of hybrid airships, able to combine both the lift generated by buoyancy forces as well as the produced by added wings, solving by this way the stability issues of traditional airships.
This document will cover the complete design, manufacturing and testing of a mini airship for surveillance and terrain mapping, including the integration of the airship envelope, propellers, controllers, micro pimp and sensors. The aim of this project will be to compare the manoeuvrability and performance of the final prototype with a conventional UAV of similar weight under the same conditions. It must be stated that this is a continuation project of the designs carried on from previous projects, so using this together with the limited literature available related to different areas of research (Haque et al. (2014)), this project will help to complete and explore these research areas that require the completion of the details of the aerodynamic and stability behaviour at different flight conditions.
1. Literature review History
The history of aviation and all the challenges that it implied, suppose one of the greatest exponents of how human dedication and tenacity served to achieve the common objective of conquering the skies.
Lighter than air vehicles began their development in 1783 with the French brothers Joshep Michael Montgolfier and Jacques Etienne, that invented the hot air balloon and were able to send it up to an altitude near to 6,000 ft (1800 m) (Miller et al. (2013)). This concept was improved the same year by Jean Pilatre de Rozier, a French physicist that was achieved to make the first manned balloon, crossing the English Channel using flapping wings to propel the balloon and a birdlike tail for steering manoeuvres (Figure 1-1).
Figure 1‑1: Pilatre de Rozier crossing the English Channel. (Pozdravish, 2011)
It was in 1900, when the Count Ferdinand von Zeppelin from Germany, invented the first rigid airship, leading to one of the most successful airships of all time. The term rigid comes from the metal framework composed by triangular girders covered with fabric that contained hydrogen-gas-filled rubber bags to generate the lift. The first one built used tail fin and rudders to stabilize the airship during flight, being powered by an internal combustion engine.
Several models where manufactured (Zeppelins) with military and civil purposes in the early 1900s, as well as for transatlantic travel (Frankfurt-Recife, Brazil). During this period, although many accidents were produced in different countries as the UK and Italy, having hundreds of dead’s, the investigation and development never stopped until 1937. Was this year when the largest and most iconic airship was built, the LZ129 Zeppelin. Designed to perform transatlantic flights, and after successfully carry out a travel between New Jersey and Germany, it crashed while landing in Lakehurst where 36 passengers died (Figure 1-2).

Figure 1‑2: Hindenburg disaster. (Syon G., Time, 2017)
This accident supposed the end of the golden era of airships. Nevertheless, the interest on lighter than air vehicles technology did not disappear, using helium as the main advantage due to its non-flammability. US Army continued to develop them until 1962.
In recent days they are being used for advertising, research purposes, tourism…, however, the investigation of the new possibilities that they can offer is still in process.
2. Designs and configurations At basic levels, an airship is a balloon that can be manoeuvred and propelled, but to the able to perform this it must accomplish two basic principles. On the one hand, in order to have a reliable and secure flight, it must sustain all the aerodynamic loads as well as the ones produced by the propulsive installations. On the other hand, the primary function of the envelope is that it should have a streamlined in other to reduce the drag coming from the air resistance (Khoury et al. 1999).
Traditionally, especially in the first half of the 19th century, there have dominated to main structural airship categories. Pressure (Blimps), and rigid airships (See Figure 2-1).
A blimp is an airship whose shape is maintained by the pressure generated by the lifting gas contained on its interior. Regardless in many pressure airships, there is no need to install a hard compartment to harbour the power plant or additional equipment, sometimes appears the need to incorporate a structure capable of sustaining the bending loads; becoming by this way in a semi-rigid airship.
Otherwise, rigid airships carry all the external loads through a surrounding framework composed of a set of cells, traditionally made of fabric skin wire-braced girders. This also helps to maintain the envelope’s shape independent of the interior pressure as well as reducing the material strength needed.

Figure 2‑1: Traditional airship configurations. (Khoury et al. 1999)
To this project, the semi-rigid configuration is considered as the most adequate due to its less complex design and manufacturing, combining the advantages of both previous configurations it will allow to sustaining bending loads without creating additional stresses on the envelope.
Starting from the base of the previous designs, many configurations had been proposed and investigated in order to adapt the models to specific missions and improve their general performance. The airships involved into this current are classified as ‘Hybrid Airships’, that at the same time can be divided into two categories.
The first one combines the characteristics of an aeroplane with a classical airship, primarily adding wings. With this premise, is tried to enhance the lift capacity aerodynamically by carrying a significant percentage of the carried payload through the dynamic lift generated by the wings. Figure 2-2 shows the Megalifter, a project developed during the 1970s using this ‘winged’ configuration.

Figure 2‑2: Megalifter winged airship. (Livejournal, 2016)
This design would have a vast scientific interest to this project due to the capabilities that it would offer during take-off and landing, having much less runway needed compared to an aircraft of similar weight, as well as a safer ground handling than a conventional airship.
The second group would involve the combination of the helicopter technology using vectored propellers to generate thrust and help to the airship buoyancy (See example in Figure ). However, many studies have gone further, developing designs where the total weight of the airship was sustained by the aerostatic lift, leaving all the power capability of the propellers to sustain the payload.

Figure 2‑3: Propelled airship configuration. (Khoury et al. 1999)
This configuration, together with the ‘winged’ previously explained, will suppose one of the bases of this document as the scope of this document pretends to mix this both technologies in the most efficient manner. With this, it will be intended to establish which is the best arrangement and the main advantages that they can offer, either separately or combined.
3. Aerostatic Principles In order to face and understand the incoming literature, there must be a basic aerostatic and aerodynamic airship knowledge regarding design purposes (Khoury et al. 1999).
The static buoyancy refers to the effect of a body immersed in a fluid (upward force), named ‘aerostatics’ when this fluid is the air. This force is represented in Equation 1 below.
B=V.ρa (1)
B is the buoyancy force;
V is the internal volume of the body
a is the mean density of the air
Then, subtracting the total weight (W) of the body to the buoyancy force generated as shown in Equation 2 it can be obtained the net lift produced upwards (L).
L=B–W (2)
In a balloon/airship case, the total amount of weight will be defined by the sum of the weight of the envelope (W0) and the weight of the gas stored inside, which is quantified multiplying the internal volume of the envelope (V) by the density of the contained lifting gas ( ρ
g), which is usually hydrogen or helium (Equation 3).
W V. ρg W0 (3)
The total dispensable lift (Ld) by the internal gas is represented in Equation 4 (from Equations 1, 2, and 3) as a result of the subtraction of the empty airship weight (W0) from the total lift generated from the gasbag (Lg).
Ld=Vρa –ρg –W0= Lg–W0 (4)
The volume of the gasbag/airship determines the lift that it can generate regardless of its shape. Nevertheless, spherical balloons offer the smallest surface area, favouring a minimum weight design and the lowest skin tension.
In the atmosphere, as the gasbag ascends the gas densities decrease with the pressure, increasing by this manner the volume of the gasbag. Despite this, at the same time the temperature decreases rising the gas densities. Nevertheless, the effects regarding the fall of pressure with the altitude are more pronounced than the ones produced by the temperature. This leads that at a certain point, after a continuous expansion the gas will occupy the entire volume of the envelope and no further expansion will be allowed. Then, from this point called ‘pressure height’, the lift will begin to decrease.
This pressure height will be dependent on the amount of gas inside the gasbag, the quantity defined as the ‘inflation fraction’ as shown in Equation 5 where V0 is the actual volume of the contained gas and V is the maximum volume of the gasbag. Then, at sea level, it will be assigned a particular I0.
I=VV0 (5)
Taking into account that pressure and temperature equally affect to the air and gas densities, it can be obtained the relation in Equation 6.
I0I=ρa ρa0 (6)
Following the International Standard Atmosphere (ISA) as a reference to establish the parameters variation with altitude, the value of I0 can be expressed. So from Equation 6, it can be obtained that the pressure height will occur when I=1; I0=pa/pa0. This means that once I0 reaches 100% of its value, the gas will be producing its maximum gross lift. However, this will only occur at sea level impeding the ascend without losing lift, meaning that at sea level I0 must be always less than 100%. Equation 7 represents the maximum dispensable lift theoretically.
LD=I0.Lgo–W0 (7)
4. Lifting Gases Lighter than air vehicles, use gases with lower density than the surrounding air. As shown in Figure 4-1, there are compared the different lift capacities of a variety of gases at sea level. As it can be appreciated, hydrogen (0.0711 lb/ft3), is the gas with the lowest density among the rest, while the helium is the second in the list with a 7.3% smaller lifting capacity (0.0659 lb/ft3). (Pasternak et al. 2009).
As it was previously explained, the use of hydrogen was abandoned after the Hindenburg disaster due to its flammability and the high risk that it supposes. Due to this, although many other alternatives have been considered such as ammonia (corrosive), natural gas and methane (flammable), it is considered that the most adequate lifting gas to carry out at these days is the helium.

Figure 4‑1: Lifting capacity of different gases. (Goodyear Aerospace Corp)
Previous Work
The investigation of a new generation of hybrid airships is considered a relatively new topic that it is still under development and continuous research in numerous investigations. The majority of the scientific documents related with this engineering field cover the design phase as well as numeric simulations, so starting from them, it will be analysed the different design aspects carried out in order to lead the project in the most efficient manner.
Similar projects
The main base and background that will sustain this dissertation will be the investigation of the design and development of a hybrid airship carried out by Adamczyk G., (2017). The aim of this study was to develop a hybrid airship capable of generating lift using an aerofoil envelope shape. There were analysed different airship designs and concepts as well as CFD analysis of different aerofoils to obtain the most appropriate to perform the work, leaving a high and detailed background for the design phase.
The second section was focused on the manufacturing of the full-scale model, that although it was unable to fly, it served as a guideline of how to manage a manufacturing process and avoid the repetition of errors on future work.
Another similar recent study, but this time looking for the design never seen before to study its performance was carried out by Liu et al. (2011). This paper provided the design of a V-shaped airship with an aerofoil design that, in addition to the buoyant lifting capacity, two propellers were installed providing yawing, rolling and pitching moments (Figure 5-1).
The properties of this V-shaped aerofoil, composed by the combination of two hulls with a thick aerofoil section, are compared with one teardrop-shaped airship of the same weight class.
On this study it was discovered that the aerodynamic efficiency of the V-shaped airship increased rapidly with the velocity compared with the conventional teardrop model, reaching the conclusion that the effectiveness of this design is achieved at high speeds. At the same time, it was also discovered how two engines installed can help to provide a wide variety of control strategies.

Figure 5‑1: V-shaped hybrid airship. (Liu et al. 2011)
On the study Stability and Take-off Ground Issues by Haque et al. 2014, it is analysed the effect of the gondola position on rotation angle during take-off, landing and ground roll on the IWHA-14 hybrid winged airship. This paper puts special emphasis on the possible configurations that can be met in order to operate at the minimum roll angle, being of great utility for the design and manufacturing phases.
This can be demonstrated as it can be observed in Figure 5-2, where the gondola position has a dominant effect during take-off on the rotation angle of attack. Moving forward the position of the gondola the rotation angle is 9.5o while moving it 2.5 m back the minimum rotation angle increases up to 12o.

Figure 5‑2: Rotation angle variation with the gondola position change. (Haque et al. 2014)

Aerodynamics and Stability
As stated in Adamczyk G., (2017), the selection of the envelope aerofoil profile is crucial in order to obtain the maximum lift to drag ratio as well as having the sufficient internal volume to fit the required gas to sustain the airship weight including the payload. Aerofoils from the NACA 4-digit series with almost flat bottom surfaces and great thickness were considered as the most suitable, where the NACA 6322 profile was finally chosen as one with the greatest characteristics.
As this inflated shape aerofoil would constitute the airship envelope, the NACA profile was cut at 70% of is chord as depicted in Figure 5-3, allowing to work with a more likely airship structure making easier the stages of the manufacturing process

Figure 5‑3: Naca 6322 70% chord length. (Adamczyk G., (2017)
The main advantages and aerodynamic differences of a winged aircraft in comparison with a wingless one have been studied in detail in Adan et al. (2012). As it was previously explained in the Unconventional Designs section, part of the total lift of hybrid winged airship comes from the aerostatic buoyancy and the results from the dynamic lift of the wings. Taking this into account, the intention was to integrate wings to a conventional airship (Figure 5-4) and, using a commercial CFD package, analyse both models as a preliminary aerodynamic analysis for a winged airship.

Figure 5‑4: Winged and wingless mesh models. (Adan et al. 2012)
The experiment was carried out at a Re = 2.16×106 at a free stream velocity of 40 m/s at different angles of attack (See Figure 5-5 for winged airship velocity contours).
This investigation outcome presented a promising reliability and performance for future winged airships flight tests. The lift generated was on average at positive angles of attack three times more compared to the wingless airship, where the highest increment is found at α = 5°. On the other hand, drag increases exponentially on the winged, increasing from 19% up to 58% in comparison. In terms of motion, both airships present a good longitudinal stability, being where the major contribution of the wings to the total stability. In addition, changing the wings position and orientation can contribute to a better static rolling moment stability.

Figure 5‑5: Wing vortex at different angles of attack. (Adan et al. 2012).
Another study (Static Longitudinal Stability of a Hybrid Airship) carried by Haque et al. (2014), investigates how different empennage configurations can affect to the longitudinal stability of a winged airship. As it can be observed in Figure 5-6, two models where analysed, an inverted ‘Y’ type empennage (left) and a ‘ ’ type empennage.
The comparative investigation showed that the ‘ ’ configuration tends to present a higher static stability with the noticeable ability to develop a restoring pitching moment.

Figure 5‑6: Airship pressure contours at at different empennage configurations. (Haque et al. 2014)
5. Manufacturing and materials In work done by Adamczyk G., (2017), there was reproduced a preliminary full-scale paper manufacturing prototype of the design in order to have an initial approach of the steps to take on before build the real model, which could not be finished due to lack of time.
The initial plan was to divide the airship into two main components, the gondola and the envelope. Two gondola configurations were considered; the first one composed of plastic rods forming four equilateral triangles, two at the bottom and two at the top. The other configuration was simpler as it was based on a cuboid-shaped gondola manufactured with carbon fibre tubes.
Both designs would serve to carry all the electronic systems proper to a surveillance aircraft; including a camera, batteries, altitude control equipment, mapping lecture systems, GPS and remote control systems. The propulsion unit was initially composed by two vectoring propellers capable of generating either thrust or lift, although despite this, a 4 engine configuration was considered as a possible alternative bringing a better control and net thrust.
For the design of the envelope, the chord of the aerofoil chosen was cut at its 80% instead of 70% to increase the volume and keep the aerodynamic characteristics (Figure 6-1).

Figure 6‑1: NACA 6322 80% chord. (Adamczyk G., 2017)
Finally, after finishing the paper model, [8] establish as the next step the creation of the definitive envelope using Tuftane Thermoplastic Polyurethane (TPU) film due to its less rigidity compared with the paper, putting emphasis on the importance of creating a preliminary full scale model with paper before start using the manufacturing materials, ensuring that all the measures fit and for the prevention of errors.
During the envelope manufacturing, there will be primordial take special attention to the pressurization, avoiding leaks that can jeopardize the airship structural integrity during a test flight.
To avoid this, Motiwala et al. (2013) establish a series of requirements and considerations for the material involved in this process:
-It must be least permeable than Helium.
-High tear strength (damage tolerance).
-Resistant to environmental corrosion due to temperature changes and humidity.
-Resistant to fatigue to be able to be inflated and deflated for a long life cycle
-Use of reliable joining techniques.

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Motiwala N. I., Khan I. A, Yelve N. P., Narkhede, Pant R. S., 2013, Conceptual Approach for Design, Fabrication and Testing Remotely Controlled Airship, Dept of Aerospace Engg, Indian Institute of Technology Mumbai, India, pp 3390-3395.