BACHELOR THESIS IN
AERONAUTICAL ENGINEERING
15 CREDITS, BASIC LEVEL 300
School of Innovation, Design and Engineering
A historical survey of solar powered airplanes
and evaluation of it’s potential market
Author: Martin Hoffborn Report code: MDH.IDT.FLYG.0218.2009.GN300.15HP.LS
ii
ABSTRACT
Project Solaris is a student research project with the goal to build a solar powered Unmanned Aerial Vehicle. This study is one in a set of studies that make up the initial phase of project Solaris. The main objective of this report is to investigate earlier solar powered airplanes as well as evaluate (or explore) potential future niche markets where solar powered UAVs could excel.
A presentation of earlier solar powered airplanes will give an overall understanding of how solar powered airplanes have evolved and also provide information about the goals and ambitions behind the projects.
Potential applications such as power line inspection and algal bloom observation will be described and a list of specifications for each application will be presented.
SAMMANFATTNING
Projekt Solaris är ett studentprojekt med målet att bygga ett solcellsdrivet obemannad flygplan. Denna studie är en i en serie studier som utgör den inledande fasen av projektet Solaris. Det främsta syftet med denna rapport är att undersöka tidigare soldrivna flygplan samt värdera (eller utforska) eventuella framtida nischmarknader där soldrivna flygplan kan överträffa traditionella system.
Tidigare soldrivna flygplan kommer att presenteras för att ge en övergripande förståelse för hur soldrivna flygplan har utvecklats och också beskriva de mål och ambitioner som drivit projekten.
Potentiella tillämpningar så som elnäts inspektion och algblomnings observationer kommer att beskrivas och en lista med specifikationer för varje tillämpning kommer att presenteras.
Date: 20 August 2009
Utfört vid / Carried out at: Mälardalen University Handledare vid MDH /Advisor at MDH: Gustaf Enebog Examinator: / Examinator: Mikael Ekström
CONTENTS
Chapter 1
INTRODUCTION 11.1 Background ... 1
1.2 Objective... 1
Chapter 2
METHOD 2 2.1 Method and Outline ... 2Chapter 3
HISTORICAL SURVEY 3 3.1 A brief history of solar powered flight ... 3Sunrise ... 3
Gossamer Penguin... 3
Solar Challenger ... 4
Solair I ... 4
Sunseeker ... 5
Icare 2 ... 5
Solitair ... 5
The NASA ERAST Program ... 6
Royal Institute of TECHNOLOGY – FLYG... 6
Solong ... 7
Sun Sailor ... 7
Sky Sailor ...8
Sun Surfer...8
QinetiQ - Zephyr...8
Projects under development ... 9
Number of solar powered fixed wing aircrafts ... 10
Chapter 4
UAV MARKET 11 4.1 UAV market forecast... 11Frost & Sullivan; emerging markets for civil & commercial UAVs (2005)... 12
4.2 Potential civil uav applications ... 12
Land Management ... 13
Earth observations ... 14
Commercial ... 14
Chapter 5
MISSION SPECIFICATIONS 15 Mission Specification ...15Chapter 6
DISCUSSION 17Chapter 7
RESULTS 18 7.1 Results from the historic survey ... 187.2 Results from the market evaluation ... 18
7.3 Recommendations for future work... 18
References
19 Solar cell efficiency development... 25Chapter 1
INTRODUCTION
1.1 BackgroundSolar technology is not anything new. The energy from the sun has been used in different ways ever since the 7th century B.C. In 212 B.C, Archimedes used bronze shields to focus the sunlight onto wooden ships so that they turned on fire, in 1839 Edmond Becquerel discovered the photovoltaic effect while experimenting with electrolytic cells and Albert Einstein later received the Nobel Prize in 1921 for explaining this 1.
The first photovoltaic cell was built in 1954 by Bell Laboratories but it wasn’t until the 1960’s that it came into serious use when NASA began to use it to power spacecrafts. As the space industry evolved so did the photovoltaic technology and both efficiency and reliability improved. During the oil crisis in the 1970’s photovoltaic cells became recognized as an alternative energy resource but sadly the interest for greener energy alternatives declined as the price for oil declined. However, in 2007 the European Union committed to a 30% reduction of greenhouse gases provided that there is an international agreement but if such an agreement is not signed then a 20% reduction by 2020 is promised 2. Today we have a much greater understanding of how we affect the environment and that has triggered more investments in environmentally friendly energy alternatives such as wind power, wave power and sun power. Hopefully the Solaris project can contribute to the evolvement of putting solar technology to use.
On November 4th 1974 R.J Boucher achieved the first solar powered flight with the airplane Sunrise1, since that day many more solar powered aircrafts have been built but very few have been put into commercial use.
Project Solaris is a student research project with the goal to build a solar powered Unmanned Aerial Vehicle (UAV). This study is one in a set of studies that make up the initial phase of project Solaris.
1.2 Objective
The main objective of this report is to investigate earlier solar powered airplanes as well as evaluate (or explore) potential future niche markets where solar powered UAVs could excel. The result of this paper will serve as guideline for decision-making to the Solaris project.
Information and tabulated data on historic solar powered aircrafts will be presented. This will serve as benchmarks for the design of the Solaris aircraft and as objects to conduct reversed engineering on.
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Chapter 2
METHOD
2.1 Method and Outline
The main issue has been addressed in the introduction and will be answered later in the report. The report has been divided into three parts. The focus of the first part has been on already developed solar powered aircrafts and on solar powered aircrafts under development. This part consists of historical information, flight data and aircraft data. The focus of the second part has been on civil applications for UAVs and developments in the UAV market. The third part of the report consists of mission specifications and recommendations for future thesis projects.
The information has been collected via Internet sources, market surveys and through interviews with scientists and with representatives from different industries.
1,2.Introduction, Objective, Method and Disposition
3. Historical Survey
4. UAV Market
5. Mission Specifications
6. Discussion
Chapter 3
HISTORICAL SURVEY
3.1 A brief history of solar powered flightIt is the author’s intent not to give a detailed description of the aircrafts mentioned in the following chapter but to give the reader an overall understanding of how solar powered fixed wing aircrafts have evolved and also the goals and ambitions behind each project.
Sunrise
The first solar powered aircraft to take to the sky was Sunrise I on November 7th 1974. Sunrise I was designed by R.J Boucher from Astro Flight Inc.
under contract with DARPA and was an extension of earlier projects involving electrical powered fixed wing aircrafts. “The use of solar power, although heavy in terms of watts per pound and expensive in terms of watts per dollar, has one singular feature: the energy source is inexhaustible”3 (R.J Boucher explaining his fascination of solar powered flight). Sunrise I performed several flights in the winter of 1974 of up to four hours but unfortunately encountered severe winds and was seriously damaged. After the crash with Sunrise I, work started on the new and improved Sunrise II, which made its first flight in September 1975. Sunrise II was lighter, had more power and had improved aerodynamics compared with the earlier aircraft. After a couple of weeks of flight test the Sunrise II encountered
flight control problems and was damaged, and the test program ended. The objective of the Sunrise program was to prove the concept of solar powered flight, which it successfully did, and it sparked an increasing interest in solar powered aviation all over the world.
Gossamer Penguin
Following the successful flights of Sunrise I and II, AeroVironment led by Dr. Paul MacCready and Dr. Peter BS Lissaman took on the challenge to build a manned solar powered aircraft. AeroVironment had in 1977 developed a man-powered aircraft called the Gossamer Albatross that won the first and second of the Kremer prizes. Since this aircraft had very low power required it was ideal for the new challenge. AeroVironment took the existing Gossamer Albatross and scaled it down to about 75% of the original size. The initial flight was conducted with batteries as power source and Paul MacCready’s thirteen-year-old
son as pilot. The reason why his son was chosen as pilot was because he weighed only 36 kg however the official test pilot Janice Brown who weighed 45 kg later replaced him. The
Picture 1 Sunrise
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Gossamer Penguin was very fragile and had limited controllability, which meant that it had almost no tolerance for crosswind and wind gusts. This resulted in that the aircraft was limited to flying only in the mornings when winds where gentle but it also meant that the angle of the sun was low so they had to construct a solar panel that could be tilted towards the sun. After a series of test flights with batteries and solar cells the project ended on August 7th 1980 with a public demonstration of the aircraft in which the Gossamer Penguin flew for 14 minutes and covered roughly three kilometers4. This event is considered as the first manned flight relying only on solar power. Lessons learned from this project helped the Aerovironment engineers in the design of the more advanced aircraft, the Solar Challenger.
Solar Challenger
The DuPont Company spurred on by the successful flights of the Gossamer penguin decided to sponsor Paul MacCready and Peter Lissamans team to build a solar powered airplane that could fly across the English Channel. Since the Gossamer Penguin was not considered safe at high altitudes the Solar Challenger was designed to be more durable and maneuverable. The new design incorporated the use of advanced composite structures, a large horizontal stabilizer and a high positioned wing with a 35% reduced wingspan compared to the Gossamer Penguin 5. It was intended to fly only with the use of solar cells as power supply so Peter Lissaman at Aerovironment came up with an unconventional design for the wing and horizontal stabilizer; he designed an airfoil with the major portion of the top surface flat (the Lissaman Hibbs 8025) so that they could accommodate the 16,128 solar cells. The project objective was to build a concept aircraft that would show the world the potential of solar powered flight and to demonstrate the advancements made in solar technology. This was done on July 7th 1981 when the Solar Challenger made the record setting flight over the English Channel.
Solair I
At the time when the Solar Challenger flew across the English Channel Günter Rochelt was conducting test flights in his Solair I. The Solair I had a much smaller wing area and could therefore not fit enough solar cells on it to
collect the energy needed to climb. After some modifications the Solair I made the cross channel flight and was able to reach an altitude of 1000 meters relying only on solar power6. Günter Rochelt later
designed a new aircraft called the Solair II for the 1996 Ulm Berblinger Contest. This was a completely different aircraft than the first one and intended to be more practical and user friendly than any of the earlier solar powered airplanes.
Picture 3 Solar Challenger
Sunseeker
Inspired by the work done by Paul MacCready and Günter Rochelt, Eric Raymond started to design the Sunseeker I in 1986. Eric Raymond studied Aeronautical engineering at the University of California, San Diego and is a two-time world aerobatics champion. He has worked with both Günter Rochelt and AeroVironment and has founded the company Solar Flight. It was with the help of Günter Rochelt he started formulating the concept for the Sunseeker I. The Sunseeker had a high positioned wing with a 17 meter wingspan and a pushing propeller that that could fold together when gliding. Originally it was powered by two brush motors but was later changed to a single brushless motor from AC Propulsions. In June 1990 the Sunseeker I crossed the USA in 21 flights7. Eric Raymond and the team at Solar Flight later went on to develop an improved version of the Sunseeker I called the Sunseeker II. This airplane became the first sun and battery-powered aircraft to fly across the Alps.
Icare 2
In 1996 the University of Stuttgart won the annual Berblinger aeronautical competition with their contribution, the Icare 2. The challenge for 1996 competition was to create a manned solar powered airplane that fulfilled the
following requirements 8:
• Horizontal flight at 500 watt per square meter of solar radiation
• Three-axis control
• Maximum speed greater than 120 km/h • Stall speed less than 60 km/h
• Glide ratio (without propulsion) greater than 20
• Climb altitude of 450 m within 225 seconds after take-off
The Icare 2 is currently at the University of Stuttgart and is used for further development in solar powered flight.
Solitair
The Solitair was built by DLR Institute of Flight Systems as a proof of concept aircraft in the mid 1990’s. It was equipped with four adjustable solar panels in the same fashion as the Gossamer Penguin so that it could absorb a maximum amount of solar radiation by always being perpendicular to the incoming sunrays. So far a prototype with a wingspan of 5,2 meter has been built and tested 9.
Picture 3 Sunseeker
Picture 3 Icare 2
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The NASA ERAST Program
In 1994 NASA started the ERAST (Environmental Research Aircraft and Sensor Technology) program in response to an increasing demand for high altitude and long endurance aircrafts. These unmanned and autonomous aircrafts would be able to conduct atmospheric measurements, surveillance mission and serve as a communications relays. NASA was interested in using such an aircraft as an “atmospheric satellite” since it would make it easier to maintain/upgrade and to control it’s flight path, this for a fraction of the cost compared to a traditional satellite in space. The first aircraft used in the program was the solar cell and battery powered Pathfinder that was originally built as a solely battery powered aircraft in the 1980’s. It set the world altitude record for solar powered aircrafts when it reached 15390 meters on September 11th 1995. It was later renamed to Pathfinder plus and modified with a larger wingspan, new solar, aerodynamic and propulsion technology. The new Pathfinder plus reached 24400 meters and set a new altitude record. The goal for the Pathfinder plus was to validate different technologies that would later be used in the larger Centurion and Helios aircrafts10.
When NASA built the Centurion they made the wingspan 70% larger than the Pathfinder plus but kept the chord length which gave the Centurion an aspect ratio of 26 to 1, thus reducing the induced drag. The materials used needed to have a very good strength to weight ratio so the decision was made to use mostly carbon fiber and Kevlar. Advancements made in solar cell technology made it possible to equip the Centurion with 19% efficient solar cells instead of the solar cells that was installed on the Pathfinder that were only 14% efficient. A few test flights were made but the Centurion was just a stepping-stone in the program and was replaced by the final prototype of the series, Helios. The primary goals set up for the Helios was to achieve sustained flight at an altitude of 100,000 feet (30,480 meters), and flying for 24 hours straight including 15 hours above 50,000 feet (15,240 meters). One potential application for Helios was to monitor the atmosphere on mars. In 2001 Helios managed to achieve sustained flight over 96,000 feet (29,260 meters) for 40 minutes and a maximum altitude of 96,863 feet (29,524 meters), which is, still the unofficial world record. Due to Helios enormous size, light weight and naturally unstable design as a flying wing it was sensitive to turbulence and had aero elasticity problems. Unfortunately the Helios crashed in 2003 when it encountered turbulence and experienced a pitch oscillation (due to the wing bending)11.
Royal Institute of TECHNOLOGY – FLYG
In June 2002 students at Sweden’s Royal Institute of Technology rolled out their solar powered UAV prototype. The prototype was the culmination of three semesters work to design and build a solar powered UAV with the ability to operate in Swedish conditions and carry a 2 kg payload12. The aircraft had a conventional design and consisted of a high aspect ratio wing fitted with 12% efficient solar cells and a carbon fiber tube which housed the avionics. During the test flight the aircraft managed to stay in the air for a few minutes but it was very unstable and didn’t gain
PICTURE 4
Picture 3 Pathfinder & Helios
much in altitude. The fundamental goal of the SAP (solar aircraft project) was never to set any new records or to prove a new concept; it was to give the students an opportunity to develop skills in all phases of aircraft design and to grow into the engineering role.
Solong
Solong is a solar powered UAV that has demonstrated the ability to stay aloft for 48 hours. This feat was demonstrated on June 1st 2005 when the Solong aircraft managed to fly through two nights and land with half loaded batteries. The success of the Solong has a lot to do with the efficiency of the aircraft. It incorporates 20 % efficient solar cells, high efficiency electric motors, high-end batteries and variable pitch control that
allow tuning for
maximum propulsion efficiency under varying flight conditions 13. During the 48-hour flight it also used very experienced pilots and thermals (currents of air that rises from the warm ground) to stay aloft. The skill and experience of the pilots proved crucial for the airplane to stay aloft for as long as it did. Even though the aircraft is very efficient it needed to fly with it’s motors off for most of the day so that the batteries could recharge.Sun Sailor
Students at Technion IIT, Haifa formed in 2006 a project with the objective to set a new FAI (World Air sports Federation) world distance record for solar powered UAVs. The project had a main and secondary objective, the main being to set a new world record and the secondary to enable the students to integrate the knowledge acquired in their academic studies and experiencing an air vehicle development, manufacturing and testing process. To set a new record the aircraft needed to fulfill the
following requirements 14.
• Electrical motor propulsion
• Radio controlled flight without the help on any telemetry
• Maximum upper surfaces area of 1.5m2 • Maximum Weight of 5 Kg
• Only Solar Cells are permitted as the propulsion system power source
After evaluating pros and cons of different aircraft designs the team decided on a
conventional sailplane design with high aspect ratio and high lift over drag ratio. Both flexible thin-film solar cells and stiff solar cells were examined but since thin-film solar cells at the time only had a 7% efficiency rate the team decided on the more fragile and stiff solar cells used on the Helios aircraft 14. The team built two aircrafts but unfortunately both crashed before setting a new world record.
Picture 10 Solong
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Sky Sailor
In 2004 André Noth, a PhD student at the Swiss Federal Institute of Technology started a project under contract with the European Space Agency to design and build a solar powered airplane. The overall project objective was to study the feasibility of a solar powered airplane with the ability to fly on Mars. The secondary objective was to develop a versatile design tool that not only could adapt to varying parameters such as wingspan and payload but also could make accurate weight predictions and study the effects of scaling. The Sky Sailor airplane was designed to be fully autonomous in both navigation and power supply. It was equipped with 18% efficient solar cells that charged the batteries and supplied flight critical systems with power. A decision was made to use silicon solar cells with an efficiency of 18% instead of triple junction cells with an efficiency of up to 28%. The reason being that the density of silicon solar cells was at the time one third of the density of triple junction solar cells.
Test flights started in 2005 and it scored several flights of up to 10 hours but it was not until 2008 that it truly demonstrated its endurance capabilities when it managed to stay in the air for 27 hours 15.
Sun Surfer
In 2007 the Sun Surfer was constructed with the help of the conceptual design methodology developed by André Noth during the Sky
Sailor Project. The project goal was to study the possibility to increase the endurance of small UAV’s by using solar cells to supply the motor and battery with power. The Sun Surfer was designed with the target to carry 20 grams of payload and be able to fly continuously during favorable weather conditions 16. The result of the study was an airplane with a 77cm wingspan and an empty weight of only 120 grams16. QinetiQ - Zephyr
The British based defense company QinetiQ developed a High Altitude Long Endurance Aircraft (HALE) named Zephyr with funding from the British Ministry of Defense and the US Department of Defense. The Zephyr was developed under a program with the fundamental goal of supplying advanced technologies rapidly into the hands of US and British troops in Afghanistan and Iraq 17. The first test flights where conducted in 2005 where the aircraft immediately showed its potential for HALE missions and in August 2008 it set a new world endurance record for UAVs when it stayed aloft for 83 hours. The aircraft was built with lightweight carbon fiber and Mylar and powered by silicon solar cells and lithium-sulphur batteries. It also uses thermals to gain altitude and reduce power consumption. A civil version of the Zephyr has been built and named Mercator. The Mercator is an ongoing collaboration between QinetiQ and Belgium’s Flemish Institute for Technical Research 17. The intended applications involve remote sensing in response to disasters. The author has not been able to find any information on performed flights by the Mercator with payload; however, a few test flights have been conducted without payload.
Picture 12 Sky Sailor
Picture 13 Sun Surfer
Projects under development
In 2007 DARPA announced the launch of the Vulture HALE program. A program that aims to develop a solar powered aircraft with the capability to stay aloft for 5 years while carrying a 453 kg payload. DARPA selected Boeing, Lockheed Martin and Aurora Flight Sciences as the contractors for the first phase of the program. On April 14th 2008 Aurora announced that they had been awarded the contract and on May 14th 2009 the first flight test was conducted with the proof of concept airplane Sunlight Eagle18.
Another ongoing solar powered aircraft project is the Solar Impulse, which has the goal of creating the first manned solar powered airplane with the capability to circumnavigate the earth. The fundamental goal of the project is to give solar energy credibility as an alternative energy resource and inspire people to use more environmentally friendly energy19. Some of the technological challenges that need to be resolved before the airplane can achieve it’s goals are according to Hannes Ross (design advisor for the Solar Impulse project).
• > 20% efficient solar arrays • High specific energy batteries
• High efficiency propellers and engines
• Thermal control systems for batteries and engines • Acceptable aero-elastic characteristics
He also stressed that if the Solar Impulse project (or any other long endurance solar powered airplane) is to be successful then it has to be very efficient considering that only a small percentage of the energy collected from the sun can be used to propel the airplane.
Hannes Ross, IBR,
Linköping, 28.04.2009 www.solarimpulse.com 10
Power Train Schematic
And Typical Losses/Efficiencies
MPPT ~95% Battery Manager 99,5% Batteries 96.5% Converter 98,5% Motor 93% Solar Cells, 20% Propeller 77% Electric Lines 99,5%
From solar energy to propeller = 89% losses!!
MPPT= Maximum Power Point Tracker
Other consumers
Picture 15 Odysseus
Picture 16 Solar Impulse
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Number of solar powered fixed wing aircrafts
As of August 2009, 94 solar powered airplanes have been built. The graph below shows the number of airplanes built per year.
0 5 10 15 20 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008
0,0 1,0 2,0 3,0 4,0 5,0 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
World UAV forecast
World R&D ($ Billions) World Procurement ($ Billions)
Chapter 4
UAV MARKET
4.1 UAV market forecastTeal Group described in their 2009 market analysis report the UAV market as the most dynamic growth sector in the aerospace industry this decade20. Since the global war on terrorism started in 2001 huge investments has been made in the UAV market and the US DoD is responsible for most of the expenditures. Today only a fraction of the world expenditures on UAVs are civil and a majority is military, but UAVs are slowly finding their way into more commercial applications and generating more civil investments (appendix 1 shows the forecasted UAV production by type). Earlier market surveys indicated a significant
upward trend in the civil market share that has not yet been realized. According to a report by NASA 21 a major factor for the slow development of the civil UAV market is the lack of access to airspace and suitable UAV standards and practices; this opinion is shared by European CAPECON. Teal Group expects that the restrictions on UAVs will be resolved before 2018, which expects to lead to more acquisitions of UAVs for non-military use.
The forecast for solar powered UAVs is much more uncertain because at the moment no solar powered UAV have been put into commercial or military use except for research and small niche markets. However, the demand for HALE and MALE aircrafts are expected to increase this decade and it is the author’s opinion that solar powered UAVs will slowly be put into such operations. Various sources list telecommunications platform as one of the most likely applications for solar powered UAVs and according to the ESA Telecommunications department the sale of satellite services in 2003 was valued to €50 billion 22. Dr KC Wong of Sydney University estimated the potential UAV share in the satellite based telecommunications market to 1% 23. The ongoing Vulture research program and the earlier
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Helios program mentioned in the previous chapter is validation that the aerospace industry sees solar powered UAVs as a very promising and cheap alternative to satellites.
Frost & Sullivan; emerging markets for civil & commercial UAVs (2005)
Frost & Sullivan, a well-known market survey company presented in may 2005 a list of potential civil markets for UAVs (displayed below) 24. This list is similar to the list presented in the civil UAV capabilities assessment made by NASA in November 200525.
• Border Management • Maritime patrol
• Critical infrastructure protection • Domestic counter-terrorism • Explosive detection systems • NBC terrorism response
• Fisheries and agricultural management • Transportation security
• Freight
• Search and Rescue • Pipeline monitoring • Crime prevention • Powerline monitoring • Crisis management
• Private infrastructure surveillance/security • Forest fire monitoring
• Aerial photography • Weather and meteorology
• Temporary telecommunications services
As mentioned in the previous chapter, a significant reason why there has been so little progress in the UAV market is the restrictions put on UAVs, and according to Frost & Sullivan it is key to prove that UAVs are safe reliable and cost effective for the market to speed up. “It is a marketing challenge-not a technological one” (Shai Shammai, Frost & Sullivan).
4.2 Potential civil uav applications
In this chapter various civil applications potentially suitable for the Solaris project will be listed. Weight has been put on applications where a solar powered UAV can perform a given task more cost effectively, or can potentially outperform systems used today. The author has also focused on applications that do not require the UAV to fly in close proximity to populated areas, where this is today heavily restricted. The potential applications suitable for the Solaris project have been divided into three categories, Land Management, Earth observations and Commercial.
Land Management
Wildlife Inventory
UAVs can be used to provide scientist with population data of a certain species, which enables effective wildlife management. Long endurance solar powered UAVs could prove ideal for the tedious task of collecting data spanning over a long time period and over a large area. An example mission could be to count the number of seals, moose, bears or wolves in Sweden.
Poaching Patrol
In Sweden poaching is considered to be one of the biggest threats to predators such as wolf, bear, lynx and wolverines26. Today patrols are performed by either people on the ground or by police helicopters. The disadvantage of having people patrol on the ground is that they can only cover a limited area and police helicopters is costly.
Wildfire - Monitoring
In case of a wildfire a low altitude UAV can be used to provide firefighters with information so that a rapid assessment of the situation can be made and also inform where to deploy the first responders. It can also provide information about the spreading and intensity of the fire, which would reduce the risk to responders and to the public.
Wildfire/Disaster – Communications relay
In the event of a disaster or wild fire, communications between central command and personnel in the field is critical. Today line-of-sight communications are used extensively throughout different safety agencies and can be rendered useless if there is an object or terrain in the way. A UAV could serve as a communications relay between ground station and responders, which would enhance the control and safety of the operation.
Ecosystem Modeling
This mission involves observation of vegetation condition, biomass and soil moisture. The collected data can be used for ecosystem modeling and support for land management decision-making.
Fisheries Management/ Marine sanctuary enforcement
Illegal fishing is a big problem in many parts of the world and it has severe affects on both the economy and the environment. It creates an imbalance in the maritime ecosystem by reducing the biodiversity and has a significant impact on the sustainability of both the targeted species and the ecosystem. UAVs can serve a vital role in fighting illegal fishing by patrolling an area for illegal fishing boats and supply authorities with information such as location, speed and heading.
Harvest optimization
Data collection for precision agriculture has to be quick and cost effective and might therefore be an excellent application for UAVs. UAVs can give detailed information about the status and health of a crop and also give farmers an easy way to determine the amount of fertilizer and pesticides needed. Today conducting a relatively small amount of checks in the field approximates the amount of fertilizer and pesticides needed, which results in inaccurate dosage and economic losses or environmental strain 27.
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Earth observations
Glacier monitoring
UAVs can contribute to research of glaciers by measuring land topography, ice volume and liquid water content. The collected data can later be used for validating simulations of glacier dynamics.
Algal bloom observation
Algal blooms can cause serious harm to humans or even entire ecosystems by either producing toxins or by excessive blooming. The later often leads to oxygen free ocean floors witch today is a serious threat to the health of the Baltic Sea. UAVs can be a valuable asset in oceanographic research by collecting data such as measurements of ocean color, sea surface temperature and surface topography. This will enable more accurate algal bloom predictions and enhance response efforts.
Commercial
Pipeline inspection
All gas and oil companies have an interest in maintaining and protecting their pipelines. The fact that they can stretch a great distance trough isolated terrain makes it very labor intensive and more suitable for UAVs. The mission would be to fly along a pipeline and search for potential leaks and for suspected sabotage. In 2008 Nigeria was forced to cut its oil exports by 40% as a result of attacks on oil facilities, which demonstrates that immense economic and environmental disasters can occur if pipelines are not carefully protected.
Power line inspection
Because of aging power lines and increasing demand for reliable power, companies are required to spend more on inspections and maintenance. Helicopters are used today in great extent to inspect power lines but UAVs can be a serious alternative to helicopters because they can fly for an extended time period at low altitudes, which is not possible with manned aircrafts. Power lines are inspected for a wide variety of items such as leaning poles, interfering trees, fuse units and insulators.
Archaeology
UAVs can be used for aerial observation of archaeological sites and digs.
Mineral exploration
UAVs such as the Georanger Aeromagnetic UAV have already been used for mineral exploration and have proved to have some advantages compared with manned aircrafts. UAVs with the ability to fly slow and close to the ground and containing less metal than manned aircrafts enables more accurate geophysical measurement to be made compared with manned aircrafts. However, the equipment needed to conduct accurate measurement might be too heavy for the projected aircraft.
Mars exploration
UAVs could potentially serve as good alternatives to satellites and rovers by providing scientist with higher resolution imagery than satellites and with a greater range than rovers.
Chapter 5
MISSION SPECIFICATIONS
The mission specifications have been put together using data from the 2005 NASA civil UAV capabilities assessment report 25, and through interviews with representatives from the industry and government agencies. The purpose of the table below is to give the reader an overall understanding of what is required of the project aircraft and should therefore be seen as a guideline. It is the author’s opinion that once a suitable application has been determined for the project that a more in depth study be made.
Mission Specification Ap p li ca ti o n Ra d iu s o f ac ti o n En d u ra n ce Op er a ti o n a l al ti tud e Payl o ad Mo d u la ri ty Poaching Patrol 3 2 2 NA No
Wildlife Inventory 3 3 3 Camera No
Wildfire – Monitoring 2 3 2 Camera, Hyperspectral sensors No
Wildfire/Disaster – Communications
relay 1 3 3 NA No
Ecosystem Modeling 2 3 1 Camera, Hyperspectral sensors Yes
Fisheries Management/ Marine sanctuary
enforcement 3 3 2 Camera No
Harvest optimization 1 1 1 Camera, Hyperspectral sensors Yes
Glacier monitoring 2 3 3 NA Yes
Algal bloom observation 3 3 3 NA Yes
Pipeline inspection 3 3 1 Camera, Hyperspectral No
Power line inspection 3 3 1 Camera, Hyperspectral sensors No
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Mineral exploration 3 3 1 Camera, Hyperspectral sensors Yes
1 2 3 Radius of action (km) 0-10 10-100 100- 1 2 3 Endurance (hours) 0-12 12-24 24- 1 2 3 Operational altitude (m) 0-150 150-3000 3000-
Chapter 6
DISCUSSION
The market forecast by Teal Group and Frost & Sullivan bring up some interesting arguments. I believe that the market for civil UAVs will expand in the near future but it’s susceptible to economic change just as any other market, and perhaps the forecasted expansion is overestimated given the current world economic circumstances.
When I created the list of potential applications for solar powered UAVs I started with finding out what applications there where for UAVs as a whole and then began to sort out which ones were more suitable for solar powered UAVs. NASA and UAVnet.com both have very good information about various potential applications. I then created a questionnaire and sent it to scientist and representatives that were involved in projects that could potentially profit from the use of a UAV. The information from these interviews together with the NASA civil UAV capabilities assessment report made it possible to construct a list of specifications for various application. If one of the mentioned applications is chosen as a goal for the project then my recommendation is that a more in depth study be made.
I have also searched for solar powered UAV competitions and world records but I have not found any competitions nor found any records that are of interest to the Solaris project other then the ones mentioned in the historic survey. It is my opinion that the students at the Royal Institute of Technology and the students at IIT had a very humble, yet interesting goals for their projects. To give the students an opportunity to experience all the different stages in aircraft design.
18
Chapter 7
RESULTS
7.1 Results from the historic survey
The reasons for conducting the historic survey was to find out how solar powered aircrafts have evolved over time and finding out where the technology stands today. It has also been of interest to find out the motivation and reason for the different projects so that one can see the project goals and how the final result turned out.
The results from the historic survey are listed below:
• Early projects were intended to simply demonstrate the feasibility of solar powered flight and were often “proof of concept” aircrafts where as the current projects under development tend to have more practical ambitions. Although that is not always the case as the vulture program aims to prove the feasibility of sustained flight for five years but the trend is defiantly towards more practical applications.
• Most projects have favored a traditional aircraft design over a flying wing design. • All of the aircrafts mentioned are of typical sailplane design, with very high aspect
ratios and designed for low speeds.
• Some long endurance solar powered UAVs use thermals to gain altitude. • Efficiency is key for the success of any solar powered aircraft.
• Monocrystaline solar arrays have historically been widely used on solar powered airplanes.
• The number of potential applications for solar powered UAVs is often limited by weight and power restrictions.
7.2 Results from the market evaluation
• The UAV market as a whole is expanding and the market for civil UAVs are expected to grow sometime before 2018 as restrictions on UAVs get resolved. The number of produced civil UAVs is expected to increase by 400% in 10 years. • The near future for solar powered UAVs is most likely in small niche markets and
in scientific projects.
• It is important to prove that UAVs are safe, reliable and cost effective for the civil UAV market to grow.
7.3 Recommendations for future work
The project is an initial study of the Solaris project, which is intended to provide recommendations for future work to the project leader. Listed below are recommendations for future work that can be of interest to the Solaris project.
• An in depth study of what is possible and what is demanded of the aircraft for various applications.
References
1 U.S Department of Energy:
http://www1.eere.energy.gov/solar/pdfs/solar_timeline.pdf
2 2007 Environment Policy Review:
http://eurlex.europa.eu/LexUriServ/LexUriServ.do?uri=COM:2008:0409:FIN:EN:HTML
3 R. J. Boucher, History of Solar Flight, AIAA Paper 84-1429, June:
http://pdf.aiaa.org/jaPreview/JA/1985/PVJAPRE45213.pdf
4 Gossamer Penguin in flight:
http://www.dfrc.nasa.gov/Gallery/Photo/Albatross/HTML/ECN-13413.html
5 New York Times (09-06-1981) article about the Solar Challenger:
http://www.nytimes.com/1981/06/09/science/physicist-s-solar-airplane-set-to-challenge-the english-channel.html 6 Solair: http://www.delago.com/solair/ESol2-2.htm 7 Sunseeker: http://www.solar-flight.com/sunseeker/index.html 8 Icare 2: http://www.flug-revue.rotor.com/FRheft/FRH9609/fr9609p.htm 9 DLR- Solitair: http://www.dlr.de/ft/Desktopdefault.aspx/tabid-1388/1918_read-3385/
10 NASA Dryden Fact Sheet - Pathfinder Solar-Powered Aircraft:
http://www.nasa.gov/centers/dryden/news/FactSheets/FS-034-DFRC.html
11 NASA, Dryden History:
http://www.nasa.gov/centers/dryden/news/ResearchUpdate/Helios/index.html
12 KTH, Solar aircraft project:
http://130.237.36.221/cdio/old_projects/sap/index.html
13 AC Propulsion SoLong UAV Flies for 48 Hours:
www.tu.no/multimedia/archive/00024/SoLong_PM_24123a.pdf
14 Faculty of Aerospace Engineering, Technion IIT:
www.aerospace.org.il/events/IACAS47-208-final.pdf
20
http://www.sky-sailor.ethz.ch/docs/Thesis_Noth_2008.pdf
16 Sun Surfer, Design and construction of a solar powered MAV:
http://www.sky-sailor.ethz.ch/docs/Report Sun-Surfer.pdf
17 QinetiQ's Zephyr UAV flies for three and a half days to set unofficial world record:
http://www.qinetiq.com/home/newsroom/news_releases_homepage/2008/3rd_quarter/qin etiq_s_zephyr_uav.html
18 Aurora Flies Large Solar-Powered Aircraft:
http://www.aurora.aero/Communications/Item.aspx?id=apr-237
19 Solar Impulse:
http://www.solarimpulse.com/en/documents/symbol.php?lang=en&group=symbol
20 S.J. Zaloga, Dr. D.Rockwell, P.Finnegan
,
World Unmanned Aerial Vehicle Systems MarketProfile and Forecast 2009 edition
www.tealgroup.com/component/docman/doc_download/195-2009-uav-sample
21 NASA-Industry Alliance Initiates UAV National Airspace Access Project:
http://www.nasa.gov/centers/dryden/news/NewsReleases/2004/04-27.html
22 Satellite TelecommunicationsMarket Perspectives and Industrial Situation
http://www.esa.int/esa-cgi/esasearch.pl?q=92-9092-434-9&Submit=GO
23 Dr K.C Wong, Aerospace Industry Opportunities in Australia UNMANNED AERIAL
VEHICLES (UAVs) Are They Ready This Time? Are We?
http://www.aeromech.usyd.edu.au/wwwdocs/UAV_RAeS_prez_26Nov97.PDF.
24 Shai Shammai, Emerging Markets for Civil & Commercial UAVs, 2005
http://docs.google.com/gview?a=v&q=cache:GVLrD2HtRTgJ:www.uavnet.com/DL/Docume nt_Library/Eilat_2005_Meeting/UAV_Markets_Shammai.pdf+Frost+%26+Sullivan%3B+e merging+markets+for+civil+%26+commercial+UAVs+%282005%29&hl=sv
25 Nasa Civil UAV Capabilities Assessment:
http://www.nasa.gov/centers/dryden/research/civuav/index.html
26 Brå – the Swedish National Council for Crime Prevention:
http://www.bra.se/extra/news/?module_instance=3&id=175
27 A.Rydberg, O.Hagner, M.Söderström, T.Börjesson, Obemannad flygfarkost
A. APPENDIX
HISTORY OF SOLAR POWERED AIRPLANES
Ai rc ra ft Ye ar Wi ng sp an [m ] Me an C ho rd [m ] Len gt [m ] Wi ng A re a[ m 2] AR Em pt y w ei gh t [ kg ] Ai rf oi l Mo to r Num be r of m ot or s Pr op el ler Pr op el ler d iam et er (m ) Conf ig ur at ion So lar ar ray s Ar ra y ar ea (m 2)
Sunrise 1974 9,75 0,86 4,38 8,36 11,4 12,25 Cobalt 40 1 Astro Fixed pitch
High wing, High AR 2,90 Sunrise II 1975 9,75 0,86 4,38 8,36 11,4 10,21 Solaris 1976 2,06 0,2 0,41 10,3 0,61 Ra 1977 1,37 0,12 0,84 0,16 11,9 0,19 Utopie 1977 2,53 0,2 1,32 0,51 12,6 0,97 Solar One 1978 20,72 1,17 6,7 24,15 17,8 104,32 Solar-‐Student 1978 1,96 0,22 1,04 0,43 8,91 0,93 Solar Riser 1979 9,14 1,04 2,44 9,52 8,78 55,8
Solar Silberfuchs 1979 4 0,25 1,52 1 16 2,1 Brushless DC 14 Flying wing Sun power A300
Solar-‐X4 1979 2,5 0,17 1,13 0,42 14,8 0,85
Gossamer
Penguin 1980 21,64 2,63 9,14 57 8,22 30,84
Solair I 1980 16 1,38 5,4 22 14 120 6 propeller 0,36 Folding
High wing,
High AR
Solar-‐HB79 1980 2,8 0,24 1,45 0,67 11,7 1,51 1 Canard, High AR Monocrystalline Silicone
Solar Challenger 1981 14,8 1,48 9,22 21,83 9 99,79 Solar-‐HB80 1981 2,84 0,23 1,48 0,65 12,5 1,72 1 High wing, High AR Solus Solar 1984 3,2 0,29 0,88 0,93 11 2,2 Poly 1986 3,24 0,29 0,88 0,97 10,8 2,48
Combi 1987 2,96 0,26 0,85 0,77 11,4 2,29 Brushless DC 14 2 Flying wing Sun power A300
Solariane 1987 3,08 0,28 1,72 0,85 11,2 1,8 Ariane Ultra 1989 1,98 0,21 1,14 0,41 11 3,02 Bleher 1989 2 0,24 0,49 8,18 1,37 1 High wing, High AR 20,70 Bloch 1989 2,9 0,24 0,7 12 1,25 Combi 2 1989 2,95 0,28 1,54 0,77 11,3 1,7 Grosholz 1989 3,07 0,19 0,6 15,8 1,85 Helios (model) 1989 2,14 0,18 0,39 11,8 1,4 Ikaros 1989 2,5 0,23 0,58 10,8 1,8 Romarino 1989 2 0,2 0,4 10 1,8 Sol-‐e-‐moi 1989 3 0,17 0,5 18 2,1 Wolf 1989 3 0,21 0,63 14,3 1,6 WS-‐Solar 1989 2,5 0,22 0,55 11,3 1,55 Bleher 1990 2 0,22 0,44 9,03 1,55
Blue Chip 1990 2,2 0,23 1,25 0,5 9,66 0,75 Brushless DC 6 Flying wing Sun power A300
Mardini 1990 2,4 0,25 0,6 9,6 2,5 Brushless DC 8 Flying wing Sun power A300
22 Phönix 1990 2,62 0,21 1,29 0,56 12,2 1,18 Playboy 1990 2,4 0,19 0,45 12,8 1,35 Solar Flyer 1990 2,64 0,23 1,48 0,61 11,5 1,6 Solar Voyager 1990 3,2 0,25 0,79 13 1,3 Solarbaby 1990 1,7 0,16 0,28 10,4 1,25 Solarmax 1990 3,48 0,3 1,59 1,04 11,6 2,54 Sole Florentino 1990 2,5 0,17 0,43 14,6 1,2 Soli 1990 2,08 0,18 0,38 11,5 1,5 Sollisolar 1990 2,98 0,23 0,69 12,9 1,23 M118752 1 Maxon Fixed pitch, Folding propeller 0,6 High wing, High AR, V-‐tail RWE-‐S-‐32 0,51 Sollisolar 89-‐2 1990 2,98 0,23 1,34 0,68 13,1 1,24
Sunseeker 1990 17 1 propeller Folding
High wing,
High AR Monocrystalline Silicone
Uccello 1990 2,7 0,23 0,63 11,5 1,9 WS12 (then WS16) 1990 2,5 0,16 1,1 0,41 15,2 0,84 Blue-‐Wing 1991 2,34 0,18 1,05 0,42 13 0,75 Silizi Solar 1991 2,25 0,21 1,3 0,47 10,7 1,08 Solar Schilti 1 1991 1,74 0,19 1,16 0,34 9 0,7 Solar Schilti 2 1991 1,99 0,18 1,05 0,36 11,1 0,82 Solar UHU 1991 2,3 0,23 1,2 0,53 10 1,45 Solix 1991 2,37 0,2 1,3 0,48 11,8 1,05 Rival-‐8 Solaris 1992 1,96 0,22 1,13 0,43 8,91 0,66 Solar mini challenger 1992 1,55 0,18 ? 0,28 8,5 0,94 Pathfinder 1994 29,5 2,4 3,6 70,8 12,3 207 MikroSol 1995 1,13 0,19 Icare II 1996 25 1,03 7,7 25,7 24,3 270 Lo 120 Solar 1996 15,46 1,03 16 14,9 NanoSol 1996 1,11 0,16
O sole mio 1996 20 1,23 24,5 16,3 130
Solair II 1996 20 0,86 6,12 17 23,5 140 Solar Solitude 1996 2,7 0,2 0,55 13,3 2 Solarflugzeug 1996 18 1,5 27 12 190 Centurion 1997 61,8 2,4 3,6 148,32 25,8 533 Global Flyer 1997 2,5 0,23 1,2 0,57 11 1,04 Helios 1997 2,7 0,6 1,2 6,17 Trosollmuffel 1997 2,5 0,25 ? 0,62 10,1 1,14 LFMA 1998 1,9 0,25 0,47 7,76 1,2 Pathfinder Plus 1998 36,3 2,4 3,6 87,12 15,1 247,5 PicoSol 1998 0,99 0,13 Solar Excel 1998 2,1 0,16 1,02 0,35 12,8 0,72 Solitair 1998 5,2 Helios 1999 75,3 2,48 3,6 186,6 30,4 600 Sunrazor (Sunriser) 2000 2,7 0,3 0,81 9,06 1,1 1 High wing, High AR, Rotating solar cells Goldcap 2 2001
Solarus 2001 2,3 0,19 0,44 12 0,48
FlyG 2002 6 0,6 2,7 3,6 10 10
No Name 2003 0,14 0,015 0,12 0 9,33 0,0017
Solar Pleaser 2003 1,04 0,15 1,01 0,15 7 0,25
Solar Splinter 2003 4,27 0,35 2,13 1,5 12,2 4,5 1 Fixed pitch 0,2
High wing, High AR,
V-‐tail Conrad 0,02
Sol-‐Mite 2004 0,81 0,12 0,1 6,5 0,13 1 Fixed pitch 0,2
High wing, High AR, V-‐tail Conrad 0,02 Sky-‐Sailor 2005 3,2 0,24 1,82 0,78 13,2 2,5 Solong 2005 4,75 0,32 1,5 15 12,6 Kontronik Tango 45-‐06 1 Folding propeller, Variable pitch High wing,
High AR Sun power A300
Zephyr 2005 18 1,55 27,9 11,6 30
Aphelion 2006 3,13 0,22 0,7 14
Howie Mark 2006 2,43 0,2 0,49 12,2 0,45 SD7032 B50-‐13S 1 Hacker
High wing, High AR,
V-‐tail Sun power A300 1,00
NanSun 2006 3,2 0,4 2,6 1,28 8 4,1 1 propeller Folding
High wing,
High AR Monocrystalline Silicone
SunSailor 2006 4,2 0,32 2,2 1,35 13,1 3,6 2.765 g Solar MAV 2007 0,14 0,04 0,15 0,0057 3,41 0,0022 Micro-‐Mite 2007 0,2 0,05 0,01 4 0,0095 SolFly 2007 0,07 0,001 Sun-‐Surfer I 2007 0,77 0 0,73 0,07 8,5 0,12 Sun-‐Surfer II 2007 0,78 0,11 0,74 0,09 7,03 0,188
Sunlight Eagle 2009 2 Fixed pitch
Mid wing,
24 B. APPENDIX 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 Civil UAVs 110 126 140 380 365 393 448 425 528 485 UCAVs 200 150 375 75 75 00 375 300 475 800 HALE UAVs 715 930 650 675 1 175 1 280 1 475 1 530 1 550 1 450 MALE UAVs 580 1 067 1 072 1 192 987 1 085 990 745 900 810 Naval UAVs 40 55 147 201 227 369 346 364 406 268 Tactical UAVs 868 557 505 627 552 870 796 555 348 327 Mini-‐UAVs 51 60 03 36 43 74 78 65 91 95 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
UAV unit produc.on forecast by type
C. APPENDIX
Lithium Ion battery development
Solar cell efficiency development
Hannes Ross,
IBR
,Linköping, 28.04.2009 www.solarimpulse.com 24
Lithium-Ion Battery Development
Wh/kg
Wh/l
US$/Wh
Source: www.battery university.com
Hannes Ross,
IBR
,Linköping, 28.04.2009 www.solarimpulse.com 23
Stand 2008
Source: ZAE Bayern
2004 2006 2008
22
20
Solar Cell Efficiency
Graph 2 Lithium Ian battery development (Hannes Ross, Solar Impulse)
26 D. APPENDIX
