FLYING LABORATORYEven before its achievement, Solar Impulse’s attempt to fl y around the world powered only by solar energy set a goal many thought “impossible” and placed the bar very high. A family group of partners took up the challenge to invent new paradigms and fi nd the answers to problems that until now had remained unsolvable. They combined their very diverse backgrounds and specialist talents to build bridges between various areas of expertise and push back the frontiers of technological knowledge. These solutions are found in all the plane’s systems from the structure to the pilot equipment, they made the airplane become a weapon to fi ght common assumptions, demonstrating what can be achieved with pioneering spirit and clean technologies.

HIGHLIGHTS

STRUCTURE Carbon fi ber sheets only 25 g / m² (0.8 oz. /11 sq ft.) – 3 times lighter than paper

SOLAR CELLS Only 135 microns thick – like an average human hair

MOTORS 3% energy loss versus 70% in normal thermal motors

BATTERIES High energy density – 260 Wh /kg (348 hp)

COCKPIT Isolation foam with very thin pores to insulate from extreme temperatures during fl ights

MAN-MACHINE INTERFACE Informing the pilot of the aircraft’s bank angle through a vibration device

LIGHTING 16 LED landing lights consuming less than 2 bedside lamp-bulbs

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FUSELAGESolar Impulse engineers developed a winded fi ber design to achieve the lowest possible weight and incredible strength.

Especially light composite materials used for competitive yachtingManufactured by Decision

A new technology that is currently being adapted to the construction of high performance yachts. Eighty-three percent of Si2’s structure is made out of extremely light composite materials. A new thin ply technology was used and the gluing process optimized.

First time carbon fi ber composites can be mass producedBrought to you by Covestro

A crucial innovation that allowed mass production of carbon fi ber composites and further weight reduction of carbon fi ber components. This could be the answer for size limitations such as for rotor blades for the wind industry or for cycle-time issues in the automotive industry. At Solar Impulse, carbon fi ber components are used in the cockpit fairing providing mechanical strength in applications which would usually require epoxy. This technology was already exploited commercially as a conductive material in electrodes.

Ultra-light thin ply technologySolution brought by EPFL and North TPT

Thanks to the new thin ply technology developed by the Swiss company North TPT, the solar airplane was built with carbon sandwich instead of epoxy-enhanced solid carbon. This technology has reduced the weight of some layer of carbon material from 100 grams per m² (3.5 oz. /11 sq ft.) to 25 g/m2 (0.8 oz. /11 sq ft.).

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WINGSOne hundred forty-four ribs were carefully placed at 50 cm (20 in.) intervals by Solar Impulse engineers. The upper surface of the wings is made of solar panels and the lower part with an ultra-light fabric. The wing spar is entirely made of carbon fi ber honeycomb sandwich panels.

Thin, UV resistant, waterproof resin Conceived by Solvay

Thin fl uorine copolymer fi lm with a potential use for electric cars currently protects Solar Impulse’s solar cells. These cells are brittle and have no mechanical resistance, but when covered with this fi lm, they can be molded into the wing curvature without breaking. The resin is UV resistant, waterproof and only 17 microns thick.

Ultra-light lighting systemDesigned by Omega

To ensure visibility when landing after sunset, a system using LED lights was devel-oped. The lights are protected by the same resilient plastic found in Swatch watches. The entire system, including the protective glass, the wiring, power transformer and connector, weighs just shy of 2 kg (4.4 lbs.) and consumes less than 100 Watts.

Solar cells as fi ne as a hairInnovation by SunPower

With industry-leading effi ciency (22.7%) Si2’s solar cells are only 135 microns thick, like an average human hair. In comparison, the effi ciency of solar panels used on homes is of 16%. The best are those used on satellites (30%), but they are also too heavy for the solar aircraft. There are 17,248 solar cells on Si2, chosen for their weight, energy and effi ciency ratio.

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GONDOLASFor optimal maintenance, Solar Impulse engineers designed molded carbon fi ber gondolas. Each gondola contains a motor, a lithium polymer battery and a propeller.

Special additive for increased energy density Solution brought by Solvay

A technology already exploited by the automotive industry as well in portable electronics, the PVDF binder (fl uorinated polymer) increases energy density. It was developed for use in the battery electrodes and as additive for making them.

Rigid, highly insulating foam Innovation by Covestro

This new foam has very thin pores, high rigidity and structural strength while remaining lightweight. It is used in the best refrigerators and in the construction sector. To insulate the cockpit from the radical temperature changes (-40°C/-40°F to +40°C/104°F) a thermal isolation technology was conceived. The temperature of the batteries never dropped below -20°C (-4°F), temperature which have reduced their capacity during the Round-the-World fl ights.

Batteries with lower oxidationInvented by Kokam

Lithium-polymer battery cells used for Si2 were made with an innovative chemical formula that improved the oxidizing process. It’s a new technology and the best battery for the project thanks to the weight, effi ciency and lifespan ratio.

DC brushless sensorless motors with exceptional effi ciencyDesigned by Nicolas Wavre, manufactured by Etel, magnets and lamination stack by Vacuumschmelze

Si2’s motors have 97% effi ciency, a technology for applications that are concerned with power to weight optimization. Designed using newly developed materials and technologies, a new treatment of the magnets and special slicing of the lamination stack in very thin pieces reduced the power losses to an impressive minimum. Solar Impulse is the fi rst to use this breakthrough technology.

High effi ciency DC/DC converters and test bench for electric systemsBuilt by Omega

This technology could be used to test the systems of electric cars. Developed especially for Solar Impulse, the test bench enabled Solar Impulse engineers to validate the entire chain of all the different electrical elements of the airplane. It provided them with the necessary data to build the most effi cient electric system.

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COCKPITThe challenge for Solar Impulse electricians was to develop effi cient electronics with the lightest materials on the market, all capable of functioning in extreme temperatures.

Highly sensitive fl ight instrument with embedded vibration alert systemDeveloped by Omega

Normal aircrafts are usually alerted of their bank angle when the aircraft is at 40° ; Si2’s pilots were alerted already at 5°. The Omega instrument was conceived to allow the pilots to keep track of their fl ight paths and bank angles while in fl ight and alerted them if the angle of the wing exceeded the normal limit. The instrument includes a vibration alert system set inside the pilot’s sleeves.

Vibration device for pilot awarenessConceived by EPFL

The vibration device and man-machine interface allowed the transfer of information to the pilot while reducing the amount of information to be handled visually and aurally.

Electrocardiogram monitoring pilot’s fatigue and vigilance levelInnovation by EPFL

The electrocardiogram has been tested by recently operated patients as a means to inform their physician about any anomalies in real-time. It could potentially be used by the automotive industry as a way to detect the driver’s level of attention. In Solar Impulse, this device accurately measured the heartbeat curve and was meant to be worn by the pilot to monitor his level of fatigue and vigilance. The size of a matchbox, it immediately transmitted the information when a problem was detected.

Tailor-made pilot support system for safetyDesigned by Altran

Without the Stability Augmentation System (SAS) combined with the Monitoring and Alert System (MAS) , the pilot wouldn’t have be able nor be allowed to fl y several days in a row. The SAS actively maintained a straight and level fl ight path while the MAS monitored independently the SAS in operation, the aircraft fl ight path and the overall system health status. In case anything abnormal occured on the system side while the pilot was resting, the MAS could disengage the SAS while alarming the pilot by several means (audio, visual and tactile alarms) to force him to take back active control of the aircraft within 10 seconds.

Lifeline to the groundSolution by Swisscom

The communication device transmitted over 100 data items to the mission room during fl ights, from temperature of the motors to the position of the aircraft and tension in the accumulators. Weighing less than 5 kg (11 lbs.) with an energy consumption not exceeding 50 watts, this solution was the pilot’s lifeline to the ground and a great tool for fans to follow the adventure online.

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PILOTSDuring the circumnavigation of the globe, each pilot had to fl y up to 4-5 days in a row. They needed 2.4 kg (5.2 lbs.) of food, 2.5 l (84.5 oz.) of water and 1 l (33.8 oz.) of sports drink per day : additional weight that needed to be carefully calculated by the Solar Impulse team. In case of an emergency, the pilot seat had an integrated parachute and life raft.

Intelligent fi bers for a stable body temperatureConceived by Solvay

Intelligent nylon fi bers were used in the pilot’s clothing. These are called “ intelligent ” fi bers because they stabilize the pilot’s body temperature. These fi bers re-injected infrared heat back to the surface of the skin when it was cold but also prevented the pilot from sweating during periods of intense heat.

Low-bandwidth solution bringing the pilot to us LIVESolution by Swisscom

Sending videos is always a challenge especially in situations where the antenna has to be small and lightweight. A low-bandwidth solution was implemented with only 50 kb/s allowing videos of the pilots to be seen LIVE while in fl ight.

High-altitude medicine for healthy pilotsExpertise provided by Hirslanden

Crucial medical advices were provided prior and during fl ights thanks to physicians and specialists of high altitude medicine (aviation), counseling the pilots in nutrition science as well as sleep and recovery methodologies.

Personalized diets for a pioneer’s appetiteDeveloped by Nestlé Research

To ensure the pilot’s dietary needs were met during the long legs of the Round-the-World fl ights, science-based personalized nutrition was developed. Nestlé Research managed to create a wide range of meals and snacks that could withstand extreme variations in temperature and climatic conditions whilst providing the pilot with a healthy balanced diet.

Business-class comfort for transatlantic and transpacifi c fl ightsNew technology developed by Lantal

In order to allow the pilot to remain alert while fl ying the plane for fl ights up to 5 days and 5 nights, the cockpit on Si2 offers enough space to stretch his legs. A reclining chair and an ergonomic infl atable cushion ensured 100% comfort for the Round-the-World mission fl ights.

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MISSION FLIGHTSApart from tailor-made fl ight planning and monitoring tools designed in tight collaboration between Solar Impulse engineers, fl ight specialists and partners, there was also ongoing cooperation between Solar Impulse and national air traffi c controllers for smooth and safe fl ights.

Real-time fl ight planning and monitoringBrought by Altran

PLATOO is the planning tool for real-time fl ight monitoring from the Mission Control Center. This extremely precise system integrated : real-time meteorological data processes, ultra-fi ne modeling of spectral phenomena and takeoff decision criteria. The long-term stochastic routing optimizers provided extremely reliable analysis to defi ne the Round-the-World fl ight strategies.

A satellite’s energy system architecture Developed by Altran

One of the project’s key successes was the energy system layout which optimized the energy system architecture. A satellite energy system specialist was involved in the system’s design because of the similarities to the challenges and requirements of satellites.

Technical and operational support for smooth fl ightsServices offered by IATA

Representing more than 240 airlines, accounting for 84% of global air traffi c, IATA provided operational and technical assistance to Solar Impulse, facilitating take-offs, landings and support to gain full cooperation of governments and air navigation services.

Safe fl ights in the European airspaceSupport provided by Eurocontrol

Eurocontrol offered operational assistance to Solar Impulse fl ights within the 38 European member-state controlled airspace. Their systems and procedures were adapted to Solar Impulse’s specifi c characteristics while ensuring the smooth handling of some 30,000 fl ights daily and the integration of the solar airplane in very dense air traffi c.

Fully covered all the wayInsured by Swiss Re Corporate Solutions

The commercial insurer provided Solar Impulse with the security of full insurance cover and was the sole insurer of this ambitious project to fl y around the world powered only by solar energy.

Public relations for successful missionsSupport provided by the Swiss Confederation

Public relations and diplomatic skill at work provided by the Swiss Confederation eased the way into establishing connections with airport authorities, public offi cials and institutional representatives for successful mission fl ights.

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SUSTAINABLE MINDSETSolar Impulse is supported by companies which strive to promote sustainability through their technological innovations or their policies, thus taking part in the diffusion and the credibility of Solar Impulse’s message.

Solar elevatorA world premiere by Schindler

Schindler is currently introducing a new solar-powered elevator to the market. Furthermore, its innovative and environmental-friendly access and transit management systems make an important contribution to mobility in urban societies. Moved by the same spirit, Schindler and Solar Impulse join forces by embedding Schindler’s engineers to provide Solar Impulse with support in applied electronics, advanced structures, new technologies and in research and development.

Electric drives to save energy A system developed by ABB

ABB supplies technologies that improve the energy effi ciency of propulsion systems from one end of the chain to the other, from source to power distribution. The ABB power conditioners installed worldwide, regulating the energy consumption of electric motors, saved 400 TWh of electricity, equivalent to the annual consumption of more than 100 million European households. The company is also the second largest supplier of solar inverters, the technology that converts sunlight into electricity, and is building a fast-charger network for electric vehicles in China.

Spreading the wordUsing Google platforms & technology

For years, Google has contributed to the adventure by providing the Internet and communications resources needed to let the World know of the Solar Impulse journey. Google designers and engineers volunteered to help building the best possible user experience across Solar Impulse online presence, and whether the plane is on the ground or in the air, Google App Engine enables Solar Impulse’s Websites to run smoothly.Solar Impulse hosts and broadcasts live discussions and performances to millions of viewers, through their YouTube channel, thanks to Google Hangouts on air; and with Google Expeditions, Solar Impulse’s technology is explained to students through a large network of highschools, making a lasting impact on the young generation of Internet users.

The carbon abatement curveA knowledge brought by McKinsey

The “ carbon abatement curve ” developed by McKinsey, provides a quantitative basis for evaluating the effectiveness and costs of the various technologies that can bring about a reduction in greenhouse gas emissions. The curve takes into account already existing technologies as well as others that have a high probability of becoming available by 2030, thereby encouraging the search for new techniques of energy-use optimization and guaranteeing a sustainable future.

Celebrate sustainabilityAn initiative set in motion by Moët Hennessy

Recognizing the role of excellence and innovation as two key drivers for progress, Moët Hennessy views Solar Impulse as a project which illustrates the strength of entrepreneurship and self-transcendence. These core values lead to great achievements and are common to Moët Hennessy’s ambition of pursuing their development with the permanent preoccupation of the future. With this initiative, they wish to celebrate the men behind this adventure, marking their every step in the making of history.

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