Solar planes are powered electrically by solar cells and electric motors and thus belong to the class of electric planes . Since they obtain their energy exclusively from solar radiation , they do not need any fossil fuel and thus do not cause any emissions (pollutant emissions) during operation . Solar planes are particularly effective at high altitudes, where solar radiation is less attenuated by the earth's atmosphere and no shadowing from clouds is possible. You need to bridge batteries ( battery ) and use part of the altitude as kinetic energy .
The first solar airplane, the Sunrise-I, took off in California in 1974 .
Several areas of responsibility are conceivable in the future. So, unmanned solar powered aircraft and. a. be used in long-term use as a communication platform , for border surveillance, as a surveillance and support aircraft in forest fires and for precision farming .
Depending on the durability of the system components and the solar radiation at the place of use, solar aircraft can be used continuously for months to years, and at the same time operate at great heights above the service ceiling of conventional aircraft. They could thus act as a cheaper complement to satellites stationed at lower altitudes . In contrast to satellites, solar planes can be relocated freely and are not restricted to a specific orbit . The construction of solar-powered large - capacity aircraft , however, is unlikely, even if extremely powerful solar cells are available, since there is not enough space available on such aircraft for sufficient solar cells.
The Solar Challenger was a solar airplane from Paul MacCready 's company AeroVironment , which was built as an improved successor to the Gossamer Penguin . The purely photovoltaic powered aircraft had a maiden flight on November 6, 1980. On July 7, 1981, Steve Ptacek flew it from Corneille-en-Verin near Paris to Manston Royal Airforce Base in England on a record flight of 262 kilometers and crossed the English Channel .
Pathfinder (Plus) - Centurion - Helios
Pathfinder was developed for a secret program in the USA in the early 1980s. After a few flights, it was found that the technology was not yet suitable for days of solar-powered flights. As a result, Pathfinder was mothballed. In 1993 it was made ready to fly again by the Ballistic Missile Defense Organization and in 1994 handed over to NASA for its ERAST ( Environmental Research Aircraft and Sensor Technology ) program, which aimed to develop unmanned aerial vehicles.
A first world record for solar-powered aircraft was set on September 11, 1995, when an altitude of 15,240 m (50,000 ft) was reached in a 12-hour flight. On July 7, 1997, that record was increased to 21,802 m (71,530 ft). That was the world record for propeller-driven planes and solar planes. In 1998 Pathfinder Plus emerged from Pathfinder .
- Span: 29.5 m
- Length: 3.6 m
- Mass: 252 kg
- Payload: 45 kg
- Speed: about 27–32 km / h (17–20 mph )
- Nominal power of the solar cells: 7.5 kW
- Drive: 6 electric motors with a maximum of 1.5 kW each
- Manufacturer: AeroVironment, Inc., Monrovia (California)
Centurion is a further development of the Pathfinder Plus .
- Wingspan: 62.8 m (206 ft)
- 14 electric motors
- Solar cells with an output of up to 31 kW
- Speed: approx. 27–33 km / h (15–18 kn )
- Start of construction: February 10, 1997
- First flight: November 10, 1998
From January 1999 the aircraft was converted to the Helios prototype.
Named after the sun god of the same name in Greek mythology , Helios was an unmanned light aircraft developed by NASA and the Californian company AeroVironment . With this aircraft it was possible on August 14, 2001 over Hawaii to break the world record for non-rocket propelled aircraft. With a height of 29,524 meters in level flight, the almost 25-year-old record of 25,929 meters for an SR-71 Blackbird spy plane was exceeded. This type of aircraft should represent an alternative to satellites or be used for research tasks at very high altitudes.
The first test flights took place in September 1999 with battery operation. The later record flight used only solar energy, which explains the range in the weight information. The climb took about six hours.
The 580 kg aircraft was powered by 14 electric motors. The wingspan was 75.3 meters, which is 10.9 meters more than that of a Boeing 747-400.
Almost 66,000 high-performance solar cells from SunPower with an efficiency of 22 percent were mounted on the surface of the wing and provided 30 kW of electrical power with full solar radiation. The price of the solar cells used was just under $ 9 million. The flight speed was about 30 to 50 km / h.
Helios crashed on June 26, 2003 near Hawaii in the Pacific. NASA claims that the cause of the crash was a problem with the control of the aircraft and the resulting structural damage.
- Span: 75.3 m
- Length: 3.7 m
- Mass: 600 to 929 kg
- Speed: about 30 to 43 km / h (19-27 mph), 274 km / h or 170 mph at peak altitude
- Drive: 14 electric motors with a maximum of 1.5 kW each
Solair II , the successor to Solair I, began as a project in 1996 and had the aim of developing and building a solar airplane that has a higher utility value than its predecessor. It was based on glider construction . Solair II has a V-tail unit with a propeller at the tip of each fin for propulsion. The aircraft was manufactured in a half-shell sandwich construction with honeycomb cores. It can self-start with charged batteries . 755 watts of drive power are required for straight flight.
- Solar generator
- Solar cells: 13.44 m² monocrystalline silicon cells
- maximum efficiency: 17.3%
- maximum power (radiation 500 W / m²): 1163 W
- Developer: Dipl.-Ing. Karl Friedel
- 2 × permanent magnet DC motor with pusher propeller (1.46 m diameter) in the tail unit
- Nominal voltage: 30 V each (motors connected in series)
- maximum power: 2 × 4500 W.
- after a modification, 2 × 4 kW motors with 2-blade folding propellers (2 m diameter) with blade adjustment were used
- Battery type: 54 cells in series, 2–4 battery packs in parallel, nominal voltage: 65 V
- Capacity: max. 4 × 5.2 Ah = 20.8 Ah, storable energy: max. 1352 Wh
The first crossing of the Alps was achieved in summer 2015 as part of a cooperation project between SolarWorld and PC Aero GmbH. The empty weight without batteries is 120 kg, the batteries with an output of 11 kW make up a considerable part of the mass with 80 kg. A payload of 100 kg was possible.
The Solar Impulse of the Swiss Bertrand Piccard and the École Polytechnique Fédérale de Lausanne (EPFL) became the first solar aircraft to complete a complete circumnavigation of the world. It is the first solar airplane that also flies overnight.
The “Solar Impulse” solar airplane completed its first test flight on April 7, 2010. The flight, controlled by pilot Markus Scherdel, took place around the Payerne military airfield in the Swiss canton of Vaud .
The first night flight took place on July 8, 2010. After a non-stop flight of more than 24 hours, “Solar Impulse” HB-SIA landed at the Payerne military airfield, from where the plane had taken off the day before.
Finally, on May 13, 2011, an international solar flight from Payerne to Brussels took place with a flight duration of 12 hours 59 minutes.
The Zephyr S is a solar aircraft designed by Airbus that has a weight of 75 kg with a wingspan of 25 meters. The aircraft took off on its maiden flight on July 11, 2018 and ended it after almost 26 days in the air, with the Zephyr S setting a new endurance record on its first mission. The plan is to manufacture the aircraft in series. It will initially be used for communication purposes, as a relay station to provide internet access even in remote areas . In addition, according to Airbus, the aircraft can also be used to support disaster management, for the early detection of forest fires, for the discovery of oil spills at sea, for border surveillance and for other tasks. It can perform these tasks more cheaply than satellites, while at the same time it is more flexible and delivers sharper images.
The Phasa-35 drone from BAE Systems and Prismatic, which has not yet been fully developed, is supposed to move autonomously. It should carry a payload of 15 kilograms and be able to stay in the air for up to a year. Initially, it should be available for June 2018. In February 2020 it had its maiden flight in Woomera , Australia. Examples of a possible payload would be surveillance cameras, sensors or mobile radio relays and should be a cost-effective alternative to satellites. It has a wingspan of 35 meters, a speed of 93 to 145 km / h and is supposed to fly 15 to 21 kilometers at the height of the stratosphere .
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