Solar powered planes have been works in progress since the 1970’s. Since then, several prototypes and experimental planes have successfully flown using solar power. NASA has created several solar planes including Pathfinder, Centurion and Helios planes dating back to the early 1980’s.(1)
As solar energy conversion technology improves, the capacity of this technology allows longer flights and heavier payloads. Private industry has also produced solar planes including the British manufactured planes named Zephyr and HB-SIA. These planes in addition to several others were test flown between the 1980’s-2000′,s and were able to stay in flight for extended periods of time including the night.
• Design
Aerodynamics and weight are key features for solar powered planes to work. For a plane that is 100% solar powered the flight design must be optimized for the greatest efficiency. This means it must also fly fast enough to maintain altitude and be able to withstand changes in temperature and atmospheric pressure. A carbon or alternate lightweight material frame support long wingspans that have very thin solar panels along those wings are features shared by several solar plane designs. Additional features of these planes include propeller(s), motor(s), on board computing panels, and solar tail fins.
• Energy
Solar planes have a surface area designed to absorb and convert solar energy into usable energy by the plane. Some of this is stored in batteries so the solar plane can work when the sun is not as strong, and when extra power is needed. Energy converters convert the solar power by regulating current and voltage.(2) Rechargeable batteries store energy gained from the solar panels and transfer the energy at a voltage compatible with the solar plane’s motor(s) and usage requirements.
• Flight
Solar planes can fly higher than commercial jets; for example, in 2010 the Zephyr flew around 60,000 feet above sea level, close to twice the height of a passenger plane. The ideal flight capacity of a working solar powered plane is continuous flight for extended periods of time with greater weight capacity. Solar planes have many potential uses and benefits both in Government and private endeavors. Government reconnaissance planes would have to be able to stay in continuous flight for years and be able to support hundreds of pounds of weight according to Technewsdaily’s coverage of the Zephyr-6.
• Technology
The technology used to make solar planes work has evolved considerably. In 2010, the Zephyr plane used rechargeable batteries made of lithium-sulphur to allow the plane to travel without sunlight. (3) The Sky-Sailer plane, intended for use on Mars according to Alternative-energy news, makes use of lithium-ion polymer batteries.(2) The solar panels used on the Zephyr-6 were also very light and maximize the suns energy by converting a range of spectral wavelengths into a usable energy source.(4)
Solar planes are similar to solar powered gliders. Gliders are designed to be lightweight to make use of lighter winds and aerodynamics, but the solar power and computing additions to glider like engineering has enabled sustained and remote controlled flight with auto pilot capability. One of the largest challenges facing solar planes is the energy storage and generation capacity that currently limits a wider range of purely solar powered plane applications.
Sources:
1) http://bit.ly/aHSJaj (NASA)
2) http://bit.ly/akUoo7 (Noth, Engel and Siegwart)
3) http://bit.ly/bX0wcP (Technewsdaily)
4) http://bit.ly/bFtcPf (Unisolar)
5) http://bit.ly/9evFiZ (Alternative energy)
