The Solar-Powered Aircraft Developments Solar One is a British

mid-wing A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple wings. A monoplane has inherently the highest efficiency and lowest drag of any wing config ...

experimental An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs whe ...

, crewed solar-powered aircraft that was designed by David Williams and produced by Solar-Powered Aircraft Developments under the direction of Freddie To. On 13 June 1979 it became one of the first solar-powered aircraft to fly, after the uncrewed AstroFlight Sunrise and the crewed Mauro Solar Riser, and the first successful British solar-powered aircraft."UK's first solar aircraft takes off", ''Flight International'', 30 June 1979, Page 233

/ref>Robert J. Boucher; "History of Solar Flight", AIAA/SAE/ASME 20th Joint Propulsion Conference, 1984, AIAA paper 84-1429.''Jane's All the World's Aircraft 1980-81'', Jane's, 1980, Page249.

Design and development

Freddie To was a member of the Kremer prize committee who started his own project to produce a

human-powered aircraft A human-powered aircraft (HPA) is an aircraft belonging to the class of vehicles known as human-powered transport. As its name suggests, HPAs have the pilot not only steer, but power the aircraft (usually propeller-driven) by means of a system ...

to compete for the prize. Its structure comprised a wooden frame covered with heat-shrunk Solarfilm

model aircraft A model aircraft is a physical model of an existing or imagined aircraft, and is built typically for display, research, or amusement. Model aircraft are divided into two basic groups: flying and non-flying. Non-flying models are also termed s ...

film. The wing was built in three sections, a centre section and two outer wing panels to simplify storage and transport. The wing spar is a laminated

spruce A spruce is a tree of the genus ''Picea'' ( ), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Northern hemisphere. ''Picea'' ...

girder box-spar design. The tail surfaces are quickly removable for storage. The resulting aircraft, at , proved too heavy for human-powered flight and so To converted it to solar power. A nose-mounted pod powerplant was installed consisting of four permanent magnet 36 V DC, 12 A Bosch electric motors, powered by a Nickel-cadmium battery pack of 24 cells with a total capacity of 25 AH, connected in series to give a maximum (open-circuit) output voltage of approximately 29 V. The motors drive a two-bladed propeller via a 3:1 bicycle-chain reduction gear. The propeller turns at a maximum of 1,100 rpm, decreasing with battery discharge. Power is controlled with a simple on/off switch. To recharge the batteries, 750 solar cells of 3 inch diameter were installed at a cost of £6,000. At that time solar cells were very expensive. They were the most costly part of the aircraft and had to be limited in capacity to remain within the project budget of £16,000. The output from the solar cells is not sufficient to sustain flight. Before flight they are used to charge the batteries. The batteries then provide power for takeoff and initial climb. The installed batteries provide for a climb of eight minutes plus a two-minute cruise allowance.

Operational history

The first flight attempt took place at Lasham Airfield,

Hampshire Hampshire (, ; abbreviated to Hants.) is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Berkshire to the north, Surrey and West Sussex to the east, the Isle of Wight across the Solent to the south, ...

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

on 19 December 1978. The propeller pitch was incorrectly set and the attempt achieved only a short hop. At the hands of pilot Ken Stewart, a successful flight took place on 13 June 1979, covering just under . The aircraft lifted off at and reached and in height. A second flight on the same day by Bill Maidment achieved a speed of . All flights were made on battery power that had been supplied on the ground from the installed solar cells. A planned flight across the

English Channel The English Channel, also known as the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France. It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busi ...

was abandoned when it was found that the aircraft did not meet its endurance targets.

Specifications (Solar One)

References

{{Photovoltaics 1970s British experimental aircraft Aircraft first flown in 1979 Solar-powered aircraft Photovoltaics Mid-wing aircraft Single-engined tractor aircraft

Design and development

Operational history

Specifications (Solar One)

See also

References