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 planes. A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...

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 when ...

, manned

solar-powered aircraft An electric aircraft is an aircraft powered by electricity. Electric aircraft are seen as a way to reduce the environmental effects of aviation, providing zero emissions and quieter flights. Electricity may be supplied by a variety of methods ...

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 unmanned

AstroFlight Sunrise The AstroFlight Sunrise was an uncrewed experimental electric aircraft technology demonstrator and the first aircraft to fly on solar power. First conceived in November 1970, the Sunrise first flew on 4 November 1974 from Bicycle Lake, a dry l ...

and the manned 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 The Kremer prizes are a series of monetary awards, established in 1959 by the industrialist Henry Kremer. Royal Aeronautical Society Human Powered Flight Group The Royal Aeronautical Society's "Man Powered Aircraft Group" was formed in 1959 b ...

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. Human-powered aircraft have been successfully flown over considerable distances. However, they are still primarily constructed ...

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

model aircraft A model aircraft is a small unmanned aircraft. Many are replicas of real aircraft. Model aircraft are divided into two basic groups: flying and non-flying. Non-flying models are also termed static, display, or shelf models. Aircraft manufactur ...

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

spar SPAR, originally DESPAR, styled as DE SPAR, is a Dutch multinational that provides branding, supplies and support services for independently owned and operated food retail stores. It was founded in the Netherlands in 1932, by Adriaan van Well ...

is a laminated

spruce A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ( taiga) regions of the Earth. ''Picea'' is the sole genus in the sub ...

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 Lasham Airfield is an aerodrome located north-west of Alton in Hampshire, England, in the village of Lasham. It was built in 1942 and was a Royal Air Force Station during the Second World War, many significant operations being flown from i ...

Hampshire Hampshire (, ; abbreviated to Hants) is a ceremonial county, ceremonial and non-metropolitan county, non-metropolitan counties of England, county in western South East England on the coast of the English Channel. Home to two major English citi ...

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, 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, "The Sleeve"; nrf, la Maunche, "The Sleeve" ( Cotentinais) or (Jèrriais), ( Guernésiais), "The Channel"; br, Mor Breizh, "Sea of Brittany"; cy, Môr Udd, "Lord's Sea"; kw, Mor Bretannek, "British Sea"; nl, Het Kan ...

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