The Berkshire Concept 70, sometimes called simply the C-70, is an

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, single seat,

high-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 co ...

, 15 metre class competition

glider Glider may refer to: Aircraft and transport Aircraft * Glider (aircraft), heavier-than-air aircraft primarily intended for unpowered flight ** Glider (sailplane), a rigid-winged glider aircraft with an undercarriage, used in the sport of glidin ...

that was designed by Arthur Zimmermann and produced by the Berkshire Manufacturing Corporation of

Lake Swannanoa, New Jersey Lake Swannanoa is a residential lake community located within Jefferson Township, in Morris County, in the U.S. state of New Jersey. It is within the scenic Skylands Region and approximately by road from New York City. Geology and hydrology ...

between 1971 and 1974.Said, Bob: ''1983 Sailplane Directory,

Soaring Magazine ''SOARING'' is a magazine published monthly as a membership benefit of the Soaring Society of America. It was first published in 1937. The headquarters is in Hobbs, New Mexico. The magazine's article topics include safety issues and accounts of in ...

'', page 11. Soaring Society of America, November 1983. USPS 499-920

Design and development

The Concept 70 was intended to be a domestic US

fiberglass Fiberglass (American English) or fibreglass ( Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clo ...

sailplane that would compete with the best European 15 metre aircraft being produced in the late 1960s. The company started out as a fiberglass aircraft repair shop founded by Zimmermann and Wolfgang Schaer, but quickly progressed to aircraft design and construction. The aircraft is made from molded fiberglass, with an internal

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraf ...

steel frame skeleton that connects the monowheel landing gear and the wing fittings to the fuselage, while also providing a protective cockpit cage for improved impact survivability. The prototype has an Eppler airfoil and an all-flying horizontal stabilator. Production aircraft featured a Wortmann airfoil, a more conventional tail, and flaps that deploy to 90° for glidepath control, as the aircraft lacks the speedbrakes or spoilers common to most sailplane designs. The flaps permit very steep approaches, allowing the aircraft to land in small fields with obstacles. The aircraft also has

retractable landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...

and was available with optional water ballast tanks with a capacity. Production of the Concept 70 ended with 21 produced, when Zimmermann died in 1974. The aircraft was never

type certified A type certificate signifies the airworthiness of a particular category of aircraft, according to its manufacturing design (''type design''). It confirms that the aircraft of a new type intended for serial production, is in compliance with applica ...

and all aircraft were registered as experimental aircraft in the ''Racing/Exhibition'' category.

Operational history

In March 2011 there were still 14 Concept 70s registered in the US.

Aircraft on display

National Soaring Museum The National Soaring Museum (NSM) is an aviation museum whose stated aim is to preserve the history of motorless flight. It is located on top of Harris Hill near Elmira, New York, United States. The NSM is the Soaring Society of America's officia ...

storage wing

Specifications (Concept 70)

References

{{reflist

External links