The Schempp-Hirth Cirrus is an Open Class

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 gliding ...

built by

Schempp-Hirth Schempp-Hirth Flugzeugbau GmbH is a glider manufacturer based in Kirchheim unter Teck, Germany. History Martin Schempp founded his own company in Göppingen in 1935, with the assistance of Wolf Hirth. The company was initially called "Sportflu ...

between 1967 and 1971 and by VTC until 1977. It was replaced by the Nimbus 2.

Development

The Cirrus was designed by Dipl.-Ing. Klaus Holighaus and was the first glass-fibre glider to be built by Schempp-Hirth. The prototype flew in 1967 with a V-tail like the

Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...

. It won the German Open Class in 1967. By 1971, 107 Cirrus had been built in Germany. Production was transferred to Vazduhoplovno Tehnicki Centar (VTC) at

Vršac Vršac ( sr-cyr, Вршац, ; hu, Versec; ro, Vârșeț) is a city and the administrative centre of the South Banat District in the autonomous province of Vojvodina, Serbia. As of 2011, the city urban area had a population of 35,701, while ...

Yugoslavia Yugoslavia (; sh-Latn-Cyrl, separator=" / ", Jugoslavija, Југославија ; sl, Jugoslavija ; mk, Југославија ;; rup, Iugoslavia; hu, Jugoszlávia; rue, label= Pannonian Rusyn, Югославия, translit=Juhoslavij ...

where an additional 63 were built. Haro Wodl won the 1968

World Gliding Championships The World Gliding Championships (WGC) is a gliding competition held every two years or so by the FAI Gliding Commission. The dates are not always exactly two years apart, often because the contests are sometimes held in the summer in the Southern ...

in the open class, flying a Cirrus.

Design

Although Holighaus had designed and built the ground-breaking D-36 together with Gerhard Waibel, Wolf Lemke and Walter Schneider, he followed a completely different design philosophy for the Cirrus, preferring a thicker airfoil and the use of PVC foam instead of balsa as a core material. The resultant Cirrus has mid-set cantilever wings with a span of 17.74 metres, and a conventional low-set cruciform tailplane. It can carry water-ballast in the wings. There are no flaps. For

glidepath Instrument landing system glide path, commonly referred to as a glide path (G/P) or glide slope (G/S), is "a system of vertical guidance embodied in the instrument landing system which indicates the vertical deviation of the aircraft from its o ...

control, there are effective top-and-bottom air brakes and a substantial drag chute built into the bottom of the rudder. The undercarriage is retractable.

Aerodynamics

Holighaus chose a rather thick flapless Wortmann airfoil (FX 66-196/161) which had low

drag Drag or The Drag may refer to: Places * Drag, Norway, a village in Tysfjord municipality, Nordland, Norway * ''Drág'', the Hungarian name for Dragu Commune in Sălaj County, Romania * Drag (Austin, Texas), the portion of Guadalupe Street adj ...

(for the time) and very gentle stall characteristics. The span and profile are optimised for the weaker gliding weather of central Europe. The result is excellent thermalling characteristics and a high

glide ratio In aerodynamics, the lift-to-drag ratio (or L/D ratio) is the lift generated by an aerodynamic body such as an aerofoil or aircraft, divided by the aerodynamic drag caused by moving through air. It describes the aerodynamic efficiency under gi ...

(for 1967).

Construction

All-fiberglass glider, with foam core sandwiches for the wing skins and fuselage bulkheads. Internal tubular-steel frame interconnects the wings, cockpit and landing gear, carrying the flight and landing stresses. This steel frame is bolted to the fiberglass shell. The Cirrus was built in female moulds, an innovation that became the standard method for all manufacturers.

Variants

*The first prototype had an all-flying V-tail. *The original Cirrus has a span of 17,74m. Sometimes it is called Open Cirrus. *Cirrus VTC were produced in Yugoslavia under license by the Vazduhoplovno Tehnicki Centar in Vršac.

Developments

* Standard Cirrus, Standard Cirrus VTC and Standard Cirrus 75 have a wingspan of 15m and a T-tail.

Specifications

References

* Selinger P, Segelflugzeuge vom Wolf aum Discus, Motorbuch Verlag Stuttgart, 1989 * Ryan J, Cirrus Test Pilot Report, Soaring, July 1967 * Foley W, The Schempp-Hirth Cirrus, Soaring, July 1967 * Simons M, Sailplanes 1965–2000, Equip, 2000

External links

Schempp-Hirth website
{{Schempp-Hirth

Cirrus Cirrus may refer to: Science *Cirrus (biology), any of various thin, thread-like structures on the body of an animal *Cirrus (botany), a tendril * Infrared cirrus, in astronomy, filamentary structures seen in infrared light *Cirrus cloud, a typ ...

1960s German sailplanes Aircraft first flown in 1967 Shoulder-wing aircraft