Elliptical dome



An elliptical dome, or an oval dome, is a dome whose bottom cross-section takes the form of an ellipse. Technically, an ellipsoidal dome has a circular cross-section, so is not quite the same.

While the cupola can take different geometries, when the ceiling's cross-section takes the form of an ellipse, and due to the reflecting properties of an ellipse, any two persons standing at a focus of the floor's ellipse can have one whisper, and the other hears; this is a whispering gallery.

The largest elliptical dome in the world is at the Sanctuary of Vicoforte in Vicoforte, Italy.

In architecture
Elliptical domes have many applications in architecture; and are useful in covering rectangular spaces. The oblate, or horizontal elliptical dome is useful when there is a need to limit height of the space that would result from a spherical dome. As the mathematical description of an elliptical dome is more complex than that of spherical dome, design care is needed.

In a geodesic dome with a circular base, the triangular elements align so their edges form great circles. Although not geodesic, a new, elliptical design was patented in 1989; it uses hexagons and pentagons to form a dome with a cross section that is elliptical. Due to its mathematical derivation, this design is called "geotangent".

World examples
Elliptical domes come up in the design of all of the following:
 * A number of mosques in Cairo, Egypt,
 * Part of St. Peter's Basilica, in Rome, Italy
 * The Basilica of St. Lawrence, Asheville, in Asheville, North Carolina,
 * The Church of Saint Roch, Žižkov, in Prague, Czech Republic,
 * The Four Domes Pavilion, in Wroclaw, Poland,
 * The Indiana Theatre, in Indiana, city of Indianapolis,
 * The Joe and Rika Mansueto Library, at the University of Chicago,
 * The Kanteerava Indoor Stadium, in Bangalore, India,
 * The Mayflower Hotel, in Washington, DC,
 * The Mosque–Cathedral of Córdoba, in Andalusia,
 * The Palau Nacional, in Barcelona, Spain,
 * The Pisa Cathedral, in Pisa, Italy,
 * The Rose Hill Mansion, Bluffton, in Bluffton, South Carolina,
 * The San Filippo Neri, in Turin, region of Piedmont, Italy,
 * The Sant'Andrea in Via Flaminia, in Rome, Italy,
 * The Santa Caterina, Casale Monferrato, in Casale Monferrato, Province of Alessandria, region of Piedmont, Italy,
 * The Seville Cathedral, Spain,
 * The Skyspace Lech, Tannegg/Oberlech in Vorarlberg, the westernmost federal state of Austria,
 * The State Savings Bank Building, in City of Sydney, Australia,
 * The Temple Sinai, in Oakland, California,
 * The Sanctuary of Vicoforte, in Italy,
 * BAPS Swaminarayan Akshardham (New Jersey), in Robbinsville, New Jersey.

Creating elliptical domes

 * Elliptical domes site
 * Creating an elliptical dome
 * Another reference, on creating ellitpical domes

Calculations

 * Site for calculating figures related to elliptical domes
 * Another site for calculations
 * Dome calculator

More general references

 * Buckling of Externally Pressurized Prolate Ellipsoidal Domes
 * An article addressing many topics, including elliptical domes
 * Use of elliptical domes, notably in Islamic architecture