###### 1. Dulles Airport

Dulles Airport, designed by Eero Saarinen, is in the

shape of a hyperbolic paraboloid. The hyperbolic paraboloid is a three-dimensional

curve that is a hyperbola in one cross-section, and a parabola in another cross
section.

2. Lampshade

A household lamp casts hyperbolic shadows on a wall.

3. Gear transmission

Two hyperboloids of revolution can provide gear
transmission between two skew axes.

The cogs of each gear are a set of generating
straight lines.

4. Sonic Boom

In 1953, a pilot flew over an Air Force Base

flying faster than the speed of sound. He damaged every building on the
base.

As the plane moves faster than the speed of sound, you get a cone-like wave.

Where the cone intersects the ground, it is an hyperbola.

The sonic boom hits every point on that curve at the same time. No sound is

heard outside the curve. The hyperbola is known as the "Sonic Boom Curve."

In the picture below, the sonic boom is "visible" due to the humidity.

The photo below was taken by Ensign John Gay, U.S. Navy from the aircraft

carrier *Constellation*. *Sports Illustrated* and *Life* both ran the photo.

Comparing Speeds in Miles per Hour

Human Walking | 3 mph |

Human Running | 34.3 mph |

Race Horse | 44.9 mph |

Cheetah Running | 65 mph |

Car on Interstate Highway in Colorado | 75 mph |

Fastest Train | 250 mph |

Passenger Jetliner (McDonald Douglas DC-9) |
575 mph |

Speed of Sound (At sea level, 59 degrees) |
761 mph |

Concorde | 1,450 mph |

Fastest Jet Fighter | 4,500 mph |

Space Shuttle in Orbit | 17,000 mph |

5. Cooling Towers of Nuclear Reactors and Coal-fired Power Plants

The hyperboloid is the design standard for all nuclear

cooling towers and some coal-fired power plants. It is structurally

sound and can be built with straight steel beams.

When designing these cooling towers, engineers are faced with two problems:

(1) the structutre must be able to withstand high winds and

(2) they should be built with as little material as possible.

The hyperbolic form solves both of these problems. For a given diameter

and height of
a tower and a given strength, this shape requires less material

than any other form.
A 500 foot tower can be made of a reinforced concrete

shell only six or eight inches wide.
See the pictures below of the F. B. Culley

Generating Station, a 369-MWe coal-fired electricity-generating power plant.

Thanks to Michael Linch for pointing out that this was not a nuclear power plant!

6. Hyperbolas from 3-dimensional shapes

7. Stones in a Lake

When two stones are thrown simultaneously into

a pool of still water, ripples move outward in concentric circles.

These circles intersect in points which form a curve known as the hyperbola.