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These balloons aren't made of lead. Friday, July 11 2008

Now that you know a lead balloon can fly, perhaps it's time to know what makes a real air balloon get up in the air.

A hot air balloon, for manned flight, uses a single-layered, fabric gas bag, called an envelope. Modern hot air balloons are usually made of light-weight and strong synthetic fabrics such as ripstop nylon, or dacron (a polyester). There is an opening at the bottom of the bag, called the mouth or throat. Attached to the envelope is a basket for carrying the passengers. Mounted above the basket and centered in the mouth is the burner, which injects a flame into the envelope, heating the air within. The burner is fueled by propane.

The heated air inside the envelope makes it buoyant because it has a lower density than the cooler air outside the envelope. Unlike gas balloons, the envelope does not have to be sealed at the bottom since the air near the bottom of the envelope is at the same pressure as the surrounding air.

The material is cut into panels and sewn together, along with structural load tapes that carry the weight of the gondola or basket. The individual sections which run from the throat to the top of the envelope are called gores.

Envelopes often have a crown ring at the very top. This is a hoop of smooth metal, usually aluminum, to which vertical load tapes attach.

Unmanned hot air balloons are popular in Chinese history. Zhuge Liang of the Shu Han kingdom, in the Three Kingdoms era (220-280 AD) used airborne lanterns for military signaling. There is also some speculation that hot air balloons could have been used by people of the Nazca culture of Peru some 1500 years ago, as a tool for designing the famous Nazca ground figures and lines.

The first documented balloon flight in Europe was by the Portuguese priest Bartolomeu de Gusmão. On August 8, 1709, in Lisbon, Bartolomeu de Gusmão managed to lift a small balloon made of paper full of hot air about 4 meters in front of king John V and the Portuguese court.

The first recorded instance of a balloon carrying passengers was built by the brothers Joseph-Michel and Jacques-Etienne Montgolfier in Annonay, France. After experimenting with unmanned balloons and flights with animals, the first tethered balloon flight with humans on board took place on October 19, 1783 in Paris.

Modern hot air ballons, with an onboard heat source, were created by Ed Yost in the 1950s. His first successful flight was on October 22, 1960.

Today, hot air balloons are used primarily for recreation - there are over 7,500 operating in the United States.

Due to the simple construction of the balloon, they are able to fly to high altitudes. On November 26, 2005, Vijaypat Singhania set the world altitude record for highest hot air balloon flight - 68,986 feet.

On January 15, 1991, the Virgin Pacific Flyer balloon completed the longest flight in a hot air balloon when Per Lindstrand and Richard Branson of the UK flew 4,767.10 mi, from Japan to Northern Canada. The envelope was the largest ever built, to withstand the slipstreams.

A range of envelope sizes is available. The smallest is a one-person, basket-less balloon, called a Cloudhopper.

The largest balloons are usually used by large commercial or sightseeing operations - these can carry well over two dozen people.

The top of the balloon usually has a vent. The most common type of vent is a disk-shaped flap of fabric called a parachute vent. The fabric is connected around its edge to a set of vent lines that converge in the center. These lines are connected to a control line that runs to the basket. A parachute vent is opened by pulling on the control line. Once the control line is released, the pressure of the remaining hot air pushes the vent fabric back into place. A parachute vent can be opened briefly while in flight to initiate a rapid descent. Slower descents are initiated by allowing the air in the balloon to cool naturally.

In modern times, balloons are made in all shapes and sizes like: hot dogs, rocket ships, and the shapes of commercial products. There are also balloons that can be propelled through the air rather than just being pushed along by the wind, called airships.

The baskets are made of woven wicker or rattan. These materials have proven to be sufficiently light, strong, and durable for balloon flight. They vary in size from just big enough for two people to large enough to carry twenty-four. Larger baskets often have internal partitions for structural bracing and to compartmentalize the passengers.

Baskets may also be made of aluminum to reduce weight or increase portability. These may be used by pilots without a ground crew or who are attempting to set altitude, duration, or distance records.

Other specialty baskets include the fully enclosed gondolas used for around-the-world attempts, and baskets that consist of little more than a seat for the pilot and perhaps one passenger.

Standard hot air balloons are called Montgolfiere balloons and rely solely on the buoyancy of hot air provided by the burner and contained by the envelope.

In the United States, a pilot of a hot air balloon must have a pilot certificate from the Federal Aviation Administration (FAA).

While most balloon pilots fly for recreation, many are able to make a living as professional balloon pilots. Now, if we could only convince them to fly one made of lead.