How a Gas Balloon Works

PHOTO BY PAUL DEBERJEOIS

Above: Mark Sullivan and Cheri White enroute to victory in the 2012 America’s Challenge.

expands, and the balloon gains altitude – and the pilots, who’ve been shivering all night in the cold, are thrilled that they can warm up. A free ride to altitude, the warmth of the sun – life is good!

However, as the sun sets and the gas cools and contracts, the balloon loses altitude. The pilots must then compensate for the loss of lift by getting rid of weight to make the balloon lighter. To facilitate this, the balloon carries disposable weight, or “ballast,” that can be tossed overboard (over open areas) specifically for this purpose. The most common form of ballast is sand, carried on the side of the basket in bags. Teams also carry jugs of water that double as ballast and drinking water. But in critical situations where pilots have to get rid of weight in a hurry, anything in the basket that has weight can be used as ballast – equipment, clothes, food. When Blanchard and Jeffries made the first crossing of the English Channel by gas balloon in the late 1700s, they famously landed in their underwear.

The pilots can also make the balloon descend by releasing gas from the balloon through a valve at the top of the envelope: small amounts for maneuvering to lose altitude, or large amounts to deflate the balloon at the end of the flight. Pilots open the valve by pulling on a rope or line that extends into the basket. Some gas balloons also have separate deflation ports that are opened at the end of the flight to deflate the balloon more quickly. But teams try to keep ballasting sand and releasing gas to a minimum. Gas and sand are a gas balloon’s “fuel,” and the teams that can most effectively conserve both can fly longer and -- usually – farther in order to win the race.

As they fly across the country, the balloonists must maintain contact with air traffic controllers in the areas they cross. They carry transponders, radios, night lighting, and other instrumentation, as well as GPSbased trackers that transmit position data to the race Command Center. This data is linked to the Balloon Fiesta Web site and the YB Tracking app so spectators can track the progress of the race.

Since gas flights often cover hundreds or even thousands of miles, getting timely, accurate weather data is not only crucial, it can be a matter of safety and survival. Pilots get weather data through the usual aviation flight service channels, but almost all also employ meteorologists who provide advice about weather and race strategy. A handful of meteorologists around the world specialize in forecasting trajectories for long-distance scientific and manned balloon flights and are valued members of the race teams. Some teams also have their own team “command centers,” with specialists who analyze weather and data, advise the pilots on strategy, and support the team’s chase crew.

Finally, the balloons must carry everything the pilots need for their safety and comfort during a flight that can last 60 hours or more. This includes food, (though most pilots say they don’t tend to eat much while aloft), water, layered clothing including heavy jackets and parkas, music, reading material for those rare moments when they aren’t busy, maps and logbooks, and – you were waiting for this, weren’t you? – a porta-pottie or some equivalent.

When it is time to land, the pilot deploys a “trail rope” – a long, heavy rope that “trails” on the ground. The rope acts as a form of retractable ballast and also helps to slow the balloon on landing.

Gas ballooning in a race like the America’s Challenge is an endeavor for the skilled and adventurous. Sitting aloft in a balloon for two or three days is not for everyone and can be, as the saying goes, hours of relative boredom punctuated by moments of sheer terror. That said, gas balloonists tell of wonderful days and evenings aloft, cruising in silence except for the sounds wafting upward from the earth. They see America in a way few people can – from a slow-moving platform suspended over an ever-changing landscape. It is a truly unique and special experience undertaken by a unique and special breed of balloonist: the America’s Challenge competitor.