Gas balloon

A gas balloon is a balloon that rises and floats in the air because it is filled with a gas lighter than air (such as helium or hydrogen). When not in flight, it is tethered to prevent it from flying away and is sealed at the bottom to prevent the escape of gas. A gas balloon may also be called a Charlière for its inventor, the Frenchman Jacques Charles. Today, familiar gas balloons include large blimps and small latex party balloons. For nearly 200 years, well into the 20th century, manned balloon flight utilized gas balloons before hot-air balloons became dominant. Without power, heat or fuel, untethered flights of gas balloons depended on the skill of the pilot. Gas balloons have greater lift for a given volume, so they do not need to be so large, and they can stay up for much longer than hot air balloons.