With the success of the demonstration flight, Charles next  made a 25.5-foot diameter globe of rubberized silk. A net  was fitted over the upper half of the balloon and tied to a  loop around the middle of the bag. From this loop, a sort of  car or boat was suspended. The bag was tied at the bottom  to contain the gas. Dropping ballast caused the balloon to  rise, and releasing gas through a valve at the top made it  fall. On December 1, 1783, Professor Charles and Nicholas  Robert made the first manned gas balloon flight. The first  flight lasted for 1 hour and 45 minutes, rose to 1,800 feet, and  covered more than 27 miles. On landing, Robert got out of the  boat and Charles, now flying solo, ascended to almost 9,000  feet. The balloon had been flaccid on first landing, but filled  out as it rose and gas was released to prevent it from bursting.  Benjamin Franklin was present for this lift off and recognized  the potential for balloons in military operations. difference between the gas inside the envelope and the  atmospheric air outside. Neither super-pressure balloons nor  Rozière (a type of gas-hot air hybrid construction) balloons  are discussed. Gas ballooning was once the most common form of aviation  in the United States. Today, due to the costs involved,  gas flights are most frequently undertaken for training,  competition, or record breaking purposes. Short, recreational  gas flights, while not unheard of, are much less common  than hot air.  The first gas balloon flight occurred just a few weeks after the  first manned balloon flight of Jean-François Pilâtre de Rozier  and the Marquis d’Arlandes. While the Montgolfiers were  experimenting with hot air balloons, the Robert brothers and  Jacques Charles were also experimenting with gas balloons. Other ascensions followed, mostly to gather scientific data.  It was through these early experiments that the design/shape  of gas balloons, lifting capacity, and weight of air were  determined. One notable early flight was the crossing of  the English Channel from Britain to France by Jean-Pierre  Blanchard and Dr. John Jeffries on January 7, 1785. Their  balloon was scarcely sufficient to carry them and they threw  out their ballast, anchors, food, and clothing to complete the  crossing. The first gas balloon was small (13 feet in diameter) and was  filled with what was called “inflammable air.”  [Figure 11-1] It generated 35 pounds of net lift and, when set free, remained  aloft for 45 minutes and traveled 15 miles. Its final, sudden  descent was attributed to a rupture in the balloon. In 1906, James Gordon Bennett needed news for his  newspaper and having been successful in starting car and  boat races, decided to initiate a gas balloon race. The first  race was organized for Paris, France. Each country could send  contestants to the race. This race, the Coupe Aéronautique  de Gordon Bennett, is still held annually although there were  years when no race occurred due to wars. Today, the race is  the most prestigious gas race in the world. It is sanctioned  by the Fédération Aéronautique Internationale (FAI). The  country of the previous year’s winner is entitled to host the  race. In 2006, the 50$^{th}$ race was held flying out of Belgium  (www.coupegordonbennett.org). The Albuquerque International Balloon Fiesta (AIBF) started  the America’s Challenge Gas Balloon Race in 1995. It has  been conducted yearly, with the exception of 1999 when  AIBF instead hosted the Gordon Bennett Race. This has  become a very prestigious and international race that offers  pilots the opportunity for extremely long flights (www. balloonfiesta.com/Education/History/). Gas balloons designs are generally classified as netted or  quick fill. $_{Figure 11-1.}$  Early style of gas balloon. Many of these terms still  apply today. Balloon Systems 11-2 The History of Gas Ballooning Valve Ripping panel Valve line Open neck Hoop or load ring Ballast Basket Neck line Ripping line