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E. Linacre |
11/'98 |
The Montgolfier brothers made the first manned ascents in Paris in November 1783, using a balloon made of paper, containing hot air (Section 1.6). Their maximum height was less than 100 m. Jacque Charles and Nicolas Roberts ascended above 100 m, the next month, using a 9-metre-diameter balloon of rubberised silk containing hydrogen. In February of the next year Charles alone rose to 1000 m, where he found the temperature was at - 5° C, i.e. 13 K lower than at the surface. It is not coincidental that all these ascents were in winter. It was believed that the low temperatures would enhance the buoyancy of the balloons. Also, the stably stratified planetary boundary layer is less turbulent.
Gradually balloons went higher and higher. In 1862 James Glaisher and Tracey Coxwell rose to the tropopause. Glaisher’s eyesight failed at 9.5 km height, and he was unconscious at 12 km, where the concentration of oxygen would be only a fifth that at the surface. Coxwell’s hands were frozen (the temperature being about -60° C), but he managed to pull the gas-release valve with his teeth so that they descended to safety.
Joseph Kittinger rose to 34 km in an open gondola above New Mexico in 1960. He then jumped out, and fell to 6 km before his parachute opened automatically.