top of page
FNRS Balloon_tope
Auguste Piccard, 1931




Auguste Piccard and his assistant Paul Kipfer reached the stratosphere for the first time in human history in a hermetically sealed aluminum gondola suspended from the largest balloon ever constructed (“Ten Miles High in an Air-tight Ball). The FNRS balloon, named after the Belgian Fonds National de la Recherche Scientifique, was a funded experiment that included the sealing of human subjects in non-livable, extreme conditions. At take-off, the balloon barely contained 50,000 cubic feet of gas, resulting in an elongated pear-shape, and was just sufficient to lift the aluminum capsule housing the two aeronauts, their equipment, and lead ballasts (“10-mile Ascent Paves Way for Stratosphere Planes”). Once at altitude, the balloon could expand to contain 500,000 cubic feet of hydrogen, making Piccard’s balloon the largest ever built at the time.

In order to protect the aeronauts from the near vacuum of the stratosphere, the suspended gondola was sealed and pressurized to one atmosphere.

To sustain human life in the stratosphere, the sealed gondola had internalized systems for pressurization, temperature control and air composition. The first two did not pose major challenges, however, Piccard’s first flight did not have sufficient temperature control and reached uncomfortably cold temperatures. Later models were painted a combination of black on the bottom half and white on the top and created a comfortable space, usually of 65ºF. The problem of pressurization was addressed through the sealing of the cabin, which would have maintained steady pressure, had a leak not occurred during the ascent. An instrument became dislodged and a whistling of air occurred through an installation hole. Piccard quickly patched the leak and pressure was regained by pouring liquid oxygen on the floor. Maintaining an air composition suitable for human respiration proved to be the biggest challenge.

Air conditioning was less a problem of producing oxygen, but of reducing carbon dioxide. In normal air, carbon dioxide occupies 0.03 per cent of the mixture. At eight per cent, humans cannot breathe. Two percent causes no adverse effect, and was thus considered to be the maximum proportion of carbon dioxide allowed in the gondola. Eliminating carbon dioxide was also difficult in a pressurized system, where air cannot simply be expelled. Instead, Piccard utilized the Draeger apparatus, a compact instrument formerly used in underwater diving technology. It is composed of compressed oxygen that is released through a blower into a tube filled with granulated potassium hydroxide. The potassium hydroxide has the ability to remove carbon dioxide from the air mix, maintaining a percentage at or below two percent.

Auguste Piccard was the first of a dynasty of balloonists, aeronauts, and hydronauts, including his brother Jean Felix and his wife Jeannette; Jacques and Bertrand, his son and grandson respectively; and his nephew Don. After several experiments with balloons, Auguste Piccard’s interests shifted to undersea exploration. The innovations of the sealed cockpit lead to the design of the bathyscaphe in 1937.

KEYWORDS: Draeger Apparatus, Carbon Dioxide, Aeronaut, Hermetic Seal



Leakage: Air leakage in cabin on ascent

Landing Issues: Inability to land when desired – the pilots had to wait until night when the air within the balloon cooled and eventually sank into the mountains. 

Unstable Temperature: Temperature was very unstable – the area at the top of the capsule was very warm and the bottom was cold

bottom of page