Pictured above is a copy of a French Caquot, the German designation was “Type Ae” Observation Balloon.
Shown above is rear view of a typical British designed observation balloon.
The British called them sausages, for obvious reasons. The balloon's shape gave it another nickname, “Nulle” or “Testicle”.
A German 75-mm Anti Aircraft Battery stands guard near an observation balloon. The German gun crew were known to mix in incendiary rounds called “flaming onions,” this was ammunition specifically designed for balloon-busters. These threw up great balls of fire, distracting all but the most determined pilots.
The Germans made excellent use of observation balloons in several configurations. An early variety made by Parseval-Sigsfeldand called “Drachen”, had a single fin, low center, and was totally cylindrical, with rounded ends. The British called them sausages, for obvious reasons. The balloon's shape gave it another nickname, “Nulle” or “Testicle”.
The Caquot was tear-drop shaped, with three stabilizing fins. The Germans used a copy of a French Caquot, the designation was "Type Ae 800" for Achthundert English 800 which was a reference to the cubic meter capacity.
English, the reason for this being the design was stolen from a captured British balloon design. The improved Caquot could ride higher, and fly in higher winds than the Parseval-Sigsfeld, so it quickly replaced the Drachen, even among the Luftschiffertruppen.
The observer suspended in the wicker basket typically had a wireless set, binoculars and one or two long-range, cameras with him. Their job was to observe actions on the front and behind it, to spot enemy troop movements, unusual activity of any sort, and to call down artillery fire onto any worthy targets. They were targets of great importance to the British HQ, especially before any sort of infantry action, so squadrons were frequently ordered to target balloons.
This was especially risky as they were well guarded with AA guns, long-range machine guns and a fighter Screen. Getting to the balloon was easy, shooting it up was difficult and getting away was very difficult. It required good nerves, quick reactions, and an all round good pilot to fight their way through the defenses, hit the balloon before it is pulled down and then get away again. It was a rule of thumb with British pilots to never go after balloons below 1,000 feet, the AA and mg fire was too dangerous. The balloons could be pulled down very quickly as they were tethered to a motorized winch, so that once a fighter was spotted the balloon could be down in under a minute.
The secret was to sneak up on them some how. As the balloons were filled with hydrogen they burned easily once they were pierced with tracer bullets or bullets especially designed for Zeppelins. The first balloon-busters fired Le Prieur rockets. The French introduced these during the Verdun fighting of 1916. Incendiary bullets replaced rockets beginning in 1917.
The balloon observers were the only people routinely outfitted with parachutes, which had been available since 1915. The parachutes had a failure rate just high enough to ensure that observers jumped only in dire emergencies. By the war's end 241 German observation balloons had been shot down.
Special thanks to Jim Streckfuss from League of World War I Aviation Historians for his input and corrections.