Although no extensive use of barrage balloons was contemplated by the Germans before the beginning of World War II, subsequent developments proved that barrage balloons have a definite psychological value as well as a practical value, and experiments conducted prior to the outbreak of the war were very soon put into practical use over strategic manufacturing centers in western Germany.

As in the U.S. Army and in the British Isles, the main purpose of the German barrage balloon is to hold a steel cable suspended vertically in the air. Thus, below the operating height of the balloon, this cable obstacle presents both a physical and mental hazard to enemy pilots attempting to enter that space. It is of course axiomatic that the type of balloon used for this purpose will be strong enough to suspend the cable, and that the balloon is designed in accordance with sound aeronautical principles (i.e., in terms of streamlining, capacity to resist wind stress, etc.). The extent of engineering developments of the German barrage balloon since the beginning of World War II is not definitely known, but it is believed that any changes effected consist only of minor modifications of the types in existence at the beginning of the war.

b. Description (fig. 14)

At the beginning of World War II, there were two general types of barrage balloons in existence in Germany. Both types were egg-shaped and had four fins at the tail end: a top fin, two side fins, and a bottom fin. The top fin and two side fins were inflated with air. The bottom fin was called the steering sack and had an opening at both ends. When the balloon was up, air entered the bottom opening of the fin and made its exit through the top opening. The fins (and especially the bottom fin) served to keep the balloon in proper position with respect to the wind and air currents. When inflated, the shape of the balloon could be likened to a short fat cigar, with a tail like a Japanese goldfish. Rubber cords were fastened tightly around the outside of the inflated balloon to assist in keeping its shape and strength.

Figure 14.—German barrage balloon.

Although both types of balloons were inflated with hydrogen gas, they differed in that one type was inflated exclusively with hydrogen gas while the second was inflated with both hydrogen gas and air, each being in separate chambers. At least the first type, and probably both types, were divided into six gas chambers. The second type had its air compartment behind the hydrogen gas compartment, the air being forced out through air valves as the gas expanded at higher altitudes. As both types were still more or less in the experimental stage, they varied in size, the largest being approximately 60 feet long and 25 feet in diameter, with a long "flutter" tail. Although various types of lethal devices were in the process of experimentation, the final decision along these lines is not known.