78 



DISCOVERY 



the Drachcn, originated in Germany, and is now obso- 

 lete. There is an American balloon, the Goodyear, 

 which closely resembles the Drachen. It has sails and 

 a parachute tail to assist its stability. The Italian 

 balloon has an elliptically-shaped gas-bag pro\aded 



FIG. I.— " SAUS.\GE " B.\I,I-00X (DR.\CHEN'). 



with a conical-shaped tail filled with air, to which a 

 rudder and stabilising fins are attached. 



The French balloon, however, is the most important 

 and most widely used. It is the standard for the 

 Naval and Military Services of England and France. 



The streamline form for a kite balloon is rather 

 bluff (i.e. not sharp-pointed at the ends) and 

 short compared with an airship. The latter has its 

 centre of buoyancy, or central point of the lifting effort 

 of the gas, immediately above the car. This allows a 

 finer nose on the streamline. Conditions are different 

 in the case of the kite balloon. Here the greater part 



no. 5— STREAMl.INE BAI,I,00N (C.\QUOT). 



of the gas-hfting force is required to lift the cable, and 

 bear the tension on the cable due to the wind forces 

 on^thc balloon. A large amount of buoyancy is there- 

 fore needed about the nose, where the cable suspensions 



arc attached, and that is why the balloon is given a 

 " bluff " nose. 



On the right-hand side of the balloon in Fig. 2 are 

 seen the air-filled stabilising fins and the rudder. To 

 these large fins the kite balloon owes much of its success. 



Kite balloons, like airships, are provided with an 

 internal air-chamber or " ballonet." The function of 

 the ballonet is to keep the balloon rigid, and to pro\'ide 

 an automatic means of operating the valve which re- 

 leases the hydrogen from the envelope as the balloon 

 ascends. 



A kite balloon of capacity 35,000 cubic feet can be 

 flown at altitudes up to 6,000 feet, carrying two ob- 

 servers. Such a balloon is about 91 feet long, and is 

 the type used for " spotting " enemy batteries and 

 for controUing gun-fire in military operations. For 

 naval work, and for operations where great altitude 

 is not of importance, a slightly smaller balloon has 



FIG. 3.— ITALIAN. 



been found more convenient. During the war much 

 valuable work was accomplished at sea in convoying 

 ships, a lookout being kept for the wake of a sub- 

 marine by the balloon observer. A submarine can 

 be seen beneath the surface just as fish can be seen in 

 a clear pond. The balloon is towed by a ship, usually 

 a destroyer or a boat of the new " p " class, the 

 observers in the balloon being in telephonic com- 

 munication with the ship by means of a wire in the 

 core of the cable. Messages may thus be sent with- 

 out delay, enabling the ship on occasion to know the 

 exact place and time to drop their depth charges so 

 as to destroy the submarine. These charges take 

 effect anywhere within 50 feet of the explosion, and 

 their effect is felt in the balloon itself at altitudes from 

 600 to 1,500 feet. On one occasion a depth charge 

 caused the magazine of a large U-boat to explode, 

 and the effect was so far-reaching that many of our 

 own ships, some even sixty miles away, felt it very 

 much. In one instance the crew came up on deck 

 expecting that the stern of the ship had been blown 

 away, although in reality they were many miles from 



