MILITARY AERONAUTICS SQUIER. 129 



the balloon house of this society at Tegel, adjoining the military bal- 

 loon house. 



The gas bag is similar in construction to that of the Drachen bal- 

 loon, used by the army for captive work; volume, 113,000 cubic feet; 

 length, 190 feet; maximum diameter, 30-J feet. It is cjdinclrical in 

 shape, rounded at the front end, and pointed at the rear. The mate- 

 rial was furnished by the Continental Tire Company. It is diagonal- 

 thread, weighing about J.1.2 ounces per square yard, and having a 

 strength of about 910 pounds pev running foot. Its inner surface is 

 covered with a layer of rubber. 



BaUonets. — There are two ballonets, one at each end, each having a 

 capacity of 10,596 cubic feet. The material in the ballonet weighs 

 about 8J ounces per square yard, the cotton layers being lighter than 

 in the material for the gas bag. Air is pumped into the rear ballonet 

 before leaving the ground, so that the airship operates with the front 

 end inclined upward. The air striking underneath exerts an upward 

 pressure, as on an aeroplane, and thus adds to its lifting capacity. 

 Air is jDumped into the ballonets from a fan operated by the motor. 

 A complex valve just under the middle of the gas bag enables the 

 engineer to drive air into either or both ballonets. The valves also 

 act automatically and release air from the ballonets at a pressure of 

 about 0.9 of an inch of water. 



In the middle of the top of the gas bag is a valve for releasing the 

 gas. It can be operated from the car, and opens automatically at a 

 pressure of about 2 inches of water. Near the two ends and on oppo- 

 site sides are two rip strips controlled from the car by cords. 



Suspension. — The suspension is one of the characteristics of the 

 airship and is protected by patents. The car has four trolleys, two 

 on each side, which run on two steel cables. The car can run back- 

 ward and forward on these cables, thus changing its position with 

 relation to the gas bag. This is called "loose" suspension. Its 

 object is to allow the car to take up, automatically, variations in 

 thrust due to the motor and variations in resistance due to the air. 

 Ramifications of hen.p rope from these steel cables are sewn onto a 

 canvas strip, which in turn is sewn onto the gas bag. This part of the 

 suspension is the same as in the Drachen balloon. The weight is dis- 

 tributed over the entire length of the gas bag. 



Car. — The car is IG.l feet long and is built of steel tubes and wire. 

 It is large enough to hold the motor and three men, though four or 

 five may be taken. 



Motor. — The motor is a 110-horsepower Daimler-Mercedes. Suf- 

 ficient gasoline is carried for a run of twelve hours. 



Propeller. — The propeller, like the suspension, is peculiar to this 

 airship and is protected by patents. It has four cloth blades, which 



