TRAVEL IN THE AIR 



309 



late in 1783 sent it up into the air carrying several 

 animals. These returned to the earth safely, and a 

 short time later Rozier and d'Arlandes, Frenchmen, 

 made a flight over Paris, staying in the air about 

 twenty-five minutes and covering a distance of five 

 miles. 



Ballooning spread throughout the world as a sport 

 and has remained so to the present day. Each year an 

 international balloon race is held with entries from 

 many countries. The record distance for free bal- 

 looning is 1,354 miles made in 1912 by Maurice 

 Bevaims, a Frenchman. 



Courtesy Goodyear Tire and Rubber Company 



FIG. 516. SEMI-RIGID DIRIGIBLE 



Balloons have been of great use for purposes of 

 observation in war and for the study of the upper 

 atmosphere. In recent years great progress has been 

 made in the exploration of the upper atmosphere by 

 means of balloons. Professor Piccard of Belgium as- 

 cended to an altitude of ten miles above the earth's 

 surface in 1932. Since that time three other ascents 

 have exceeded Piccard's. altitude. Three Russian 

 scientists reached 11.4 miles in September, 1933; two 

 Americans, Settle and Fordney, reached 11.6 miles in 

 November of the same year; and in November of 1935 

 two other Americans, Stevens and Anderson, reached 

 the record altitude of 13.7 miles. 



What are the various types of dirigible balloons, 

 and what principles control them? In free ballooning 

 the altitude of the balloon may be controlled by the 

 pilot. The balloon may be raised by throwing out 

 ballast in the form of sand or it may be lowered by 

 allowing gas to escape through a valve. The direction 

 which a free balloon will take, however, is dependent 

 largely upon the wind. 



As early as 1852 a Frenchman, Henri Giffard, made 

 a flight in a cigar-shaped balloon 143 feet long and 

 39 feet in diameter. The balloon was driven at the 

 rate of six miles an hour by a three-horse-power steam 

 engine connected to a screw propeller. The ship could 

 be controlled not only for altitude but also for direc- 

 tion. This was the first dirigible balloon. 



Following this pioneer dirigible, many attempts 



were made to perfect it as a means of transportation, 

 but the chief difficulty was the lack of suitable motors. 

 The modern dirigible had to await the perfection of 

 the gasoline engine. 



There are three types of dirigible balloons. They 

 are the non-rigid, the semi-rigid, and the rigid. In the 

 first, a cigar-shaped bag is filled with gas; the second 

 is a gas-filled bag reenforced by wire netting and some 

 metal attachments. Sometimes it has a brace of dur- 

 alumin (a light alloy of aluminum) running from 

 one end to the other. The third type is the rigid dirigi- 

 ble and is built usually on a structural framework of 

 duralumin. Figures 515, 516, and 518 show dirigi- 

 bles of these types. 



The first rigid dirigible was built by Count Ferdi- 

 nand von Zeppelin in 1900. The framework was built 

 of aluminum, and it contained seventeen gas compart- 

 ments inside the huge bag, which was 406 feet long 

 and thirty-eight feet in diameter. It held 400,000 cubic 

 feet of gas. Since 1900 the dirigible has undergone 

 many improvements. The Graf Zeppelin, a modern 

 dirigible built in Germany, shows some of the ad- 

 vances. The framework of this modern Zeppelin is 

 built of duralumin, a new alloy which is better than 

 pure aluminum because it is just as light and much 

 stronger. It is 770 feet long, 115 feet high, and 102 

 feet in diameter and holds 3,708,000 cubic feet of gas. 

 It has a cruising speed of eighty miles per hour. Fig- 

 ure 517 shows an early Zeppelin. 



After the Graf Zeppelin was built in 1927, two larger 

 ships, the ill-fated Akron and the Macon, were built in 

 this country for the United States Navy. The Akron, 

 which was destroyed in a storm with the loss of 

 seventy-three lives in April, 1933, was 785 feet in 

 length and 132.9 feet in diameter and had a gas 

 capacity of 6,500,000 cubic feet. The Macon, sister 

 ship of the Akron, completed in 1933, was slightly 

 larger. The Macon was later destroyed. 



Recently the Hmdenburg, the largest lighter-than- 

 air craft, was built in Germany. This ship has a 



Courtesy Goodyear Tire and Rubber Comfany 



FIG. 517. AN EARLY ZEPPELIN 



