Prior to the outbreak of the war, German zeppelins had captivated public attention and raised fears, fanned in part by the media, that these goliath airships would lay great cities to waste. Indeed, as indicated earlier, H. G. Wells had made the zeppelin the centerpiece of his 1908 book, The War in the Air. Although Germany possessed just nine airships when war broke out in August 1914, these were used in the opening stages of the German invasion through Belgium to drop bombs on Antwerp in an effort to force the Belgians to submit. Beginning in January 1915, the Germans launched their first attacks against Great Britain. The zeppelins used in these initial raids were carried out by the M-type, of which the naval zeppelin L-3 had been the first to enter service in May 1914. The airships in this class had a length of 518 ft 5 in., a diameter of 48 ft 8 in., and a gas volume of 793,518 cubic ft, which provided a lifting capacity of 20,282 lbs and a service ceiling of 2,800 m (9,186 ft). They were powered by three 200 hp Maybach CX inline motors, which produced a maximum speed of 53 mph and gave them a range of 683 miles.
During the course of the war, the Germans would introduce three series of larger zeppelins in an effort to increase their bomb-carrying capacity, their service ceiling, and their range. The first class of zeppelins introduced during the war was the P-type, the first of which entered service in May 1915 as the L-10. It had a length of 536 ft 5 in., a diameter of 61 ft 5 in., and a gas volume of 1,126,533 cubic ft, which provided a lifting capacity of 35,715 lbs and a service ceiling of 3,900 m (12,795 ft). The P-type was powered by four 210 hp Maybach CX inline engines, which produced a maximum speed of 59 mph and gave it a range of 1,336 miles. In May 1916, Germany introduced the R-type or “super zeppelin,” the first of which was designated the L-30. It had a length of 649 ft 7 in., a diameter of 78 ft 7 in., and a gas volume of 1,949,373 cubic ft, which provided a lifting capacity of 71,650 lbs and a service ceiling of 5,395 m (17,700 ft). The R-type was powered by six 240 hp Maybach HSLu inline motors, which produced a maximum speed of 64 mph and a range of 2,300 miles. In August 1917, the Zeppelin company introduced the last type to enter service during the war, the V-type, of which the L-59 is most famous for its November 1917 attempt to carry supplies from Bulgaria to Colonel Paul von Lettow-Vorbeck’s forces in German East Africa. It had a length of 743 ft, a diameter of 78 ft 7 in., and a gas volume of 2,419,057 cubic ft, which provided a lifting capacity of 114,860 lbs and a service ceiling of 8,200 m (26,902 ft). The V-type was powered by five 240 hp Maybach Mb IVa inline engines, which produced a maximum speed of 67 mph and a range of 4,970 miles.
More than two-thirds of the 140 airships used by Germany during the war were destroyed as the result of enemy fire or bombs, storms, or accidents, leading many historians to question whether the Germans had squandered precious resources that could have been poured into the development of bombers. It should be noted that, whereas the Germany Navy continued to invest heavily in zeppelins until the end of the war, the Germany Army began to turn toward bomber aircraft by 1915. These included a series of G-type light to medium bombers and the gigantic R-type (Risenflugzeug) heavy bombers.
In early 1915 Allgemeine Elektrizitäts Gesellschaft (A. E. G.) introduced the first of its series of G-types, the G. I twin-engine biplane. Production was limited because its two 100 hp Mercedes D. I inline motors proved to be underpowered. By the end of the year, A. E. G. had introduced the G. II (powered by two 150 hp Benz inline engines and capable of carrying up to 440 lbs of bombs) and the G. III (powered by two 220 hp Mercedes D. IV inline engines and capable of carrying up to 660 lbs of bombs). Neither was produced in significant numbers; however, in late 1916 A. E. G. introduced the G. IV, which resembled the earlier versions, but was larger, better powered, and produced in greater numbers. With a wingspan of 60 ft 4.5 in., a length of 31 ft 10 in., and a loaded weight of 7,986 lbs, the G. IV was a sturdy bomber, utilizing steel-tube framing with a plywood nose section and fabric covering elsewhere. It was powered by two 260 hp Mercedes D. IVa inline motors, which produced a maximum speed of 103 mph and a service ceiling of 4,500 m (14,764 ft), provided an endurance of 4 hours 30 minutes, and carried a bomb load of up to 880 lbs. It was protected by two ring-mounted Parabellum machine guns-one in the forward cockpit and one in the rear cockpit. Because of its rather limited bomb load, the G. IV was used primarily for tactical bombing in support of ground troops. The G. IV most likely comprised more than 75 percent of the 542 total G-types built by A. E. G. Unlike other G-types produced by other manufacturers, all the A. E. G. G-types utilized a tractor-engine configuration instead of a pusher configuration.
Another early bomber that would lead to more successful versions was the Friedrichshafen G. II biplane, which entered service in limited numbers in 1916. Powered by two 200 hp Benz Bz. IV inline motors, which were configured as pushers, the G. II could carry a 1,000 lb-bomb load. In early 1917 Freidrichshafen introduced the G. III, which along with the Gotha G. IV and G. V, would serve as the primary German bombers during the last 2 years of the war. The G. III had a wingspan of 77 ft 9.25 in., a length of 42 ft, and a loaded weight of 8,646 lbs. Its wings consisted of a center section that was built around steel-tube spars and detachable outer sections that were constructed from spruce spars and braced with cables and steel tubes. This enabled it to be shipped easily by rail and reassembled. Powered by two 260 hp Mercedes D. IV inline engines, which were configured as pushers, the G. III could reach a maximum speed of 87 mph, climb to a service ceiling of 4,500 m (14,764 ft), and had an endurance of up to 5 hours. Well defended with two or three Parabellum machine guns and capable of carrying a bomb load of up to 3,300 lbs, the Friedrichshafen G. III was widely used on the Western Front. A total of 338 G. III and G. IIIa types (the later had a biplane tail unit for added stability) were produced in addition to less than 50 of the earlier G. II versions.
By far the most famous German bombers of the war were the Gotha G. IV and G. V biplanes, which carried out highly successful raids on London in the summer of 1917. They were derived from the earlier Gotha G. II and G. III, which were designed by Hans Burkhard and introduced in 1916. The former proved to be underpowered with its twin 220 hp Benz inline motors, limiting production to just ten aircraft. The latter, however, were powered by two 260 hp Mercedes inline engines and could carry a bomb load of approximately 1,100 lbs. The G. III was also the first bomber that attempted to provide the tail gunner with the ability to fire downward as well as laterally and upward. Replaced on the Western Front fairly quickly by the much-improved G. IV, the G. III was transferred to the Balkans after Romania entered the war against Germany and Austria-Hungary.
The G. IV was introduced in late 1916 and formed the nucleus of Heavy Bomber Squadron No. 3, which by war’s end was to drop more than 186,000 lbs of bombs on London in a series of raids that began with a daylight raid on 25 May 1917. With a wingspan of 77 ft 9.25 in., a length of 38 ft 11 in., and a loaded weight of 7,997 lbs, the G. IV was capable of carrying between 660 and 1,100 lbs of bombs, depending on the mission and the amount of fuel carried on board. In order to have maximum range for the attacks on London, for example, the G. IV carried just 660 lbs of bombs. One of the chief reasons for its success was that its twin 260 hp Mercedes D. IVa inline motors (configured in a pusher arrangement) enabled it to reach a maximum speed of 87 mph and to operate from a service ceiling of 6,500 m (21,325 ft)-a height that was beyond the capabilities of the home defense aircraft used by the British. As a result of the raids, the British were forced to divert top-of-the-line fighters to home defense, forcing the Gothas to switch to nighttime raids. The G. V was a heavier version that had a better center of gravity and featured an improved tail gunner firing arrangement. All versions of the Gothas had a three-man crew. Although precise production figures are not available, it is estimated that 230 G. IVs entered service in 1917. Total production probably exceeded 400, of which forty airframes produced by L. V. G. were supplied to Austria-Hungary and equipped by Oeffag with 230 hp Hiero inline engines.
At the same time that Germany began development of G-type bombers, a number of German manufactures-A. E. G., Deutsche Flugzeugwerke, Siemens-Schuckert-Werke, and Zeppelin Werke Staaken-attempted to develop huge R-type bombers. Although several difficulties had to be overcome to achieve a successful design, the most important were developing engines powerful enough to provide enough lift for takeoff and climbing, and an undercarriage system that could withstand the impact of landing such heavy aircraft. After the first prototypes appeared in late 1915, a process of trial and error eventually led to the production of R-types by Siemens-Schuckert and Zeppelin Staaken.
A total of seven production aircraft (the R. I through R. VII) were constructed by Siemens-Schuckert. All of them were powered by three engines that were housed within the front fuselage and used a chain and gear system to operate two tractor propellers that were installed on each side of the fuselage within the first bay opening between the upper and lower wings. The R. I had a wingspan of 91 ft 10 in., a length of 57 ft 5 in., and was powered by three 150 hp Benz Bz. III inline engines. The remaining Siemens-Schuckerts had wingspans in excess of 100 ft with the R. VII reaching 126 ft 1.5 in. Powered by three 260 hp Mercedes D. IVa inline motors, the R. VII was capable of a maximum speed of 81 mph, could climb to a service ceiling of 3,500 m (11,4843 ft), had an endurance of 7 hours, and could carry a bomb load of approximately 3,000 lbs. It was protected by up to three machine guns. Although the first three were used strictly for training, the last four saw service on the Russian Front in 1916 and 1917. Siemens-Schuckert was in the final stages of developing a massive R. VIII bomber that had a wingspan of 157 ft 6 in. and was to be powered by six 300 hp Mercedes inline engines, but the war ended before they were completed.
After achieving a successful flight with its R-prototype in April 1915, Zeppelin Staaken experimented with a variety of engines and configurations before finally beginning production of the R. VI, which entered service in June 1917. With a wingspan of 138 ft 5 in., a length of 72 ft 6.25 in., and a loaded weight of 26,066 lbs, the R. VI was the largest aircraft to see service in the war. Its undercarriage consisted of three chassis and a total of eighteen wheels. It was powered by either four 245 hp Maybach Mb. IV inline motors or four 260 hp Mercedes D. IVa inline motors, which were placed back to back in a tractor-pusher configuration. The R. VI had a maximum speed of 84 mph and a service ceiling of 4,320 m (14,173 ft). Its endurance varied from 7 to 10 hours depending upon the amount of fuel carried, which also resulted in a bomb load that varied from 1,650 to 4,400 lbs. It was also the first bomber to carry the huge 2,200-lb (1,000-kg) bomb, the largest used in the war. The R. VI was protected by four Parabellum machine guns. Noted for its rugged construction, which combined a wooden frame fuselage and steel-tube bracing and struts, the R. VI was used extensively on the Western Front and carried out numerous raids (some solo and others in conjunction with Gotha G. IV and G. V bombers) against Britain. In contrast to the Gothas, not a single R. VI was lost from enemy fire. A total of eighteen R. VI bombers were constructed. Of these, just one was built by Zeppelin Staaken; the other seventeen were licensed built by Albatros, Aviatik, and Schütte Lanz.