Multi Engine Bombers
The First Big Bombers
Respectable bomb loads, increased fuel supply, and a crew sufficient to operate the airplane and its armament, required much larger machines than the frail scouting types then available. Builders began bomber designs by adding a second or more engines to their aircraft for the additional power needed.
Only Russia had such a plane at the war’s beginning: Igor Sikorsky’s Ilya Mourometz was an improvement on the world’s first four-engine airplane, the Sikorsky Grand flown on April 27, 1913. The 113-foot span Mourometz had four 100-hp engines on the lower wing and an enclosed cabin for the crew. It was ordered into production in 1914, and after the war began, a “squadron of flying ships” was formed. On February 15, 1915, an Ilya Mourometz V carried 600 pounds of bombs over the German lines on its first combat mission.
Germany also formed bombing units in 1915 using the twin-engine G types by AEG and Gotha, and the larger multi-engine R types by Siemens and VGO. Italy began operations with the three-engine Caproni biplanes in 1915.
The general arrangement which became the classic pattern for the next dozen years of bombers was established by the first British Handley-Page O/100 bomber flown on December 18, 1915. While the Handley-Page first went into action in March 1917 with a Royal Navy unit, the improved O/400 version was also ordered for the RAF’s strategic bombing “Independent Force” which began operations in 1918. These twin-engine planes were listed as night bombers, since deep penetrations of hostile areas by these slow biplanes were considered too dangerous unless covered by darkness.
The upper wing spanned 100 feet, overhanging a smaller lower wing; between them was suspended two 350-hp Rolls-Royce engines. A squared fuselage began with a gunner’s cockpit in the bow, followed by side-by-side seats for the pilot and co-pilot. A rear gunner sitting behind the wings had his rearward view limited by a box-like tail of two horizontal and two vertical surfaces. A pair of .30-caliber Lewis guns were mounted at the front and rear cockpits, and a fifth gun aimed downward through a trap door. Eight 250 or 16 112-pound bombs could be carried on eight-hour missions, or a single 1,650-pound bomb could be used.
Although none of these big bombers made any real difference as far as the strategy or outcome of the war was concerned, they brought the war to civilians behind the lines who, in past history, had not feared for their lives. The most severe of these raids was on June 13, 1917, when twenty Gothas attacking London killed 162 and injured 432 persons. A modest piece of homicide, considering World War II, but it was the best the earlier war could offer, and caused many to imagine then that the likelihood of such horrors might cause nations to abstain from any more war.
Bomber production in the United States, however, was delayed by the inability to decide how many should be made, and of what type. The role of fighters had been clear, to destroy enemy aircraft, and the Army also knew what it wanted from its short-range two-seater observation/day bomber types. But how much long-distance bombing would be done, and of what targets? No such doctrine of airpower employment had yet been formulated by American military leaders.
Therefore, the number of bombers programmed was based on an inaccurate guess of production capacity. Production goals fluctuated until the program of July 1918 finally projected a ratio of 3:5:2 for pursuit, observation, and bombardment plane production.
The first true multi-engine bomber seen in the United States was the three-engine Caproni Ca 33 sent from Italy with Italian pilots and flown at Langley Field September 11, 1917. As the largest plane yet seen in America, it attracted much attention flying over Liberty Bond parades to drop patriotic leaflets and advertise the Italian air force.
Although Curtiss had received a contract on September 19, 1917, to build 500 Capronis with Liberty engines, it was canceled November 17 because there were no plans on hand for that aircraft, nor any firm decision as to whether the Caproni or Handley-Page bombers would be used.
While the Caproni project was stalled, in December 1917 the British proposed that parts for Handley-Page bombers be manufactured in America for assembly in England, along with Liberty engines. An agreement was signed on January 26, 1918, by British and American officials, and several manufacturers were lined up to make the parts for 500 aircraft by contracts made from March 12 to April 13, 1918. Standard Aircraft, at Elizabeth, New Jersey, contracted on April 1 to assemble 50 of the bombers for tests and training in America, while the other components were to be packed and shipped to England.