Aircraft, Bomber

The first bomber developed by the United States, the Martin MB-1, first flown in August 1918, was developed too late for use in World War I. In the 1920s the United States had only a few British DH-4 and Martin NBS-1 bombers, which the celebrated general William (Billy) Mitchell used to sink retired battleships to prove his theory that a separate air force could successfully defend the U.S. coastline. The twin-engine, 107 mph Key stone biplane was standard until 1932. The Boeing Y1B-9 twin-engine all-metal 188 mph monoplane replaced the Key stone but was eclipsed by the Martin B-10, which, at 210 mph, was faster than any other American pursuit plane. Its replacements were the Douglas twin-engine 218 mph B-18 and the Boeing four-engine B-17.

World War II was fought with bombers developed during the late 1930s and early 1940s. They were designed for strategic bombardment or for tactical and supplemental strategic tasks. The main strategic bombers were the Boeing B-17 Flying Fortress and the Consolidated twin-tailed B-24 Liberator. Both were used in Europe, but the B-24's greater range made it more valuable in the Pacific arena. The B-17F and the B-17G, armed with twelve .50 caliber guns, carried 4,000 pounds of bombs over 2,000 miles at 300 mph; the B-24H and the B-24J, similarly armed, carried a 2,500-pound payload about 1,925 miles at 300 mph. The Boeing B-29 Super-fortress, the war's largest bomber, carried twelve .50 caliber guns. Both the B-29A and the B-29B carried 20,000 pounds of bombs and had a range of 5,000 miles.

Medium and attack bombers carried out tactical and supplemental strategic tasks. The medium bombers included the North American B-25 Mitchell, used in Lieutenant Colonel Jimmy Doolittle's famous Tokyo Raid in 1942, and the Martin B-26 Marauder. Both were heavily armed, twin-engine, midwing planes capable of 285 mph flight speeds, with a range of 1,100 miles. Quick and highly maneuverable, attack bombers operated at low altitudes. The Douglas A-26 Invader (1944) was the war's most advanced medium—a 360 mph twin-engine mid-wing carrying eighteen .50 caliber guns, 6,000 pounds of bombs, and fourteen rockets and ranging over 1,000 miles.

The first intercontinental bomber, the Consolidated-Vultee B-36 (1946), attained a maximum speed of 383 mph and carried 10,000 pounds of bombs 7,500 miles. Fully jet powered bombers were developed late because of the jet engine's high fuel consumption. The first was the North American B-45 Tornado (1948), powered by four jets, with a maximum speed of 579 mph, a 10,000-pound payload, and a 1,910-mile range. The second fully jet powered bomber, the Boeing B-47 Stratojet, came armed with twin radar-aimed .50 caliber tailguns. The B-47 replaced the B-29 and the B-50 as a medium bomber until it was retired during the 1960s.

In 1954 the Boeing B-52 Stratofortress began replacing the B-36 as the mainstay of the Strategic Air Command. Powered by eight jets, the B-52G attained a maximum speed of 650 mph and carried 65,000 pounds of bombs. Refitted for low-altitude flight, the B-52 served remarkably into the twenty-first century. General Dynamics's B-58 Hustler served the Strategic Air Command through 1970. Powered by four jets, its maximum speed was 1,324 mph with a 1,200-mile combat radius. It carried "mission pods" under the fuselage, or four nuclear weapons underwing, as it had no internal bomb bay.

The U.S. Air Force's mid-1970s bomber force included the B-52G, the B-52H, the B-56G, and a few General Dynamics FB-111A bombers. Derived from the F-111 fighter-bomber, the FB-111A carries 37,000 pounds externally and internally at subsonic speeds; once the ordnance is dropped, the maximum speed is Mach 2.2. The FB-111A remained operational until the development of the B-1 class of bomber in the 1980s. Intended as a successor to the B-52 Stratofortress, Rockwell International's B-1 was a variable-wing strategic bomber that could fly low to penetrate radar defenses. The prototype B-1A, which first flew in 1974, could reach twice the speed of sound at high altitudes while carrying nuclear bombs to their targets.

The development of stealth technology removed the only glaring weakness of the bomber as a tool of mass destruction: its vulnerability to radar detection. The B-1B, airborne by 1984, incorporated some stealth features, including contoured exteriors built of radar-absorbing materials. Despite the prohibitive cost, research and development into stealth planes—aircraft that would be invisible to enemy radar—culminated in the Northrop Grumman B-2 advanced technology bomber, first flown in 1989. Like the single-seat fighter Lockheed F-117A, which debuted in 1981, the B-2 uses a pyramid-shaped fuselage and swept wings made of carbon-fiber composites and high-strength plastics to reduce its radar signature. Engine intakes and exhausts are set low to the surface to avoid leaving a heat trace. Although the B-2 is slow, hard to maneuver, and can carry only limited munitions, it proved devastatingly effective during NATO's extended bombing campaign against the Serbian regime in Kosovo, Yugoslavia, in 1999 and in Operation Enduring Freedom in Afghanistan in 2001 and 2002.

Bibliography

Craven, Wesley F., and James L. Cate, eds. The Army Air Forces in World War II. Volume 6: Men and Planes. Washington, D.C.: Office of Air Force History, 1983.

Gunston, Bill. American Warplanes: A Full-Color Technical Directory of 200 of the Most Important Combat Aircraft to Serve the United States. New York: Crescent Books, 1986.

Wagner, Ray. American Combat Planes. Garden City, N.Y.: Doubleday, 1981.

—Warner Stark/C. W.