B-24, also called Liberator, long-range heavy bomber used during World War II by the U.S. and British air forces. It was designed by the Consolidated Aircraft Company (later Consolidated-Vultee) in response to a January 1939 U.S. Army Air Force (USAAF) requirement for a four-engined heavy bomber. The B-24 was powered by four air-cooled radial engines and had a spacious boxlike fuselage slung beneath a high wing, a tricycle landing gear, and a twin tail assembly. The first prototype flew in December 1939, and, by the spring of 1941, B-24s were being delivered to the British Royal Air Force on a cash-and-carry basis. Early models of the B-24 lacked self-sealing fuel tanks and the heavy defensive armament deemed essential by the USAAF for a strategic daylight bomber; therefore, they were used primarily to transport high-priority cargo and VIPs (British Prime Minister Winston Churchill used one as his personal transport) and for antisubmarine patrols. Antisubmarine B-24s, some fitted with radar, played a major role in the Battle of the Atlantic and were instrumental in closing the mid-Atlantic “gap” where German U-boats had previously operated with impunity.

A B-24 Liberator of the U.S. Army Air Forces releasing its bombs on the rail yards at Muhldorf, Ger., on March 19, 1945. U.S. Air Force Photo

The first version of the Liberator considered battle-worthy by the USAAF was the B-24D, with turbo-supercharged engines and powered turrets mounting twin 0.50-inch (12.7-mm) machine guns on the upper fuselage and tail. Subsequent models acquired additional armament, and the B-24H and J models, which began entering service in early 1944, added powered nose and belly turrets and sported a total of 10 0.50-inch machine guns. Like the B-17 Flying Fortress, the B-24 was flown in defensive “box” formations, though the boxes could not be stacked as closely because the Liberator was appreciably more difficult to fly in formation. Also like the B-17, it carried the Norden bombsight. A normal bomb load for high-altitude missions was 5,000 pounds (2,250 kg), though it could accommodate an additional 3,000 pounds (1,350 kg) in the bomb bay and 8,000 pounds (3,600 kg) on external racks beneath the wings for short-range missions. On high-altitude missions the Liberator had a maximum range of nearly 1,600 miles (2,600 km)—40 percent greater than that of its partner the B-17—but it had a service ceiling of only 28,000 feet (8,500 metres), some 7,000 feet (2,100 metres) below that of the B-17. As a result, the B-24 was more exposed to German antiaircraft artillery; this and the B-24’s greater vulnerability to battle damage (the leaky fuel system was a particular problem) made the B-17 the preferred strategic bomber in the European theatre. Still, B-24s equipped one entire bomb division of the 8th Air Force and, because of their greater range, were assigned some of the most difficult targets in the latter stages of the war in Europe.

The B-24 came into its own in the Pacific, where long range was at a premium and Japanese defenses were comparatively sparse; there the Liberator effectively replaced the B-17 from 1942. The B-24 also played a major role in the Mediterranean and China-Burma-India theatres, and the U.S. Navy fielded a heavily armed single-tailed variant, the PB4Y, as a patrol bomber toward the end of the war. More than 18,000 B-24s were built between 1940 and 1945, the largest total for any U.S. aircraft—some 10,000 by Consolidated-Vultee and the rest under license by Douglas Aircraft, North American Aviation, and the Ford Motor Company. Of this total, just under 1,700 went to the British. The B-24 was retired from U.S. service almost immediately after the war ended in 1945. A handful of PB4Ys were transferred to the French navy and saw combat in Indochina during 1953–54.