Consolidated B-24 Liberator

The United States Army Air Corps were looking for an aircraft that would be an improvement on the Boeing B-17 Flying Fortress, so in January 1939 they asked Consolidated to produce a design study of a heavy bomber. Known as the Model 32, Consolidated's design featured a Davis wing, and on the 30th March 1939 a contract to build a prototype, which would be known as the XB-24, was awarded. It was required that the prototype should be ready by the end of 1939.

On the 29th December 1939, two days before the end of year deadline, the XB-24 made its maiden flight. Powered by four 1,200-hp Pratt & Whitney R-1830-33 Twin Wasp engines, it featured tricycle landing gear and would eventually house a crew of ten, consisting of pilot, co-pilot, navigator, bombardier, flight engineer/mid-upper turret gunner, wireless operator, two waist gunners, ball turret gunner and rear gunner.

After undergoing flight tests, a few changes to the aircraft were needed to meet the specification set out by the United States Army Air Corps and seven YB-24s were ordered for service testing. In the end, six of these would be supplied to the Royal Air Force under the designation LB-30A, also known as the Liberator Mk I, with the first example flying on the 17th January 1941 and the first arriving in the UK in March 1941. They would be used by Ferry Command to fly back pilots and crew who had delivered aircraft to the UK.

The B-24A, also known as the Liberator Mk I, was next, with a number supplied to the Royal Air Force as LB-30B and nine were produced for the United States Army Air Corps. This was followed by the XB-24B prototype, which was a modified XB-24 and now powered by the 1,200-hp Pratt & Whitney R-1830-41 Twin Wasp engine, other changes included installation of a dorsal turret, tail turret and self-sealing fuel tanks. This would be developed into the B-24C, of which nine were built and delivered to the United States Army Air Force.

None of the previous variants of the B-24 had been used in its intended bomber role, and it would be with the Royal Air Force that the aircraft was first used in this role. Known as the LB-30, and also as the Liberator Mk II, it would equip a number of Coastal Command squadrons.

It was the B-24D, also known as the Liberator Mk III or Liberator Mk V, which became the first variant to be mass produced. Powered by the 1,200-hp Pratt & Whitney R-1830-43 Twin Wasp engine, its top speed was 303 mph, range 2,850 miles with a service ceiling of 28,000 ft. Armament consisted of nine 0.50-in machine-guns and bomb load was 8,000lb. It would be this variant that the United States Army Air Force used for the first time in the aircraft's intended role as a bomber, with deliveries of the type beginning in January 1942.

One of the earliest raids the B-24 undertook for the United States Army Air Force was on the 12th June 1942, when thirteen were sent to Ploesti, Romania to attack the oilfields there. The following year saw 178 B-24s take part in another raid on the oilfields at Ploesti, Romania on the 1st August 1943. Known as operation Tidal Wave, they suffered heavy losses with fifty four aircraft lost, 310 aircrew killed and 186 becoming prisoners of war.

B-24M at the Imperial War Museum, Duxford

The B-24E was the next variant produced and these featured minor changes. It was powered by the 1,200-hp Pratt % Whitney R-1830-65 Twin Wasp engine, giving the aircraft a top speed of 303 mph, a range of 2,850 miles and a service ceiling of 32,000 ft. Armament was ten 0.50-in machine-guns, with a bomb load of 8,000lb

The XB-24F was a modified B-24D used to test thermal de-icers. The next two designations were given to aircraft built by other companies. B-24Gs were built by North American, while B-24Hs were built by other manufacturers. Both were also known as Liberator Mk VIs.

The next variant was the B-24J, also known as the Liberator Mk Vi and Liberator Mk VIII. Powered by the 1,200-hp Pratt & Whitney R-1830-65 Twin Wasp engine, its top speed was 290 mph, range 2,850 miles with a service ceiling of 28,000 ft. Armament consisted of ten 0.50-in machine-guns, bomb load was 8,000lb.

A B-24D fitted with a single tail, as opposed to the usual twin-tail, would provide the basis for the XB-24K. It was found that this new tail improved both the handling and stability of the aircraft. A new variant, known as the B-24N, was to be put into production and fitted with the single tail, however, with the Second World War (1939 – 1945) coming to an end, only eight were built. A single XB-24N prototype and seven YB-24Ns to be used for service tests.

The B-24L was the next variant, it was powered by the 1,200-hp Pratt & Whitney R-1830-65 Twin Wasp engine, giving the aircraft a top speed of 290 mph, a range of 2,850 miles and a service ceiling of 28,000 ft. Armament was ten 0.50-in machine-guns, with a bomb load of 8,000lb.

This was followed by the B-24M. Powered by the 1,200-hp Pratt & Whitney R-1830-65 Twin Wasp engine, its top speed was 290 mph, range 2,850 miles with a service ceiling of 28,000 ft. Armament consisted of ten 0.50-in machine-guns, bomb load was 8,000lb.

The United States Navy also used the type under the designation PB4Y-1, which led to a fully navalised version known as the Consolidated PB4Y-2 Privateer. The B-24 was also used by the Royal Australian Air Force and Royal Canadian Air Force and captured aircraft were used by KG 200, the special operations unit of the Luftwaffe. British Prime Minster Winston Churchill would also use a B-24 named 'Commando' as transport and post-war the type was used in the Berlin Airlift (26th June 1948 - 30th September 1949).

In total, 18,482 aircraft were built.

B-24M at the Imperial War Museum, Duxford