The Consolidated B-24 Liberator was an American four-engine heavy bomber that served with distinction with Allied forces in the Second World War. Not as generally well known as the more famous B-17 Flying Fortress, the B-24 was employed as a heavy bomber, maritime patrol aircraft and a high-capacity transport aircraft.
The Liberator was one of the most versatile heavy aircraft available to the Western allies, and was also the most produced multi-engine platform during the Second World War, with over 18,500 units manufactured before production ceased abruptly in 1945.
At one stage a Liberator was being produced every 55 minutes in US factories during the conflict.
Whilst best known for its contribution to the strategic bombing campaign in Europe, the B-24 also served valiantly over the wide areas of the Pacific Ocean but its major achievement was the role it played in winning the Battle of the Atlantic.
Specially configured Liberators patrolled over the Mid-Atlantic Gap in all weather conditions, forcing German U-boats to spend much of their time submerged, constraining travel times for these vessels and helping reduce attacks on Allied convoys.
In this vital campaign, the B-24 can well lay claim to being a war-winning weapon, as a victory in the Battle of the Atlantic was vital to Allied success in the European Theatre of Operations.
Design and Development
Consolidated was originally approached by the USAAC to manufacture the B-17 under licence in 1938, but after a tour of the Boeing plant in Seattle, it was decided that the company would submit a design for a heavy bomber with higher performance and bomb-carrying capacity than the Flying Fortress.
Read More: Boeing B-17 – The Flying Fortress
In January 1939 the USAAC invited Consolidated to submit a proposal for a heavy bomber that outperformed the B-17 in speed, range and bomb-carrying capacity.
Barely two months into the design process Consolidated offered a proposal to the USAAC which was known within the company as the Model 32, and a contract was awarded for a prototype, with the proviso that these aircraft be ready for test flights before the end of the year.
This XB-24 prototype achieved most of the contract specifications, and six pre-production models were ordered for further development work.
The Model 32 was an innovative design for its time, with a high-mounted ‘Davis’ wing and also featured tricycle landing gear, which was a first for American bomber design. The ‘Davis’ wing endowed the B-24 with a high speed and greater load-carrying capacity than the B-17, along with the ability to carry more fuel but this design also had several drawbacks.
This wing design ensured that the low-speed handling characteristics of the Liberator could be very dangerous at times, especially when the aircraft was fully loaded.
It also had the unfortunate effect of making the B-24 a deadly aircraft when attempting to ditch in water, as the position of the wing meant the B-24 often broke apart when attempting to ditch at sea.
The B-24A/LB-30B was the first model ordered by the US, and orders were also submitted by the French air force and the RAF. In RAF service the B-24 were equipped with British gun turrets mounting .303 calibre machine guns, but this variant was found to be inadequate for bombing operations, and the RAF and the USAAC employed them in the unarmed, high-speed transport role instead.
France had surrendered before Consolidated could fill their order, and the 120 aircraft of this contract were diverted to British use instead.
A further modest order for the RAF saw the introduction of the Liberator II/LB-30A model supplied to Britain. The first version to be used as a heavy bomber, most aircraft were assigned to Coastal Command, with some aircraft going to Bomber Command and the British Overseas Airways Corporation (BOAC).
The US equivalent to this model was the B-24C, which was also ordered in small numbers by the USAAC.
The B-24D was the first mass-produced variant, offered improvements in armament and was fitted with improved engines. The very similar B-24E followed on from this, but all of the production runs of this model were retained in the US for use as training aircraft.
The B-24G was the designation for ‘D’ models manufactured by North American Aviation, but this model was only made in small numbers.
The B-24H incorporated many improvements mandated by the operational use of the Liberator in Europe, with the major modification being the installation of a powered ball turret on the nose of the aircraft.
This was done to reduce the vulnerability of the B-24 to head-on attacks by Luftwaffe fighters, similar to the installation of a chin turret to the B-17G. The follow-up B-24J was ordered due to the shortage of Emerson turrets, and new Consolidated A-6 turrets were fitted instead, with the added benefit that this new turret could be used in both the nose and tail gunner positions, reducing manufacturing costs significantly.
Operational complaints about the weight of the Liberator saw the adoption of the B-24L, with a re-design of some gunner stations in an effort to lighten the aircraft. This was mainly successful, but this variant was ordered in relatively small numbers compared to other models.
The last major variant of the Liberator as a heavy bomber was the B-24M, which introduced increased weight-saving measures, more defensive armament modifications and re-designed glass panels on the flight deck to allow greater visibility for the pilots.
Many of these models never made it into combat and were flown direct from the manufacturing plants to scrapping yards after the end of the war in 1945.
Two major sub-variants were manufactured as maritime patrol aircraft for use by the USN and the RAF in the Atlantic Ocean. The first of these was the PB4Y-1, adapted from D, J, L and M models for anti-submarine and maritime patrol duties.
This model was fitted with belly gun packs, a new nose turret and provision for the employment of depth charges and other specialised ASW equipment. Consolidated also introduced the PB4Y-2 Privateer, a heavily modified design with a single large tail fin in place of the twin tails on most other variants, as well as a lengthened fuselage and many other modifications and improvements.
The Liberator had some impressive dimensions and statistics, as befitting its status as a large, heavy four-engine bomber.
The B-24 had a height of 17 feet 7 inches (5.3 metres), a length of 67 feet (20 metres) and a wingspan of 110 feet (34 metres). Empty, the B-24 weighed in at 36,500 lbs (16,500 kg) and had a fully loaded total of 55,000 lbs (25,000 kg). The MTOW of the Liberator was 65,000 lbs (30,000 kg).
The Liberator was powered by four Pratt & Whitney R-1830 Twin Wasp radial air-cooled engines, which were turbo-supercharged and produced 1,200hp each. Fuel capacity was normally 1,950 Imperial gallons (8,800 litres), but when fitted with fuel tanks in the bomb bays could carry 3,000 Imperial gallons (16,800 litres) and the engines were fitted with Hamilton 3-bladed propellers of 11 feet (3.5 metres) in diameter.
The crew of a B-24 consisted of 10-11 personnel: Pilot, co-pilot, navigator, bombardier, radio operator, nose gunner, tail gunner, top turret gunner, ball turret gunner and two waist gunners. Earlier models lacking the nose turret often had the navigator and bombardier manning flexible gun positions in the glazed nose of these aircraft.
The B-24 boasted the following performance figures: a maximum speed of 297 mph (478 km/h), a cruise speed of 215 mph (346 km/h), but the aircraft had a very high (and dangerous) stall speed of 95 mph (155 km/h).
The normal range on bombing missions was 1,340 miles (2,480 km) but when fitted with extra tankage for ferry missions could exceed 3,700 miles (6,000 km) which explains the success of the Liberator as a long-range transport aircraft. The B-24 had a service ceiling of 28,000 feet (8,500 metres).
The Liberator was equipped with 10 M-2 Browning .50 calibre machine guns for defensive firepower, fitted into four powered turrets and two waist gun positions. The B-24 could carry up to 8,000 lbs (3,400 kg) of bombs, which was twice the capacity of the B-17, but in practice, lesser loads were carried for extremely long-range missions.
Maritime patrol versions often carried four 20 mm cannons in a belly pack for the surface attack, as well as a Leigh light and other specialised ASW equipment.
Read More: Curtiss XP-55 Ascender – The Flawed Fighter
The Liberator was the bombing workhorse of the Eighth Air Force, participating in the strategic bombing campaign over Europe, along with the B-17. Flight crews often preferred the B-17 for its more robust design, but the Liberator flew faster and at a greater range with a larger bomb load.
It equipped over a third of the squadrons in the 8th, and also fought in Italy and the Mediterranean theatres. The RAF did not use the B-24 as a heavy bomber in Europe but did employ the type in the Pacific War.
In the Pacific War, the USAAF gradually replaced all its B-17 units with Liberators, as the greater range of the B-24 meant that it was better suited to operating in the vast expanses of the Pacific Ocean. The Royal Australian Air Force also operated the B-24 in significant numbers and was mainly employed on bombing raids in the South West Pacific Area (SWPA).
The RAF and Luftwaffe had switched to night bombing raids early on during the war, but the USAAF persisted in daylight attacks over occupied Europe, often at a heavy cost. A good example of this was the second Ploiesti raid in August 1943.
177 Liberators attacked the oil refineries at this location and destroyed all targets, but at a very heavy cost. A navigational error led to the attack becoming somewhat disorganised, and the alerted German defenders reacted vigorously against the bombing raid, with 54 of the attacking aircraft shot down.
The ‘Davis’ wing of the B-24 was more susceptible to battle damage than that of the Flying Fortress, and the Liberator was not as stoutly constructed as the B-17 and was not as able to absorb combat abuse as well as the earlier aircraft.
The USAAF employed the B-24 extensively in the Pacific Theatre, as the excellent range of the Liberator meant that it was employed on some very long-range bombing missions, and the maritime patrol versions operated over the vast vista of the Pacific Ocean, attacking Japanese submarines and merchant shipping wherever they were encountered.
It was during the Battle of the Atlantic that the B-24 operated as a game-changing weapon. The size of the Atlantic battle area meant that air power could not cover the Mid-Atlantic Gap during the early part of this vital battle, and U-boats were able to operate with impunity in this area, assured of immunity from aerial attack.
However, the Allies quickly employed early models of the Liberator as long-range patrol aircraft, modified to attack U-boats and German maritime patrol aircraft like the Focke-Wulf C200 Condor.
These early modified Liberators, as well as the specialised PB4Y-1 patrol aircraft quickly came to dominate the Mid-Atlantic Gap and forced the U-boats to spend the majority of their time submerged, with consequent reductions in travel speed resulting in greatly reduced attacks on Allied supply convoys.
The Liberator was widely recognised as being one of the major contributors to victory in this vital battle, and as success in this battle led to further Allied victories. Elsewhere it can be said that the B-24 was a war-winning weapon, with results out of proportion to the numbers of aircraft actually employed in the vital role of ASW work.
A small number of Liberators were modified to act as formation leaders for bombing raids over Europe, with distinctive colour schemes to allow other aircraft to easily visually identify them, and also had extra radios fitted to allow better coordination of bombing raids.
Read More: Edgley EA-7 Optica – The Flying Eye
Several squadrons worth of aircraft were also equipped as electronic warfare aircraft, fitted with electronic equipment to jam German radio signals and disrupt German radar coverage in an attempt to support daylight bombing raids over Europe.
While not as well-known as the more famous B-17, the Liberator served with distinction during the Second World War, primarily as a heavy bomber but also more crucially as a maritime patrol aircraft of very long-range endurance.
Playing a war-winning role in the Atlantic Theatre, and a robust contributor to the strategic bombing campaign over Europe, the B-24 had a distinguished combat record, but at the cessation of hostilities in 1945 the Liberator was swiftly replaced in Allied inventories.
The widespread adoption of the advanced B-29 Superfortress meant that many earlier designs like the Liberator quickly became obsolescent, and were scrapped in huge numbers at the war’s end. While some B-24s were employed as fast transport aircraft after the war (winning further kudos during the Berlin Airlift 1948-9) the platform had practically disappeared from Western air forces by the war’s end but continued to serve in smaller air forces for many years.
The last Liberator in military service retired from the Indian Air Force in 1968.
- Crew: 11 (pilot, co-pilot, navigator, bombardier, radio operator, nose turret, top turret, 2 waist gunners, ball turret, tail gunner)
- Length: 67 ft 2 in (20.47 m)
- Wingspan: 110 ft (34 m)
- Height: 17 ft 7.5 in (5.372 m)
- Empty weight: 36,500 lb (16,556 kg)
- Max takeoff weight: 65,000 lb (29,484 kg)
- Powerplant: 4 × Pratt & Whitney R-1830-35 Twin Wasp, R-1830-41 or R-1830-65 14-cylinder two-row air-cooled turbosupercharged radial piston engines, 1,200 hp (890 kW) each
- Maximum speed: 297 mph (478 km/h, 258 kn) at 25,000 ft (7,600 m)
- Range: 1,540 mi (2,480 km, 1,340 nmi) at 237 mph (206 kn; 381 km/h) and 25,000 ft (7,600 m) with normal fuel and maximum internal bomb load
- Service ceiling: 28,000 ft (8,500 m)
- Rate of climb: 1,025 ft/min (5.21 m/s)