The origins of the Liberator stretch back to the earlylmid-1930s, an era in which projects such as the Boeing XB-15 and Douglas XB-19, and development of the B-17, brought a far wider knowledge and appreciation of the 'big bomber'. The Liberator represents the next generation, its evolution spurred by the tense political situation in Europe and the growing threat of Japanese militancy. In January 1939 the US Army Air Corps invited Consolidated to prepare a design study for a heavy bomber with performance superior to that of the B-l7.

Consolidated wasted little time in submitting a design proposal, identifying it as the Consolidated Model 32 and, as long range was paramount, it was designed round the Davis wing, first introduced on the company's Model 31 flying-boat design, of which a prototype was then nearing completion. In reaching a decision togo ahead with prototype construction of the Model 32, the US Army almost matched the speed set by Consolidated, and in awarding the contract on 30 March 1939 they maintained the tempo, insisting that construction of the prototype, designated XS-24, must be completed by the end of the year. This was achieved by the company, with the first flight being made on 29 December 1939.

In size the XB-24 was marginally smaller than the Fortress except in span; in terms of wlng.area that of the XB-24 was approximately 26 per cent less, emphasizing the high aspect ratio of the Davis wing, To ensure maximum capacity within the fuselage structure, the wing was high-mounted in shoulder wing configuration, and to provide good low-speed handling characteristics and an acceptable landing speed, wide-span Fowler-type trailing-edge flaps were fitted. Construction of the fuselage was conventional, but deep in section to allow for installation of a bomb bay which could accommodate up to 3629 kg (8,000 lb) of bombs stowed vertically. The bay was divided into two sections by the fuselage keel beam, this being utilized to provide a catwalk for crew transition between the fore and aft sections of the fuselage.

The most unusual feature of the bomb-bay was the provision of unique 'roller shutter' doors which retracted within the fuselage when opened for attack, causing less drag than conventional bomb-bay doors. The tail unit, with its easily recognizable oval-shaped endplate fins and rudders, was generally similar to that developed for the Model 31 flying boat. Retractable tricycle landing gear and four wing-mounted 895-kW (1,200hp) Pratt & Whitney R-1830-33 Twin Wasp engines completed the configuration.

Even before the prototype had flown, Consolidated had begun to receive orders for its new bomber, These included seven of the service test Y~24 and 36 of the initial production S-24A models for the USAAC, and 120 aircraft 'off the drawing board' for a French purchasing mission. Early flight tests proved successful, but to meet the USAAC specification some development was necessary to achieve higher speed; however, there was no doubt that the XB-24 was able to demonstrate excellent long-range capability. Furthermore, the large-volume fuselage lent itself to adaptation to fulfil other roles and it was this versatility combined with long range that was the key to success for the B-24.

The XB-24 was followed during 1940 by the seven YB-24s for service trials, and these differed from the prototype by the provision of pneumatic dc-icing boots for the leading-edges of wings, tailplane and fins. By the time that the first production aircraft began to come off the line at San Diego, France had already capitulated, and the aircraft of the French order were completed to British requirements, as specified in an order for 164 which had been placed soon after that of 120 for France: the French order was later transferred to Britain.

Army Air Force, Bolling Field USA, October 1941 An example of neutrality markings is shown this transport Liberator, built against a British order and requisitioned by the USAAF. A pointed-out RAF roundel can be discerned on the fuselage, while on the top of the cabin is another US flag marking. Aircraft of this type shuttled about the world just before Pearl Harbor.

 

B-24 D, 93rd BOMB GROUP, USAAF, HARDWICK, UK, 1943 Standard Olive Drab and Neutral Gray finish with the short-lived red-outline to the national insignia, individual aircraft letter (N) on the lower fin and group symbol above, overlapping on to the rudder. This was the oldest B-24 Group in the 8th AF and flew more missions than any other unit. After the war the unit flew the B-29, B-47 and, more recently, the B-52

 

B-24D-90 491st BOMB GROUP, USAAF, NORTH PICKENHAM, UK, AUTUMN1944 To assist the huge 8th AF bomber formations to form up in the right order and position, each group had a brightly-painted lead ship on which the rest of the unit would format. This done, the lead ship would head for home, leaving the group to the mission. Little Gramper is typical and, like most lead ships, was a war-weary aircraft.

 

PB4Y-1, PATROL BOMEBER SQUADRON VPB-110, US NAVY, DEVON, UK, WINTER 1944 Anti U-boat patrols over the Atlantic was one of the tasks of these aircraft based in the west of England. Colors were non-specular Sea Blue on the top surfaces, intermediate blue on the vertical surfaces with Insignia white undersides.

The USME began to receive its first B-24As and these, duplicating the role of the LB-3OAs in the UK were allocated first to equip the Air Corps Ferrying Command, operating similar services across the North Atlantic as those of RAF Ferry Command. The first true operational bomber version, however, was the Liberator Mk II (Consolidated LU-30L for which there was no USMF equivalent. It differed from the Liberator Mk I primarily by having the fuselage nose extended 0.79 m (2 ft 7 ml by the insertion of a 'plug', by accommodating a maximum crew of l0 and by the installation of Boulton Paul power-operated turrets, each housing four7.7-mm (0.303-in) machine guns in mid-upper and rear fuselage positions. The RAF received 139 of this version and when Nos 159 and 160 Squadrons began operations with their Liberators in the Middle East in June 1942, they were the first to deploy these aircraft in a bombing role. One aircraft of this batch (At504) became the personal transport of Britain's prime minister, Winston Churchill, operated under the name Commando.

Meanwhile, the XB-24 prototype had been modified to a new XR-24B standard, introducing self-sealing fuel tanks and armour, but the most significant improvement was the installation of turbo charged R-1830-41 engines. This resulted in the second of the Liberator's easily identifiable features, oval-shaped nacelles, entailed by the relocation of the oil coolers in the sides of the front cowlings. With the introduction of these features, plus dorsal and tail turrets each with two 12.7-mm 10,5-in) machine-guns to supplement the original hand-held guns in beam and nose positions, nine aircraft were produced for the USAAF with the designation R-24C.

They were followed by the in-24D, the first major production variant and the first to be employed operationally by USMF bomber squadrons. This differed initially by the installation of R-1830-43 engines, but subsequent production batches introduced progressive changes in armament, provision of auxiliary fuel in the outer wings, increases in gross weight and bomb load, and in some late production examples external bomb racks below the inner wing for the carriage of two 1814-kg (4,000-Ib) bombs. In RAF service the B-24D was designated Uberstor Mk Ill: Uberator Mk EllA identified similar aircraft supplied under Lend Lease with US armament and equipment. Most Liberator Mk III/IIIA's served with Coastal Command, eventually equipping 12 squadrons. A total of 122 was modified extensively in the UK, receiving ASV radar equipment including chin and retractable ventral radomes, a Leigh Light for the illumination of targets at night especially surfaced U-boats), increased fuel capacity, but reduced armament, armour and weapon load. These were designated Liberator GA. Mk V.

Some were provided with small stub wings on the forward fuselage to carry eight rocket projectiles. The USMF also operated A-24Ds in an anti-submarine role, and in 1942 the US Navy began to receive small numbers of this version under the designation PB4Y-1. However, at the end of August 1943 the USAAF disbanded its Anti-Submarine Command, handing over its aircraft to the US Navy in exchange for an equivalent number of aircraft of bomber configuration to be produced against outstanding US Navy orders. These ex-USMF B-24s, which were equipped with ASV radar, were also designated PB4y-1 by the US Navy. This service later acquired the specially-developed PB4Y-2 privateer, which introduced a new tail unit with a single tall fin and rudder, a lengthened forward fuselage, changes in the armament to provide a maximum of 12 12.7-mm (0.5-in) machine-guns, and the installation of Pratt & Whitney R-1830-94 Twin Wasp engines without turbochargers.

The deployment of USAAF B-24Ds in the Middle East began in June1942, one of the first operations being launched by 13 aircraft against the Romanian oilfields at Ploesti on 11/12 June 1942. All 13 aircraft completed what the USAAF described as 'an unsuccessful attack. its only success being to alert the defenses of their vulnerability. Consequently, it was a very different story on 1 August 1943 when units of the 8th and 9thAirForces sent 177 B-24sagainstthe same target. Although rather more successful in terms of damage caused, of the force which set out from Benghazi 55 Liberators were lost, 53 damaged, and 440 crew killed or posted missing.

By that time, of course. B-24s were being built at an enormous rate, by Consolidated at San Diego and Fort Worth, Douglas at Tulsa, and Ford with a specially built new plant at Willow Run. In mid-1942 the first transport variants began to appear, with nose and tail gun positions deleted, a large cargo door installed in the port side of the fuselage, and accommodation provided for passengers or cargo. The USAAF acquired 276 under the designation C-87 with accommodation for a crew of five and 20 passengers; 24 similar aircraft, but provided with side windows, served with RAF Transport Command as the Uberetor C. Mk VII and examples flown by the US Navy were designated RY-2, Similar aircraft, but with R-1830-45 engines and equipped as VIP transports, were identified as NY-i and C-87A by the US Navy and USAAF respectively.

The US Navy also acquired 46 of a transport variant designated RY-3, and 27 similar aircraft were delivered in early 1945 for use by RAF Transport Command. One special logistics version was the C-lOB fuel tanker, used to ferry 10977 liters (2,900 US gal) of aviation fuel per load over the Himalayan 'hump', to supply Boeing B-29 Super fortresses operating from forward bases in China, An XF-7 prototype of a reconnaissance version was also produced in 1943, with bomb racks removed and extra fuel tanks provided in the forward section of the bomb bay. This retained the normal defensive armament, and could also accommodate up to 11 cameras. F-7s were used extensively in the Pacific theatre, and later versions included the F-7A and F-79 with differing camera installations.

The first production aircraft to come from the Ford plant at Willow Run was the B-24E, generally similar to the B-24D except for different propellers and minor detail changes, and this version was built also by Consolidated and Douglas, some having R-1830-65 engines. There followed the 9-24G. all but the first 25 of which introduced an upper nose turret and had the fuselage nose lengthened by 0.25 m (10 ml, These came from a new production line operated by North American Aviation at Dallas, Texas. Similar aircraft produced by Consolidated at Fort Worth, by Douglas and by Ford were designated 9-24H.

The major production variant was the B-24.J 16,678 built, which came from all five production lines, and which differed from the B-24H in only minor details. B-24H and B-24Js supplied to the RAF under Lend-Lease were designated Liberator GR. Mk V~ when equipped for ASW/maritime reconnaissance by Coastal Command, or Uberator B. Mk VI when used as a heavy bomber in the Middle East and Far East. Those used by the US Navy were identified as the PB4Y-1.

The final production versions were the 9-241, similar to the B-24D with the tail turret replaced by two manually controlled 12.7-mm (0.5-in) machine-guns, of which Consolidated San Diego built 417 and Ford 1,250; and the B-24M which differed from the B-24J in having a different tail turret. Convair built 916 of this latter version at San Diego and Ford another 1,677. Odd variants included a single B-24D provided with an experimental thermal de-icing system as the X9-24F; the XU-24K prototype of the single vertical tail version which it was intended should be produced in large numbers as the B-24N, although only the XB-24N prototype and seven YB-24N service test aircraft were built before production ended on 31 March 1945; the single experimental XB-41 bomber escort, armed with 14 12.7-mm (0.5-in) machine-guns and converted for flight engineer training under the designation AT-22 (later TB-241, Most of the USAAF's Liberators were declared war surplus at the war's end, only a few remaining in service and the very last of these was disposed of in 1953.

From first to last more than 19,000 Liberators had been built. In addition to those supplied to the RAF, USMF and US Navy, others had been operated by units of the Royal Australian Air Force, Royal Canadian Air Force and South African Air Force. Nowhere had they been of greater value than in the Pacific theatre, where their long range and versatility made them true 'maids of all work'.

Variant

ConvaIr Model SO~ this was an attempt to break into the post-war transport market, and took the form of the wings, powerplant and landing gear of the 6-24, the tail unit of the PB4Y-2 and a new fuselage able to carry 45 passengers or 5443 kg (12,000 lb) of freight; the sole prototype was evaluated by the US Navy as the R2Y.

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Specifications

Crew: 7-10 Length: 67 ft 8 in Wingspan: 110 ft 0 in Height: 18 ft 0 in Wing area: 1,048 ft² Empty weight: 36,500 lb Loaded weight: 55,000 lb Max takeoff weight: 65,000 lb Powerplant: 4× Pratt & Whitney R-1830 turbosupercharged radial engines, 1,200 hp each Zero-lift drag coefficient: 0.0406 Drag area: 42.54 ft² Aspect ratio: 11.55 Performance Maximum speed: 290 mph Cruise speed: 215 mph Stall speed: 95 mph Combat radius: 2,100 mi Ferry range: 3,700 mi Service ceiling: 28,000 ft Rate of climb: 1,025 ft/min Wing loading: 52.5 lb/ft² Power/mass: 0.0873 hp/lb Lift-to-drag ratio: 12.9 Armament Guns: 10 × .50 caliber (12.7 mm) M2 Browning machine guns in 4 turrets and two waist positions Bombs: Short range (˜400 mi): 8,000 lb Long range (˜800 mi): 5,000 lb Very long range (˜1,200 mi): 2,700 lb

 

A:The long span wing gave the B-24 excellent range and great performance al high altitude	B:Some late-model B-24s could carry bombs on racks under the inner wing. Antisubmarine versions in RAF service carried rockets.	C:The tricycle undercarriage was another modern feature of the B-24.

 

A:The Bombardier sat in the glazed nose compartment, aiming his bombs with a Norden sight.	B:The deep fuselage was designed so the 4 ton bomb load could be stored vertically. A catwalk gave the crew access to the rear fuselage.	C: The gunner fired a pair of .50 caliber machine guns from a powered turret.