The Consolidated B-24 Liberator is an American heavy bomber, designed by Consolidated Aircraft of San Diego, California.
It was known within the company as the Model 32, and some initial production aircraft were laid down as export models designated as various LB-30s, in the Land Bomber design category.
At its inception, the B-24 was a modern design featuring a highly efficient shoulder-mounted, high aspect ratio Davis wing.
The wing gave the Liberator a high cruise speed, long range and the ability to carry a heavy bomb load.
Early RAF Liberators were the first aircraft to cross the Atlantic Ocean as a matter of routine.
In comparison with its contemporaries, the B-24 was relatively difficult to fly and had poor low-speed performance; it also had a lower ceiling and was less robust than the Boeing B-17 Flying Fortress.
While aircrews tended to prefer the B-17, General Staff favoured the B-24 and procured it in huge numbers for a wide variety of roles.
At approximately 18,500 units, including 8,685 manufactured by Ford Motor Company, it holds records as the world’s most produced bomber, heavy bomber, multi-engine aircraft, and American military aircraft in history.
Variants
U.S. Army Air Forces variants
XB-24
Single prototype ordered by Army Air Corps on 30 March 1939. Powered by four Pratt & Whitney R-1830-33 Twin Wasps rated at 1,200 horsepower (890 kW) for take-off and 1,000 horsepower (750 kW) at 14,500 feet (4,400 m).
Bomb load of eight 1,000 lb (450 kg) bombs, with defensive armament of three 0.5 in (12.7 mm) and four 0.30 in (7.62 mm) machine guns.
First flew 29 December 1939.
Later converted to XB-24B.
YB-24/LB-30A Pre-production prototypes
Six examples were sold to the UK directly as designated LB-30A.
US funds and serial numbers were deferred to the B-24D production.
The seventh (40-702) remained in U.S. Service as the sole YB-24 for service test.
B-24
Ordered on 27 April 1939, less than 30 days after the XB-24 was ordered and before its completion.
A number of minor modifications were made e.g. elimination of leading-edge slots, addition of de-icing boots.
B-24A/LB-30B
Ordered in 1939, the B-24A was the first production model.
Due to the need for long-range aircraft, the B-24A was ordered before any version of the B-24 flew.
The main improvement over the XB-24 was improved aerodynamics, which led to better performance.
Nine as transports transferred to Ferrying Command. while twenty were sold directly to the UK (this was pre-Lend-Lease) as LB-30Bs.
Deferred US funds and serial numbers allocated to future B-24D production.
Liberator B Mk II/LB-30
The modifications included a three-foot nose extension as well as a deeper aft fuselage and wider tail plane and self-sealing fuel tanks and armour, built to meet British specifications with British equipment and armament, there was no direct B-24 equivalent but similar to the B-24C.
Except for the first aircraft off the lines, the rest of the run was completed without armament, which the British would fit after aerial delivery to the UK.
With the sudden American entry into the war in December 1941, some 75 were requisitioned by the USAAF during delivery and retaining the LB-30 designation in service.
The aircraft that the USAAF requisitioned from the delivery process were in an unarmed state pre-delivery, so the aircraft had to be given armament.
Browning M2 .50 guns were fitted throughout; single .50s were mounted in the nose, two waist positions, and a single ventral tunnel, a twin .50 manual mount in the tail was substituted for the British tail turret with 4 .303 Brownings, and a Martin powered turret with two .50 supplanted the intended Boulton Paul dorsal turret.
Fifteen were sent to the SW Pacific, while three went to Alaska, six to Midway Island immediately after the naval battle in June, and six were lost in various accidents.
Twenty-three were later returned to the UK in 1943.
Seventeen were fitted with ASV radar & used in the Panama Canal Zone.
XB-24B
A newly funded conversion of the XB-24 after it failed to reach its projected top speed.
The Pratt & Whitney R-1830-33 radials rated at 1,000 hp (750 kW) it carried were replaced with R-1830-41 turbo-supercharged radials rated at 1,200 hp (890 kW), increasing its top speed by 37 mph (60 km/h).
The engine cowlings were made elliptical to accommodate the addition of the turbo-superchargers.
The XB-24B version also lacked the engine slots of the original.
It was re-serial numbered.
XB-24B 39-680 was converted into a luxury airliner for Consairway.
The conversion included gutting the interior, cutting new windows, and dividing the interior into compartments with individual and bench seating and two-tier Pullman-style sleeping berths.
It featured generous trim – possibly for sound-proofing – an in-flight galley with refrigerator and hot plates in bare metal (probably stainless steel) with lighting and services for the main deck controlled by a panel over the main passenger door, but photographs of the conversion dated 19 April 1945 show no visible seat belts or other passenger safety arrangements.
B-24C
New production funded from deferred funds after LB-30A to the UK.
Used the engine package prototyped in the XB-24B and the new fuselage of the LB-30.
The tail air gunner position was improved by adding a hydraulically powered Consolidated A-6 turret with twin .50 calibre (12.7 mm) machine guns, a Martin powered dorsal turret was added to the forward fuselage.
One (#84) converted to prototype the “three in nose” armament for the B-24D. FY funds and serial numbers transferred from B-24A.
B-24D
First model produced on a large scale; ordered from 1940 to 1942, as a B-24C with better engines (R-1830-43 supercharged engines).
The D model was initially equipped with a remotely operated and periscopically sighted Bendix belly turret, as the first examples of the B-17E Flying Fortress and some early models of the B-25 Mitchell medium bomber had used, but this proved unsatisfactory in service and was discontinued after the 287th aircraft.
Production aircraft reverted to the earlier manually operated “tunnel” mounting with a single .50 calibre (12.7 mm) machine.
The tunnel gun was eventually replaced by the Sperry ball turret, which had also been adopted by the later B-17E Fortresses, but made retractable for the Liberator when not in use as the ventral area of its fuselage was very close to the ground on landing.
In late B-24Ds, “cheek” guns mounted on either side of the forward nose, just behind the framed “greenhouse” nose glazing were added.
B-24E
A slight alteration of the B-24D built by Ford, using R-1830-65 engines. Unlike the B-24D, the B-24E retained the tunnel gun in the belly.
The USAAF used the B-24Es primarily as training aircraft since this series and other technology as were the aircraft being produced by Consolidated / San Diego (CO).
Ford also built sub-assemblies for Douglas and Convair Fort Worth; these sub-assemblies were identical to Ford-built B-24Es, except that they used the same engines as the B-24D (R-1830-43 radials).
These sub-assemblies were called KD (knock down) ships and were trucked from Willow Run to the Southwest for the final assembly.
XB-24F
A prototype made to test thermal de-icers instead of the standard inflatable rubber “boots”.
B-24G
Designation for B-24D aircraft built by North American Aviation pursuant to a 1942 contract.
Equipped with Sperry ball turret and three flexible .50 calibre (12.7 mm) machine guns in nose.
B-24G-1
as B-24G but with A-6 nose turret.
Most B-24G aircraft were delivered to the 15th Air Force in Italy.
B-24H
Because of the obvious vulnerability of the B-24 to head-on attack with the earlier, 24-panel “greenhouse” nose glazing, the B-24H design incorporated an electrically powered Emerson A-15 nose turret above the bombardier’s position, somewhat similar to where the Frazer-Nash FN5 nose turret on the Avro Lancaster was placed.
Approximately 50 other airframe changes were made, including a redesigned bombardier compartment possessing a glazed three-panel bombsight window unit replacing the “greenhouse” nose design.
The tail turret was given larger windows for better visibility and the Martin A-3 dorsal turret received an enlarged “high hat” dome.
The waist gunner positions were enclosed with Plexiglas windows and laterally offset (as the later B-17G’s waist positions had been) to reduce mutual interference between the two waist gunners during battle.
Most H model aircraft were built by Ford at the Willow Run factory. (Total: 3,100)
B-24J
The B-24J was very similar to the B-24H, but shortages of the Emerson nose turret required use of a modified, hydraulically powered Consolidated A-6 turret in most J model aircraft built at Consolidated’s San Diego and Fort Worth factories.
The B-24J featured an improved autopilot (type C-1) and a bombsight of the M-1 series.
B-24H sub-assemblies made by Ford and constructed by other companies and any model with a C-1 or M-1 retrofit, were all designated B-24J.
The J model was the only version to be built by all five factories involved in B-24 production. (Total: 6,678)
XB-24K
Developed from the B-24ST, with the B-23 Dragon empennage replaced by the tail of a Douglas C-54 Skymaster.
The improved performance and handling of the B-24ST and XB-24K led to the decision to incorporate a single tail in the PB4Y-2 and B-24N.
B-24L
Because of the excessively high gross weight of the B-24J, the Army pushed for a lighter version.
In the B-24L, the Sperry ball turret was replaced by a floor ring mount with two .50 calibre (12.7 mm) machine guns, and the A-6B tail turret by an M-6A.
Later aircraft were delivered from the factory without tail armament.
An A-6B or M-6A turret (190 total), a hand-held but hydraulically assisted twin .50 mount (42) or a manually operated twin .50 calibre (12.7 mm) mounting was then installed at a depot before arrival at operational units.
The L model was built only at Willow Run and Consolidated’s San Diego factory.
B-24M
An enhancement of the B-24L with further weight-saving devices.
The B-24M used a more lightweight version of the A-6B tail turret; the waist gunner positions were left open, and the retractable Sperry ventral ball turret was reintroduced.
For better visibility from the flight deck, the windshield in Ford-built aircraft was replaced by a version with less framing from Block 20 onward.
The B-24M became the last production model of the B-24; a number of the B-24s built flew only the course between the factory and the scrapheap.
XB-24N
A redesign of the B-24J, made to accommodate a single tail.
It also featured an Emerson 128 ball turret in the nose and a stationary tail gunner’s position.
While 5,168 B-24Ns were ordered, the end of the war resulted in cancellation of all contracts before production could begin.
Its single tail was said to be the inspiration for the PB4Y-2 Privateer’s similar single fin/rudder tail design.(Total: one)
YB-24N
Pre-production service test version of the XB-24N.
XB-24P
A modified B-24D, used by Sperry Gyroscope Company to test airborne fire control systems.
XB-24Q
A General Electric conversion of the B-24L.
Used to test a radar-controlled tail turret intended for use in the Boeing B-47 Stratojet.
XB-41
Because there were no fighters capable of escorting bomber formations on deep strike missions early in World War II, the Army authorized tests for heavily armed bombers to act as “gunship” escorts for bombing missions, which inspired both the B-17 derived YB-40 Flying Fortress gunship and its Liberator-derived XB-41 counterpart.
The XB-41 had fourteen .50 calibre (12.7 mm) machine guns, including a Bendix chin turret and a second Martin A-3 turret on the upper fuselage.
A single aircraft was completed in 1942.
Performance changed drastically with the addition of more turrets.
The escorts were also unable to keep up with bomber formations once the bombs had been dropped.
The results of 1943 testing were very negative and the project was quickly cancelled. (Total: one converted B-24D)
B-24ST
An experimental aircraft, The B-24ST (for Single Tail, an unofficial designation applied by Ford) was made by Ford by fitting a Douglas B-23 Dragon empennage onto a B-24D airframe.
The aircraft was more stable and had better handling than other models.
It was used as the basis of the XB-24K.
AT-22 or TB-24
C-87 used for flight engineer training.
RB-24L
Developed for training B-29 gunners on an identical remote gun system installed on a B-24L.
TB-24L
As with the RB-24L, but with additional radar equipment.
Experimental B-24J-15-CO, 42-73130, with B-17G nose section, containing chin turret, grafted on, modification not adopted for production
C-87 Liberator Express
Passenger transports with accommodation for 20 passengers.
C-87A
VIP transports with R-1830-45 instead of -43 engines and sleep accommodations for 16 passengers.
C-87C
U.S. Army Air Force/Air Force designation for the RY-3.
XC-109/C-109
Tankers with specialized equipment to help prevent explosions, used to ferry fuel from India to China to support initial B-29 raids against Japan.
XF-7
Photographic reconnaissance variant developed from the B-24D.
F-7
Photographic reconnaissance variant developed from the B-24H; -FO block.
F-7A
Photographic reconnaissance variant developed from the B-24J; three cameras in the nose and three in the bomb bay.
F-7B
Photographic reconnaissance variant developed from the B-24J; six cameras in the bomb bay.
BQ-8
A number of worn-out B-24D and B-24Js were converted as radio-controlled flying bombs to attack German targets.
U.S. Navy nomenclature and sub-variants
PB4Y-1
U.S. Navy designation applied to 976 navalized B-24D, J, L and M models built at Consolidated’s San Diego factory, as well as one North American-built B-24G. Later aircraft were equipped with an ERCO bow turret.
PB4Y-1P
Photographic reconnaissance variant developed from the PB4Y-1.
PB4Y-2 Privateer
A developed PB4Y with a large single fin and many other improvements and changes.
RY-1
U.S. Navy designation for the C-87A.
RY-2
U.S. Navy designation for the C-87.
RY-3
Transport variant of the PB4Y-2.
R2Y
Liberator Liner built using a new fuselage for the US Navy as an airliner with 48 seats
British Commonwealth nomenclature and sub-variants
Liberator C Mk I
YB-24/LB-30A, direct purchase aircraft for the RAF.
Considered unsuitable for combat, all rebuilt as the C.1 and used by BOAC to initiate a ferry service between the UK and Canada to bring/return RAF aircrew to Canada for ferrying Lend-Lease aircraft to the UK.
Liberator B Mk I
B-24A/LB-30B, direct purchase aircraft for the RAF.
Considered unsuitable for combat, some rebuilt as the GR.1 and used in British anti-submarine patrol squadrons.
Liberator B Mk II
LB-30. The first combat-ready B-24.
The modifications included a three-foot nose extension as well as a deeper aft fuselage and wider tail plane and self-sealing fuel tanks and armour; built to meet British specifications with British equipment and armament, there was no direct B-24 equivalent but similar to the B-24C.
Except for the first aircraft off the lines (completed to specifications as a pattern aircraft and subsequently lost in a test flight over San Diego Bay), the rest of the run was completed without armament, which the British would fit after aerial delivery to the UK.
With the American entry into the war in December 1941, some 75 were requisitioned by the USAAF and retaining the LB-30 designation in service, but 23 were returned in 1943.
A small series of B Mk IIs were reconstructed late in the war as unarmed transports both for the RAF and the USAAF, including one modified as the personal transport of PM Winston Churchill, named ‘Commando’.
Liberator B Mk III
B-24D variant with single .303 in (7.7 mm) Browning machine gun in the nose, two in each waist position, and four in a Boulton Paul tail turret, similar to that on contemporary British heavy bombers such as the Halifax, as well as other British equipment.
The Martin dorsal turret was retained.
Liberator B Mk IIIA
Lend-Lease B-24Ds with American equipment and weapons.
Liberator B Mk IV
Reserved for the B-24E, but there is no record of the RAF actually receiving any.
Liberator B Mk V
B-24D modified for extra fuel capacity at the cost or armor, with the same armament fit as the Liberator Mk III.
Liberator B Mk VI
B-24Hs in RAF service fitted with Boulton Paul tail turrets, but retaining the rest of their armament.
Liberator B Mk VIII
RAF designation for B-24Js.
RAF Coastal Command ASV Mk. II-equipped Liberator GR.III of No. 120 Squadron RAF.
Liberator GR Mk V
B-24D modified by RAF Coastal Command for the anti-submarine role with search radar and Leigh Light.
Some were fitted with eight zero-length rocket launchers, four on each wing, with others being fitted with eight RP-3 rails under stub-wings, either side of the lower forward fuselage.
Liberator GR Mk VI
B-24G/H/J type used as a long-range general reconnaissance aircraft by RAF Coastal Command.
Liberator GR Mk VIII
B-24J modified by RAF Coastal Command for the anti-submarine role.
Liberator C Mk VI
Liberator B Mk VIII converted for use as a transport.
Liberator C Mk VII
British designation for C-87.
Liberator C Mk VIII
Liberator G Mk VIII converted for use as a transport.
Liberator C Mk IX
RAF designation for the RY-3/C-87C
Late in the war RAF Liberator aircraft modified in England for use in South East Asia had the suffix “Snake” stencilled below the serial number to give them priority delivery through the Mediterranean and the Middle East.
It served in every branch of the American armed forces as well as several Allied air forces and navies.
It saw use in every theatre of operations.
Specifications
Crew
11
Length
67 ft 2 in (20.47 m)
Wingspan
110 ft (34 m)
Height
17 ft 7.5 in (5.372 m)
Wing area
1,048 sq ft (97.4 m2)
Aspect ratio
11.55
Zero-lift drag coefficient
CD0.0406
Frontal area
42.54 sq ft (3.952 m2)
Airfoil
Root
Davis (22%)
Tip
Davis (9.3%)
Empty weight
36,500 lb (16,556 kg)
Gross weight
55,000 lb (24,948 kg)
Max take-off weight
65,000 lb (29,484 kg)
Fuel capacity
2,344 US gal (1,952 imp gal; 8,870 l) normal capacity; 3,614 US gal (3,009 imp gal; 13,680 l) with long-range tanks in the bomb bay
Oil capacity
131.6 US gal (109.6 imp gal; 498 l) in four self-sealing nacelle hopper tanks
Powerplant
4 × Pratt & Whitney R-1830-35 Twin Wasp, R-1830-41 or R-1830-65 14-cylinder two-row air-cooled turbo supercharged radial piston engines, 1,200 hp (890 kW) each
Propellers
3-bladed Hamilton Standard, 11 ft 7 in (3.53 m) diameter constant-speed fully-feathering propellers
Performance
Maximum speed
297 mph (478 km/h, 258 kn) at 25,000 ft (7,600 m)
Cruise speed
215 mph (346 km/h, 187 kn)
Stall speed
95 mph (153 km/h, 83 kn)
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
Ferry range
3,700 mi (6,000 km, 3,200 nmi)
Service ceiling
28,000 ft (8,500 m)
Rate of climb
1,025 ft/min (5.21 m/s)
Time to altitude
20,000 ft (6,100 m) in 25 minutes
Lift-to-drag
12.9
Wing loading
52.5 lb/sq ft (256 kg/m2)
Power/mass
0.0873 hp/lb (0.1435 kW/kg)
Armament
Guns
10 × .50 calibre (12.7 mm) M2 Browning machine guns in 4 turrets and two waist positions
