The "Flying Boxcar"
The Consolidated B-24 Liberator was an American heavy bomber, designed and largely built by the Consolidated Aircraft Company of San Diego, California. It was produced in greater numbers than any other American combat aircraft of World War II, and still holds the record as the most-produced American military or naval aircraft.
Often compared with the better-known B-17 Flying Fortress, the B-24 was a more modern design with a higher top speed, greater range, and a heavier bomb load; however, it was also more difficult to fly, with heavy control forces and poor formation-flying characteristics. Nevertheless, popular opinion among aircrews and general's staffs tended to favour the B-17's rugged qualities above all other considerations in the European Theatre. The placement of the B-24's fuel tanks throughout the upper fuselage and its lightweight construction, designed to increase range and optimize assembly line production, made the aircraft vulnerable to battle damage. The B-24 was notorious among American aircrews for its tendency to catch fire, but it nevertheless provided excellent service in a variety of roles thanks to its large payload and long range.
The Liberator originated from a United States Army Air Corps (USAAC) request in 1938 for Consolidated to produce the B-17 under license. This was part of "Project A", a program to expand American industrial capacity for production of the key components of air power. After company executives including President Reuben Fleet visited the Boeing factory in Seattle, Consolidated decided instead to submit a more modern design of its own. In January 1939, the USAAC, under Specification C-212, formally invited the Consolidated company to submit a design study for a bomber with longer range, higher speed, and greater ceiling than the B-17.
The contract for a prototype was awarded in March 1939, with the requirement that one should be ready before the end of the year. The design was simple in concept but nevertheless advanced for its time. Compared to the B-17, the proposed Model 32 was shorter with 25% less wing area, but had a 6 ft (1.8 m) greater wingspan and a substantially larger carrying capacity, as well as a distinctive twin tail. Whereas the B-17 used 9-cylinder Wright R-1820 Cyclone engines, the Consolidated design used twin-row, 14-cylinder Pratt & Whitney R-1830 "Twin Wasp" radials of 1,000 hp (746 kW). The 70,547 lb (32,000 kg) maximum takeoff weight was one of the highest of the period. Consolidated incorporated innovative features: the new design would be the first American bomber to use tricycle landing gear, and it had long, thin wings with the efficient "Davis" high aspect ratio design promising to provide maximum fuel efficiency.
Consolidated finished the prototype, by then known as the XB-24, and had it ready for its first flight two days before the end of 1939. Seven more YB-24 development aircraft flew in 1940 and Consolidated began preparing production tooling. Early orders—placed before the XB-24 had flown—included 36 for the USAAC, 120 for the French Armée de l'Air and 164 for the Royal Air Force (RAF). Most of the first production B-24s went to Great Britain, including all those originally ordered by the Armée de l'Air after France collapsed and surrendered in 1940. Its nicknamed, the "Liberator", was originally assigned to it by the RAF, and subsequently adopted by the USAAF as the official name for the type.
The B-24's spacious slab-sided fuselage (which earned the aircraft the nickname "Flying Boxcar") was built around a central bomb bay that could accommodate up to 8,000 lb (3,629 kg) of ordnance. The bomb bay was divided into front and rear compartments and had a central catwalk, which was also the fuselage keel beam. A universal complaint arose over the extremely narrow catwalk. The aircraft was sometimes disparaged as "The Flying Coffin" because the only entry and exit from the bomber was in the rear and it was almost impossible for the flight crew and nose gunner to get from the flight deck to the rear when wearing parachutes. An unusual set of "roller-type" bomb bay doors retracted into the fuselage, creating a minimum of aerodynamic drag to keep speed high over the target area.
Like the B-17, the B-24 had an array of .50 calibre (12.7 mm) M2 Browning machine guns in the tail, belly, top, sides and nose to defend it from attacking enemy fighters. However, unlike the B-17, the ball turret could be retracted into the fuselage when not in use.
B-24 Liberators were crewed (depending on the model) by
7 to 10 personnel. The pilot and co-pilot were situated
in the high-mounted stepped flight deck with views
forward, to the sides and above. Of the two seats in the
cockpit, the pilot occupied the left hand seat while the
co-pilot sat to his right. The pilot maintained the
Liberator's position in flight and was called upon to
deliver the aircraft to the target area and back or make
split-second decisions based on actions to keep his crew
alive. The co-pilot was equally trained in the systems
afforded the pilot and was, for all intents and
purposes, the pilots right-hand man. He participated in
the operation and controls of the Liberator to help
alleviate the responsibilities of the pilot. Like the
pilot, the co-pilot could be called upon to fully
operate the aircraft to and from the target area and,
like the navigator, was trained in the fine art of
nose gunner, bomber and navigator were housed under a
glazed nose well forward in the design. The nose gunner
was perhaps afforded the most stunning (and
oft-targeted) position in the Liberator, watching every
bombing mission unfold like no other crewman. The nose
gunner had access to the powered nose turret if the
model of Liberator called for one, fitting 2 x .50
machine guns. Since the front of the Liberator was most
susceptible to incoming enemy fighters, this position
was also one of the more dangerous on the aircraft.
The bombardier held the most important job in the flight
crew. For the Liberator's were designed with bombing in
mind, a flight crew without a trained bomber crewmember
was ultimately useless in the Allied air campaign.
Bombardiers and pilots shared a common role for the
bombardier would be called on to take flight control of
the bomber when engaging in the bombing run via
auto-pilot. Calculations were necessary to unleash
payloads directly over target areas, thus requiring
bombardiers to maintain a certain level of mettle while
blocking out enemy fighters, flak, structural damage or
personal combat wounds. Lead bombers were also the
elements that triggered the rest of the formation to
drop their bombs. Later advances in airborne
technologies allowed bombardiers to achieve direct hits
even through cloud and smoke coverage.
The navigator was given the important responsibility of
getting the crew to the target and back home. This was
particularly important of the lead bomber in a given
flight group but all navigators needed exceptional
know-how of their position to lead a bomber through
should the aircraft become displaced from his group. The
navigator could utilize the forward-mounted Plexiglas
dome to get his bearings as well as relying on physical
landmarks down below and his training in the fine art of
navigation. Essentially, the pilot and navigator needed
to maintain a close working partnership to get everyone
to the target area and back home.
The dorsal turret gunner also doubled as the flight
engineer and probably maintained the best defensive
vantage point, offering an exceptional firing arc when
compared to all other available gunner positions. The
turret mounted 2 x .50 machine guns. As the aircraft's
in-flight mechanic, these individuals maintained a
certain level of expert knowledge on the inner workings
of the aircraft. His primary duty - along with defence
of the upper side of the bomber - also lay in assisting
the pilots on the engine condition and fuel usage.
The radioman was situated within the upper portion of
the Liberator's deep fuselage, positioned just behind
the cockpit and not aft of the wings as in a B-17. His
position required him to stay hours on his headset
listing for friendly communications, reporting updates
to the navigator, reporting situational updates at
intervals and communicating with headquarters on mission
results. Radiomen were required to keep logs of all
pertinent actions and could be called upon to man one of
the waist guns if needed.
The forward flight crew was removed from the rear flight
crew, with access between the two sections of the bomber
made via a thin scaffold running the length of the two
bomb compartments. Entry and exit to the aircraft was
through a door positioned towards the rear which made
for harrowing emergency exits. Forward crewmen were
expected to exit the aircraft by walking across the bomb
bay scaffold and make their way to the rear all the
while fitted with their parachutes and bulky warming
The smallest bomber personnel were generally enlisted
for operation of the ball turret fitting 2 x .50 heavy
machine guns. The gunners wore no parachutes (the small
size of the ball turret necessitated this) and made
their way inside their turrets after the aircraft was in
flight. The ball turret - unlike that on the B-17 -
could be retracted into the Liberator's fuselage during
take-off and landing. The ball turret was perhaps the
coldest position on a given B-24 with many a crewmember
reporting frostbite through those frigid high-altitude
sorties. At any rate, the ball turret gunner held a
distinct view of the action like no other crew member.
Waist gunners were charged with the defence of the
Liberator's vulnerable sides through use of single .50
machine guns. As such, these positions aboard Liberators
suffered the most casualties by incoming fighters ready
to strafe the large profile sides of the bomber. These
two positions - left and right - were later staggered to
compensate for each gunners firing arc. Unlike other
turreted positions in the B-24, spent shell casings at
these waist positions were not jettisoned from the
aircraft automatically, forcing crewmembers to clear
their areas themselves. Since firing from these
side-perspective positions required a great deal of
hand-to-eye coordination via tracer rounds while taking
into account target speed and the Liberator's airspeed
itself, waist gunners relied on simple targeting sights
in the early years. Only later did they receive
assistance in the form of compensating sights to help
The tail gunner was given perhaps the most important defensive position aboard the Liberator, manning a powered 2 x .50 machine gun turret. Afforded a spectacular view, the tail gunner was charged with defence of the aircraft's "six", a position most often to encounter trailing enemy fighters eager for the easy kill. The turret was glazed with laminated Perspex, designed to enemy fire. The effectiveness of the Perspex can be seen in this photo on the right. Tail Gunner Joe Rapoza who flew in the "Liberty Belle" (450th Bomb Group/47th Bomber Wing) was attacked by Luftwaffe fighters. A 2cm cannon shell has impacted on the plastic but not penetrated. Rapoza survived and lives in retirement in the US.
Liberator GR Is in British service were the first B-24s to be used operationally. The very first use of a Liberator I in March 1941 was as a long-range transport used to ferry pilots back from the United Kingdom, while the most important role for the first batch of the Liberator GR Is was in service with RAF Coastal Command on anti-submarine patrols in the Battle of the Atlantic.
The Liberators made a great contribution to Allied victory in the Battle of the Atlantic against German U-boats. The decision to allocate some Liberator Is to Coastal Command in 1941 to patrol the eastern Atlantic Ocean produced immediate results. The Very Long Range (VLR) Liberators almost doubled the reach of Britain's maritime reconnaissance force. This extended range enabled Coastal Command patrols to cover part of the Mid-Atlantic gap, where U-boats had operated without risking being attacked and sunk by Allied aircraft.
For 12 months, No. 120 Squadron RAF of Coastal Command with its handful of much-patched and modified early model Liberators, supplied the only air cover for convoys in the Atlantic Gap, the Liberator being the only warplane with sufficient range. The VLR Liberators sacrificed some armour and often gun turrets in order to save weight, while carrying extra aviation gasoline in their bomb-bay tanks. Liberator Is were equipped with ASV (Air to Surface Vessel) Mark II radar, which together with the Leigh light gave them the ability to hunt U-boats by day and by night.
These Liberators operated from both sides of the Atlantic with the Royal Canadian Air Force and the U.S. Navy from the west; and with the RAF from the east, based in Northern Ireland, Scotland, Iceland, and beginning in mid-1943 from the Azores. This role was dangerous, especially after many U-boats were armed with extra anti-aircraft guns, some adopting the policy of staying on the surface to fight, rather than submerging and risking being sunk by ASW (anti-submarine warfare) torpedoes and depth charges from the bombers. In addition to flying from the East Coast of the United States, American Liberators flew from Greenland, the Azores, Bermuda, the Bahamas, Puerto Rico, Cuba, Trinidad, and from wherever else they could fly far out over the Atlantic.
The rather sudden and decisive turning of the Battle of the Atlantic in favour of the Allies in May 1943 was the result of many factors. However, it was no accident that it coincided with the long delayed arrival of many more VLR Liberators for maritime patrols. Liberators were credited in full or in part with 72 U-boat sinkings.
America enters the war
The United States Army Air Forces (USAAF) took delivery of its first B-24As in 1941. The sole B-24 in Hawaii was destroyed by the Japanese on Pearl Harbour on 7 December 1941. Like the RAF, the USAAF used them as transports at first. American B-24s entered combat service in 1942 when on 6 June, four B-24s from Hawaii staging through Midway Island attempted an attack Wake Island, but were unable to find it. On 12 June 1942, 13 B-24s flying from Egypt attacked the Axis-controlled oil fields and refineries around Ploesti, Romania.
Over the next three years, B-24 squadrons deployed to all theatres of the war: African, European, China-Burma-India, the Battle of the Atlantic, the Southwest Pacific Theatre and the Pacific Theatre. In the Pacific, the B-24 (and its twin, the U.S. Navy PB4Y Privateer) was eventually designated as the standard heavy bomber to simplify logistics and to take advantage of their longer range, replacing the shorter-range B-17 which had served early in the war along the perimeter of the Pacific from the Philippines, Australia, Espiritu Santo, Guadalcanal, Hawaii, and during the Battle of Midway from Midway Island.
Later development and production
Continued development work by Consolidated produced a handful of transitional B-24Cs with turbocharged instead of supercharged engines. The turbocharged engines led to the flattened oval nacelles that distinguished all subsequent Liberator models.
The first mass-produced model was the B-24D (Liberator III in British service), entering service in early 1943. It had turbocharged engines and increased fuel capacity. Three more 0.50 calibre (12.7 mm) machine guns brought the defensive armament up to 10 machine guns. At 59,524 lb (27,000 kg) maximum takeoff weight, it was one of the heaviest aircraft in the world; comparable with the British "heavies" the Stirling, Lancaster and Halifax.
In 1943, the model of Liberator considered by many the "definitive" version was introduced. The B-24H was 10 in (25 cm) longer, had a powered gun turret in the nose to reduce vulnerability to head-on attack and was fitted with an improved bomb sight, autopilot, and fuel transfer system. Consolidated, Douglas and Ford all manufactured the B-24H, while North American made the slightly different B-24G. All five plants switched over to the almost identical B-24J in August 1943. The later B-24L and B-24M were lighter-weight versions and differed mainly in defensive armament.
In all, 18,482 B-24s were built by September 1945. Twelve thousand saw service with the USAAF. The U.S. Navy operated about 1,000 PB4Y-1s, and almost 800 PB4Y-2 Privateers which were derived from the B-24. The Royal Air Force flew about 2,100 B-24s in 46 bomber groups and 41 squadrons; the Royal Canadian Air Force 1,200 B-24Js; and the Royal Australian Air Force (RAAF) 287 B-24Js, B-24Ls, and B-24Ms. Liberators were the only heavy bomber flown by the RAAF in the Pacific. Two squadrons of the South African Air Force based in Italy flew B-24s.
The B-24 was one of the workhorse bombers of the U.S. Eighth Air Force in the Combined Bomber Offensive against Germany, forming about one-third of its heavy bomber strength, with the other two-thirds being B-17s. Thousands of B-24s, flying from bases in England, dropped hundreds of thousands of tons of bombs and incendiaries on German military, industrial, and civilian targets.
B-24s of the Ninth Air Force, operating from Africa and Italy, and the Fifteenth Air Force, also operating from Italy, took a major role in strategic bombing. Thirteen of the 15th AF's 18 bombardment groups flew B-24s. The Ninth Air Force moved to England in 1944 to become a tactical air force, and all of its B-24s were transferred to other Air Forces, such as the Fifteenth Air Force in Italy.
The first B-24 loss over German territory occurred on 26 February 1943. By a cruel twist of fate there had been 11 men aboard the aircraft. For some time newspapers had been requesting permission for a reporter to go on one of the missions, and on this date Robert B. Post, and five other reporters of the New York Times were granted permission.
Mr. Post was the only reporter assigned to a B-24-equipped group, the 44th Bomb Group, and flew in B-24 41-23777 Maisey on Mission No. 37 to Bremen, Germany. Intercepted just short of the target, the B-24 came under attack from JG 1's Messerschmitt Bf 109s. Leutnant Heinz Knoke (who finished the war with 31 kills) shot down the Liberator, with only two of the 11 men surviving. Neither was Post. Knoke reported:
"The fire spread out along the right wing. The inboard propeller windmilled to a stop. And then, suddenly, the whole wing broke off. At an altitude of 900 metres there was a tremendous explosion. The bomber had disintegrated. The blazing wreckage landed just outside Bad Zwischenahn airfield"
Sometimes the best flying skills or gunnery were not enough: 2 B-24s take direct hits
In February 1944, the 2nd Division authorized the use of war-weary aircraft specially fitted to aid assembly of individual group formations. Known as Assembly or Formation Ships, they were equipped with signal lighting, provision for quantity discharge of pyrotechnics, and featured distinctive individual paint schemes of psychedelic colours in stripes, checkers, or polka dots to enable easy recognition by their flock of bombers. The aircraft used in the first allocation were B-24Ds retired by the 44th, 93rd and 389th Groups. Arrangements for signal lighting varied from group to group, but generally consisted of white flashing lamps on both sides of the fuselage arranged to form the identification letter of the group. All armament and armour was removed, and in some cases the tail turret. Following incidents when flare guns were accidentally discharged inside the rear fuselage, some Formation Ships had pyrotechnic guns fixed through the fuselage sides. As these aircraft normally returned to base once a formation had been established, a skeleton crew of two pilots, navigator, radio operator and one or two flare discharge men were carried. In some groups an observer officer flew in the tail position to monitor the formation. These aircraft became known as Judas Goats.
From August 1943 until the end of the war in Europe, specially modified B-24Ds were used in classified missions. In a joint venture between the Army Air Force and the Office of Strategic Services (OSS) code named "Operation Carpetbagger", pilots and crews flew specially modified B-24Ds painted with a glossy black anti-searchlight paint to supply friendly underground forces throughout German occupied Europe. They also flew C-47s, A-26 Invaders, and British de Havilland Mosquitos. They flew spies called "Joes" and commando groups prior to the Allied invasion of Europe on D-Day and afterwards, and retrieved over 5,000 officers and enlisted men who had escaped capture after being shot down. The low-altitude, night-time operation was extremely dangerous and took its toll on these airmen. The first aircrews chosen for this operation came from the anti-submarine bomb groups because of their special training in low altitude flying and pinpoint navigation skills.
Early model Liberators were used as unarmed long-range cargo carriers. They flew between Britain and Egypt (with an extensive detour around Spain over the Atlantic), and they were used in the evacuation of Java in the East Indies. Liberator IIs were converted for this role and were used by the British Overseas Airways Corporation (BOAC) for trans-Atlantic services and other various long-range air transportation routes. This version of the Liberator was designated the LB-30A by the USAAF.
In early 1942, a B-24 Liberator that had been damaged in an accident was converted into a cargo transport aircraft by elimination of its transparent nose and the installation of a flat cargo floor. In April 1942, the C-87 Liberator Express transport version of the B-24 entered production at Fort Worth, Texas. The C-87 had a large cargo door, less powerful supercharged engines, no gun turrets, a floor in the bomb bay for freight, and some side windows. The navigator's position was relocated behind the pilot. Early versions were fitted with a single .50 calibre Browning machine gun in their tails, and a few C-87s were also equipped with two .50 calibre fixed machine guns in their noses, operable by the pilot, though these were eventually removed. A more elaborate VIP transport, the C-87A, was also built in small numbers.
The C-87 was also designated the RY-2 or Liberator Cargo VII. The U.S. produced about 300 C-87s but they were still important in the Army Air Force's heavy airlift operations. The C-87 flew in many theatres of war, including much hazardous duty in flights from Labrador to Greenland and Iceland in the North Atlantic. This airplane proved to be quite vulnerable to icing conditions, and was prone to fall into a spin with even small amounts of ice accumulated onto its Davis wing.
Main Variants and conversions
- XB-24 (Consolidated Model 32)
Designed in 1938 as an improvement on the B-17 Flying Fortress, at the request of the Army Air Corps. It had a wing specially designed for a high aspect ratio, tricycle landing gear, and twin vertical stabilizers. The XB-24 was ordered in 1939 March, and first flew on 29 December 1939. (Total: one)
- YB-24/LB-30A Preproduction prototypes
Six examples were sent to Great Britain under lend-lease, designated LB-30A.
Service test version of the XB-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: elimination of leading edge slots, addition of de-icing boots. (Total: seven; only one used for actual testing.
Ordered in 1939, the B-24A was the first production model. Due to the need for heavy bombers, 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. Some sent to Great Britain under lend-lease as LB-30B. (Total: 38,20 LB-30Bs, 9 B-24Cs)
When the XB-24 failed to reach its projected top speed, the Pratt & Whitney R-1830-33 radials rated at 1,000 hp (746 kW) it carried were replaced with R-1830-41 turbo-supercharged radials rated at 1,200 hp (895 kW), increasing its top speed by 37 mph (59 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. (Total: one converted XB-24)
Conversion of the B-24A using turbo-supercharged R-1830-41 engines. To hold the supercharger and the intercooler intake, the cowlings were made elliptical and the new items added on the sides. The tail air gunner position was improved by adding an Emerson A-6 power turret with twin .50 calibre machine guns; a Martin power turret was added to the forward fuselage.
First model produced on a large scale; ordered from 1940 to 1942, as a B-24C with better engines (R-1830-43 supercharged engines). During the production run, the tunnel gun in the belly was replaced by a remote-sited Bendix belly turret; this was later replaced by a Sperry ball turret. In late B-24Ds, "cheek" guns were added. (Total: 2,696: 2,381 Consolidated, San Diego; 305 Consolidated, Fort Worth; 10 Douglas, Tulsa, Oklahoma).
Because of obvious vulnerability of the B-24 to head-on attack, the B-24H design made by Ford used a nose turret, generally a modified Emerson A-6 tail turret. The entire aircraft was redesigned to better fit the turret; 50 airframe changes were made, including a redesigned bombardier compartment. The tail turret was given larger windows for better visibility, the top turret a higher bubble, and the waist gunner positions were offset to reduce their interference during battle. (Total: 3,100)
Data from Quest for Performance
Length: 67 ft 8 in (20.6 m)
Wingspan: 110 ft 0 in (33.5 m)
Height: 18 ft 0 in (5.5 m)
Wing area: 1,048 ft² (97.4 m²)
Empty weight: 36,500 lb (16,590 kg)
Loaded weight: 55,000 lb (25,000 kg)
Max takeoff weight: 65,000 lb (29,500 kg)
Zero-lift drag coefficient: 0.0406
Drag area: 42.54 ft² (3.95 m²)
Aspect ratio: 11.55
Cruise speed: 215 mph (187 kn, 346 km/h)
Stall speed: 95 mph (83 kn, 153 km/h)
Ferry range: 3,700 mi (3,200 nmi, 6,000 km)
Service ceiling: 28,000 ft (8,500 m)
Rate of climb: 1,025 ft/min (5.2 m/s)
Wing loading: 52.5 lb/ft² (256 kg/m²)
Power/mass: 0.0873 hp/lb (144 W/kg)
Lift-to-drag ratio: 12.9
Guns: 10 × .50 calibre M2 Browning machine guns in 4 turrets and two waist positions
Short range (˜400 mi): 8,000 lb (3,600 kg)
Long range (˜800 mi): 5,000 lb (2,300 kg)
Very long range (˜1,200 mi): 2,700 lb (1,200 kg