After company executives including President Reuben Fleet visited the Boeing factory in Seattle, Washington, Consolidated decided to submit a more modern design of its own.

In January 1939, the USAAC, under Specification C-212, formally invited Consolidated[7] to submit a design study for a bomber with longer range, higher speed and greater ceiling than the B-17.

[10][11][12] The B-24's spacious, slab-sided fuselage (which earned the aircraft the nickname "Flying Boxcar")[13] was built around two central bomb bays that could accommodate up to 8,000 pounds (3,600 kg) of ordnance in each compartment (but rarely did, as this decreased range and altitude).

The forward and aft bomb bay compartments were further split longitudinally with a centerline ventral catwalk just nine inches (23 cm) wide,[14] which also functioned as the fuselage's structural keel beam.

An unusual four-panel set of all-metal, tambour-panel "roller-type" bomb bay doors, which operated very much like the movable enclosure of a rolltop desk, retracted into the fuselage.

Compared to the B-17, the proposed Model 32 had a shorter fuselage and 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.

The new design would be the first American heavy bomber in production to use tricycle landing gear – the North American B-25 Mitchell medium bomber's predecessor, the NA-40 introduced this feature in January 1939 – with the Consolidated Model 32 having long, thin wings with the efficient "Davis" high aspect ratio design (also used on the projected Model 31 twin-engined commercial flying boat)[17] promising to provide maximum fuel efficiency.

Wind tunnel testing and experimental programs using an existing Consolidated Model 31 provided extensive data on the flight characteristics of the Davis airfoil.

[citation needed] The most important role, however, 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.

This model introduced self-sealing fuel tanks, a 2 ft 7 in (79 cm) plug in the forward fuselage to create more space for crew members and, more vitally, ever more equipment such as ASV Mark II radar (anticipated early in the Liberator's development when Reuben Fleet told the engineering team he had a gut feeling the nose was too short).

In October 1944, two RAF Liberator squadrons (357 and 358) were deployed to Jessore, India, in support of British SAS, American OSS and French SIS underground operations throughout SE Asia.

The introduction of Very Long Range (VLR) Liberators vastly increased the reach of the UK's maritime reconnaissance force, closing the Mid Atlantic Gap where a lack of air cover had allowed U-boats to operate without risk of aerial attack.

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 aerial weapons such as rockets, gunfire, torpedoes and depth charges from the bombers.

American Liberators flew from Nova Scotia, Greenland, the Azores, Bermuda, the Bahamas, Puerto Rico, Cuba, Panama, Trinidad, Ascension Island and from wherever else they could fly far out over the Atlantic.

The gradual arrival of many more VLR and in October, PB4Y navalized Liberators for anti-submarine missions over the Mid-Atlantic gap ("black pit") and the Bay of Biscay was an important contribution to the Allies' greater success.

[28] The B-24 was vital for missions of a radius less than 1,000 mi (1,600 km), in both the Atlantic and Pacific theaters where U.S. Navy PB4Y-1s and USAAF SB-24s took a heavy toll of enemy submarines and surface combatants and shipping.

[13] The B-24 advanced the use of electronic warfare and equipped Search Bomber (SB), Low Altitude (LAB) and Radar Counter Measure (RCM) squadrons in addition to high-altitude bombing.

They were equipped with signal lighting, provision for quantity discharge of pyrotechnics, and were painted with distinctive group-specific high-contrast patterns of stripes, checkers or polka dots to enable easy recognition by their flock of bombers.

Carpetbagger aircraft flew spies called "Joes" and commando groups prior to the Allied invasion of Europe on D-Day and afterward, and retrieved over 5,000 officers and enlisted men who had escaped capture after being shot down.

Although only 287 C-87 and eight U.S. Navy RY variants were produced, they were still important in the Army Air Forces' airlift operations early in the war when aircraft with high-altitude, long-range heavy hauling abilities were in short supply.

Early in the campaign, the C-87 was the only readily available American transport that could fly over the Himalayas while heavily loaded, rather than relying on circuitous and highly dangerous routes through valleys and mountain passes, but the type was not very popular with crews: they complained of various hazards including the fuel system, engines and cockpit accessories, while the type was notorious for leaking fuel tanks and mid-air fires a constant danger.

Consequently, it was relatively easy for a poorly trained ground crew to load a C-87 with its center of gravity too far forward or aft, rendering the aircraft difficult to control due to inadequate or excessive longitudinal stability.

In his autobiography, Fate is the Hunter, the writer Ernest K. Gann reported that, while flying air cargo in India, he barely avoided crashing an improperly loaded C-87 into the Taj Mahal.

[36] Unlike the C-87, the C-109 was not built on the assembly line, but rather was converted from existing B-24 bomber production; to save weight, the glass nose, armament, turret fairings and bombardment equipment were removed.

The aircraft demonstrated unstable flight characteristics with all storage tanks filled, and proved very difficult to land fully loaded at airfields above 6,000 ft (1,800 m) MSL in elevation, such as those around Chengdu.

After it was discovered that these problems could be alleviated by flying with the forward storage tank empty, this practice became fairly routine, enhancing aircrew safety at the cost of some fuel-carrying capacity.

The Singing Cowboy Gene Autry served in the Air Transport Command (in the same squadron as Barry Goldwater), and described flying the C-109 over "The Hump" as "the thrill that lasts a lifetime".

The Privateer had non-turbosupercharged engines for weight savings and optimal performance at low to medium patrol altitudes, and was visually distinguishable from the B-24 and PB4Y-1 by its longer fuselage, single tall vertical stabilizer (rather than a twin tail), two dorsal turrets, and teardrop-shaped waist gun blisters (similar in appearance to those on Consolidated's own PBY Catalina).

Flying mainly from bases in the Northern Territory, Queensland and Western Australia, aircraft conducted bombing raids against Japanese positions, ships and strategic targets in New Guinea, Borneo and the Netherlands East Indies.

At Ford's Ypsilanti, Michigan based Willow Run Bomber plant alone, one B-24 was being produced every 59 minutes at its peak, a rate so large that production exceeded the military's ability to use the aircraft.