XB-24B. The first B-24 to be fitted with turbo-supercharged engines, self-sealing tanks, armor, and other modern refinements.

    B-24C. Four Pratt & Whitney R-1830-41 engines with exhaust-driven turbo-superchargers. Armament augmented to include two power-driven turrets, one dorsal and one tail, each fitted with two .50-cal. guns. In addition, there was one .50-cal. nose gun and two similar guns in waist positions.

    B-24D (PB4Y-l and Liberator B.III and G.R.V.). Four Pratt & Whitney R-1830-43 engines. Armament further increased by the addition of two further nose guns and one tunnel gun, making a total of ten .50-cal. guns. Fuel capacity increased by the addition of auxiliary self-sealing fuel cells in the outer wings and there was provision for long-range tanks in the bomb-bay. The first model to be equipped to carry two 4,000 lb. bombs on external racks, one under each inner wing. The Liberator G.R.V. was used as a long-range general reconnaissance type by RAF Coastal Command. Fuel capacity was increased at the expense of amour and tank protection. Armament consisted of one .303-in. or .50-cal. gun in the nose, two .50-cal. guns in the upper turret, four .303 -in. or two .50-cal. guns in waist positions and four .303-in. guns in a Boulton Paul tail turret. Bombs or depth charges 5,400 lbs.

    B-24E (Liberator IV). Similar to B-24D except for minor equipment details. Built by Consolidated (Forth Worth), Ford (Willow Run) and Douglas (Tulsa).

    B-24F. An experimental version of the B-24E fitted with exhaust-heated surface anti-icing equipment on wings and tail surfaces.

    B-24G, B-24H and B-24J (PB4Y-l and Liberator B.VI and G.R.VI). Similar except for details of equipment and minor differences associated with different manufacturing methods. B-24J built by North American (Dallas). B-24H built by Consolidated (Forth Worth), Ford (Willow Run) and Douglas (Tulsa). B-24J built by Consolidated (San Diego and Fort Worth), Ford, Douglas and North American (Dallas). Four Pratt & Whitney R-1830-43 or 65 engines. Armament further improved to include four two-gun turrets, in nose and tail and above and below the fuselage (details below). Later models of the B-24J were fitted with exhaust-heated anti-icing equipment. The Liberator G.R.VI was used as a long-range general reconnaissance type by RAF Coastal Command. Armament consisted of six .50-cal. guns, two each in nose and dorsal turrets and in waist positions, and four .303-in. guns in a Boulton Paul tail turret. Bombs or depth charges 4,500 lbs. (2,045 kg.).

    XB-24K. The first Liberator to be fitted with a single fin and rudder. An experimental model only.

    B-24L. Similar to the B-24J but fitted with a new tail turret with two manually-operated .50-cal. guns. The two guns had a wider field of fire and the new turret, which was designed by the Consolidated Vultee Modification Center at Tucson permitted a saving of 200 lbs. (91 kg.) in weight.

    B-24M. Same as the B-24L except fitted with a new Motor Products two-gun power-operated tail turret. A B-24M was the 6,725th and last Liberator built by Consolidated Vultee at San Diego.

    B-24N. The first production single-tail Liberator. Fitted with new nose and tail gun mountings. Only a few were built before the Liberator was withdrawn from production on May 31,1945.

    CB-24. Numbers of B-24 bombers withdrawn from operational flying in the European Theater of Operations were stripped of all armament and adapted to various duties, including utility transport, etc. Painted in distinctive colors and patterns, they were also used as Group Identity Aircraft to facilitate the assembly of large numbers of bombers into their battle formations through and above overcast weather. All these carried the designation CB-24.

    TB-24 (formerly AT-22). A conversion of the B-24D for specialized advanced training duties. All bombing equipment and armament removed and six stations provided in the fuselage for the instruction of air engineers in powerplant operation, essentially for such aircraft as the Boeing B-29 and the Consolidated Vultee B-32, which are the first large combat aircraft in the USAAF to have separate completely equipped engineer's stations.

    C-109. A conversion of the B-24 into a fuel-carrying aircraft. The first version, modified by the USAAF had metal tanks in the nose, above the bomb-bay and in the bomb-bay holding a total of 2,900 US gallons. Standard fuel transfer system for loading and unloading through single hose union in side of fuselage. Inert gas injected into tanks as fuel pumped out to eliminate danger of explosion. Developed for transporting fuel from India to China to supply the needs of the B-29s operating therefrom. Later version modified by the Glenn L. Martin Company, fitted with collapsible Mareng fuel cells.