The B-24C was the production breakdown aircraft used to finalize the production line for mass production of a fully-combat capable Liberator. Serials were 40-2378/2386, which had originally been allocated to a B-24A production lot.
The B-24C incorporated changes which had been first tried out on the XB-24B plus changes that had been recommended as a result of combat experience in Europe with the Liberator I and II of the RAF. These changes included the turbosupercharged Pratt & Whitney R-1830-41 engines and self-sealing tanks that had first been tested on the XB-24B. The turbosupercharged engines were capable of maintaining a rating of 1200 hp to altitudes above 20,000 feet, increasing the top speed to more than 300 mph. With the turbosupercharged engines, the engine cowlings took on a distinctly oval cross section when viewed from the front, a feature which remained with all future Liberators. In addition, the B-24C incorporated the three-foot-longer nose that had been introduced on the RAF Liberator II. The B-24C also introduced a twin-gun Martin Model 250CE-3 power-operated turret on the upper fuselage immediately behind the cockpit (the turret on the LB-30 for the RAF was on the upper fuselage aft of the wing). An interrupter switch was provided to prevent the gunner from accidentally firing into the vertical tail surfaces of the aircraft. A twin-gun Consolidated-designed A-6 power turret was mounted in the tail position, with a total of 825 rounds provided. A single 0.50-inch machine gun was mounted in the nose. Another 0.50-inch machine gun was installed on a flexible mount firing from the "tunnel" position underneath the rear fuselage facing aft. A 0.50-inch machine gun was mounted at each waist position. The total armament of the B-24C was eight 0.50-inch machine guns. The B-24C reverted to Hamilton Standard propellers, as did all subsequent Liberators.
The nine B-24Cs were delivered to the USAAF at the end of 1941. No B-24Cs were to see combat, all nine planes being used for crew training and various tests. They were later redesignated RB-24C, where the R stood for "restricted from combat use".
The B-24C was immediately followed off the line by the B-24D, the first fully combat-capable version.