During World War II, complaints from the operational theatres concerning lack of aircraft performance could often be traced to the fact that the aircraft was being operated under conditions far in excess of design specifications. Yet when changes were made to improve lagging performance, the theatres invariably used these improvements to further increase maximum loads instead of taking the improvement in terms of the increased performance that was originally requested.
Under this axiom, the B-24J was as a routine being flown on missions at gross weights in excess of 36 tons and flying characteristics suffered accordingly. Liberator controls had always been heavy, and continual addition of weight made them worse. It was extremely difficult to fly a tight formation with the B-24J, and so tiring that many pilots found it physically impossible after a few hours. The slow rate of roll, an inborn characteristic of the Liberator because of the large wing span, had been made slower by the addition of the outer wing tanks. Initial climb of a combat-loaded B-24 was slow, usually taking about six minutes to reach the 1,000 ft mark. Visibility from the flight deck was inadequate for formation flying. Because of the manner in which the side windows sloped inward, the pilot and co-pilot had be be seated low in order to have enough head room. This made it difficult to see over the instrument panel. In addition, the astrodome and the top of the nose turret were directly in front of the windshield which, to begin with, was considered too narrow and already partly blocked by the above-the-dash location of the compass. Furthermore, the side windows were so small that it was dangerous for the pilot to put his head through the window while taxiing. Lack of visibility from the nose compartment was equally serious—the only way the bombardier could adequately see was to get down on his hands and knees, and it was impossible for the navigator to help in target identification because of the lack of window area.
The Eighth Air Force experimented with various means of reducing the weight and visibility problems of the Liberator, including the removal of all ball turrets in July 1944 and the addition of various additional window areas in the nose. General Doolittle eventually rejected the Liberator on the grounds of too much weight and too little visibility and it was his intention, if sufficient B-17's could be obtained, to convert the entire Eighth Air Force to the Fortress.
— The B-24 Liberator: A Pictorial History by Allan G. Blue, pp. 61 and 63