As the Eighth Air Force began its daylight bombing campaign over Europe it soon discovered that its formations of four engined heavy bombers could not defend themselves against German fighter attack, and losses began to reach unacceptable levels. The eventual solution to the problem was to extend the range of the P-38 Lightning and P-51 Mustang escort fighters, but this would take time.
One alternative that was serious considered was the possibility of creating heavily armed “escort fighters” based on the B-17 Flying Fortress and B-24 Liberator bombers. This approach would have one big advantage – the basic aircraft already existed, and had the range required to accompany the bombers, so if the idea was a success then it would not take too long to produce a large number of these gunships.
The XB-41 was the escort “fighter” based on the B-24 Liberator. It was armed with a total of fourteen .50in machine guns, three to five more than the standard B-24D (which could carry either one or three guns in the nose, two in the waist positions and two each in dorsal, ventral and tail turrets). All fourteen of the guns on the XB-41 were carried in twin gun mountings or turrets. The nose gun or guns were replaced by a twin gun chin turret, similar to the one used on the B-17. A second dorsal turret was added, just behind the wing. Two guns were carried in power boosted mounts in each waist position. The remaining six guns were carried in the standard ventral, dorsal and tail positions. The XB-41 was to carry 12,420 rounds of ammunition. The final aircraft was 6,000lbs heavier than a standard B-24D.
Work on the XB-41 began in the summer of 1942. The completed XB-41 prototype was delivered to the Army Air Force Proving Ground at Eglin Field on 29 January 1943, for the start of two months of trials. On 16 March 1943 the design was approved, a step that would have led to the production of YB-41 service test aircraft, but five days later, on 21 March 1943, the project was cancelled.
This sudden change was triggered by experience with the YB-40, based on the B-17 Flying Fortress. Work on this progress was much more advanced, and a small number of aircraft had actually entered combat over Europe. Two serious problems soon emerged. The first was a technical issue – the heavily loaded YB-40 could keep up with the B-17s on the way out, while they were carrying their bombs, but once the bombers had dropped their bombs, their speed increased, and the heavy YB-40 was unable to keep up. The second problem was that the idea simply did not work. Despite all of the extra weight, all that was achieved was to add a few more guns to the firepower of a bomber formation, and combat experience suggested that these extra guns made little or no difference to the number of losses suffered. The concept of the heavily armed gunship escort “fighter” was abandoned in favour of the conventional escort fighter.