Consolidated XB-41 Liberator

The Consolidated XB-41 Liberator was a single Consolidated B-24D Liberator bomber, serial 41-11822, which was modified for the long-range escort role for U.S. Eighth Air Force bombing missions over Europe during World War II. == Design and development == When the USAAF started strategic bombing in Europe there were no fighters available to escort the bombers all the way to distant targets. The bombers carried several defensive guns and formed up in boxes so that they could provide mutually covering fire but there was interest in providing more firepower for the formation.

Source: Wikipedia — Consolidated XB-41 Liberator (CC BY-SA 4.0)