10 Nov. 1942: A specially equipped B-17F loaded down with 16 .50-cal. machine guns was designated the XB-40 "escort bomber" and made its initial flight on this date.

The big changes were the addition of a "chin" turret under the bombardier's nose position, a second upper turret over the radio room behind the bombay, and twin .50-cal. machine guns mounted in each waist window. Rather than carry bombs, the aircraft carried additional ammo that brought its gross weight to 6,000 more pounds than a fully loaded B-17F.

This proved to be too much for the YB-40s, which couldn't keep up with the bombers they were supposed to protect. In the end, the project was scrubbed in the late spring of 1943. The one positive development was the decision to make the chin turret standard equipment on the B-17G.

ILLUSTRATIONS: (1) The gunners on a 92d BG YB-40 experimental gunship blast an Fw-190A out of the sky and damage another over Oldenburg, Germany, on 25 June 1943. (2) The prototype XB-40 was made by Lockheed-Vega by converting the second production model of the B-17F, which was retained at the factory. (3) This diagram depicts the machine-gun positions in the YB-40 gunship. (4) The redesigned ammo feed system for the waist guns, ball turret, and central upper turret inside the YB-40 gunship. (5) Closeup of the modified waist guns and second upper turret mounted over the radio room on a YB-40 gunship. (6) Disney artwork applied to the fuselage of the Lockheed-Vega XB-40.