this aircraft was used for special armament tests for an idea of what it was modified like see also xb-40,yb-40,x/yb-41 (bomber escort) extra 50 cals, 20mm,37mm, 40mm??, you get the idea, another they used for tests with the british 22,000 lb grand slam bomb 11/16/2001 @ 21:49 [ref: 3653]