Fuel tanks, reduced guns, and the improvised bombsight

Crews removed the lower turret and liaison radio to save weight and fitted deicing equipment for the long flight. Steel blast plates protected the fuselage near the upper turret. A collapsible neoprene tank and additional fuel cells increased capacity from roughly 646 to 1,141 US gallons. Broomsticks in the tail cone simulated defensive guns without adding the weight of weapons and ammunition. Captain C. Ross Greening's Mark Twain bombsight replaced the Norden sight at a stated cost of about 20 cents. Each aircraft carried three 500-pound high-explosive bombs and one 500-pound incendiary, with some bombs carrying returned Japanese friendship medals.