The turrets on the earlier models (B-17F) are supplied with F-l type
cylinders having a capacity of approximately 14 cubic feet when fully
charged to 450 pounds. Under these conditions a fully charged bottle
lasts one man approximately 2 hours. (Note: these bottles are recharged
from the ship's supply during flight, so it will not be possible to
fully charge them after several hours of flight on oxygen. They will be
no fuller than the pressure in the system from which they are
charged--front left system for top turret; rear left system for ball
turret).
[Illustration: Fig. 10 OXYGEN SYSTEMS B-17G]
B-17G models are modified so that the turrets are supplied oxygen
directly through a flexible hose -- the top turret from the front left
system -- the ball turret from the rear right system. The same changes
may be found in the ball turret of the B-24.