those on a real .50 caliber machine gun.
When the image is thrown on the screen,
they can see the wing tips of their own
bomber, as well as the approaching fighter.
They lead it in their standard Mark 9
reflector sights, pulling the trigger when
they think they are on the correct "point
of aim." If they are in a free-gun position,
instead of a turret position, the gun handles
start jumping, the vibrations carefully
reproduced to simulate those of a real gun.
Through earphones they can hear the
authentic sound of their own guns. When a
hit is scored, it sounds a 1,000-cycle
"beep" in their ears and moves a register
on the instructor's control panel. The
Army Air Forces also use the Waller