Clark Gable served as an aerial gunner on a B-17 during WW2. He signed up for duty following the tragic death of his wife Carole Lombard, who was on a war bond tour when her plane crashed.
From Instagram: A ball-turret gunner, sits in his position on a B-17 "Flying Fortress" shortly before take off for a mission into Germany, 1943. The ball-turrer gunner was one of the most dangerous positions to have on a B-17. It was cramped and very loud when the guns began to fire. This is why ball-turret gunners were shorter in height compaired to other memebers of the crew. It was also very exposed to flak and had a tendency to jam. Their movement depended on the aircraft's hydraulic system and when the aircraft's hydraulic system was malfunctioning or shot up so bad it wasn't working the ball-turret couldn't move. To exit the ball-turret the gunner would have to point it to the ground so the hatch was inside the aircraft. If the hydraulics weren't working the ball-turret gunner couldn't get out. In most cases this meant the landing gear couldn't be lowered. Unless the crew manually lowered the gear which took a lot of time and effort, they would have to belly land. The majority of crews would choose to belly land, condemning the ball-turret gunner to his fate. As the aircraft hit the tarmac the ball-turret would be instantly crushed and the gunner would go with it. It would of been a very grim and grotesque thing to witness. A famous American soldier/poet, Randall Jarell, wrote "The Death of a Ball Turret Gunner" which captures the brutally and dangers of flying in that position. I highly recommend you check it out.
Major Thomas Ferebee (1918 - 2000), left and Captain Kermit Beahan (1918 - 1989), on the right. Ferebee threw the atomic bomb on Hiroshima, Beahan did it on Nagasaki.