More behind the scenes footage from our friends at BGI supplies, who created the B-17s for the Apple TV series “Masters of the Air.” This video shows the ball turret they constructed for footage shot on the soundstage. In the first segment, you can also see the custom rig they developed to rotate the ball turret for these shots. During WWII, the ball turret was a vital part of the B-17’s defenses, and was equipped with two .50 caliber Browning machines guns to provide fire power from below. The