开敞式炮位最初投入使用的军用轰炸机既有单翼机也有双翼机。一战开始后,双翼机凭借其卓越性逐渐成为各国轰炸机的主力。最初的双翼双座轰炸机的座位布置方式是观察员在前,驾驶员在后。这导致观察员的视野狭窄,不便于射击,所以第二代军用轰炸机中,观察员的位置被挪到后座。这使得他可以使用灵活的机枪保护飞机脆弱而易受攻击的后半球区域。当时 Military bombers that were initially put into use in open-ended cannon have both monoplane and biplane aircraft. After the start of World War I, biplane aircraft gradually became the main force of bombers of various countries by virtue of their excellence. The first two-seat bomber bomber seat layout is the observer in the front, the driver behind. As a result, the observer’s field of vision was narrow and inconvenient to shoot, so in the second generation of military bombers, the position of the observer was moved to the back seat. This allows him to use flexible machine guns to protect the fragile and vulnerable rear hemisphere of the aircraft. then