The Bell aircraft was also unusual in having an engine mounted behind the pilot, with a driveshaft running between his legs, and having a 37mm cannon which fired through the propeller spinner.

• 贝尔飞机也有不寻常的发动机在后面的试点安装，运行与驱动轴之间他的腿，并具有37毫米发射炮而通过螺旋桨旋转。