The Focke-Wulf Fw 190’s canopy rails are not parallel. They taper inward as they extend toward the tail. As the canopy slides backwards on these rails, Focke-Wulf designers came up with a solution to make sure the brittle acrylic glass doesn’t crack. A hinge at the top front edge of the canopy relieves the pressure, actually making the canopy slightly taller and narrower when it is in the open position than when it is closed. The bowing canopy is an ingenious engineering feat, but it’s also a nightmare for modelers to accurately depict!