Naval Museum Constanta Flak 8.8 German naval AA gun Krupp 40mm Bofors German naval AA gun 37mm German naval AA gun 37mm Flak 18 German naval AA gun 20mm Flakvierling C38 naval German AA gun quadruple 20mm C30 Rheinmetall German AA naval gun 14.5 mm Russian anti-aircraft naval machine gun 76.2mm British naval AA gun Armstrong