China's helicopter expo

Chinese Army Z-9WZ attack helicopters, designed and manufactured by China, make a flight demonstration during the 2nd China Helicopter Expo in Tianjin, China, Sept. 5, 2013.

Chinese Army Z-9WZ attack helicopters make an aerobatic flight demonstration during the 2nd China Helicopter Expo in Tianjin, China, Sept. 5, 2013.

A helicopter performs during the 2nd China Helicopter Exhibition in Tianjin, China, Sept. 1, 2013.

A Chinese Army Z-10WZ attack helicopter, designed and manufactured by China, makes an aerobatic flight demonstration during the 2nd China Helicopter Expo in Tianjin, China, Sept. 5, 2013.

Two helicopters perform during the 2nd China Helicopter Exhibition in Tianjin, China, on Sept. 1, 2013.

Chinese visitors try out a EC135 helicopter, manufactured by Eurocopter, on display at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.

A helicopter performs during the 2nd China Helicopter Exhibition in Tianjin, Sept. 1, 2013

Two helicopters perform during the 2nd China Helicopter Exhibition in Tianjin, Sept. 1, 2013.

A paramilitary police officer stands guard near a Chinese Army Z-10WZ attack helicopter, designed and manufactured by China, on display at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.

Visitors watch Chinese Army Z-10WZ attack helicopters performing a flight demonstration at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.

A Chinese Army Z-10WZ attack helicopter, designed and manufactured by China, flies as a paramilitary policeman stands guard during a demonstration at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.

Chinese Army Z-10WZ attack helicopters, designed and manufactured by China, perform an aerobatic fight demonstration during the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.

A Chinese Army Z-10WZ attack helicopter releases flares while performing a flight demonstration at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.

Visitors look at Chinese Army attack helicopters Z-10WZ, right, and Z-19WZ , both designed and manufactured by China, on display at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.

Paramilitary policemen stand guard near a Chinese Army Z-10WZ attack helicopter, designed and manufactured by China, on display at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.

Visitors watch Chinese Army Z-9WZ attack helicopters, designed and manufactured by China, make a flight demonstration during the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.

A man takes a closer look at a replica model of a Chinese Army Z-10WZ attack helicopter on display for sale at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.

A Chinese Army Z-10WZ attack helicopter, designed and manufactured by China, makes a flight demonstration at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.

A Chinese Army Z-10WZ attack helicopter flies over the crowd during a flight demonstration at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.

Chinese Army Z-10WZ attack helicopters, designed and manufactured by China, make a flight demonstration at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.