In 1933 Germany's largest shipbuilder Blohm & Voss in Hamburg opened an aircraft subsidiary under the name of Hamburger Flugzeugbau. RLM assigned this factory the designation prefix of Ha. However the connection with Blohm & Voss was just too strong and the aircraft coming from the Hamburger Flugzeugwerke were commonly known as 'Blohm & Voss type Ha xxx' .