During the years after the flight of the
Silver Dart and up to the start of the
First World War, Bell used his laboratories to develop hydrofoils. Dr. Bell and, long-time collaborator,
Casey Baldwin started their first major designs of hydrofoils in 1911 after viewing
Enrico Forlanini's
hydrofoil while on a world tour in Italy in 1910. In order to build the experiments labelled
HD 1,
HD 2,
HD 3, and
HD 4, (HD standing for Hydrodrome) Dr. Bell and Casey used the laboratories and staff to construct the various pieces needed. As work progressed on the hydrofoils the main focus was for them to become submarine chasers. Before a full working prototype could be completed
World War I broke out. As a citizen of the neutral
United States, Dr. Bell did not want to risk breaking his country's neutrality law. So he switched the boatyard's focus from developing the military applicable HD vessels to building life boats for the Canadian Navy. == World War I ==