Enrico Forlanini, was an Italian engineer whose interests included airships, aircraft and helicopters. His hydrofoil developments started in 1898 with a series of model tests from which he arrived at several simple mathematical relationships. These allowed him to proceed with the design and construction of a full scale craft.
Forlanini's designs were characterized by a "ladder" foil system. You can see from a drawing of his concept and a copy of an old photograph what is meant by this aptly named ladder foil. Forlanini's model experiments had shown him that lift was proportional to the square of speed, therefore less foil area was required as speed increased. He conveniently obtained this decrease in foil area with the ladder scheme. The craft weighed about 2,650 pounds and had a 60 hp engine driving contrarotating airscrews. Although designed to fly at a speed of 56 mph, records, according to Leslie Hayward, show that during tests on Lake Maggiore, Italy in 1906 a speed of 42.5 mph was obtained.
Although the foil system was a rather complicated structure, Forlanini's craft operated well and represented an advancement in the state of the art. He obtained a number of British and American patents on his ideas and designs, most of which were aimed at seaplane applications.
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