An Italian professor, Enrico Forlanini, had an ingenious idea for overcoming the weight of a boiler and its hearth: shortly before his experiment started, he forced steam superheated to a pressure of about 10 kilos per square centimetre into a small metal sphere, from which a calibrated valve allowed it to escape into the cylinders.
The complete assembly, including the two rotors, weighed hardly more than 3.5 kilos. It successfully became airborne, and in 1878 actually rose to a height of nearly 13 metres, where it remained for some 20 seconds.
P.Lambermont "Helicopters and Autogyros of the World", 1958
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One of the most ingenious solutions was that adopted by Enrico Forlanini, who flew a model helicopter in 1877 with a pair of two-bladed, coaxial, contra-rotating rotors, using a steam engine fed by a small boiler heated by a stove which also served as a stand for the model when at rest.
The helicopter was officially demonstrated at La Scala in Milan. It rose to about 13m.
G.Apostolo "The Illustrated Encyclopedia of Helicopters", 1984