Ruthenberg built a flapping wing monoplane (‘Schwingenflieger’ in German) in 1909. In his complex construction the wings were moved (flapped) by rods moved by an engine which was mounted in the fuselage. The same engine also drove two pusher propellers in contrary motion. The undercarriage was fitted with a four wheel undercarriage. To make the tests of this machine less dangerous a small balloon was mounted in the fuselage, which as was said could lift the machine almost on its own. Tests revealed that the machine did not leave the ground.
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