tisdag 6 november 2012

Otto Lilienthal: The Flying Man

Otto Lilienthal, German aviation pioneer named the Glider King and The Father of Flight, reported in Birdflight as the Basis of Aviation measurements during 1866 - 89 of The Carrying Capacity of Arched Surfaces in Sailing Flight collected in a set of diagrams giving the lift L for different angles of attack.

The above legendary Table IV shows a lift coefficient C_L= 0.1 x alpha, with alpha = angle of attack (in degrees), of an arched wing with camber 1/12, up to stall at 15-20 degrees (compared to a plane wing with much smaller C_L as the dotted curve).  This is close to the generic formula found to describe many wings, also captured by the basic lift formula of circulation theory.

Lilienthal computed from the diagram that a wing of area of A = 15 m2 should be able to carry himself in sustained flight at a speed V = 10 m/s powered by 2/3 hp. It took 100 years for Lilientahl's dream to come true in the form of the Gossamer Condor on 60 m2 wings at a speed of 5 m/s powered by human 1/3 hp.

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