Excellent. The Challenge picture shows the assembly of the Santos-Dumont hélicoptère designed / built in 1905 / 1906.
It is known that the Dufeaux brothers demonstrated their hélicopter in 1905 in Paris, which attracted great interest in aviation circles. L'Aérophile published a long and detailed article about the Dufaux machine.
As hélicopters were in the center of interest in Paris and together with the prize of Archdeacon-Deutsch of 50.000 Francs (specifically for heavier than air machines) for the first who would fly a distance of 500 meter. Santos-Dumont decided to have a go at an hélicoptère to win the prize. The design was a complex construction consisting of two vertical propellers (diameter 6 meter) to lift the machine in the air and one propeller to move the machine in the vertical. The general arrangement looks like this
The propellers were designed with the help of Victor Tatin. They look from the outside remarkably like the propellers from earlier dirigibles of Santos-Dumont. As can be seen they were of ultra light construction.
Measurement of the Santos-Dumont hélicoptére were impressive, length 12,50 meter - height 6 meter - total weight (inclusive engine) 104 kg
. The construction was made entirely of bamboo (shades of the coming ultra light S-D Demoiselle). The engine fitted was a 24 hp eight-cylinder V-engine of Antoinette-Levavasseur with a weight of 35 kg
The calculated lifting power was 180 kg, which made it theoretically possible that the slender Santos-Dumont could be lifted in the air.
But ... a control calculation made by Archdeacon came to a total weight (inclusive 54 kg weight of the pilot Santos=Dumont) till 212 kg. According to the calculations of Archdeacon the machine was 32 kg
too heavy to be lifted from the ground with this 24 hp engine.
It is not known what happened further and if the machine was completed, but it is certain that it did not win the 50.000 franc Archdeacon-Deutsch contest for a distance of 500 meter covered by heavier than air machines.
See also part 2.