Bonjour tout le monde !
I'm launching this topic to gather as much information as possible on one of the most massive objects and most likely to be found regarding the 'White Bird'. This is its propeller.
Before becoming an aircraft manufacturer, Levasseur was renowned in France and Europe for the quality of its propellers. Since 1920, one of his specialties had been fixed-pitch metal propellers of the 'Reed' type (from whom he had acquired the license).
Between 1924 and 1928, Levasseur produced over 150 types of these propellers.
The raw parts were made by Schneider, in Le Creusot, in an alloy specific to this firm: Alférium. These parts were then drilled, machined, shaped and bent to form the propeller pitch in the Levasseur workshops.
The two company had a quite long a profitable partnership here from 1924 to 1935 but finacial weaknesses of Levasseur put an end to it.
Reed propellers were more durable, easier to craft/repair and produced fewer marginal vortices than their wooden counterparts.
In the books I have consulted, Alferium is referred to as Duralumin. There were slight differences anyway.
composition:
Duralumin
Aluminium: 93,5-95%
Copper: 4-5,5%.
Magnesium: 0.5%
Manganese: 0.5%.
Alférium (1922)
Aluminium: 95,15%
Copper: 3,25%.
Magnesium: 0.5%
Manganese: 0.6%.
Silicium : 0,5%
mecanical properties (1929) :
density: 2.85
yield strength: 22 kgs minimum (20 kgs for duralumin)
strength (breaking load): 38 kgs (40 kgs for duralumin)
elongation 16% minimum (20% for duralumin)
Like duraluminium, alférium is quenched at around 450°c.
Alferium is not altered by atmospheric agents or ordinary water. However, it is attacked by salt water and hydrochloric acid.
This comment is, however, theoretical, as depending on the environment of the acidic agents, where the presence of sodium chloride can expose the alloy to significant corrosion.
[edit] I have no idea if Alférium-made propellers were coated by pure aluminium, as alclad items are. [Actually, This is highly unlikely, since the invention of this alloy was not reported until August 1927. From what I've read then, the propellers were most likely varnished.]
From what I've read, Schneider took a long time to find a good compromise between the hardness and ductility of its parts. Alferium generally has a lower copper content than conventional duralumin to improve its strength, but for propeller manufacturers (including mainly Levasseur) this hardness comes at the price of more time-consuming, difficult and costly machining. Also when machined, Alférium (early variants) tends to be more brittle.
Schneider was continuously modifying the components of its product to adapt to its customers' needs. [to be continued below]
