Dave, the 8H12 aerofoil does not look like the one that Cornu used, whatever the terminology:
From this thread:
http://rotaryforum.com/forum/showthread.php?p=66738
Originally Posted by Dave Jackson
Momentum Theory,
which Leishman used to evaluated Cornu's helicopter, considers a rotor disk that has; ideal twist, constant chord, no cutout, and a consistent induced velocity across the surface of the disk. As you can see from the pictures, Corn's rotors are about as far as one can get from the momentum theory actuator disk.
Which would be why he chose a sensible Figure of Merit of 0.5. He also justifies this choice with typical FM values throughout the century.
In 1907 hardly anyone knew about either Reynold Number scaling or about Prandtl aerofoil theory. In fact few understood how to build a flying machine. Cornu's accomplishment was impressive regardless or not of whether it hovered long enough to be photographed.
Several potentially useful applets:
http://www.geocities.com/CapeCanaver.../nvfoilen.html
http://www.mh-aerotools.de/airfoils/javafoil.htm