Ancient wooden post mill

From the 1600s, I think.

 

Seen at Museumsdorf Cloppenburg, Germany in the summer of 2017.

 

A post mill is mounted on a vertical axis and can be rotated into the wind by pushing the long beam that sticks out to the back. Turning the mill was hard work, though.

 

Note the warp in the sail structure to optimise the angle of attack of each section of the airfoil. The farther out the section, the faster the flow speed, so the angle of attack had to be reduced. This design shows quite some understanding of the principles of aerodynamics, at a time when aircraft were still hundreds of years in the future.

 

The tower mill design made things easier. There, just the top part with the rotor and sails was rotated. Later this happened automatically via the fantail at the back end of the cap.

 

Leica IIIa (AGNOO), made in 1938

Camera received a CLA in 2017 at Leica Gallery Frankfurt

Leitz Summaron 35mm f/3.5 (SOONC), made in 1948

Ilford Pan-F Plus professional grade B&W film

Developed and scanned by www.meinfilmlab.de

Done