Aerodynamic of the ellipse where the area at point DD is small. The small area creates less resistance for the plane while in flight.
H. Barber The Aeroplane Speaks (New York, NY: Robert M. McBride & Co, 1917)
2400×1377, 937.3 KiB
1024×587, 137.6 KiB
640×367, 71.5 KiB
320×183, 24.5 KiB