"A strange glider of Frenchman Dervaux during games on the plateau of Auvergne / France. Photo 1922" (via)
from Paul Dunlop:
"This flying machine is the Somalvico So.1 "David", built by Guiseppe Somalvico in Lake Como, Italy, 1921. The two discs, above and below the cockpit, are supposed to spin around, and generate lift in the same way that frisbees and discuses do."
The Douglas C-1 air ambulance, circa 1928
A modified Dayton-Wright USD-9A became, in 1921, the first aircraft to feature a pressurised cockpit. The aircraft had “..an airtight spherical chamber in place of a cockpit. The chamber had only a control stick and small portholes to view the instruments, which had been located outside..” (via)
"Black and white photograph of a La Cierva Autogyro C-6 aircraft made by Juan de la Cierva, which made its maiden flight in 1924. It was a prototype aircraft vertical takeoff and landing. It was built on the fuselage of an Avro 504. This model began rotating the rotor by a rope pulled by several men” (via)
"Original caption:5/26/1928-Rockford, IL - Robert Myers of Rockford, IL, has invented an ornithopter, which he designed after an intensive study of heavy birds in flight, particularly the great horned owl. The above photo shows Myers seated in his wing-flapping ornithopter, the wings of which have not as yet been covered. He will attempt a test flight soon." (via Corbis)