Any type of wing flapping machine.
A wing flapping machine that imitates bird flight.
A biplane with the upper and lower leading edges in line.
The transfer of hydrogen or other gas through a balloon envelope by a molecular process. This must not be confused with leakage due to holes.
See Boom.
A type of machine adapted for use over "Water and Land."
P
PANCAKE.
A straight vertical drop due to stalling.
The path of the center of gravity of an aircraft in reference to the air.