Although
fixed-wing aircraft receive all the attention by most historians,
helicopter flight was the first flight envisioned by man. In fact,
the ancient Chinese were playing with a hand-spun toy that rose
upward when revolved rapidly and as early as the mid 1500's, the
great Italian inventor Leonardo Da Vinci had used his fertile mind
to make drawings of a machine that we now know as the helicopter.
His design, like many others to follow, would work theoretically
but would have been impractical in full-sized form.
Many extraordinary models were developed by an ever increasing
number of great thinkers, but all the pioneers were missing two
essentials: a true understanding of the nature of lift and an adequate
engine.
The great breakthrough came at the end of the nineteenth century.
The invention of the internal combustion engine made it possible
for the pioneers to develop full-sized models with an adequate
power source. It was then they found the first of many great problems:
torque, the effect produced by the rotor to force the fuselage
to rotate in the opposite direction as the engine.
The beginning of the 20th century saw the pioneers experimenting
and resolving many of the problems that appeared with each advancement.
The old saying,"One step forward and two steps back," was
the order of the day for the early pioneers. Dissymmetry of lift,
the action that tended to cause the early helicopters to flip over,
confounded the early pioneers until the invention of the swashplate.
The swashplate, with cyclic pitch control allowed the rotor blade
angles to be altered so that lift would be equal on each side of
the central shaft.
However, there were many problems that had not been worked out
on any one individual helicopter. Then on November 13, 1907, the
French pioneer Paul Cornu lifted a twin- rotored helicopter into
the air entirely without assistance from the ground for a few seconds.
After that, several models were produced by many designs but there
were no more great advances until another French pioneer, Etienne
Oehmichen, became the first to fly a helicopter a kilometer in
a closed circuit in 1924. It was a historic flight taking 7 minutes
and 40 seconds.
Advances began to come fast and furious. One of the more important
advances in the development of vertical flight was made by the
Spaniard Juan de la Cierva. His design, called the autogyro, was
not a true helicopter but his contribution was very important.
By 1936, many of the problems had solutions and with the introduction
of the German Focke-Wulf Fw 61, the first practical helicopter
was a reality.
Vertical flight was not a dream anymore.
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