Today, we invent the helicopter. The University of
Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
created them.
Throughout the 19th century
we tried to fly. We had a highly-honed technology
of lighter-than-air flight before the Wright
Brothers. We'd also spent vast human energy on two
kinds of heavier-than-air flight: flapping-wing
machines and helicopters. We never did master
flapping wings, but helicopters were another story.
Heavier-than-air flight takes three forms:
Airplanes lift off the ground when a
propeller or jet pulls a lifting wing through the
air. A powered propeller also pulls an
autogyro forward; but instead of a wing it
has a large freewheeling propeller on top. But in a
helicopter, the propeller on top is powered.
It lifts the machine directly upward, combining
power and lift in the same place.
Five centuries ago, Leonardo da Vinci suggested the
seductively simple idea that we might pull
ourselves into the air with a vertically mounted
propeller. The idea resurfaced in 18th-century
France. The same year the first balloon went up, a
model helicopter, driven by a bowstring, appeared.
During the 19th century, all kinds of ingenious
helicopter models were built in Europe.
Around 1872 a young French
experimenter, Alphonse
Penaud, managed to stabilize a
rubber-band-powered toy helicopter. He used
counter-rotating propellers at either end of a
vertical shaft, one above, the other below. Bishop
Milton Wright brought a Penaud-type helicopter
model home to his boys Orville and Wilbur, and the
rest is history.
So attempts to build helicopters escalated. Three
years after Penaud made his model helicopter,
Enrico Forlanini flew a steam-powered helicopter
forty feet into the air in Italy. In 1907 Paul
Cornu hovered just off the ground for twenty
seconds in his delicate double-propeller
helicopter. Cornu, like the Wright Brothers, was a
bicycle maker.
Other helicopters were built, but they were all
hard to control. Then the autogyro appeared, and
attention drifted away from helicopters. But Igor
Sikorsky, who'd tried to build one in Tzarist
Russia, finally tried again with vastly improved
technology in America. He succeeded in 1939.
The late '30s actually produced a spate of European
attempts to build helicopters or, in some cases,
autogyros with engine-driven upper propellers. But
Sikorsky built the first pure helicopter that
actually performed well. The Germans soon followed.
The Russians copied the Germans. And we all had
military helicopters in the late years of WW-II.
Helicopters were in people's minds long before
airplanes. But the very simplicity of combining
power and lift in one big propeller led to terrible
design problems. Leonardo, drawn in by its
simplicity, couldn't see how hard it would be to
control motion with a single propeller. Complexity,
masking as simplicity, teased designers for
centuries. Lucky for us, it kept right on teasing
them even after we had DC-3s, Spitfires, and Piper Cubs.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
