Flight Training - January/February 2021 - 15
HOW IT WORKS
BY IAN J. TWOMBLY
FLIGHT CONTROLS
THE HUMAN-MACHINE INTERFACE
THE WRIGHT BROTHERS USED A
wooden cradle to warp the wings. Other
builders of the time used a steering
wheel connected to hinged ailerons.
For many years the debate over how an
airplane is best controlled played out
between rival designers. Thankfully by
World War I hinged control surfaces had
won. Can you imagine wing warping a
Boeing 747?
With few exceptions, modern airplanes feature a control stick or yoke
and two pedals that control the ailerons,
elevator, and rudder. What happens
between the hand and foot controls
and the outside control surfaces varies,
depending on the manufacturer. In most
training aircraft a chain and sprocket
system connects the two yokes, enabling
them to move simultaneously. From
there, a series of pulleys and cables run
to the ailerons, elevator, and rudder, sort
of like a cross between a Rube Goldberg
machine and a marionette doll. A Cessna
172 has about five pulleys or guides
between the yoke and each aileron.
In some advanced airplanes, control
is achieved through a series of metal
rods that are directly connected to one
another through bearings. Pushrods
snake their way from the yoke or stick
to the wings and tail through individual
rods of different lengths. Unlike cables,
which stretch and wear over time, pushrods provide a more direct, crisp feel in
the controls.
New airplanes are increasingly doing
away with mechanical control and
trusting the computer to fly the airplane.
Fly-by-wire, long proven in the military
and commercial aircraft arenas, is finally
making its way to general aviation.
In these systems, the stick or yoke is
attached to sensors that send the input
signal to a computer, which is constantly
tracking everything from air temperature to angle of attack. In normal modes
the computer sends the pilot input signal
through wires to a servo near the control
surface, prompting it to move. When
things start to become unsafe, such as
high angles of attack, the computer
becomes a little more assertive and
combines the pilot input with computer
control to help make the correct inputs.
ian.twombly@aopa.org
Rudder
Aileron
Elevator
Pulley
Control cables
Interconnected yokes
STEVE KARP
Bellcrank
Interconnected
rudder pedals
AOPA.ORG/FT
15
http://www.AOPA.ORG/FT
Flight Training - January/February 2021
Table of Contents for the Digital Edition of Flight Training - January/February 2021
Contents
Flight Training - January/February 2021 - Intro
Flight Training - January/February 2021 - Cover1
Flight Training - January/February 2021 - Cover2
Flight Training - January/February 2021 - Contents
Flight Training - January/February 2021 - 2
Flight Training - January/February 2021 - 3
Flight Training - January/February 2021 - 4
Flight Training - January/February 2021 - 5
Flight Training - January/February 2021 - 6
Flight Training - January/February 2021 - 7
Flight Training - January/February 2021 - 8
Flight Training - January/February 2021 - 9
Flight Training - January/February 2021 - 10
Flight Training - January/February 2021 - 11
Flight Training - January/February 2021 - 12
Flight Training - January/February 2021 - 13
Flight Training - January/February 2021 - 14
Flight Training - January/February 2021 - 15
Flight Training - January/February 2021 - 16
Flight Training - January/February 2021 - 17
Flight Training - January/February 2021 - 18
Flight Training - January/February 2021 - 19
Flight Training - January/February 2021 - 20
Flight Training - January/February 2021 - 21
Flight Training - January/February 2021 - 22
Flight Training - January/February 2021 - 23
Flight Training - January/February 2021 - 24
Flight Training - January/February 2021 - 25
Flight Training - January/February 2021 - 26
Flight Training - January/February 2021 - 27
Flight Training - January/February 2021 - 28
Flight Training - January/February 2021 - 29
Flight Training - January/February 2021 - 30
Flight Training - January/February 2021 - 31
Flight Training - January/February 2021 - 32
Flight Training - January/February 2021 - 33
Flight Training - January/February 2021 - 34
Flight Training - January/February 2021 - 35
Flight Training - January/February 2021 - 36
Flight Training - January/February 2021 - 37
Flight Training - January/February 2021 - 38
Flight Training - January/February 2021 - 39
Flight Training - January/February 2021 - 40
Flight Training - January/February 2021 - 41
Flight Training - January/February 2021 - 42
Flight Training - January/February 2021 - 43
Flight Training - January/February 2021 - 44
Flight Training - January/February 2021 - 45
Flight Training - January/February 2021 - 46
Flight Training - January/February 2021 - 47
Flight Training - January/February 2021 - 48
Flight Training - January/February 2021 - 49
Flight Training - January/February 2021 - 50
Flight Training - January/February 2021 - 51
Flight Training - January/February 2021 - 52
Flight Training - January/February 2021 - 53
Flight Training - January/February 2021 - 54
Flight Training - January/February 2021 - 55
Flight Training - January/February 2021 - 56
Flight Training - January/February 2021 - Cover3
Flight Training - January/February 2021 - Cover4
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