User Guide

61
Flight Instruction
60
Flight Instruction
A MATTER OF CONTROL:
The lift produced by an airplane’s wing does a lot more than
just hold it up in the air. A car is steered by the side forces gener-
ated by its tires against the pavement. The airplane, though, has
nothing to push against but air, and nothing to push with but its
wing. To get the airplane to move in the direction you want - and
that includes up and down as well as to the side in turns - you
have to direct the wing’s lift in the desired direction and/or change
its amount. This is where the flight controls come in.
You may be using a joystick or a yoke with FLY!, and you
may or may not have rudder pedals, but the basic principle of all
these controls is the same: you’re going to use them to point the
airplane in the desired direction, then use the lift forces generated
by the wing to actually determine where you go. As long as the air
isn’t too bumpy, just about any airplane will fly along quite nice-
ly, continuing in whatever direction it’s pointed without much
attention required from the pilot, as long as all the controls are
centered. (A well-aligned car on a straight road is in a similar situ-
ation.) Where the difference between airplanes and cars becomes
clear, however, is how the controls are used when you want to
make a change.
If you want to turn a car - say, to follow a curve in the road
- you’d turn the steering wheel until the car was turning at the rate
you wanted, then hold it in that position until you’d completed the
turn. In the airplane, it’s quite different. To start a turn, you’ll move
your yoke or joystick to start banking in the desired direction - but
as long as you hold the controls in that direction, the airplane will
continue to increase its bank angle, steeper and steeper. (In fact, if
you held the controls into a turn long enough, the airplane would
perform a complete roll, something not recommended in any of
the five real-world airplanes currently simulated in FLY!).
Instead, move your controls only until you’ve reached the
desired bank angle, then return them to the center. The airplane
will tend to hold that bank angle and continue around the turn,
pretty much on its own. When you want to roll out to level flight,
you’ll actually have to move the controls the other way until the
wings are level once again. Similarly, if you want to climb, pull the
stick or yoke back gently until the nose rises to the angle you want;
then return it to, or near, the center to hold that position. To level
off from a climb, ease the controls gently forward until the nose is
back down where you want it, then re-center them once again.
LIFT IS WHERE YOU FIND POINT IT:
The lift a wing produces is, for all practical purposes, at right
angles to its surface. Bank the airplane into a turn, for example,
and the lift banks with it; instead of lifting straight up, the wing is
now also pulling the airplane toward the inside of the turn. (In fact,
that’s what makes the airplane turn in the first place.) Of course,
this also means that there’s less lift available to counteract the pull
of gravity, so unless we take appropriate measures, the airplane
will tend to sink a bit when it’s turning.
IT’S ALL IN THE ANGLES:
To deal with this, as well as with many
other situations in flight, we have to control the
amount of lift the wing produces. In a turn, for
example, we have to increase the amount of lift
so there’s enough available both to hold the air-
plane up and to pull it into the turn. To do this,
we’ll increase something called angle of attack,
and this is a concept important enough to merit
a few paragraphs in its own right.
The amount of lift produced by any wing is
dependent on two major factors: the speed at
which it moves through the air, and the angle be-
tween the airflow and the wing’s chord line, an
imaginary line between the centers of its leading
and trailing edges. We’ve probably all performed
(and been yelled at for) the classic basic experi-
ment of aerodynamics: sticking our hands out of
the window of a moving car. Tilt the front of your
hand up (increasing the angle of attack), and
your arm rises; tilt it down, and it sinks. This can
occupy simple minds for many miles.
What may have been a bit less obvious
was that it took a lot more tilt to hold the weight
of your arm at lower speeds than at high ones.
Indeed, once the speed got low enough - usual-
ly right before you got dropped off at school - no
amount of tilting would be sufficient, and your
arm would drop painfully onto the doorframe.
You’d reached the stalling speed of your wing -
er, arm. We’ll discuss stalls in considerably more
detail when we start flying the Cessna 172.
Normal Lift
Increasing Angle
of Attack
Stalling
Chord Line runs
thru center
of wing