User Guide

96
97
Cessna 172R -
Intermediate
THE DREADED STALL
In this lesson, we’ll begin by looking at what some students
consider a stressful maneuver - at least (and probably only!) the
first time around. This is the stall: the condition in which the air-
plane is maneuvered to, and past, the critical angle of attack, at
which the airflow separates from the wings and the production of
lift effectively ceases.
Notice that at no point have I said “stalling speed,” and
that’s entirely intentional. I’m trying to underscore, here, that a
stall is solely the result of exceeding the critical angle of attack.
True, in many flight regimes, this exceedance often comes at low
airspeeds - but it’s important to remember that, with a hard
enough pull on the yoke, it can come at any speed. We’ll look at
some of these “accelerated stalls” as we go along.
Let’s begin by getting the airplane up to a safe altitude for stall
practice. This means at least 3500 feet AGL; I’m even happier at
5000 feet. Not that it takes nearly that much altitude to recover from
a stall, of course; in fact, later on, we’ll practice recovering with
minimum loss of altitude. On the other hand, a botched recovery
can eat up quite a bit of altitude, particularly if you let it develop
into a full-blown spin. And since the 172R, when operated in utili-
ty category (no more than two folks, half fuel, and no baggage), is
signed off for spins…yes, we’ll do those, too (urp!).
If you want more practice in engine start, taxi, and takeoff, by all
means use the opportunity. On the other hand, if you don’t want to
take the roughly ten minutes we’ll need to get off the ground and up
to 5000 feet, just pre-position the simulator to an appropriate location
and altitude.
LOOK OUT BELOW!
The first thing we’ll do before any stalls is a couple of steep
turns, one in each direction. These are called clearing turns, and
they serve two purposes. Not only do they loosen you up a bit,
and let you get the airplane “in hand;” if they’re steep enough
(let’s use 45 degrees), they also give you a chance to look out the
side windows and make sure there’s no one flying right below us,
in the airspace we’ll descend into during the stalls.
Flight Instruction
Flight Instruction
First, let’s try something weird: rather than using the yoke,
try to make a turn simply by applying full rudder in the direction
you want to go.
The airplane will, in fact, try feebly to turn; it will even drop
the appropriate wing a little. Mostly, though, it’ll just sort of slith-
er along sideways, going more or less the way it was to begin
with, and with the ball in the turn coordinator all the way to the
outside of the turn.
What’s happening? This is a great illustration of how lift,
aimed by banking, rather than the rudder, is what actually turns
the airplane. All you’ve managed to do is point the nose a bit to
the inside of the turn (and, given enough time, the change in
engine thrust direction will, in fact, change your direction alto-
gether); but it’s pretty ineffective, and also uncomfortable as cen-
trifugal force slings you, your passengers, and the skid-indicating
ball to the outside of the sloppy turn.
Now let’s try the other extreme: rack the airplane over into
a steep turn, using the yoke only, without any rudder pressure.
The ball will drop to the inside of the turn. The nose, however,
may not point all the way into the turn; indeed, as you start the
turn, it’ll momentarily slew in the opposite (outward) direction,
since the aileron on the raised wing produces more drag than that
on the lowered one (a phenomenon called “adverse yaw”).
The function of the rudder is to balance out these forces. In
a properly executed (“coordinated”) turn, the ball will remain cen-
tered throughout, and passengers should not feel “the leans” in
either direction - in fact, if they can’t see out, they shouldn’t even
know you’re turning. The ball will always move away from the
side with excessive rudder pressure, so if in doubt, the rule is sim-
ple: “step on the ball,” adjusting rudder pressure until it’s in the
middle between the index lines.
THE EASY WAY OUT
We’ve done a lot of work for a first lesson. If you’re feeling
feisty, you can try to get the airplane back onto an airport by hit-
ting the M key to bring up a local map, turning the airplane until
you’re headed for a blue or magenta airport symbol, then using
your own combination of turns, descents, and power adjustments
to get down onto the end of a runway. In a real airplane, your
instructor would take you home at this point - if you’re ready for a
break, just hit the Z key to activate Auto Land.