AOPA Pilot Magazine - April 2013 - 22

LICENSE TO LEARN

Bang for your buck

BY ROD MACHADO

Four lessons from steep turns
AS A FLIGHT INSTRUCTOR, I’ve taken a fancy to certain
flight maneuvers that offer a lot of educational bang
for the bank. One of these is the steep turn. From an
airmanship perspective, practicing steep turns is like
receiving a pregnant cat for your birthday. It’s a gift
that keeps on giving.
According to the FAA, the steep turn helps improve
your coordination, control smoothness, division of
attention, and orientation (even if you’re not from
the Orient). All true, and there are additional benefits that the FAA does not even mention. One of these
is the message the airplane sends your way in the
form of an immediate increase in apparent weight, as
if it suddenly qualified for a Jenny Craig weight-loss
scholarship.

The only good thing that comes from an increase
in load factor is the ability to recognize the bad
things that come with it.

ROD MACHADO

is an aviation
humorist, active
CFI, and a member
of the Aviation
Speakers Bureau.

22 | AOPA PILOT April 2013

So what does this message mean? It means the
wings are not only producing the lift necessary to
keep you aloft, but they’re also producing an extra
amount to pull you sideways, too. Your airplane and
its contents (yes, you are contents) always resist
any change in motion and protest it loudly with a
silent increase in load factor. This is why you feel
heavier in the turn, as if your machine and fanny have
suddenly become too fat to fly. Consider this message
the aviation version of a Western Union stall-o-gram:
You’ve just experienced an increase in load factor. Stop. This tells you something. Stop. Your wings
have moved closer to their critical angle of attack.
Stop. Your stall speed has increased. Stop. This is just
one of the many lessons steep turns teach. Please
stay seated with your seatbelts fastened, because
class isn’t over.
In a 60-degree bank, the wings are supporting two
airplanes’ worth of weight. As you pull aft on the yoke
to extract more lift from those wings, the increase in
angle of attack induces them to throw a portion of their
lift rearward—the same direction in which drag acts.
Lift induced to act like drag becomes drag. We call this
induced drag, and it’s the primary reason your airplane
decelerates when turning.

Of all the mischievous things you can do with a pair
of wings, who would have thought you could make them
work in opposition to engine thrust when flying at relatively low cruise airspeeds? Now you know why nothing
happens quickly when you move the throttle forward in
a steep turn. There’s simply more induced drag to overcome. If your machine had barrel-sized pistons under
the cowl, you could accelerate in a steep turn, remaining
above the increased stall speed and below the critical angle of attack. Smaller airplanes can’t accelerate
as well because of their power-to-wait ratio, meaning
that there’s always a long wait for anything to happen
when power is applied—if anything happens at all. This
is another valuable lesson that steep turns teach.
If you didn’t consume too many Pop Rocks in the
early 1980s, you can still visualize what happens to
the airspeed as you enter a steep turn using limited
power or without using power at all. Imagine making a power-off turn to final approach from base leg
with a combination crosswind/tailwind. The unanticipated higher groundspeed results in your overshooting
the runway. You steepen the turn and pull aft on the
yoke, only to find that the previous airspeed margin
above stall has disappeared. Unless you immediately
release elevator back pressure and unload those wings,
you will receive another stall-o-gram—an accelerated
stall-o-gram.
Steep turn practice should teach you at least four
important lessons. The maneuver helps you understand how an increase in bank angle is associated with
increasing angle of attack. It demonstrates how quickly
any airspeed margin above stall speed can disappear as
the bank angle steepens, especially during power-off
approaches. In airplane engines equipped with little
pistons, steep turns teach that you can’t necessarily
trust the thrust to keep you well above an increased
stall speed. Finally, the steep turn teaches you that
the only good thing that comes from an increase in
load factor is the ability to recognize the bad things
that come with it. To make these bad things go away,
you need only unload those wings by releasing elevator back pressure and/or by reducing your bank angle.
If you understand these fundamentals, then
you’ve learned the essence of what steep turns have
to teach.
AOPA
WEB

www.rodmachado.com

http://www.rodmachado.com

AOPA Pilot Magazine - April 2013

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