User Guide

Learning To Fly with Rod Machado
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Tutorial 5: Stalls
You did your homework, right? (Click the Help menu, then click Homework.)
Several years ago a farmer called the fire department to report that his barn was on fire. The fireman
said, “Okay, we’ll be right over, but how do we get there?” With his country drawl the farmer replied,
“Well, you still have that big red truck, don’t ya?”
That’s what psychologists call a communication problem. Flight instructors have a similar problem
with the term stall. Some people think a stall is where the airplane is kept at night or what you do
when you have a lot of aviation homework to complete. Seriously, though, many people think it has to
do with the airplane’s engine faltering, since that’s how a car stalls.
Actually, it’s none of these; stalls have nothing to do with the engine at all. Stall is a term identifying
what happens when the smooth airflow over the wings is disrupted, thereby preventing the airplane
from developing sufficient lift for flight.
Sharp student that you are, I’m sure you’re thinking, “Why do I need to learn about stalls in the first
place?” The sad fact is that pilots continue to accidentally stall airplanes. They may become
distracted and let their airspeed get too slow for a given condition of flight or they get a little too
aggressive on the flight controls. Either one can cause an airplane to stall. The solution to this
dilemma is to recognize the onset of a stall and prevent it from occurring in the first place. And, if you
accidentally enter one, know how to recover quickly with a minimum loss of altitude.
When stalls happen close to the ground, such as when approaching to land, it can be a real downer
for the pilot. And I mean that both figuratively and literally. That’s why I’m here: to teach you to
identify a stall, prevent it from happening and, if it happens, show you how to recover. So let’s get
started.
First, a Little Theory
I’ve assumed that you’ve completed your homework assignment. If not, now is a good time to do so.
No stalling here!
In Tutorial 4, I showed how, in order to maintain sufficient lift for flight, the wing’s angle of attack
increased as the airspeed decreased. Perhaps you’ve wondered if there is a limit to how much the
angle of attack could increase. After all, common sense suggests there are limits to all things. The
ancient Egyptians had common sense limits, especially regarding the size of pyramids they could
build (I think this is known as Tut-an-kommon sense). Wings have limits, too.
In the stall homework you observed air begin to burble over the top of the wing when the wing
reached a very large angle of attack (about 18 degrees for most airplanes). The angle at which the air
begins burbling, followed by the wings stalling, is known as the critical angle of attack.