Adverse Yaw and Coordinated Turns

She explains, “We’re going to do coordinated turns. That means that you coordinate your rudder and ailerons.

“We turn by banking in the direction we want to turn.

“Let’s say we’re going to turn left. We bank left by rolling the wheel left. That raises the left aileron and lower the right aileron. When the left aileron goes up it lowers the lift of the left wing. Less lift means less drag. Your right aileron goes down increasing the lift on the right wing. More lift means more drag. There are two result to this simple movement.

“The greater lift on the right wing causes the airplane to roll to the left. The greater drag on the right wing causes the right wing to be pulled back. That effect causes the nose to yaw to the right. Since you wanted to turn left, that is not good. Let me demonstrate adverse yaw for you. Look straight ahead and watch the nose swing right.”

She abruptly rolls the wheel as far as it will go to the left. The nose swings right for a moment then starts to move back to the left. She levels the wings a bit more slowly and smoothly.

“Now look at the ball. I’ll do the same thing again. Watch the ball shoot out to the left.” She does and it does. “That wasn’t particularly comfortable, was it?”

“Nope. I didn’t like it at all.”

“This is where the expression, ‘step on the ball’ comes into play. That is a way of remembering that if the ball goes out of its little cage to the left, you need to push harder on the left rudder and vice versa.

“By the way, that effect is called ‘adverse yaw.’

“I moved the controls far more violently than you should. I just wanted to illustrate the effect. The less aileron you use, the less rudder you’ll need to offset the adverse yaw. So, like everything else you do in flying, enter and leave your turns slowly and smoothly. You can tell if you’re doing it right by monitoring the ball. Ideally it should not move as you enter and leave turns.”

She demonstrates a slow smooth roll-in and roll-out. The ball never moves perceptively.

“As your angle of bank increases, the wing’s lift becomes less vertical. In fact, the wing’s lift is perpendicular the wings. Of course, it is the vertical component of lift that keeps the airplane at a constant altitude. The result is that the greater the angle of bank the harder you have to pull back on the elevator to keep a constant altitude in a turn.”

She demonstrates this again, going to a thirty-degree bank then returning to wings level. “You can see why it is called a coordinated turn. You have to coordinate your ailerons, rudder and elevator to pull it off. You try it.”

You find that when you get the ball in the center, that you are either climbing or diving. Once you have altitude under control, you notice that the ball is no longer centered. She says, “That’s normal first few times. Don’t be impatient… slow and smooth does it.

“The trick is to look outside of the airplane. See where the horizon cuts across the windscreen and intersects the cowling. If you’re low, raise the nose a bit but don’t change the angle of bank. Now glance at the ball … don’t fixate on it. Just glance at it to see how you’re doing. Before you do anything, look out of the airplane. Only then change rudder, aileron or elevator.

“I think you’ve got it now. Very good. You’re going to fly us back to the airport and I’ll work the radios. A few degrees before we are pointed at the airport start to roll to wings level. You roll out of a bank just like you rolled into a bank with one exception. As the angle of bank get shallower, relax your back-pressure on the elevator until you are not pulling back noticeably when you come to wings level.

“That’s why I don’t trim my elevator in an airplane this size. That way the elevator is very nearly properly trimmed when I exit the trim.

“Okay, this is a good place to start your roll-out… it looks like you have to give us a little corrective turn in the opposite direction. It takes a few times to get it down right.

“Reduce your power to 2000 RPM, push your mixture full in, keep your airspeed at 90, except when you consciously decide to turn, keep your wings level with ailerons and the nose pointed straight ahead with your rudder.

“We’re going to call it a day.

“Tomorrow, you’ll take off.”

After the thousands of hour that I have flown, I still practice slow flight and stalls. Their importance was driven home to me when I read the accident report of the Air France Airbus 340 that crashed because the pilot failed to recognise the symptoms of an impending stall — something that every student pilot masters before soloing. Like many flying skills, detecting the onset of a stall is a perishable skill. Look for Slow flight and Stalls can be very Exciting. You’ll enjoy it.

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