How to stay on Altitude without Concentrating Intently

Now your instructor decides to introduce one more control – a control you’ll learn to appreciate and use frequently: the elevator trim.

During your walk-around you noticed a small hinged flap on the trailing edge of the elevator that your instructor called a ‘trim tab.’ And in the cockpit below the throttle, mixture and carburetor heat controls, you saw a knobbed wheel about 4 to 5 inches in diameter mounted on a horizontal axis. This is the trim tab control.

Like many other controls in the cockpit, it is frequently simply referred to by the name of the surface it controls – the trim tab.

The trim tab control moves in the direction you want to move the airplane. Since you have access to the back of the knobbed wheel, you pull up on the back of the wheel to lift the back of the airplane.

She tells you that in airplanes equipped with aileron trims, the control is mounted vertically on a longitudinal axis so when you want the aileron trim to apply left aileron force, you rotate the control to the left. The rudder trim is typically a horizontal knobbed wheel that rotates around a vertical axis. She mentions that they are typically clustered together below the engine controls. But that is in far more complex airplanes. This one only has an elevator trim wheel.

She advises to keep the elevator trimmed so you don’t have to continuously push or pull on the elevator.

Once again, she emphasizes being mentally outside of the cockpit. In this case you want to maintain constant altitude without needing to exert force on the elevator. So you look at the horizon and keep a constant distance between the horizon and the top of the cowling as you turn the trim wheel.

She explains that since she had trimmed the airplane for climb airspeed and cruise speed is always higher than climb speed, you have to push forward on the elevator to keep the nose from rising. Once your hand is on the trim wheel, you focus forward, intent on keeping the horizon in the same place relative to the top of the cowling. You start pulling up on the back of the trim control. You continue to rotate the trim wheel forward with your right hand until you no longer need to exert force on the elevator with your left hand.

She starts to philosophize a bit now, “One of the secrets of flying like a pro is to do everything you can to make your job as easy as you can. That’s why to want to keep the airplane trimmed … you don’t have to focus on your elevator. You do everything you can before you land … you just focus only on landing. Before you takeoff, you trim the airplane for climb, set the altimeter to field elevation, etc. etc. and many other situations.”

She continues to lay the foundations of flying, “Straight and level flight is the most fundamental ‘maneuver’ in flying. You know that you’re doing it right by looking at the wings and noting that both are the same distance above or below the horizon. The airplane is not turning and you are neither gaining nor losing altitude. Try to imprint this image in your mind.

“I want to make a very important point here: These are the criteria – not turning, not climbing or descending with wings level. Many pilots look at the ball to check themselves. That’s wrong. If the ball is not centered but the wings are level and the plane is not turning, then the ball is wrong. It happens more often than you might think.

“My last point on this subject is that you keep the wings level with the ailerons and keep the airplane from turning with your rudder. Because virtually all pilots learn to drive before they learn to fly, they tend to use the wheel – meaning the ailerons – for directional control. I want you to develop the right habit from the start… so focus on pointing the airplane with your rudder and controlling angle of bank with ailerons.”

She sticks a rubber disc (called a no-peeky) over the turn and bank instrument, hiding the ball. You fly straight and level for a few minutes until she is satisfied that you have mastered the maneuver without depending on the ball.

Your instructor continues her monologue: “Now we’re going to do a gentle descent straight ahead. We’re going 90 knots indicated now. I want you to maintain 90 KIAS (knots indicated airspeed). That means that you’ll use your elevator to control airspeed and not altitude. Continue to point straight ahead with your rudder and keep your wings level with your ailerons. Reduce your power to 2,000 RPM and keep the elevator trimmed.”

As you reduce power, your nose drops and the airplane accelerates. After you land, you ask your instructor about this. It is certainly counterintuitive that the airplane would go faster when the engine is producing less power.

Her explanation is that the propeller is not blowing as much wind across the elevator making it less effective. She goes on to say that light airplanes have inherent pitch stability because the faster they go, the more the tail pushes down making the airplane fly just a little more level, descent a little less so it flies a little slower. Conversely when the airplane goes slower, the tail tends to rise. When the tail rises, the airplane dives more and accelerates. These two tendencies balance each other out at what is know as the trim airspeed. You change that ‘equilibrium’ airspeed with the trim tab.

Once again, you find this to be a little much to assimilate quickly and resolve to find a reference that explains it with diagrams and perhaps a video. Back in the cockpit, you find that you’re trimming the nose up to maintain 90 KIAS. You need almost no pressure on either of the rudder pedals to keep the nose from turning.

Now she puts another no-peeky over the airspeed indicator and tells you go to full power and to climb at the ‘same airspeed we were using before.’ You know to go to the pitch attitude that you used earlier. After trimming the pressure out of the elevator, you are climbing at a constant and steady pitch attitude. She removes the no-peeky and says, “Congratulations! You’re within a knot of the climb airspeed. Your instructor says, “You’ve got that down pretty well. Let’s go into turns.”

I’ll get into turns later. In my next post, we discuss radios. Look for Communicating over Aviation Radios is an Acquired Skill

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