Table of Contents

1. Why Lift Matters
2. Wings: The Main Lift Producer
3. Lift vs. Weight (Steady Flight)
4. Two Ways Airplanes Create Lift
5. Bernoulli’s Principle (Written Exam Focus)
6. Venturi Effect Explained
7. Low Pressure Top / High Pressure Bottom
8. How to Increase Lift
9. Relative Wind: What It’s Made Of
10. Why We Take Off and Land Into the Wind
11. Camber and Airfoil Shape
12. Flaps: More Camber, More Lift, More Drag
13. Angle of Attack (AOA)
14. Newton’s Third Law
15. Using Lift Knowledge to Control the Aircraft
16. Increase Power/Airspeed (No Yoke Pull)
17. Lower Flaps (Camber Increase)
18. Pitch Up (AOA Increase + Airspeed Bleed-Off)
19. Wrap-Up + Next Lesson Teaser

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Why Lift Matters

If you want to learn how to fly, you really need to understand a few basic things about aerodynamics. In the last lesson we talked about the four forces that affect an aircraft in flight, but today I want to focus on lift.

I think we can all agree that LIFT is possibly the most important aspect of flying, so let's dig right in and talk about what you should know.

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Wings: The Main Lift Producer

Hopefully, you already noticed this, but airplanes have these things called wings. Wings are an important part of creating lift—actually, on most airplanes, they’re the only part that creates lift.

Our wings use two things to create lift:

• Relative wind
• The Shape of the Wing

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Lift vs. Weight 

I don’t want to insult your intelligence, but as I mentioned in the last lesson: lift is an upward force that opposes the weight—the weight of the aircraft and everything onboard.

Remember: in steady, unaccelerated flight, lift equals weight.

But if we want to climb or create more lift, we have to do something. We’ll get to that more in a minute, but for now, let’s take a look at how an airplane creates lift.

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Two Ways Airplanes Create Lift

There are really two ways an airplane creates lift, and we’re going to discuss both. But for the written exam, the FAA mainly wants you to know about something called Bernoulli’s Principle—so let’s take a closer look.

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Bernoulli’s Principle (Written Exam Focus)

In a nutshell, Bernoulli’s Principle states that as the velocity of a moving fluid increases, the pressure within that fluid decreases.

When air moves faster, pressure is reduced. When air moves slower, the pressure is higher.

The top of an airplane wing is curved. Because of that curve, air moving over the top of the wing has to travel faster than the air underneath it. Since the air on top is moving faster, it creates lower pressure. The air underneath is moving slower, so it creates higher pressure.

That higher pressure under the wing pushes upward toward the lower pressure on top. That upward push is what helps lift the airplane into the air.

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Venturi Effect Explained

Narrow areas like this force a fluid to increase its speed. You’ll sometimes hear these narrow areas referred to as a Venturi.

When air (or any fluid) is forced through a narrow space, it has to speed up to get through.

As the air speeds up in that tight space, its pressure drops. So whenever you see air moving faster through a narrow area, remember this simple rule:

Faster air = lower pressure.

This happens because the air has a certain amount of energy. When it speeds up, more of that energy goes into motion, and less is left for pressure. A simple example is putting your thumb over the end of a garden hose—the water speeds up as the opening gets smaller. In the same way, the curved top of an airplane wing acts like a Venturi, helping the air move faster and lowering the pressure above the wing.

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Low Pressure Top / High Pressure Bottom

Just like a Venturi, the curved surface of the upper wing forces the air on top of the wing to travel faster than the air on the bottom of the wing.

• Faster air on top creates an area of lower pressure on top of the wing
• Slower air below creates an area of higher pressure on the bottom

And what do you think happens when you have low pressure on top and high air pressure on the bottom?

That’s right: the high air pressure pushes the wing up—creating an upward force, and that’s what we’re calling lift.

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How to Increase Lift

To increase lift, we can do a few different things. One of the ways is to increase the speed of the air going over the top of the wing.

When we add more power, the airplane moves faster, which increases the airflow over and under the wings. As that airflow speeds up, the pressure difference between the top and bottom of the wing becomes greater, creating more lift. This is why increasing airspeed can cause the airplane to climb, even without pulling back on the controls.

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Relative Wind: What It’s Made Of

We call the air going over and under the wing relative wind, because it’s a combination of multiple different types of wind:

• Wind caused by thrust: as we increase the thrust our aircraft is producing, the speed of air going over the wings increases as well.
  
  
• Prop wash: the backwards wind caused by the propeller pushing the aircraft forward—like a fan blowing on you when it’s hot outside.

• Actual outside wind:you have absolutely no control over it.
  • Sometimes you have a headwind that helps you create more lift.
  • Sometimes you have a tailwind that takes away some of your relative wind.

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Why We Take Off and Land Into the Wind

This is actually one of the reasons why we take off and land into the wind. This gives us the most amount of relative wind possible so our wings can produce plenty of lift.

When we face into a headwind, the airplane reaches the required lift speed at a lower ground speed. That means a shorter takeoff roll and better performance. During landing, it also allows for slower ground speed, better control, and a shorter landing distance.

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Camber and Airfoil Shape

The other thing we can do is change the shape of the wing. Another name for this side-angle view of the wing is an airfoil.

When we change the airfoil design and make it more curved on top, this increases something called the camber of the wing.

This simply means the air on top has to travel even faster than the air on the bottom.

That creates even less pressure on the top of the wing, which creates more lift—but this also increases the drag on the airplane.  This makes it difficult to fly really fast when the wing has a high camber.

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Flaps: More Camber, More Lift, More Drag

Increasing camber increases lift, but it also creates more induced drag.

One way we can increase the camber on our wings is by lowering the flaps on our aircraft. This lengthens the upper surface of the wing, which creates more lift—but it also increases drag on our airplane.

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Angle of Attack (AOA)

Another way we can increase the lift our wing produces is to increase the angle of attack
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I’m going to go into a lot more detail on this in the next lesson, but in a nutshell, this means we’re raising the nose of our airplane so the relative wind has to travel a longer distance around the upper surface of the wing.

Our lift is increased when we do this—because wind on the top has to travel even faster, just like when we increased camber.

But once again, increasing our angle of attack increases our induced drag because we’re exposing a bigger portion of our wing to the relative wind.

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Newton’s Third Law

Another thing that creates lift is Newton’s Third Law, which says that for every action there’s an equal and opposite reaction.

We know Bernoulli’s Principle creates lift by creating lower air pressure on the upper surface of the wing. But in addition to that, air can strike the lower surface of the wing and push it up.

When relative wind hits the lower surface of the wing, it pushes the wing up and back. And when we raise our wing to a higher angle of attack, there’s more surface area on the bottom exposed—allowing the wind to push the wing up and back even harder.

So as we increase angle of attack, lift increases, but drag also increases.

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Using Lift Knowledge to Control the Aircraft

Right now you might be thinking, “Who cares? I want to fly airplanes. I don’t want to be a NASA engineer.” Well, me neither—but check this out...

Now that we know the things that cause lift, we can start using that knowledge to control the aircraft.

If I trim the airplane out for level, unaccelerated flight, but I want to increase my lift. What’s something I can do?

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Increase Power/Airspeed

If the airplane is trimmed for level, unaccelerated flight. The controls are set so it naturally maintains altitude without constant input. BUT, what would happen if I added power, instead of pulling back on the yoke?

As engine power increases, thrust increases. That added thrust causes the airplane to accelerate, increasing airspeed. With greater airspeed, more air flows over and under the wings. This stronger airflow increases the pressure difference between the top and bottom of the wing, producing more lift.

Since lift now exceeds weight, the airplane begins to climb—even though you never pulled back on the controls. The only change was adding power, which increased airspeed and, in turn, increased lift.

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Lower Flaps (Camber Increase)

Another way to increase lift is by increasing the camber of the wing. Camber refers to how curved the wing is. When flaps are lowered, the upper surface of the wing becomes more curved, effectively increasing its camber.

If the airplane is flying within the safe flap operating range (the white arc on the airspeed indicator), lowering the flaps changes the wing’s shape. This increased curvature causes the air traveling over the top of the wing to move faster and creates a greater pressure difference. As a result, lift increases, and the airplane will begin to climb.

However, increasing camber also increases drag. While lift improves, the added drag slows the airplane down. That’s why airspeed typically decreases when flaps are extended. Once the desired effect is achieved, retracting the flaps reduces drag and allows airspeed to build back up.

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Angle of Attack Increases... Airspeed Bleeds Off

Another way to increase lift is by increasing the angle of attack, which simply means pitching the nose of the airplane upward. When the nose rises, the wing meets the relative wind at a steeper angle.

As the angle of attack increases, lift increases—up to a certain point—because more of the wing’s surface is exposed to the airflow. However, this also increases induced drag. As drag increases, the airplane naturally begins to lose airspeed if additional power is not added.

For example, if the airplane is maintaining level flight at 2,600 feet and the pilot pitches the nose up without adding power, lift initially increases. But because drag also increases, airspeed begins to decrease. In this situation, the airplane may stop climbing unless power is increased to overcome the added drag.

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Wrap-Up + Next Lesson Teaser

Now you know how an airplane creates lift.

Lift is the upward force that opposes weight, and in steady flight, lift equals weight. Wings create lift mainly through Bernoulli’s Principle—faster air over the curved top of the wing creates lower pressure, while slower air underneath creates higher pressure, pushing the wing upward. Lift can be increased three main ways: increasing airspeed (adding power), increasing camber (lowering flaps), or increasing angle of attack (pitching up). However, increasing camber or angle of attack also increases drag. Understanding these relationships helps pilots safely control climb, speed, and overall aircraft performance.

In my next lesson, we’re going to talk about something you could do that could cause a rapid loss of lift—and if you’re not expecting it, it can be pretty stinking scary.

I’ll put the next blog right here when you’re ready to get learned.