Aerodynamics Aviation | Understand How Things Fly
You might be surprised to learn that, regardless of whether an aircraft is pointing the right way up or upside down, only four forces are acting upon it at any given time. Aerodynamics in aviation is actually quite simple in concept. Today, we will give you a great understanding of how things fly and tell you a little about what is going on when an aircraft does stunts.
The Four Forces of Flight
To understand how things fly, we need first to look at the four forces of flight. They are:
Lift
This is generated primarily by the wings. If you drew a line straight up from the wing’s curved upper surface, this is the direction in which lift acts.
Remember this, as it is vitally important to know when discussing aerobatics.
Weight
Weight is the effect of gravity on the aircraft and the opposing force to lift. Unlike lift, which acts wherever the wing’s upper surface points, the weight always acts in the same direction. Point straight down towards the center of the earth.
Thrust
Thrust is what differentiates an airplane from a glider. It is the forward force provided by the engines. Thrust is what enables the airplane to fly faster.
Generally speaking, the more thrust there is, the faster the airplane will go. And, the faster the airplane goes, the more lift is generated by the wings
Drag
If you’ve stuck your head out of a car window as it is driving, you’ll have felt the strong force of the wind on your face. This force has a name. It is called drag. Drag acts in the opposite direction to thrust and is caused by the air resisting the movement of a body through it.
Drag slows the airplane down and is not really considered a good thing. The shape can either increase or decrease drag, which is why aircraft are aerodynamically designed to be all sleek, smooth, and pointy.
Aerodynamics and Stunts | What’s Going On?
Before discussing fancy maneuvers and stunts, it is worth looking at an aircraft in what is known as ‘straight-and-level’ flight.
When an aircraft is flying ‘straight and level’, it could be said that all of the forces are in equilibrium. The lift produced by the wings exactly matches the weight produced by the earth’s gravity. If the lift increases, the airplane will climb, and if it decreases, there is no longer equilibrium, and it will descend.
At this stage, the force of lift points straight up, and the force of weight points straight down.
The aircraft thrust is exactly equaling the drag produced. The airplane is neither accelerating nor slowing down.
All that make sense?
Now let’s look at a few maneuvers and discuss some interesting things…
Aerodynamics in Inverted Flight
The pilot in our straight and level airplane pulls back on the stick. This causes an increase in lift, and as we said, that will lead to a climb. If they keep pulling back, this increases the lift further.
Remember what we said about which way lift acts? Wherever the upper surface of the wing is pointing… In a steep climb, the lift is no longer opposed to the force of weight. It might actually be pointing more at a 45° angle towards the horizon! If the pilot keeps pulling, the nose will rise higher and higher until the airplane is inverted.
The eagle-eyed among you will be aware of something.
Lift will be pointing straight down and added to the weight’s downward force. So, why doesn’t the airplane descend or fall out of the sky?
Well, this is due to some clever aerodynamics. You see, most aerobatic stunt planes have wings that produce lift on the underside when they are inverted! They are symmetrical in cross-section! As a result, although the airplane is upside down, lift is still being produced to oppose the weight!
Rolls and Sideways Flight
Now that you know about the four forces of flight and aviation aerodynamics, you might be surprised to learn that most airplanes can’t actually fly on their side!
When stunt airplanes are side on to the earth, this is called flying a ‘knife edge’… However, it is a little bit of an illusion.
Why?
Well, think about it. If the aircraft is on its side, what is there to generate lift to oppose the force of the earth’s gravity?
There are high-powered aircraft like fighters that fly nearly on their side. They actually use a mixture of inertia, centrifugal force, and thrust to compensate for the lack of lift.
Stalls and Spins
At airshows, you can often see aircraft spinning and appearing to tumble out of the sky. The start of this maneuver is actually called a stall. This is where the wing ceases to produce and lift at all. And as a result, the airplane heads in one direction and one direction only. Straight down!
The pilot will normally begin the maneuver by pointing the aircraft’s nose straight up to the sky without adding any thrust. Slowly the airplane speed washes off until it is far exceeded by both drag and gravity. The airplane will tumble towards the earth, and using the flight controls, such as the rudder, the pilot can press to make it fall to either the left or the right.
Whether you want to see stall turns, wingovers, loops, rolls, or flying on a knife-edge, the Wings Over Camarillo Airshow is the place to see all of the above aerodynamic theories put into practice. There are nimble and agile aircraft on display, such as the Pitts Special Biplane, or phenomenal displays of speed and power from aircraft like the FA18 Hornet or MiG-17! While these aircraft may all look and perform differently, airplane aerodynamics allow them to fly and perform all work exactly the same way using the above basic principles.
Why not head over to our schedule and see when we next have an event planned and who will be flying?
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