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How does an aircraft fly? What are the forces of flight? Students will learn about the four forces keeping aircraft in the air and investigate the fundamentals of flying with four activities.
Recommended for Year 1 to 6
Curriculum Links to Science
“Explore everyday examples of physical phenomena, such as movement, forces, electricity and magnetism, light, sound, waves, and heat.” Physical world Level 1 & 2
“Explore, describe, and represent patterns and trends for everyday examples of physical phenomena, such as movement, forces, electricity and magnetism, light, sound, waves, and heat” Level 3
“Extend their experiences and personal explanations of the natural world through exploration, play, asking questions, and discussing simple models.” Nature of science Level 1 & 2
“Appreciate that science is a way of explaining the world and that science knowledge changes over time.” Nature of science Level 3
The fundamentals of flying
Introduce the topic of flying and discover what knowledge your class has about the subject. Below are some questions to help focus your discussion on a variety of flying things.
Setting the scene
- What are some things that can fly?
- Are they alive, does they have wings, do they have an engine?
- How do these things stay in the air?
- What do they use to propel (move) themselves?
The forces involved in flight
There are a lot of misconceptions about what flying means. Ask your students to consider the following list, which of these things are flying?
- Frisbee hurling through the air
- Frogs leaping and hopping
- A rugby ball sailing over the goal posts
- Paper planes gliding across the room
- Parachutes descending slowly to earth
- A helium balloon floating away
- Dandelion seeds drifting through the air
Answer: None of these things are flying!
They are simply falling, gliding, jumping, floating, or soaring.
True flight is sustained, controlled and powered. Ask your students to think of flying things that meet this definition.
Flight requires a combination of the four forces of flight: Drag, weight, thrust and lift.
This workshop will focus on each of these forces in turn. For each force we have provided an activity, an experiment and a scientific explanation. Younger children may require assistance with the activities and experiments, and older children may like to investigate further into these forces.
Each force acts in a specific direction:
Thrust moves the plane forward. The thrust comes from the engines or propellers which point backwards. The plane moves in the opposite direction to the engines because of Newton’s 3rd law: For every action, there is an equal and opposite reaction! Birds produce thrust by flapping their wings using their strong breast muscles.
Lift lifts the plane upwards. The wings help produce lift by curving downwards. Air flows over the wings and then down, causing the plane to lift upwards. Birds and helicopters also have curved wings.
Drag opposes the flight of the plane. Planes are designed to be streamlined and aerodynamic, this reduces drag. Dolphins, fish and penguins are also streamlined, to reduce their drag in the water.
Weight pulls against lift. Planes need to be as light as possible in order to make flying easy. Birds reduce their weight by having lightweight hollow bones.
In order to fly, the forces of lift and thrust need to overcome the forces of weight and drag.
Share this great YouTube video explaining how planes fly. Discuss the video with your class.
Lift – Tōpana hiki
Younger students will enjoy this activity and experimenting with making different objects fly. Older students will get a lot out of experimenting with the lift tube and applying their observations to the construction of a paper plane.
What is lift?
Lift is crucial for keeping flying things in the air. The shape of the wing is what causes the plane to lift upwards as it moves through the air. As the plane moves forwards, air rushes over the wing. This rushing air creates an area of low pressure above the wing.
Whenever there is an area of low pressure, air rushes in to fill the space. Air from below the wing pushes upwards and this also pushes the wing upwards.
Activity: Make an amazing lift tube!
You will need:
- Long tube ( A paper towel tube)
Video: How to make a lift tube!
What to do:
If you do not have a long tube you can create one by taping toilet rolls or hollowed-out paper cups together. Once you have your tube, practice the ‘windscreen wiper’ motion of tilting the tube back and forth but keeping the bottom end in the same place. Keep practicing until you get the hang of it. Place a feather under the bottom of the tube and start tilting. Whoosh! the feather will suck up the tube and fly out the top.
Get the students to experiment with this activity. Ask them to change something, and then predict what they expect to happen. Some ideas are: Experiment with tubes of different lengths and diameters. Experiment with different objects. Experiment with different tilting speeds.
What’s going on?
Because you are quickly tilting the tube back and forth the air around the top of the tube is moving, faster than the air at the bottom of the tube. Fast moving air creates an area of low pressure, just like the area of low pressure on top of a wing. Air pressure always tries to equalise from an area of high pressure to an area or low pressure. This results in the air inside the tube rushing upwards to replace the air at the top. This rushing air sucks the feather up with it.
Thrust – Tōkiri
Students of all ages will enjoy this activity. Older students may enjoy finding out what is creating the thrust in different types of flying things. You could encourage your students to research other demonstrations of Newton’s third law.
What is thrust?
Thrust is the force the pushes a flying thing through the air. On a plane it is the engines and propellers that provide the thrust. On a rocket, thrust is created by burning rocket fuel. Birds create thrust by flapping their wings. In every case the thrust pushing in one direction causes the flying thing to move in the other direction.
This is because of Newton’s third law: for every reaction there is an equal and opposite reaction. We can see Newton’s third law for ourselves by creating a balloon rocket at home.
Activity: Make a balloon rocket
You will need:
- Long piece of string (3-4 metres)
- Two extra people or chairs
Check out this awesome balloon rocket video:
What to do:
Thread the string through the straw. Have two people (or chairs) hold each end of the string, making sure the string is tight. Blow up the balloon, but do not fasten it off. Attach the balloon to the straw with a piece of tape. Hold the balloon in the middle of the string and guess (make a prediction) which direction the balloon will fly in when you let it go.
Release your balloon and test your prediction!
Ge the students to experiment with this activity. Use the following questions to guide their experiments. They may come up with other questions themselves.
- Does the balloon rocket behave the same way each time?
- What happens when you put a lot of air into the balloon?
- What happens when you put just a little air into the balloon?
- What happens when you attach the balloon to the string sideways?
- If the balloon is not attached to the string, which direction does it fly in?
What’s going on?
The air pushing out the neck of the balloon is causing the thrust.
As you blow up the balloon you are adding more and more air which causes the balloon to stretch and expand. The air pressure inside the balloon is higher than the air pressure outside. Air pressure always equalises from high to low, so the air rushes out of the balloon when it is released.
Drag – Tōpana Ātete
Use this simple demonstration to show how drag acts on a flying object.
Hold a piece of paper out at arm’s length and drop it. Notice how slowly the paper falls. Now scrunch the paper up into a ball and drop it again. Notice how quickly the paper falls. Why does the same piece of paper fall more quickly when it is scrunched into a ball?
What is drag?
Drag is not very useful for flying objects. Most flying objects try to reduce drag by being more aerodynamic. Falling objects can slow themselves down by increasing their drag. A great example of this is the parachute.
Activity: Deploy a parachute
You will need:
- Small toys
- Plastic bag
Watch this cool parachute video:
What to do:
Cut four lengths of string to the same length. Attach the string to each corner of the parachute. Tie the four pieces of string to the toy. Scrunch up the parachute and throw the toy as high as you can. The parachute should unfurl and float the toy gently back down to the ground. You may need to practice throwing the parachute a few times!
Encourage the students to experiment with different types and sizes of parachute. Ask them to measure and record the time it takes for the toy to reach the ground. They could also experiment with toys with different weights
What’s going on?
The larger the parachute, the more drag it creates. This is also true of flying things.
Planes use drag when they are slowing down for landing. They extend special wing flaps to increase their size and drag. Another way to think it is that the plane becomes less streamlined when it wants to slow down.
Weight – Taumaha
Students of all ages will enjoy this activity. Older students may enjoy replicating the levitation with a straw and their own breath. Challenge them to turn this into a game or class competition.
What is weight?
If you have ever flown on a plane, you might remember checking the weight of your luggage before you board. Airlines have strict rules about how much weight can be brought onto an aircraft. This is because the heavier the plane, the more difficult it is to fly.
Weight plays an important role in keeping a plane in the air. This simple experiment will show you how increasing the weight of an object can affect its flight.
Activity: Hairdryer levitation
You will need:
- Toilet paper
- Ping pong ball
Fun hairdryer video:
What to do:
Find a low heat, high air flow setting on the hair dryer. Hold the hair dryer so the air stream is pointing upwards. Try levitating the paper in the airstream by gently placing the paper above the hairdryer. What happens? Now scrunch the paper into a tight ball and try again, what happens?
If you have them on hand, try levitating the ping pong ball, feather and balloon in the air stream. Try out different objects from around the house.
Ask the students to experiment with different speeds, and how they place the objects into the air stream. The following questions will help to expand their experimentation.
- What happens when you place the objects above the hair dryer?
- Compare a small and large balloon, or two balls of different sizes
- Add another layer of paper to your scrunched-up ball, does it still levitate?
- Can you get two objects to levitate at once?
- Try dropping the objects down into the airstream from higher up, what happens?
- Try tilting the hair dryer gently to one side, what happens?
- If you have two hair dryers, you can try passing the ball from one to another.
- See if you can levitate the same objects using just your breath through the straw
What’s going on?
The round objects are captured by the air stream causing them to levitate. The objects that are not round are blown away. Some objects are just too heavy to levitate no matter what shape they are! The round objects stay in the air stream because the air flows around the sides of the objects and then flows back into the middle. This flow of air traps the round objects in the air stream. This is known as the Coandᾰ effect.
The objects levitate at the point where the force of the air stream (pushing upwards), and the force of gravity (pulling downwards) are in balance. This levitation height is different for objects with different weights.
Have the students record their experiments, observations and thoughts in the workbook.
Think of ways you can combine the experiments together!
- Use a hairdryer to lift a feather through the lift tube
- Add some drag to your balloon rocket
- Fold a paper plane and see hoe much weight you can carry
We love to hear from you
- Tell us about your experiments and send us a photo
- Did you share these experiments with your family? How did they react?
Send your pictures to firstname.lastname@example.org
- Try your hand and folding a paper plane
- Read about flying legend Cliff Tait who flew around the world in 1969: The Flying Kiwi: a photo essay
- Look through the MOTAT online collection for objects from famous kiwi aviators
- Explore the physics of jumping with this origami jumping frog
- Make a paper helicopter, experiment with different sizes and weights
This resource is also available for classroom sharing as Google Slides.