How birds fly
How a feather is built, what the different flight feathers do, how a wing makes lift, and how a bird's body is kept light. Then test lift with a strip of paper and a fair test with paper gliders.
Read
Feathers are made of keratin. The shaft is hollow, and the vanes are made of thousands of barbs held together by tiny hooks on the barbules. Birds preen to hook the barbs back together.[4]
Different feathers have different jobs. The primary feathers at the tip of the wing push the bird forward; the secondary feathers nearer the body give most of the lift; tail feathers steer and act as a brake for landing.[4][1]
Birds flap their wings with strong breast muscles. Without feathers a bird could not make enough lift to fly.[9][5]
A wing makes lift by turning the air that flows past it. The air above the wing moves faster, and faster-moving air has lower pressure, so the wing is pushed up.[7][9]
Lift is bigger when the wing is bigger and when it moves faster through the air.[6]
A bird's body is light for its size: many bones are hollow, with thin struts inside for strength, and a light beak replaces heavy jaws and teeth.[1]
Try it: Lift and gliders
You need
- Strips of paper about 4 cm × 20 cm
- A4 paper
- Scissors (adult help), tape, paper clips
- Tape measure
- A clear space such as a hall
Safety
Launch gliders in one direction only, never towards people's faces. Keep the flight path clear. An adult helps with scissors.
What to do
- Part A: hold a paper strip just below your bottom lip so that it hangs down. Blow hard over the top of it. What happens?
- Part B: make three paper gliders from the same paper: one with small wings, one with medium wings and one with large wings. Add one paper clip to the nose of each.
- Decide what you will keep the same: the paper, the paper clip, the launch height, how hard you throw.
- Launch each glider three times from the same line and measure how far it flies.
- Work out the average distance for each glider and draw a bar chart.
- Which wing size flew furthest? Can you explain why?
What happens, and why?
In part A, the fast air over the top of the paper has lower pressure, so the paper rises. In part B, bigger wings give more lift, but they also add weight and drag, so the best size is found by testing. Changing only the wing size and repeating each launch makes the test fair and more reliable.[9][6][7]
Play: Which feather does the job?
Which kind of feather does this describe?
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Quiz
Other ages: Ages 6–7 · Ages 15–16