Changing the forces: how living things fly

What your class asks

This lesson asks you to describe ways in which the four forces of flight can be altered, and to describe the characteristics and adaptations that enable organisms to fly. The museum offers NASA Glenn's explanation of how the ratio of lift to drag sets a glider's descent angle, and what al-Jahiz says of creatures that fly on two wings; ways of altering the forces, such as wing size and angle, and the body features of birds and insects, have to come from another source in your class. ¹

Curriculum expectations, with their official codes

D2.4 describe ways in which the four forces of flight can be altered
D2.5 describe characteristics and adaptations that enable organisms to fly

Before you start

A thought to carry into the lesson.

The lesson

What changes if you change one thing?

Make two identical paper gliders and change just one thing on one of them, such as folding its nose. Release each gently from a low place and compare how far they glide. Which force do you think you changed, and what is your evidence?

What do wings share?

Compare a bird's wing and an insect's wing from pictures. Write what they share and how they differ, and what that says about what a living thing needs in order to fly.

Go deeper

In the editor's list, the third part of Kitab al-Hayawan opens with the chapter on pigeons "and the kinds of knowledge God placed in them", then takes up, among others, the kinds of flies, crows, dung beetles, the hoopoe, the Egyptian vulture and the bat ² ³. Elsewhere al-Jahiz says that wisdom may show more plainly in the fly, small as it is, than in the splendid horse, and that he does not dwell on the great-bodied for their size ⁴ ⁵.

Think about it

Al-Jahiz notes that not everything that flies on two wings is a bird, and that locusts, bees and flies are not called birds ⁶. Choose two flying creatures you know and list what their wings share and how they differ. Does your list help you decide what the word "bird" should mean, and why?

Into the museum

Kitab al-Hayawan: the seven parts chapter by chapter, and how the editor describes the book.
al-Jahiz: what the Encyclopaedia of Islam says of his life, and where the sources differ on the year of his birth.
Ibn Firnas's reported winged flight: NASA Glenn's glide angle, and its modern paper example.

Try this

In the record of Ibn Firnas's attempt you will find NASA's paper example of one unit of height lost across ten horizontal units. Draw it on squared paper, then draw the case where the same height is lost across only five units, and compare the two slopes.

Check yourself

Nothing here is marked or sent anywhere. It is for you.

Which of these did you meet in this lesson?

Farouk El-Baz

Not in this lesson. Look again at the cards above.

Astronomer

Not in this lesson. Look again at the cards above.

Ibn Firnas's reported winged flight

Yes. That is the one from this lesson.

In your own words: what does Ibn Firnas's reported winged flight have to do with this lesson?

Compare with the card

How the forces set the glide angle. In steady gliding, NASA Glenn relates the ratio of lift to drag to the angle at which a glider descends; the height lost divided by the horizontal distance gives the tangent of that angle. The record's modern paper example loses one unit of height across ten horizontal units, a slope of one to ten, and descends more steeply if only five are crossed. It does not calculate Ibn Firnas's range. Which force would you change to flatten the slope?

In your own words: what does Kitab al-Hayawan (The Book of Animals) have to do with this lesson?

Compare with the card

Flying, but not called birds. Kitab al-Hayawan is al-Jahiz's book on animals, divided into seven parts. In it he notes that not everything that flies on two wings is a bird: locusts, bees and flies fly but are not called birds. Name three small creatures you have seen fly: what do their wings have in common, and how do they differ?

I can now

D2.4describe ways in which the four forces of flight can be altered
D2.5describe characteristics and adaptations that enable organisms to fly

1 What your class asks

2 Before you start

3 The lesson