D. Structures and Mechanisms · Flight

Design Challenge: Build a Better Glider

A1.3 A1.4 A1.5 A2.1 A3.2 D2.2 D2.4About 60 minutes

Learning goals

I can use the engineering design process to design, build, test and improve a glider.
I can explain my design using lift, weight, thrust and drag.
I can test fairly, calculate averages and use my results to make improvements.
I can follow safety rules and share my design clearly.

Words to know

engineering design process
The steps engineers use to solve a problem: define, research, plan, build, test, improve and communicate.

criteria
What a design must do to be successful.

constraints
Limits on a design, like the materials you can use or the size.

prototype
A first model of a design, built to test and improve.

iterate
To repeat the test-and-improve steps to make a design better.

centre of mass
The balance point of an object, where its weight seems to act.

Your mission

A wildlife team wants a simple paper glider to show at a nature centre. It must glide far and straight after a gentle launch. Your job is to be the aerospace engineer: design, build, test and improve a glider using what you know about the four forces of flight.

A white folded paper glider with wide wings on a classroom table, next to paper, scissors and paper clips. — A paper glider is a quick prototype. Change one thing at a time, like the wing size or a paper clip on the nose, and test again. AI-generated image

Criteria (it must...)	Constraints (limits)
glide as far as possible from a gentle, level hand launch	materials: 1 drinking straw, 1 sheet of paper (about 21 cm by 28 cm), tape, up to 2 paper clips
fly fairly straight (land within 1 m to either side of a straight line on the floor)	no rubber bands or other launchers: hand launch only
survive at least 10 test flights	build time: about 20 minutes

Design brief

The engineering design process

Define the problem: read the criteria and constraints.
Research: what makes a glider fly far? (Big lift for little weight, low drag, and good balance.)
Plan: sketch your design and label it. Predict how far it will fly.
Build your prototype.
Test it 3 times and find the average distance.
Improve one thing at a time and test again (iterate).
Communicate: share your final design, your results and what you learned.

The engineering design process. Steps 5 and 6 form a loop: test, improve one thing, and test again until the design meets the criteria. Then communicate what you learned.

A starting design: the hoop glider

A hoop glider is a drinking straw with a paper ring taped near each end: a small hoop at the front and a bigger hoop at the back. It doesn't look like a plane, but it flies well!

The hoops are wings. As the glider moves, the curved paper turns air downward, making lift.
The straw is a light body (low weight) with a thin, streamlined shape (low drag).
There is no thrust after it leaves your hand, so it glides slowly downward.

To build it: cut two strips of paper, each about 2.5 cm wide: one about 12 cm long for the front hoop and one about 25 cm long for the back hoop (cut it along the long side of the sheet). Curl each strip into a loop, overlap the ends about 1 cm and tape them. Tape the small hoop to one end of the straw and the big hoop to the other end, with both hoops lined up on the same side of the straw. Hold the straw in the middle with the hoops on top and the small hoop at the front, and launch it gently forward.

A hoop glider. The small hoop goes at the front and the big hoop at the back, both on top of the straw. Launch it gently, small hoop first.

Engineer's troubleshooting

Change only one variable at a time: hoop size, hoop position, straw length or paper clip position.
If it dives nose-first, the front may be too heavy: move a paper clip back (or take it off).
If it climbs and then drops (stalls), the front may be too light: add a paper clip near the front.
If it curves to one side, check that the hoops are lined up straight.

set [total] to 0

repeat 3

ask [Distance of this flight in cm?] and wait

change [total] by (answer)

end

set [average] to (total / 3)

say (join [Average distance: ] (average))

if <(average) > (best)> then

set [best] to (average)

say [New best design!]

A block-code plan to record 3 flights, find the average and keep track of the best design so far. (Set best to 0 before your first design.)

Worked example

Let's use test results to improve

Kai tests his hoop glider. Design 1: 320 cm, 280 cm, 300 cm. It dives at the end. He changes one thing: he moves the paper clip from the very front to just behind the front hoop (Design 2): 410 cm, 380 cm, 440 cm.

Design 1 average: 320 + 280 + 300 = 900; 900 ÷ 3 = 300 cm.
Design 2 average: 410 + 380 + 440 = 1230; 1230 ÷ 3 = 410 cm.
Kai changed only the paper clip's position, so it was a fair test.
Diving means the nose was too heavy. Moving the clip back balanced the glider (moved its centre of mass), so its wings could make lift more evenly and it glided farther.

Design 2 flew 110 cm farther on average (410 cm compared to 300 cm). Moving the paper clip back fixed the dive.

Worked example

Let's explain a design with the four forces

Explain how a hoop glider uses the four forces of flight.

Thrust: only from your launch; after that there is none.
Lift: the curved hoops turn air downward as the glider moves, so the air pushes them up.
Weight: the straw, paper, tape and clips. Keeping it light means less lift is needed.
Drag: the thin straw and narrow paper hoops cut through the air with little drag. Because drag is bigger than thrust after launch and weight is a little bigger than lift, it slowly slows and sinks to the ground.

The hoops give lift, the light straw keeps weight and drag low, and with no thrust after launch it slowly glides down.

Just for fun

An engineer's motto for paper gliders: "If at first you don't succeed... fold, fold again!"

Hands-on activity

The glider challenge

You need: 3 or 4 drinking straws, several sheets of paper, tape, 2 paper clips, scissors, a measuring tape, masking tape and a notebook.

Safety: use scissors with a grown-up nearby. Launch only in a clear space (a hallway or a gym, or outside on a calm day). Never aim a glider at anyone's face or at pets. Walk, don't run, to pick it up.

Plan: sketch your first design and label the lift, weight, thrust and drag arrows. Write a prediction of the distance.
Build your prototype (the hoop glider, or your own design that meets the constraints).
Test: put masking tape on the floor as a start line. Launch gently and level, the same way each time. Measure from the line to where it first touches the floor. Do 3 flights.
Record in a table and find the average (use the code above in Scratch if you like).
Improve: change one thing. Test 3 more times. Repeat at least twice.
Communicate: make a one-page design report: your final sketch, your results table, which change helped most and why (using the four forces), and one more idea you would try next.

What to look for: at least three designs tested 3 times each with averages, only one change between designs, a final glider that meets the criteria, and a report that explains the best change with a force (for example, "Bigger back hoop = more lift").

Your turn

List the steps of the engineering design process.

What is the difference between criteria and constraints?

In a hoop glider, which parts make the lift?

After launch, does a glider have thrust?

A glider dives nose-first. Suggest one fix.

Why test each design 3 times?

Find the average of 250 cm, 300 cm and 350 cm.

More practice: warm-up

What is a prototype?

What does "iterate" mean?

Name one safety rule for testing gliders.

Which force pulls the glider down?

Which force slows the glider as it moves forward?

More practice: on your own

Priya's glider climbs steeply, slows down and then drops. What is probably happening, and what could she change?

Ben's averages: Design A = 350 cm, Design B = 420 cm. How much farther did B fly on average?

Ben changed the hoop size and the straw length between A and B. What is the problem?

Why does a light glider usually fly farther than a heavy one of the same shape?

Why should you launch the glider the same way every time?

Challenge

Kai's three designs had averages of 300 cm, 410 cm and 395 cm. Which design should he choose? Is the difference between the last two important? Explain.

Using the code above, what will the program say after flights of 300, 330 and 360 cm if best was 310 before?

A real aircraft company tests new wing designs in a wind tunnel and with computer models before building a full plane. How is this like your glider challenge?

Check your understanding

Quiz

What is the first step of the engineering design process?

Which is a constraint?

After launch, a glider has:

A glider dives nose-first. A good first fix is to:

Why test each design 3 times?

What is the average of 400 cm, 420 cm and 440 cm?

For parents and teachers

Big idea: this design challenge pulls the unit together (A1.3 engineering design process, D2.2 four forces, D2.4 changing the forces). Students also use safety rules (A1.4), code an average calculator (A2.1), use math (A3.2) and communicate in a design report (A1.5).

How to help: be the "launch assistant" and recorder. Resist fixing the glider for your child; instead ask "What did it do? Which force might cause that? What one thing will you change?" A design that improves from test to test is a success even if it never flies very far.

Common difficulties:

Changing several things at once. Insist on one change per test round.
Throwing hard instead of designing better. Keep launches gentle and the same.
Hoop glider tips: the hoops must be lined up on the same side of the straw, and the tape joins should be smooth.
Safety: supervise scissors; test in a clear area; never aim at faces or pets.