How do you fold a paper plane that actually flies?

Before you foldPaper, space, and one promise

Ordinary A4 copier paper works better than origami paper here, because it is stiffer and rectangular. You need no scissors, glue or tape.

1. Clear a table. Losing track of which way the paper is facing is the most common way this goes wrong.
2. Decide where you will throw before you start folding: indoors with space, or outside with little wind.
3. The promise: never throw it towards a person, an animal, a road, a window or a light.

The foldsOne fold at a time, checking the shape

After each fold, check the shape before moving on. If it looks wrong, open one fold — not all of them.

1. Place the paper portrait, short edge at the top.
2. Fold in half lengthways to make a centre crease, press firmly, and open it again.
3. Fold the two top corners in to meet the centre crease.
4. Fold the resulting point down towards you.
5. Fold the new top corners in to the centre again.
6. Fold the small triangle up to lock the previous folds in place.
7. Fold the whole thing in half, outside faces together.
8. Fold each wing down so the wing edge lines up with the bottom of the body.
9. Open the wings out flat, so the plane makes a shallow Y shape seen from the front.

Test itThree throws, and what to look at

A single throw tells you almost nothing — your arm varies more than the plane does. Throw three times the same way and watch the pattern.

Throw level, with a smooth push rather than a hard flick. Aim slightly above horizontal.

1. Throw 1: just watch. Did it climb, dive, or fly level?
2. Throw 2: watch left and right. Did it consistently turn one way?
3. Throw 3: watch the end. Did it stall and drop, or glide down?

Fix itWhat to change, one thing at a time

Change one thing, then throw three more times. Changing two things at once means you learn nothing from the result.

Why it fliesFour forces, on a piece of paper

A paper plane is a glider: it has no engine, so it is always trading height for forward motion. The same four forces act on it as on an airliner — lift, weight, thrust and drag — but here the only thrust is your arm, once.

That is why the shape of the wings matters more than how hard you throw. After the throw, the plane can only manage what it already has.

SourcesWhere we checked this.

• Paper Airplanes PlansNASA Glenn Research Center — Used for the folding sequence and for how paper planes are treated as gliders.
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• What Is Aerodynamics?NASA STEM Team — Used for lift, weight, thrust and drag at a level suitable for this age.
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• Make a Paper GliderNASA JPL Education — Used for the test-and-adjust method: change one thing, then throw again.
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