Fix your paper plane

Its nose is too heavy for the lift its wings make, so the nose drops and nothing lifts it back up. Every paper plane carries its weight a little ahead of where its lift pushes; trim decides how much.

1. Bend the back edges of both wings up a little, a couple of millimetres, the same on each side. The air pushes the raised edges down, and that lifts the nose. Real planes do this with their elevators.
2. Throw it level and a little softer. Pointed down, or thrown too hard, even a good plane heads for the floor.
3. Still diving? Bend a little more, a bit at a time, and throw again after each bend. Small bends do a lot.

See the angle at work: the glide lab.

It’s stalling. The nose rises until the wings meet the air at too steep an angle; then the air can’t follow the wing, lift falls away, and the plane drops, nose first.

1. Flatten the back edges of the wings, or bend them down a touch if they’re already flat. That lowers the nose.
2. Throw it level, not upward, and not as hard: a fast plane with its nose up climbs straight into a stall.
3. Add a little weight at the nose. A plane that swoops up and stalls has its weight a little too far back. Fold the nose tighter, or pick a design with more folds at the front; for fun (not records), a paper clip on the nose works too.

Tip the nose up until it stalls, in the glide lab.

Its two sides don’t match. One wing is bigger, bent or twisted, or the body under the wings is crooked, so one side lifts more and it banks round.

1. Look at it from the front and from behind. Are the wings the same size, at the same angle? Is the body straight down the middle? Straighten whatever isn’t.
2. Then steer it with the back edges. If it turns left, bend the back edge of the right wing up a little (and the other way round). That wing drops, and the plane rolls back the other way.
3. A spiral into the floor is the same problem, only more: straighten it first, then trim it a little at a time.

Something is soft. Loose layers and rounded creases bend in the air, so the wings flap and the plane rocks instead of slicing through.

1. Sharpen every crease. Run a fingernail (or a ruler) along each fold, both ways. Crisp creases make a stiff plane.
2. Hold the layers together. Pinch the body shut under the wings, and refold any flap that springs open. A design with a lock, like the Nakamura lock, holds itself together.
3. Set the wings like a Y, not a T. From behind, they should rise a little from the body to the tips. A slight V rolls back to level by itself; drooping wings rock and tip over.

Folds that lock themselves: the Nakamura lock.

Its wings droop, or its weight is too far back. Wings that slope down from the body (a T or an upside-down V, not a Y) tip the plane over; a plane that’s light at the nose tumbles.

1. Raise the wings into a shallow V, rising a little from the body to the tips, the same on both sides.
2. Make the nose heavier. Fold the nose tighter, or pick a design with more folds at the front. For fun (not for records), a paper clip on the nose works too.
3. Check it isn’t twisted: look along the body from behind. A twist, or one wing bent up more than the other, sets it spinning.

Planes with a weighty nose: the Bulldog dart.

Distance takes speed and a clean glide: a slim, well-trimmed plane, thrown hard. Wide, floaty wings are built to go slow and stay up, not to go far.

1. Fold a plane built for distance: a slim, pointed one with a firm nose, like Suzanne, the Hammer or the Dart.
2. Throw it hard, and upward, with a smooth follow-through, not a flick. Grip it firmly toward the middle, but not too tight. (The team behind the 2022 distance record worked out 40 degrees up as their best angle.)
3. Trim it for a flat glide. If it dives, bend the back edges up a hair; if it swoops, flatten them. A plane that flies straight goes farthest.

Which planes fly farthest: the best paper airplanes.

Staying up takes big wings and a slow, gentle glide. Lift grows with wing area, so broad wings can hold a light plane up even when it’s slow.

1. Fold a plane with broad wings, like the Glider: it floats where a slim dart would sink.
2. Throw it gently, level or a little up, and let it go. A hard throw just makes a floaty plane loop or stall.
3. Trim it so it just doesn’t stall: a little up at the back edges, then a little less, until it glides down slowly without swooping.
4. Go high. The higher it starts, the longer it has to glide. Takuo Toda and Ken Blackburn, who both held the time-aloft record, threw their planes nearly straight up.

Which planes stay up longest: the best paper airplanes.