The Paper Aerodrome

The flight is simulated, not animated. Each throw integrates a longitudinal point-mass model at half-millisecond steps: lift and drag from the wing’s lift-curve slope corrected for its aspect ratio, induced drag from CL²/πARe, a stall above about thirteen degrees of incidence, and a pitching moment about the centre of gravity that gives the aeroplane its own nose-up-and-down response. Nothing is scripted — the porpoising you see on a badly trimmed glider is the phugoid falling out of the arithmetic.

The nose clips move the centre of gravity forward, which increases the static margin: the aeroplane becomes more stubbornly stable and trims faster and steeper. Bending the trailing edge up trades speed for incidence. Both of those are the real reasons those two tricks work on a real paper aeroplane, and both can be overdone here exactly as they can on the carpet.

The five patterns are the familiar families — a dart, a wide-winged glider, a hoop and so on — drawn here as original diagrams. Real distances depend on the paper, the room and the arm; this bench holds still air at sea level and a perfectly repeatable throw.