Walkalong glider

A walkalong glider is a model aircraft that is both light and slow-flying. It stays airborne through controllable slope soaring, using the rising air created by the pilot walking beneath it, typically while holding a paddle. Updrafts can also be generated with hands or even the forehead. This form of soaring is distinct from other slope-soaring methods because the orographic lift—the "hill" of air—moves along with the plane, so no external wind is needed.

Several walkalong glider types have been patented, with named designs including the air surfer, the windrider, the tumblewing, and the follow foil. The activity is sometimes called controllable slope soaring, but it should not be mistaken for dynamic soaring. Ground effect is also not the same as ridge lift when explaining how these gliders stay up.

Ground effect involves a horizontal surface, while ridge lift requires a sloping one. In ground effect, air does not need to move relative to the ground, whereas ridge lift demands wind blowing horizontally against a ridge. Walkalong gliders are sustained and steered by the ridge lift produced by the moving paddle.

History

The earliest known description of a walkalong glider comes from a 1955 patent by J. E. Grant. The first flight of a working walkalong glider appears briefly in the Academy Award-winning documentary The Flight of the Gossamer Condor.

Walkalong glider design

For a walkalong glider to function, it must fly at or below walking speed. Using light materials and specific design choices reduces its flying speed. For instance, a paper walkalong glider made from lower-density paper has reduced wing loading and thus a lower airspeed.

Different designs have varying wing loadings; tumblewing types, for example, have lower wing loading than traditional nose-weighted paper airplanes made from the same paper. In nose-weighted designs, the wings should include twist or washout to improve roll control near stall speed. While most walkalong gliders are flying wings (as are nearly all flying and gliding animals), designs based on traditional fixed-wing aircraft—with a tail or empennage—have been built from balsa wood sticks and tissue paper.

The paddle should be made from a lightweight but rigid sheet, such as corrugated cardboard or foamcore. A larger sheet creates a stronger updraft at its top edge.