Stagger (aeronautics)

In aviation, stagger is the relative horizontal fore-aft positioning of stacked wings in a biplane, triplane, or multiplane.

[1] An aircraft is said to have positive stagger, or simply stagger, when the upper wing is positioned forward of the lower (bottom) wing,[2] Examples include the de Havilland Tiger Moth or Stearman.

s is the distance from the leading edge of the upper wing along its chord to the point of intersection of the chord with a line drawn perpendicularly to the chord of the upper wing at the leading edge of the lower wing, all lines being drawn in a plane parallel to the plane of symmetry.

When unstaggered, the centers of pressure for upper and lower wings are almost coincidental.

As increasing the gap may introduce other undesirable effects, stagger is usually applied to reduce the loss of lift.