US Patent 7172158 Ram air parachute canopy with trapezoidal cells

The canopy of the ram air parachute of the present invention has cells which are trapezoidal in shape. The non-loaded ribs of the canopy are shorter in height than the loaded ribs. The different height ribs results in tensioning of the bottom skin and transfer of forces from the loaded rib-bottom skin junction through the bottom skin to the non-loaded rib. The non-loaded rib is then tensioned to not float up as high. Thus, the spanwise distortion of the top skin is reduced and the aerodynamics are improved.