The Collaborative International Dictionary of English v.0.48:

Box kite \Box kite\
   A kite, invented by Lawrence Hargrave, of Sydney, Australia,
   which consist of two light rectangular boxes, or cells open
   on two sides, and fastened together horizontally. Called also
   Hargrave kite, or cellular kite.
   [Webster 1913 Suppl.] boxlike

WordNet (r) 3.0 (2006):

box kite
    n 1: a kite shaped like a box open at both ends