Allison's Flexible Kite (United States Patent and Trademark Office number 2,737,360)
William  M.   Allison was born in  Canada and  moved  to  the   U.S.A.   state   of Dayton,   Ohio in the early  1930's.
 At the age of 13 he built model planes that displayed fine detail and craftsmanship for a boy his age, according to kite expert Tal Streeter who has researched the early years of Allison for his book ?Great Kites of the Western World? .
  As an  adult  he worked for the Westinghouse refrigerator factory in Dayton as a mechanic.
 Allison enjoyed  flying  kites  and helping  others  in  the  art   of   fine tuning  and  kite  flying.   He   enjoyed experimenting  with designs of  his  own.
 Sometime  in the  early  1950's  an  idea  came to him  that maybe  a  kite could conform to the  flow  of  wind  and still   obtain  lift.   As  a  result  he developed  a    flexible    kite,   which Allison referred to as a polymorphic kite when describing how  the   kite  conform to the fluctuations of  the  air stream.
 It is unknown what  influenced  Allison's invention,  it may have been a windsock or a  sail boat spinnaker but  according  to his patent application on  September  8th 1950 the kite was an instant  invention. Allison's invention  was basically a semi-rigid canopy kite " built from   any   light   material,  relatively impervious to the  passage  of air, for    example    paper." (ref from patent number 2,737,360). The reference to  paper  points to  the  fact that   when    Allison    designed    the flexible    kite    in    early     1950, Polyethylene  of the linear  low  density type (film)  was not available until  the very  late  1950's  and   early  1960's. Another  indication  that  the   original design was made of paper is found in  his patent (2,737,360)  "The marginal area of the  air foil panel is  folded  back  and bonded   to   the   surface   panel   for reinforced     perimeter".      Allison's original design was flown with the  spines (longitudinal or brace members) on the back of the kite.  His idea was to have  a smooth passage of wind  over  the lifting surface of the kite.  The  patent text  makes reference  to  this. "Slight resistance  to the air  flow,  being  the thin edge of panel,  the tethers (bridle) and  the small  ends  of  brace  members" (Spines).  The Illustrated drawing of  his patent   shows how the  kite  appears  in flight with the braces on the back. It's  shape was similar   to   a  windsock cut   in half  (along  it's  length)  and shortened, the    canopy      is      only supported in it's longitudinal plan by  3 braces (spines), tapering   towards   the trailing edge. The  braces (spines) are  not linked,   and the kite  can  be   rolled  lengthwise   and easily   stored    without   having    to dismantled  the   frame.     The   bridle which   are   part   of    the    lateral extremities  of the kite and  form  keels that  help  the stability and  guide  the wind over the main surface of  the  kite. The kite is tailless and requires a  long bridle from  the  keels to  maintain it's shape when in flight. Allison applied for a  patent not long after  perfecting  his kite  (1950). The patent  office  withheld  approval of his invention for  6   years. The  patent appeared   to  conflict  with another   patent   issued    to   Francis Rogallo   of   the   U.S.A.   In    1948. Rogallo,   an aeronautical engineer  also invented  a Flexible  kite.   filed   1948 and  issued  in 1951. The wording 'flexible kite' had the United States Patent examiners look further into Allison's application and the examiner made reference to,
 Wickersham :Patent  1,617,976
 Van Ittersum :Patant   2,107,808
 Wheelwright :Patent   2,386,762
 Bach             :Patent   2,463,135
 Rogallo         :Patent   2,546,078
 Allison's patent was  approved on  March 6th 1956.  The  kite languished  in this form    with the  possibility of the  use of   plastic film for  the  sail,    from 1956  until    1962.

Web Page by Tom Lehane (update 2013)
Francis Rogallo  Patent  2,546,078  issued 1951.
The patent filed in 1948 and issued in 1951 was the reason Allison was not given approvel for his flexible kite for six  years as there was a possible conflict with Rogallo's flexible kite.

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