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 suddenly 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.
R.D.Wickersham
Patent 1,617,976 ( year 1927)
made reference to a kite that could be un-assembled
and re-assembled by unskilled persons.
W.A.G.
Van Ittersum Patent 2,107,808 U.S. issue 1938.
He applied for a patent in France in 1936.
The kite has twin cylindrical rotors built of cardboard and mounted in
a frame.
W.
M. Allison Patent 2,737,360 isuued March
6,1956 Application September 8, 1950.
J.S.
Wheelwright Patent 2,386,762 issued 1945.
The kites advantage to be folded into a small package
and fired from a life-saving raft and to open once it
reached the lenght of its' wire radio aerial.
The mention of a kite to be compactly fold by Allison
was the reason for the patent office to make comparison
J.S. Whellwright's patent.
Francis
Rogallo Patent 2,546,078 issued 1951.
This is concidered to be the most significant
contributions to the development of the truly modern kite.
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.
R.F.
Bach Patent 2,463,135 issued 1949.
The kite is refered to as a 'FLYING WING' which is flexible
in performance. The word 'flexible' was the reason the patent was
compaired to Allison's.
It's of interest to note that the application was applied for in May
1947 and Francis Rogallo filed his patent in 1948.
