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National Advisory Committee for Aeronautics, Technical Notes - An Investigation of Cotton for Parachute Cloth

This is_a resume of-the work of the Bureau of Stand—
ards on a cotton parachute cloth for use as a substitute
for silk in" the‘ evant of an emer gency curtailing the sup-
ply. Cotton yarn of high strength in proportion to its
weight and otherwise specially suitable for parachute
cloth was developed. Cloth woven from this yarn in the
bureau mill was equal or superior to parachute silk in
strength and tear resistance, met the requirements with
respect to air permeability, and weighed only a few tenths
of an ounbe per square yard more than the silk cloth.
Practical trials of cotton parachutes carried out by the
Navy Department clearly indicate that the cotton parachute
closely approaches the silk parachute in performance as to
rate of descent, opening time, strength and ability to
function when stored in the pack for sixty days. The in—
crease in weight of the equipment resulting from the use
of cotton cloth instead of silk is considered to be well
within practicable limits. A specification for cotton
parachute cloth and the way in which the requirements of
the specification have been met are given. Gotten yarns
suitable for parachute cloth are now being woven commer—
cially in the United States.”

The development _of a parachute cloth made from mate—
rials grown in the United States was undertaken by the
Bureau of Standards late in 1924 at the request and with
the financial assistance of the National Advisory Committee
for'Aeronautics. At that time imported silk cloth was gen-
erally considered to be the only reliable material for the
construction of parachutes. The purpose of the project
was to develop a cloth from domestic materials for use as
a substitute for silk in the event of an eme'rgency cur-
tailing the supply. This_object Was attained and the Work
was concluded in 1930. A review of the investigation and
the principal results are given in this report.

Preliminary to the search for substitutes, in cooper—
ation with the Bureau of Aeronautics, Navy Department, and
the Silk Association of America, Incorporated. a compari—
son was made of silk cloth Woven in the United States With
that imported from abroad. Contrary to the general belief,
cloth woven in this country was feund to be equal or supe—
rior to the imported. This result at once made it safe
for the military services to use American silks for para-
chutes and, since a certain amount of raw silk is always
in stock in the silk mills of the country, lengthened the
time between a failure of the supply and an urgent need
for a substitute. A report of the tests of silk parachute
cloth submitted by the Silk Association of America has been
issued in mimeographed form. (Reference 1.) No further
mention need he made of this part of the work.