fire-resistant fabric for aircraft

Fire-Resistant Fabric for AircraftAuthor(s): Gordon M. KlineSource: The Scientific Monthly, Vol. 41, No. 2 (Aug., 1935), pp. 190-192Published by: American Association for the Advancement of ScienceStable URL: http://www.jstor.org/stable/16015 .

Accessed: 01/05/2014 10:10

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact [email protected].

.

American Association for the Advancement of Science is collaborating with JSTOR to digitize, preserve andextend access to The Scientific Monthly.

http://www.jstor.org

This content downloaded from 62.122.78.18 on Thu, 1 May 2014 10:10:49 AMAll use subject to JSTOR Terms and Conditions

http://www.jstor.org/action/showPublisher?publisherCode=aaas

http://www.jstor.org/stable/16015?origin=JSTOR-pdf

http://www.jstor.org/page/info/about/policies/terms.jsp


190 THE SCIENTIFIC MONTHLY

The truck has a bunk, and the operator sleeps on location. He is ready to record at the crack of day. A second Ford truck is also used. This contains sleep- ing q-uarters for two men and carries the various cameras and camping equipment. A collapsible platform which is used in bird photography has been built for the roof of this truck. This platform can be raised about eight feet above the roof of the truck. The photographer can be, in many instances, on the same level with

the nesting bird, and, if need be, a blind can be erected on the platform. In this way, the camera is often over twenty feet above the ground. When not in use the platform folds up and adds less than a foot to the clearance of the trcek. It can be raised by two men in less than ten minntes, and has proved invaluable in seeuring intimate close-ups of the birds.

ALBERT RI. BRAND AMERICAN MUSEUM OF

NATURAL HISTORY

FIRE-RESISTANT FABRIC FOR AIRCRAFT'

THE rapid growth of the aviation industry in this country has brought to the fore the problem of eliminating the fire hazard inherent in fabric doped with cellulose nitrate, now commonly used to cover the wings and fuselage of airplanes. The destruction of costly aircraft because of the accidental ignition of the flammable covering by the back- firing of the motor, the careless toss of a lighted match or cigarette or the chance settling of a spark from a nearby flue has become too general an oceur- rence. The rapid spread of flames fol- lowing a minor crash presents a formid- able obstacle to the reseue of trapped survivors. It has been stated that the -Lse of metal will eliminate this hazard, but it is probable that, particularly for service airplanes, fabric will continue in use for some time to come because of its lower cost, availability and ease of application and repair, factors which facilitate rapid replacement of losses in time of war. An investigation was, therefore, undertaken by the National Bureau of Standards with the financial assistance of the National Advisory Committee for Aeronauties to develop a non-flammable doped fabric for aircraft.

A satisfactory airplane dope shoulld tauten the fabric to which it is applied, dry relatively rapidly without " blush-

1 Publication approved by the director of the National Bureau of Standards of the U. S. De- partment of Commerce.

ing, " i.e., precipitating the cellulose derivative in white patches because of moisture condensation, give a smooth, durable surface and permit a low film wei,ght. To these we believe should be added the req-uirement that the doped fabric should be fire-resistant.

Natural and synthetic resins and mix- tures of synthetic resins with cellulose nitrate and cellulose acetate were inves- tigated. The resins did not tighten the fabric sufficiently to be satisfactory as airplane dopes. In general a 3: 1 ratio of cellulose derivative to resin was neces- sary to attain satisfactory tautness. In this proportion even the least combusti- ble resins did not markedly improve the fire-resistance of the doped fabric. No method was found to fireproof airplane fabric doped with cellulose nitrate and maintain satisfactory tautness and weight req-uirements. An airplane covering with excellent resistance to ignition was obtained by the application of a 3: 7 boric acid-borax mixture to airplane cloth and snbseq-uently dopiing it with cellulose acetate. This doped and fireproof ed cloth, containinog approximately 5 per cent. of the boric acid-borax inixture by weight, did not burn in a horizontal or vertical positioni and was not ignited by lighted matches or burn- ing gasoline.

Although it is preferable to have a combination which is self-extinguishing,



THE PROGRESS OF SCIENCE 191

....

FLAMMABILITY TESTS ON DOPED FABRICS 1. UNTREATED AIRPLANE CLOTH DOPED WITH CELLULOSE NITRATE. 2. UNTREATED AIRPLANE CLOTH

DOPED WITH CELLULOSE ACETATE. 3. FIREPROOFED AIRPLANE CLOTH DOPED WITH CELLULOSE ACE-

TATE. 4. FIREROOFED AIRPLANE CLOTH DOPED WITH CELLULOSE NITRATE ON THE UPPER HALF OF

THE PANEL AND WITH CELLULOSE ACETATE ON THE LOWER HALF.

such as can be obtained by fireproofing the airplane cloth before doping with cellulose acetate, if one is choosingf be- tween two materials which will support combustion, it is important to have the ignition temperature as high as possible. Various definitions and methods of measurement of ignition temperature have been proposed by investigators in this field, but there is general agreement that the ignition temperature of cellulose nitrate is approximately 200? C. below that of cellulose acetate. When it is considered that the temperature of ordinary incandescent lights, steam pipes and lighted cigarettes and matches exceeds the ianition temperature of cellulose

nitrate, the constant risk of fire on an airplane covered with nitrate dope is readily apparent.

Published reports indicate that cellulose nitrate was considered undesirable for use at the "front" during the war, because of its flammability, and that cellulose acetate dope was preferred and, in general, prescribed for airplanes to be used in the zone of fire. Consider- ing the comparative meagerness of the technological information concerning cellulose acetate in that period, its preferential use for doping airplanes is surprising and is indicative of the atti- tude of the wartime aeronautical engi- neers toward the fire hazard of cellulose



192 THE SCIENTIF'IC MONTHLY

nitrate dope. After the war the devel- opment of cellulose nitrate lacquers re- ceived a remarkable impetus in the need of a low-cost, quiek-drying coating mnate- rial for many industrial purposes, nota- bly automobile bodies, and rapid technical advances were made. New solvents were developed for cellulose nitrate, the common solvents were reduced in price by improvements in manufacturing methods and volume prodclution, and the spraying process was perfected. As a result the improved cellulose nitrate lacq-uers, with a few changes to make them suitable for doping airplane cloth, gradually replaced th e less hazardous cellulose acetate dope which was techni- cally dead in that post-war period. To-day, however, the technical position of cellulose acetate has been altered. The rapid increase in the use of motion picture and x-ray films made from cellu-

lose nitrate was accompanied by a num- ber of serious conflagrations, which centered attention on the desirability of a relatively non-flammable film pre- pared from cellulose acetate. This acted as a stimulus to research on the produc- tion of cellulose acetate and its solvents, and resulted in a rapid growth of the manufacture of safety film and cellulose acetate plastics. Cellulose acetate dopes are, therefore, now only moderately more expensive than cellulose nitrate dopes. When it is considered that the cost of the dope is much less than 1 per cent. of the total cost of an airplane, this difference in price of the two dopes becomes insignificant as compared with the potential loss resulting from the destruction of the airplane by the accidental ignition of the fabric doped with the very flammable cellulose nitrate.

GORDON M. KLINE



fire-resistant fabric for aircraft

Documents