Closed-cell, semirigid, fiber-loaded, self-extinguishing polyurethane foam material fills voids around fuel cells in aircraft. Material prevents leakage of fuel and spreading of fire in case of ballistic incendiary impact. It also protects fuel cell in case of exterior fire

Fish, R. H.

Parker, J. A.

Rosser, R. W.

English

NASA Technical Reports Server

April 1975	 B75-10062 
•
	
NASA TECH BRIEF 
Ames Research Center 	 A £ 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Fiber-Modified Polyurethane Foam for Ballistic Protection 
The problem: 
To provide a foam material for filling voids around 
fuel cells in aircraft. The material must prevent leak-
age of fuel and spreading of fire in case of a ballistic 
incendiary impact and also must protect the fuel cell 
in case of an exterior fire; ideally, the material should 
be self-supporting and provide an insulative char 
residue. 
The solution: 
A closed-cell, semirigid, fiber-loaded, self-extin-
guishing polyurethane foam material. 
How it's done: 
The foam is made of a polyurethane resin which 
incorporates a fire-retardant material and plane-
oriented, randomly-distributed, chopped glass fibers. 
The foam is a white or light amber solid with a fibrous 
texture, having a density of 0.040 to 0.045 g/cc and 
an open-cell content of less than 15%. 
The formulation is adjusted to have a cream time 
of about 9 seconds, a rise time of about 17 seconds, 
and tack-free time of about 45 seconds at an ambient 
temperature of 24°C and relative humidity of 50%. 
Then a chopper for the glass fibers is appropriately 
installed on a spray machine; the chopper is to be run 
while the foam spray head is operating. The foam 
ingredients are loaded into the spray machine and 
the convergence of fibers and the foam spray is 
made to occur at a distance of 30 to 38 cm from the 
spray nozzle. The foam-fiber layup is accomplished 
by moving the spray head in an uniform side-to-side
motion about 46 to 61 cm from the mounting sub-
strate. The speed at which the passes are made must 
be controlled; if the passes are made too fast, the 
previously-deposited foam will not have creamed and 
risen, and a nonplanar fiber distribution will result. 
On the other hand, if the passes are made too slow, 
the foam becomes tack-free between passes, resulting 
in interlaininar separation. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: TSP 75-10062 
Patent status: 
This invention is owned by NASA, and a patent 
application has been filed. Inquiries concerning non-
exclusive or exclusive license for its commercial de-
velopment should be addressed to: 
NASA Patent Counsel 
Mail Code 200-1 1A 
Ames Research Center 
Moffett Field, California 94035 
Source: Richard H. Fish, John A. Parker, 
and Robert W. Rosser
Ames Research Center
(ARC-10714) 
Category 04 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
S
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Fiber-modified polyurethane foam for ballistic protection

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