Adding soluble solid oxidizers to hydrazine and similar fuels makes them useful in low temperature bipropellant systems. These oxidizers improve the low specific impulse, high freezing point, low boiling point, and low density of the fuels

Hendel, F. J.

English

NASA Technical Reports Server

April 1967	 Brief 67-10058 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Addition of Solid Oxidizer Increases Liquid Fuel Specific Impulse 
The problem: 
Hydrazine and similar fuels, while useful, exhibit 
undesirable properties of low specific impulse, high 
freezing point, low boiling point, and low density. To 
make such fuels more useful in low temperature bipro-
pellant systems, it is necessary to improve these 
properties. 
The solution: 
The addition of solid oxidizers, commonly used in 
solid propellants, that are soluble in hydrazine and 
like fuels. 
How it's done: 
Ammonium perchlorate is dissolved in fuels such as 
hydrazine, UDMH (Unsymmetrical dimethyl hydra-
zine), and Aerozine—a 1:1 mixture of hydrazine and 
UDMH. The addition of the oxidizer to hydrazine 
increases the standard specific impulse from 198 to 
250 lbf-sec/lbm, lowers the freezing point from +35° F 
to the range of 0°F to —100°F, raises the boiling 
point from 2360 F to above 270°F, and increases the 
density from 1.0 to about 1.4 g/cc, depending upon 
the proportion of ammonium perchlorate in the solu-
tion. Similar improvements result from addition of 
the oxidizer to UDMH and Aerozine. Maximum 
calculated specific impulses of 265 and 318 lbf-sec/ 
Ibm for standard and vacuum conditions, respectively, 
result from a solution containing 73% ammonium 
perchlorate and 27% hydrazine. The solution has a 
density of 1.56, but suffers the disadvantage of 
extreme sensitivity to impact. The following table 
presents the impact sensitivity of pure hydrazine and 
two solutions of ammonium perchlorate in hydrazine.
NH4004 Sensitivity Value* Number of Explosion 
Wt. % = Potential Energy, Tests 
kg-cm  
0 300 15** No 
Sensitivity value of pure 
N2H4_is_
 above_300  333*** 120-126 9 No 
121.5-126.5 7 Yes  
Sensitivity_value _=123  
50 5-120 14 No 
50 5-150 23 Yes 
Sensitivity value = approx. 
40 (since the spread is too 
great the value is not accurate)
*Impact sensitivity determined by the Drop-Weight Test 
("Test No. 4") recommended by the JANAF Panel on Liquid 
Propellants. A sample in an amount of 0.03 cc, enclosed in a 
cavity (0.06 cc) and covered with a steel diaphragm, is exploded 
by puncturing the diaphragm with a piston onto which a 
weight is dropped from a certain height. The sensitivity value 
is the potential energy (height x weight) at which the probability 
of explosion is 50%. 
**The impact tests with hydrazine alone include 10 tests with 
frozen N2H4 which performed in an apparatus for solid 
propellants. 
***The freezing point of this mixture is below -100° F. At -30°F 
the viscosity of the mixture was low while at -100°F it was 
very high. 
Note: 
Inquiries concerning this invention may be di-
rected to:
Technology Utilization Officer 
Jet Propulsion Laboratory 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: B67-10058
(continued overleul) 
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. 
https://ntrs.nasa.gov/search.jsp?R=19670000058 2020-03-11T20:22:03+00:00Z
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: Frank J. Hendel 
(JPL-861) 
Brief 67-10058	 Category 03


Addition of solid oxidizer increases liquid fuel specific impulse

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