Study relates geometry of an internally burning, single, solid-propellant grain to propellant characteristics, engine requirements, and selected starting pressure. Study derives curves for selecting propellants to meet specific engine requirements, or for tailoring engine requirements to propellant limitations

Gill, G. S.

English

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December 1970	 Brief 70-10701 
NASA TECH BRIEF 
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 progam may be directed to the Tech-
nology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Starter Propellants and Auxiliary Generators for Gas Turbines 
Concepts and designs of gas generators were studied 
in an effort to delineate a better starter system for gas 
turbines that require a source of clean moderate-
temperature hot gas and progressively greater power. 
The most severe constraint was that the propellants be 
operable at temperatures between —250° and +200°F. 
None of the solid propellants were satisfactory. 
They were all limited by the fact that their burning-
rate temperature sensitivities (irK) at constant K 
were considerably higher than the maximum allow-
able. No liquid bipropellant or monopropellant was 
sufficiently liquid at —250'F while retaining a rea-
sonable vapor pressure at 200'F. Hybrids proved to be 
unsuitable, and a gaseous oxygen-hydrogen system 
met the temperature requirements but failed in other 
aspects. 
It is unlikely that a solid propellant with a irk' low 
enough to meet the temperature requirements could 
be developed. A solid propellant with a grain-tem-
perature-compensating device was determined to be 
the best solution, and various techniques for produc-
ing such devices were studied. Preliminary designs of 
two devices—a thermal coil and a bimetallic strip—
were made. 
A parametric study -relates the geometry (length, 
and initial and final diameters) of an internally burn-
ing, single, solid-propellant grain to the propellant 
characteristics (burn rate, burn-rate exponent, and 
grain density), the engine requirements (equilibrium 
mass flow rate at the beginning of the burn, and ratio 
between equilibrium mass flow rates at the start and 
finish of the burn), and the selected starting pressure. 
The curves derived from the study analysis can be 
used for selecting propellants to meet specific engine 
requirements, or for tailoring engine requirements to 
propellant limitations. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Code A&TS-TU 
Huntsville, Alabama 35812 
Reference: B70-10701 
Patent status: 
No patent action is contemplated by NASA. 
Source: G. S. Gill of 
North American Rockwell Corp. 
under contract to 
Marshall Space Flight Center 
(M FS- 188l3) 
Category 07 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
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Starter propellants and auxiliary generators for gas turbines

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