## Foreword

NASA experience has indicated need for uniform criteria for the design of space vehicles. Accordingly, criteria are being developed in the following areas of technology Guidance and Control Chemical Propulsion Individual components of this work will be issued as separate monographs as soon as they are completed. This document, part of the series on Chemical Propulsion, is one such monograph. A list of all monographs issued prior to this one can be found on the last page of this document. These...

## Density

Thrust and impulse are direct functions of the flowrate of the mass being discharged by a rocket motor. For accurate performance predictions, the density of the propellent generating this discharging mass must be known. Propellant density is determined from samples of the propellant being used in the motor design under analysis by one of the following general methods for measuring density of solids 1 Weight volume method A propellant specimen is cut to specified dimensions and weighed. This...

## Prediction of Performance Variability Variables

Variables shall include both the variations in propellant ballistic characteristics and the dimensional tolerances on the grain and inert components. Propellant ballistic parameter variations considered should be those demonstrated in small motor tests and substantiated, if possible, by variations determined frcm statistical analyses of similar full-scale motors. Parameters for which variations should be determined include burning rate, pressure exponent, temperature sensitivity, specific...

## Prediction of Variations

Prediction of variability for a performance parameter shall utilize a mathematical combination of propellant variations and grain and inert component tolerances. To make a prediction of variability, all variables that affect a single performance parameter must be combined. The mathematical technique recommended is to take the square root of the sum of the squares of tolerances and variations involved. This technique is applicable when taking the sum or difference of independent errors. A more...

## Specific Impulse

The propellant specific Impulse value used In motor performance predictions shall be the specific Impulse that can be delivered by the motor. The methods provided in section 3.3.1.1 should be used to account for losses and to predict l,, f the techniques of section 3.3.1.2 should be used to confirm and verify the predicted values. In the final evaluation of the motor design, the demonstrated values for ltpa obtained as recommended in section 3.3.1.2 provide the basis for performance...

## Internal Flow Field Modeling

Selection of the mathematical model used to simulate the motor internal flow field shall be based on the equations of continuity, momentum, and energy and on quasi-steady-state or transient gas dynamics. One-dimensional gas dynamic models should be used to simulate the combustion chamber internal flow fields. Computer programs of the type documented in references 2 and 3 are recommended for general use. The program described in reference 2 is recommended for motors with relatively high...

## Burning Front Progression

Burning-rate relationships utilized in prediction of burning-front progression shall account for the effects of internat flow, propellant temperature, and motor dynamics. Propellant burning-front progression rate should be calculated by using sections 3.1.2.1, 3.1.2.2, and 3.1.2.3. The necessary semi-empirical relationships should be developed from the results of propellant tests in small BEM firings as recommended in section 3.3.3. Burning-rate relationships ihuit utilize locally predicted...

## State Of The

In a solid rocket motor, hot gases generated by the chemical reaction between a fuel and an oxidizer stored within the motor are accelerated to supersonic velocities through a nozzle designed to develop the resultant force. Propulsion thus is achieved by the conversion of the thermal energy of a chemical reaction into the kinetic energy of combustion products. The effectiveness of this process is predicted and assessed by evaluating the reaction thrust developed through the pressure-imparted...

## Burning Rate

Th'i recommended techniques to be used in determining augmented rates are presented in section 3.3.3.2. 3.3.3.1 Linear Burning-Rate Characteristics Prediction of full-scale-motor propellant linear burning rates shall be based on the characteristics demonstrated in small-ballistic-evaluation-motor tests. Linear burning rates of solid pmpellants depend primarily on formulation, chambcr pressure, and temperature of the propellant grain. To provide burning-rate data for...

## Nozzle Performance

The prediction of motor pressure- and thrust-time histories shall include the evaluation of the nozzle performance parameters throat area and thrust coefficient as functions of motor operation time. The dependency of chamber pressure on the nozzle throat area is expressed by equation 44 equation 3 relates the instantaneous value of thrust-to-nozzle characteristics and chamber pressure. The variations in these parameters with motor operating time should be determined by the methods described in...

## Aiaa Solid Propellant Hercules

A. and Uecker, R. L. The Integrated Design Computer Program and the ACP-1103 Interior Ballistics Computer Program. STM-180. Aerojet-General Corp., Dec. 1964 AD 466965 . 2. Anon. Solid Propellant Rocket Motor Internal Ballistics Computer Programs. Program Manual, RK-TR-67-7, The Boeing Co., Sept. 1967 AD 822349 . 3. Anon. Grain Design and Internal Ballistics Evaluation Program IBM 7094 FORTRAN IV , Program 64101. Bacchus Works, Hercules Powder Co., July 1967 AD...

## Prediction of Motor Mass and Motor Balance Versus Time

Commonly used performance prediction programs treat the propellant only and do not account for the discharge of inert material. The source anJ quantity of inert discharge products are predicted from heat-transfer analyses of the thrust chamber made in the design of insulation and nozzle systems. Ther.e time histories for propellant and inert mass and balance are combined as in rrf. 103 with those of the hardware in separate predictions for the total motor. 2.3 Evaluation of Propellant...