This volume brings together international scientists in the field of solid rocket propulsion. Thirty-nine papers present in-depth coverage on a wide range of topics including: advanced materials and non-traditional formulations; the chemical aspects of organic and inorganic components in relation to decomposition mechanisms, kinetics, combustion and modelling; safety issues, hazards and explosive characteristics; and experimental and computational interior ballistics research, including chemical information and the physics of the complex flow field.

Solid propellant chemistry, combustion, and motor interior ballistics

: Surface ignition of solid propellants has been represented by several analytical models, each involving obvious compromises with regard to scope of applicability. These models are distinguishable primarily in terms of site of the exothermic reaction governing ignition. Early research with nitrocellulose led to development of a theory involving chemical heat generation in the condensed phase. Two subsequent theoretical models were developed to explain ignition of the solid fuel ingredient of a composite propellant in an oxidizing atmosphere, and these two models were then extended on a heuristic basis to encompass a composite propellant in an inert atmosphere in which the oxidizing gas was produced by decomposition of the solid oxidizer. These two models are distinguished by whether the oxidation occurs at the surface or in the gas film above the surface. This report reviews the solid, heterogeneous, and gas-phase ignition theories and reviews the nature and implications of the assumptions involved. It is concluded that, while possessing certain drastic simplifications in common, the various quantitative models differ so conspicuously in their assumptions regarding external initiating stimulus as to make quantitative comparisons or tests of validity impossible.

Theory of ignition of solid propellants.

H + 62 + M -> HO2 + M Reaction in Lean Hydrogen-Oxygen Mixtures," Journal of Chemical Physics, Vol 43, No 9, Nov 1965, pp 3237-3247 7 Getzinger, R W, "A Shock Wave Study of Recombination in Near Stoichiometric Hydrogen-Oxygen Mixtures," Eleventh Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, Pa, 1967, pp 117-124 s Stull, D R, JANAF Thermochemical Tables, Dow Chemical Co, Midland, Mich; may be purchased as Rept PB-168370 ($1000) and addenda PB-168370-1 and PB-168370-2 ($300 each), National Bureau of Standards, CFSTI, US Dept of Commerce, Springfield, Va 9 Bird, P F, Duff, R E, and Schott, G L, "HUG, a Fortran-Fap Code for Computing Normal Shock and Detonation Parameters in Gases," Rept LA-2980, Feb 1964, Los Alamos Scientific Lab, The Univ of California, Los Alamos, N Mex 10 White, D R and Millikan, R C, "Oxygen Vibrational Relaxation in O2-H2 Mixtures," Journal of Chemical Physics, Vol 39, No 8, Oct 1963, pp 2107-2108 11 White, D R and Millikan, R C, "Vibrational Relaxation of Oxygen," Journal of Chemical Physics, Vol 39, No 7 Oct 1963, pp1803-1806 12 White, D R and Millikan, R C, "Oxygen Vibrational Relaxation in O2-He and O2-Ar Mixtures," Journal of Chemical Physics, Vol 39, No 7, Oct 1963, pp 1807-1808 13 Gilbert, R B and Strehlow, R A, "Theory of Detonation Initiation Behind Reflected Shock Waves," AIAA Journal, Vol 4, No 10, Oct 1966, pp 1777-1783 14 Getzinger, R W and Blair, L S, "A Shock Tube Study of the Effects of Nitrogen and Water Vapor on Recombination in the Hydrogen-Oxygen System," 6th International Shock Tube Symposium, Freiberg, Germany, April 12-14, 1967; also The Physics of Fluids, to be published 15 Shchelkin, K I and Troshin, Ya K, Gas Dynamics of Combustion, Mono Book Corp, Baltimore, Md, 1965, pp 1-53 16 Voitsekhovskii, B V, Mitrofanov, V V, and Topchian, M E, Struktura Fronta Detonatsii v Gaza, Akademiya Nauk SSSR Novosibirsk, 1963, pp 81-96; transl as The Structure of a Detonation Front in Gases, Rept FTD-MT-64-527 (AD 633821), Feb 1966, Foreign Technology Div, Wright-Patterson Air Force Base, Ohio, pp 81-97 17 Strehlow, R A and Engels, C D, "Transverse Waves in Detonations II Structure and Spacing in H2—O-2, C2H2—O2, C2H4—O2 and CEU—O2 Systems," AIAA Journal, to be published

Location of action of burning-rate catalysts in composite propellantcombustion.

Composite propellent catalysts: Copper chromate and chromite

Recent studies on the decomposition and combustion of ammonium perchlorate are reviewed with particular emphasis on the chemistry of the process and on the role of catalysts. This is used for a detailed discussion of the possible reaction mechanisms to attempt to select the specific areas requiring further investigation, both to extend the understanding of the combustion mechanism and to improve the basis of the theoretical models.

The Role of Catalysts in the Ignition and Combustion of Solid Propellants

: The ignition of polyisobutene, polyurethane, polystyrene and polymethyl-methacrylate has been studied with oxygen gas and with perchloric acid vapour under the same experimental conditions. All these fuels ignited with perchloric acid vapour at 200-250C whereas ignitions with oxygen were only achieved at temperatures above 350C. Less volatile fuels such as carbon black, nylon and terylene also ignited with perchloric acid vapour at 200-250C. ignition of ammonia, methane, ethylene and isobutene was not achieved by perchloric acid vapour in the absence of a surface at 200-250C. In the presence of a surface the order of decreasing ignitability was ammonia, isobutene, ethylene, methane. Cupric chromate and ferric oxide were effective catalysts in the ignition of gaseous fuels with perchloric acid vapour. Titanium dioxide, silica and alumina had no detectable effect. It is concluded that in ammonium perchlorate propellents the important reactions leading to ignition are heterogeneous rather than homogeneous, and that in a catalysed propellent the reaction of ammonia and perchloric acid on the surface of the catalyst is the significant reaction. The results are discussed in relation to current theories of the mechanism of the ignition of composite solid propellents containing ammonium perchlorate.

G. S. Pearson

Papers

Composite solid propellant ignition - Ignition of ammonia and other fuels by perchloric acid vapor.