Rocket propellant characteristics

Gun Propellents. Although the stresses on individual gun propellant grains are less severe because of the small size, these propellants must withstand much higher weapon pressures and accelerations. Formulation options are usually more limited for gun propellants than for rocket propellants because the products of combustion must not foul or corrode a gun, should have a low flame temperature, and should exhibit minimum flash and smoke characteristics. Gun propellants are examined microscopically for porosity, are tested for mechanical characteristics, and fired in closed bombs to determine the burning characteristics. 

Oxidizers. The characteristics of the oxidizer affect the baUistic and mechanical properties of a composite propellant as well as the processibihty. Oxidizers are selected to provide the best combination of available oxygen, high density, low heat of formation, and maximum gas volume in reaction with binders. Increases in oxidizer content increase the density, the adiabatic flame temperature, and the specific impulse of a propellant up to a maximum. The most commonly used inorganic oxidizer in both composite and nitroceUulose-based rocket propellant is ammonium perchlorate. The primary combustion products of an ammonium perchlorate propellant and a polymeric binder containing C, H, and O are CO2, H2, O2, and HCl. Ammonium nitrate has been used in slow burning propellants, and where a smokeless exhaust is requited. Nitramines such as RDX and HMX have also been used where maximum energy is essential. 

When mixed with hydrocarbons in approximately stoicheiometric proportions, a sensitive highly explosive mixture is produced which needs careful handling [1,2], The use of such mixtures as rocket propellants has also been investigated [3], Explosion of only 10 g of a mixture with toluene caused 10 deaths and 20 severe injuries [4], The mixture contained excess toluene in error [5], Detonation characteristics of mixtures with benzene, toluene (and nitrobenzene) were studied [6],... 

Kubota, N., Survey of Rocket Propellants and Their Combustion Characteristics , fundamentals of Solid-Propellant Combustion (Eds. Kuo, K. K., Summer-field, M.), Progress in Astronautics and Aeronautics, Vol. 90, Chapter 1, AlAA, Washington DC (1984). 

Since the combustion temperature of AN pyrolants is very low compared with other composite pyrolants, their specific impulse when used as rocket propellants is also low. However, they are used as gas generators for the control of various types of mechanics owing to the low temperature and low burning rate characteristics. 

Hybrid Rocket Propellants. A special proplnt combination of unlike materials, particularly of unlike physical characteristics. Typical hybrid proplnt combinations are a solid fuel (or oxidizer) in combination with a liquid oxidizer (or fuel) in tjiat order. Sometimes a grain of solid fuel is encased in the combustion chamber of a rocket engine and burned in combination with liq oxygen. Similarly, a liq fuel may be injected into a combustion chamber in contact with a solid oxidizer. Another example is the use of concentrated hydrogen peroxide and a hydrocarbon fuel. In this case, the hydrogen peroxide is converted by decompn into a hot gas contg oxygen. The fuel is injected downstream of the first reaction, mixed with the hot oxidizer-rich gas, and burns (Ref 1)... 

Hydrocellulose differs from hydrated cellulose in its properties (Ref 3). According to Stettbacher (Ref 5) hydrocellulose lies between the hydrated cellulose and oxycellulose. Its use as a flash reducer in a propellant has been claimed by C.R. Franklin in USP 1564549 (1925) CA 20, 505 (1926). Accdg to CIOS Rept 31-68 (1945), pp 6-7, hydrocellulose was used during WWII by Germans in some rocket propellants, presumably to improve their burning characteristics. For instance the so-called Ammon-pulver contained 5% hydrocellulose and the EP (Einheitspulver) contained about 3%. Hydrocellulose was also used in some rocket propellants to increase the rate of burning at low temperature... 

K. Yamazaki, Solid Rocket Propellants Burning Characteristics , KKK 28 (5), 356—63... 

Since the development of this terpolymer in 1957, more solid composite rocket propellant has been produced from PBAN than from any other single prepolymer. Propellants based on this material have been used successfully in applications ranging from small tactical motors to the 260-in. diameter motor containing greater than 2,000,000 lb. of propellant. PBAN propellants, therefore, have been and are expected to be a major factor in making solid rocket motors during the next several years. The thermal stability which has been achieved, low temperature cycling characteristics, and low cost of propellants based on this prepolymer make this system attractive. 

The physical and chemical characteristics of these candidate liquid propellants vary widely. However, all of the liquids which have found application as rocket propellants have one common characteristic—they are designed to fit the particular requirements of at least one particular rocket engine and vehicle system. Obviously, few liquids initially fulfill the requirements of a propulsion system designed to perform a particular mission. Thus, various compromises must be undertaken between the... 

The synthesis and structural aspects of metal salts of NTO, that is, K, Cu and Pb NTO reveal that they have special characteristics and may find applications in several fields including ballistic modification of rocket propellants. The study of their thermal behavior with differential scanning calorimetry (DSC) suggests that ... 

DAATz, having a high positive heat of formation (1032 kj moT1), is considered a potential HEM to be used in rocket propellant and IHE formulations. On the other hand, DHTz may find application as an eco-friendly smoke ingredient in pyrotechnic formulations for special applications. As regards tetrazolates, the tri-aminoguanidinium salt having a heat of formation equal to 560 kj mol 1 and reasonable sensitivity characteristics, these salts compete with DAATz. 

The propellant is the most vital sub-system of a gun and rocket or missile system and accordingly, the performance of a gun, rocket or missile mainly depends on the propellant used. Some basic performance parameters are used to define the characteristics of these propellants and they are different for gun and rocket propellants. 

Novolac epoxy flexibilizers Improve low and high temperature characteristics of novolac epoxy resins for inhibition of composite rocket propellants [164]. 

NANOCAT Superfine Iron Oxide(SFIO) is a novel bum-rate catalyst and performs superbly in solid rocket propellants based on ammonium perchlorate (AP). SFIO provides a higher burn rate and lower pressure exponent compared with commercial iron oxides at equal concentrations. Some characteristics of NANOCAT SFIO as a burn-rate catalyst are as follows ... 

The characteristics desired of a rocket propellant axe several in number and can be divided into economic, safety, materials compatibility, engine-cycle needs and vehicle requirements. 

PATR 1637(1947XBurning and other characteristics of stick rocket proplnts) 6)S.S.Penner, JApplPhys 19, 392-8(1948) CA 42, 6512(1948)(Effect of radiation on rate of burning of solid fuel rocket proplnts) 7)L.H.Eriksen, Investigation of Asphalt-Perchlorate and Resin-Perchlorate Rocket Propellants , PATR 1676(1948) 8)S.S.Penner, JApplPhys 19, 511-13(1948) CA 42, 8475(1948) (The theory that burning rates of rocket proplnts increase slightly with an increase in radiation path length was verified experimentally for two double-base rocket proplnts) 9)W.G.Thummel,... 

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