Rocket Propellants, Burning Characteristics

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

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. 

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. 

Burning (Combustion) and Burning Characteristics of Propellants for Rockets. See Vol 2, pp B350-R to B355-R and the following Addnl Ref Anon, "Sources of Energy ,... 

Vol 3, p C428-L also "Burning and Burning Characteristics of Propellants for Rockets ,... 

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... 

Lead salts of aliphatic acids Burning characteristics remain substantially unaffected by variations in pressure during operation. Such propellants are suitable for use in rockets and guided missiles [235]. 

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 ... 

Experimental procedures for detn of burning rates of rocket proplnts are practically identical with those described under "Burning and Burning Characteristics of Propellants for Artillery Weapons and Small Arms The method described by Warren(Ref 25,PP 90-1) uses a modified Crawshaw strand-burning apparatus. This method is used with solid strands ca 1/8 in diam and 7 long and which are coated with a plastic so that they burn from one end only... 

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,... 

Burning and Burning characteristics of Propellants for Rockets in Vol 2,p B350-R and the following refs ... 

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