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Fiber-Reinforced Elastomers
Published in Anil K. Bhowmick, Current Topics in ELASTOMERS RESEARCH, 2008
A solid propellant rocket motor consists of a solid propellant placed inside a metallic or composite casing which is protected from the hot combustion gases by means of insulators, liners, and inhibitors. The solid propellant on combustion is decomposed into low molecular weight gaseous products liberating very high temperature, of the order of 2500–3500 K. The chamber is to be protected from these hot combustion gases for its smooth functioning. This thermal protection is achieved by insulating the inner surface of the metallic case by suitable materials. Organic compounds are considered to be the most suitable material for rocket motor insulators because of the formation of surface char layer, which plays a predominant role in the absorption of heat because of its high heat capacity. The high heat capacity of the char reduces the heating rate to the surface of the material to be protected and coupled with a high surface emittance dissipate a large fraction of the incident heat [195]. Also, the insulator should be resilient enough to withstand the high thermal stresses generated during the burning of the propellant and it should be able to tolerate the thermal expansions and contractions at the time of launching of the rocket so that it will not debond from the metallic casing and propellant. All these requirements show that vulcanized elastomers are an ideal choice as the matrix material for solid rocket motor insulators.
Method of Measurement of Admittance of Composite Solid Propellants Using Impedance Tube Technique
Published in Combustion Science and Technology, 2023
S. Ganesan, S. R. Chakravarthy, B. S. Subhash Chandran
This paper describes the attempt of obtaining the admittance and response of a composite solid propellant using the Impedance tube technique. A novel approach of positioning the inner tube outside the outer tube was explored. This avoided the use of feed-through of signals which is a major simplification of the test set up against the literature. The details of the experimental set up and the procedure to conduct the experiment were listed. The governing equations were simplified and solved for the acoustic pressure and velocity at the burning surface by different methods including numerical/direct method, analytical method and “T”-matrix method. The results were matching well and the verification of the determination of “T”-matrix was also discussed. The initial assumption of a constant temperature distribution and then its relaxation to consider its variation along the tube lead to a systematic approach of determining the “T”-matrix and hence the admittance. The minimization of error between the experimentally obtained pressure and the theoretically calculated pressure has been carried out. The determined admittance is comparable to that of T-burner results for the same propellant and the results would be extended to different initial grain temperatures which would make a meaningful outcome of this work. These results will be useful for the prediction of the stability of the solid propellant rocket motor. The imaginary part of the response determined by this technique is an essential information useful for the stability prediction which is not otherwise possible to determine experimentally using a T-burner.
The transfer and exploitation of German air-to-air rocket and guided missile technology by the Western Allies after World War II
Published in The International Journal for the History of Engineering & Technology, 2020
American research and development on aircraft rockets began before the US entered the war in December 1941, and was largely built upon British dry-extruded double-based solid propellant rocket technology that was passed to the Americans in 1940. The US Army, with some support from the US Navy, had a 4.5-inch folding-fin air-to-air rocket in development that was fired from a three-tube jettisonable launcher, but disappointing results led the Americans to produce their own versions of the British 3-inch rocket and Mk. I launching installation. US Navy research and development with aircraft rockets was predominately directed towards anti-shipping and anti-submarine weapons, with considerable success from 1943 onwards. As a result of these efforts, by 1945 the US was beginning to surpass the UK in aircraft rocket development, but no air-to-air rockets entered service during the war. In the guided AAM field, the US Navy Bureau of Aeronautics (BuAer) initiated two projects, both planned to be powered by liquid propellant rocket engines (LPREs) – an air-to-air version of a SAM called the ‘Lark’; and the ‘Gorgon IIA’, which became a test vehicle after the war.17
Combustion Characteristics of Boron-HTPB-Based Solid Fuels for Hybrid Gas Generator in Ducted Rocket Applications
Published in Combustion Science and Technology, 2019
Syed Alay Hashim, Srinibas Karmakar, Arnab Roy
The ramjet engine is considered to be an attractive propulsive device which offers simplicity, higher thrust, higher specific impulse, safety and working stability as compared to an equivalent rocket motor (Fry, 2004). Refinement of the fundamental design of solid fuel ramjet (SFRJ) engine has happened over last several decades and continues to be an active research area till date. In this field, Gany and Netzer and few other researchers have been working for last several years to build a small-scale ramjet combustion chamber which could be utilized to support analytical and numerical studies (Mady et al., 1978; Netzer, 1978; Netzer and Gany, 1991). The SFRJ have also been used to examine high-density fuel formulations containing polymer with embedded metal particles (Gany and Netzer, 1986; Natan and Gany, 1991). The most commonly used fuel is hydroxyl-terminated polybutadiene (HTPB) which also works as a binder for additives (Chiaverini et al., 1999) and provides higher specific impulse (Jain, 2002). Use of HTPB is significant to the propulsion community due to its extensive application in solid propellant rocket motors. The widespread use of HTPB is due to its desirable mechanical properties at a wide range of temperatures, even when it is highly loaded with metal particles (Muthiah et al., 1992, 1991).