Rocket propellant thrust

The ratio of rocket thrust to propellant mass flow, commonly called the specific impulse (/9p) of the propellant, represents a measure of the force developed per unit mass flow of propellant. From Eq. (2), it is apparent that high propellant-flame temperatures and low molecular-weight combustion products are required to produce high 7sp. 

The third type of propellent explosive, the composite type, is a more recent development, the purpose of which is to provide rocket propellants of increased thrust, compared with the ordinary varieties. Composite propellants are based on an oxidising solid, commonly a perchlorate, together with an organic binder which both acts as fuel and gives adequate mechanical strength to the mixture. The search for even more energetic compositions continues, but because of the military importance of the... 

The performance of rocket propellants is commonly studied by means of the specific impulse which can be expressed as the thrust delivered per unit weight of propellant consumed as shown by equation (3.9). 

In organizing the symposium, we made the usual division into solid and liquid rocket propellants. Most readers no doubt already know the relative merits of solid vs. liquid systems—viz., the instant readiness of solids (compared with cryogenic liquids), their higher density (important in volume-limited systems), and the relative simplicity of rocket construction liquids offer easy variation in thrust level and the attainment of higher specific impulses, the latter because physical separation permits the use of fuels and oxidizers that would be incompatible if premixed. 

The specific impulse Is is used to compare the performances of rocket propellants and is dependent on the thrust and flow rate of the gases through the nozzle as shown in Equation 8.4. 

Liquid rocket propellants are subdivided into monopropellants and bipropellants. Monopropellants are liquids which burn in the absence of external oxygen. They have comparatively low energy and specific impulse and are used in small missiles which require low thrust. Hydrazine is currently the most widely used monopropellant however, hydrogen peroxide, ethylene oxide, isopropyl nitrate and nitromethane have all been considered or used as monopropellants. Information on the performance of some monopropellants is presented in Table 8.3. 

CA 83, 82252 (1975) [The system RFNA/ UDMH was examined in a rocket motor of lOOdaN thrust. The optimum pressure for this system was found to be 7 x 106 Pascals. At one atm the H2—02 flame was almost invisible, but under increased pressure a bright, bluish-white light was emitted because of a flame continuum. This flame continuum was concluded as being the emission from transient, excited species characterized by the nonequil state] Compatibility. 1) W.K. Boyd et al, Compatibility of Materials with Rocket Propellants and Oxidizers , DM C Mem 201, Battelle Mem Inst, Columbus, Contract AF 33 (615)-l 121 (1965) CA 67,23666 (1967) [UDMH compatibility data reported is summarized in Table 1. The compatibility data for UDMH/hydrazine (50/50 wt %) is summarized in Table 2. The explanation of the numeric evaluation code used in these tables for metals is presented in Table 3 for nonmetals in Table 4 2) M.J. Spanger T.J. Reinhart, Jr, Development of Filament-Wound Tankage for Rocket... 

Before any form of antimatter rocket can exist, a lightweight method must be developed for producing antiparticles at a flow rate of grains/second in contrast with the few dozen of antiparlicles produced in research laboratory generators. Also, a practical storage or containment method must arise inasmuch as antiparticles explode violently upon contact with normal matter. Reference 5 gives a performance estimate of an Ip of 3.06 x 10 seconds for a rocket propelled vehicle with a thrust/weight ratio of 10 1... 

A thermal rocket of recent development which produces low thrust and specific impulse for satellite control purposes is the subliming propellant rocket. In this rocket the propellant is ordinarily a high vapor pressure solid. Propellant flow rate is controlled by the addition of heat to the subliming propellant. Desirable properties of propellants for such rockets is stability in the solid phase, high vapor pressure, and, as for all thermal rocket propellants, low molecular weight of the vapor produced. 

Uses Replacement for TATB, main component of thermally stable explosives, addictive with initiating compositions to protect against premature firing of blasting caps or detonators as a result of EMF s, and EMP bursts, and component in rocket propellants with HMX or RDX to increase thrust. ... 

Use Intermediate in the manufacture of other high explosives, and as an ingredient in demolition charges, and rocket propellants—increase thrust by providing chlorine, but increases smoke trails. ... 

Uses Can be used in priming compositions when mixed with lead styphnate or lead azide, explosives compositions with TNT, ammonium nitrate, RDX, HMX, or PETN, and in missile warheads in combination with HNS. PNT can also be used as a filler for rocket propellants as it increases thrust to weight ration. ... 

Fluorine has been considered for use as an oxidant in rocket propellants. Its high reactivity ensures high energy release, and consequently high thrust. Its reaction with ammonia ... 

Solid-fueled and liquid-fueled rockets were developed because of the characteristics of travel beyond the Earth s atmosphere. First, a spacecraft must develop a speed of more than 25,000 mile per hour to break the gravitational puU. Second, in space oxygen is absent, so turbojet engines and internal-combustion engines will not operate. Therefore, alternative types of propulsion needed to be developed, which is why solid-fueled and liquid-fueled rockets were developed. Rockets develop thrust without having oxygen available to burn. Engineers term the types of chemical mixtures used in rockets that produce thrust as propellants. 

The two most important properties of rocket propellants are the thrust they impart to the rocket and their specific impulse The thrust T, expressed in newtons, is given by the product of the mass flow rate of propellant in kg.s and the velocity v of exhaust gases in m.s according to the simple equation ... 

The important performance parameters for the performance of a rocket propellant are the thrust Fand the specific impulse 4. ... 

Manned space flight began with the Air Force X-1 airplane, which, like the V-2, was propelled with alcohol and liquid oxygen. The X-1 was the first aircraft in the world to break the sound barrier. The later and more advanced X-15, which was provided with a 254 kN (57,000 Ibf) thrust rocket engine, achieved speeds of over 2km/s (4500 mph)—and altitudes of over 108 km (67 miles) above the earth, or 27 km beyond the arbitrary boundary of space. 

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