Density impulse

A relatively new class of fluorocarbon composite nronlrits with relatively high specific impulse and a high density impulse have been tested as booster rockets for 5-inch projectiles. 

The influence of metal type on the specific impulse of propints has been described previously in this article (Table 16). The max theoretical specific impulse and density impulses (ISp x p ) for the oxidizers AN, AP and hydrazinium nitrate with 15 weight percent -fCH2)- binder have been calculated for various fuels (Ref 24). These data are in Tables 49-51. The ISp performance of nitronium perchlorate, lithium perchlorate and potassium perchlorate and metallized fuels with 4CH2>- binder are given in Table 52 (Ref 43)... 

Oxidizer Fuel Specific impulse (sec) Density impulse (gm seo/om )... 

In systems in which the vehicle configuration is volume limited, theoretical performance comparisons, using density impulse (Isd) are also necessary. This nomenclature, which is the product of the Is and the bulk density of the propellants, defines the amount of thrust available in a unit volume of the propellant. The relative importance of Isd to Is must be defined in the mission analysis. 

Military applications can be subdivided into two distinct types— fixed launch site systems and mobile systems. Both types place emphasis on specific impulse, density impulse, excellent storability and stability, and instant readiness. Fixed-site systems, which include most of the long range ballistic missiles, are systems whose launch facilities are well established and are usually environmentally controlled. These vehicles are usually pump fed and regeneratively cooled. Hypergolicity is preferred, but not necessarily required. 

Mobile weapon systems include the ordnance weapon systems, such as the air-to-air, air-to-surface, surface-to-air, and short-range, surface-to-surface missile. Because of the limited volume requirements, heavy emphasis is placed on density impulse. These systems are completely prepackaged (including propellants) and require complete storability of the propellant as a liquid over a temperature range — 65°-160°F. Because of personnel proximity at all times, toxicity is sometimes an important factor. The large number of units which are utilized usually imposes restrictions on propellant cost. 

Other MAF fuels, MAF-1 (DETA-UDMH-acetonitrile, 50-40-10), and MAF-3 (UDMH-DETA, 20-80) were formulated primarily to increase density. These formulations were based on density impulse requirements of various prepackaged propulsion systems as well as to maintain the freezing point and viscosity characteristics of the UDMH. 

MACH I, Inc. USA, has developed a process to make zirconium powder as safe as aluminum powder (passivated Zr powder) and is in the process to develop propellants with high density-impulse for potential use in the ballistic missile defense system. These propellants would produce a high degree of impulse or thrust per unit of volume. 

J.L. Fields and J.D. Martin, The Combustion of Zirconium in Rocket Motors Containing High Density Impulse P ropellants, Vol IH, 12th JANNAF Combustion Meeting, CPIA Publication 273, (December 1975), 159-166... 

Density of fragments (splinters) test 1 XII 3 D84 Density impulse 3 D84... 

Density Impulse. The density impulse (I4) equal to the product of specific impulse by mass density, is a useful parameter in liq - proplnt rocket engineering. It gives the performance on the basis of wt per unit vol of the proplnts which yielded the performance... 

In volume limited applications, high density propellant combinations are favored and some appropriate trade-off between performance and density is established. In a truly volume limited system as shown in section IV. A. 1., the appropriate performance parameter is the product of the specific impulse and the propellant bulk density, a quantity usually labeled the density impulse. Conceivably, mixture ratio may be determined by yet other vehicle system considerations. If a new propellant combination is to be utilized in an existing vehicle, the optimum mixture ratio may be influenced by such considerations as existing pump flow rate capacities, tank volumes, and structure load carrying capacities. Even other system considerations, such as the desirability of operating at equal fuel and oxidizer volume flow rates to allow interchange of fuel and oxidizer flow hardware, may determine the propellant mixture ratio. 

The compns are based upon a copolymer of vinylidene fluoride and perfluoropropylene (Viton A) with polytetrafluoroethylene (Teflon) and various metals and oxidizers. A number of extrudable formulations are listed in Table 15 (Ref 57). The major advantages claimed for these proplnts are high density impulse, compatibility with highly energetic proplnt ingredients and resistance to high centrifugal forces... 

Zahalka, E. A., Seidler, F, J., Lappi, S, E., Yanai, J and Slotkin. T. A. (1993). Differential development of cholinergic nerve terminal markers in rat brain regions Implications for nerve terminal density, impulse activity and specific gene expression. Brain Ren. 601,221-229. 

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