AP-HTPB composite propellant

Fig.4.13 Adiabatic flame temperature vs. composition of aluminized AP-HTPB composite propellants.

Fig. 7.3 Burning rates of three AP-HTPB composite propellants at low pressures below 1 MPa.

In order to clarify the combustion wave structure of AP composite propellants, photographic observations of the gas phase at low pressure are very informative. The reaction rate is lowered and the thickness of the reaction zone is increased at low pressure. Fig. 7.3 shows the reduced burning rates of three AP-HTPB composite propellants at low pressures below 0.1 MPa.FI The chemical compositions of the propellants are shown in Table 7.1. The burning rate of the propellant with the composition ap(0-86) is higher than that of the one with ap(0-80) at constant pressure. However, the pressure exponents are 0.62 and 0.65 for the ap(0-86) and Iap(0.80) propellants, respectively that is, the burning rate is represented by r for the p(0.86) propellant and by r for the p(0.80) propellant. 

If the binder (BDR) concentration of AP-HTPB composite propellants is less than the stoichiometric ratio, the burning rate increases as (BDR) increases, as shown in Fig. 7.6. The burning rate of a propellant with the composition bdr(0-08) is... 

Fig. 7.19 shows the burning rates of AP-HTPB composite propellants at 243 K and 343 K. The propellants are composed of bimodal fine or coarse AP particles. The chemical composihons of the propellants are shown in Table 7.2. The burning rates of both propellants are seen to increase linearly in an In r versus In p plot in the pressure range 1.5-5 MPa, and also increase with increasing initial propellant temperature at constant pressure.Ii l The burning rate increases and the temperature sensitivity decreases with decreasing AP particle size. 

Fig. 7.19 Burning rates and their temperature sensitivity for AP-HTPB composite propellants composed of fine or coarse AP particles.

Fig. 7.21 Temperature sensitivity characteristics of AP-HTPB composite propellants.

As shown in Fig. 7.20, the burning rate of the AP composite propellant is increased approximately twofold by the addihon of 1 % BEFP. In general, the degree of the burning rate increase is proportional to the amount of catalyst added when the catalyst conshtutes less than about 3 % of the total mass, and the effect of the catalyst addihon shows saturation behavior at about 5% by mass. Fig. 7.23 shows the burning rates of AP-HTPB composite propellants composed of ap(0-80) and... 

When HNF or ADN particles are mixed with a GAP copolymer containing aluminum particles, HNF-GAP and ADN-GAP composite propellants are formed, respectively. A higher theoretical specific impulse is obtained as compared to those of aluminized AP-HTPB composite propellants.However, the ballistic properties of ADN, HNIW, and HNF composite propellants, such as pressure exponent, temperature sensitivity, combustion instability, and mechanical properties, still need to be improved if they are to be used as rocket propellants. 

Hori, K., Iwama, A., and Fukuda, T. (1987) Enhancement of matrix-filler in HMX/AP/HTPB composite propellant. Proc. 18th Inti Ann. Conf. ICT,... 

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