Solid-fuel ramjet

However, it must be noted that Eq. (1.62) is applicable for ramjet propulsion, as in ducted rockets and solid-fuel ramjets, because in these cases air enters through the inlet and a pressure difference between the inlet and the exit is set up. The mass flow rate from the inlet m plays a significant role in the generation of thmst in the case of ramjet propulsion. 

Boron has been studied as a possible fuel for solid fuel ramjets (10,11). Fine particle sized boron, where the average particle size is 0.3 Lm, has been studied for use as a gas-generating agent for solid fuel ram rockets (12). 

Figure 14.8 Structure of a solid fuel ramjet (SFRj).

Ducted rockets are intermediate between solid rockets and liquid ramjets in their propulsion characteristics. The propulsive force of soHd rockets is generated by the combustion of propellants composed of oxidizer and fuel components. Thus, no additional fuels or oxidizers need to be introduced from the atmosphere into the rocket motor. The momentum change of the exhaust gas from the nozzle attached to the aft-end of the combustion chamber is converted into the thrust for propulsion. On the other hand, the propulsive force of Hquid ramjets is generated by the combustion of a liquid hydrocarbon fuel with air introduced from the atmo-sphere.Ii] jjjg incoming air is compressed by a shock wave formed at the air-intake attached to the front end of the combustor. The air taken in from the atmosphere serves only as the oxidizer for the ramjets. The thrust is created by the momentum difference between the exhaust gas from the combustor and the air taken in from the atmosphere. 

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