Two series of antihail rocket propellant grains failed only 3 months after production, due to the appearance of cracks in the grain channel. Structural integrity analysis demonstrated sufficient reliability at the beginning of service life. Further analysis showed that under temperature loads, cumulative damage during the short period in field stocks caused the grain failure, despite the established opinion that such failure can become significant only after lengthy storage. A linear cumulative damage law is evaluated by exposing a number of hydroxyl-terminated polybutadiene (HTPB) composite propellant specimens to different but constant stress levels. The analysis showed that cumulative damage must not be overlooked at the design stage. Further, a positive correlation between the propellant cumulative damage law and tensile strength is strongly indicated.

Composite solid propellants based on ammonium perchlorate/hydroxyterminated polybutadiene/isophorone dyisocyanate including different contents of octogene (HMX) have been represented in this paper. The mass of HMX increased in relation to oxidant, with constant bimodal fraction ratio. Combustion of the propellants has been improved by adding of titanium (IV) oxide powder as stabilizer. Parameters of burning rate laws were determined and compared for the propellants of the same total solid phase. Also, the apparent viscosity, uniaxial mechanical characteristic, density and energetic values were determined for the same formulations.

The effect of four different compounds as the combustion stabilizers of composite solid propellants based on the AP/HTPB/IPDI has been presented in this paper. Except that, various total solid content, ammonium-perchlorate bimodal and trimodal combination of particle sizes ratio have been made by preparing the eleven formulations. For all of them, the burning rate law's parameters and temperature sensitivity, uniaxial mechanical characteristics, apparent viscosity of uncured propellants and physico-chemical and energetic values have been determined and compared.

Rocket motor nozzle flow geometry is considered through its influence on the thrust vector control (TVC) performances. Extensive research is conducted using theoretical and software simulations and compared with experimental results. Cold and hot flow test equipments are used. The main objective of the research is to establish the methodology of flow geometry optimisation on the TVC hardware system. Several geometry parameters are examined in detail and their effects on the system performances are presented. The discovered effects are used as guidelines in the TVC system design process. A numerical method is presented for the determination of dynamic response time upper limit for the TVC system based on the gas flow dynamics performances.