The study of burning characteristics of Ap/Htpb/Al basic components of a composite propellant

Abstract

Starting the research on a solid propellant would be very much easier if the burning characteristics of a simple propellant is known. A simple propellant is a propellant made of three basic components namely oxidizer, fuel and binder without any additive substance to alter its characteristics. Unfortunately, a very limited number of references were published discussing the burning characteristics of simple propellant. This paper describes the burning characteristics of basic formulations of Ammonium perchlorate based propellant. Thirteen sets of propellant formulations have been selected and manually prepared without adding any additives. The simple propellant consists of Ammonium Perchlorate (AP) as an oxidizer, Aluminum (Al) as fuel and Hydroxy-Terminated Polybutadiene (HTPB) as fuel and binder. For each mixture, HTPB binder was fixed at 15% and cured with Isophorone isocyanate (IPDI). By varying AP and Al, the effect of oxidizer- fuel (O/F) ratio on the whole propellant can be determined. The propellant strands were manufactured using press-moulding method and burnt in strand burner at ambient pressure to obtain the initial burning characteristics. Then, four propellant compositions namely p60, p66, p74 and p80 were selected for further evaluation over a range of pressures from 1atm to 31atm. The results show that the increasing of O/F ratio and combustion pressure lead to increase in burning rate. The highest burning rate achieved is 12mmsec-1at combustion pressure of 31atm for propellant p80 which has O/F ratio of 4.0.