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International Journal of Energetic Materials and Chemical Propulsion
ESCI SJR: 0.142 SNIP: 0.16 CiteScore™: 0.29

ISSN Print: 2150-766X
ISSN Online: 2150-7678

International Journal of Energetic Materials and Chemical Propulsion

DOI: 10.1615/IntJEnergeticMaterialsChemProp.2017011278
pages 351-369


Yutaka Wada
Chiba Institute of Technology, Tsudanuma 2-17-1, Narashino, Chiba 275-0016, Japan
Yo Kawabata
Chiba Institute of Technology
Ryuichi Kato
Akita University, Akita, Japan
Nobuji Kato
Katazen Corporation, Obu, Japan
Keiichi Hori
Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-Ku, Sagamihara, Kanagawa 252-5210, Japan


The hybrid rocket system is a promising next-generation space propulsion system owing to its low cost, high safety ability, and green characteristics. Conventional hybrid rocket systems have difficulty implementing large thrust motors owing to the low fuel regression rate. Studies regarding high regression rates of hybrid rocket fuel have been necessary for large motor designs. The high regression rate of low melting point fuels was confirmed in static firing tests by several researchers, where small droplets of the liquefied fuel were observed popping out from the burning surface using a slab motor in atmospheric conditions. However, the mechanism for the generation of small droplets from the fuel surface is unknown. The behavior of droplets under high pressure needs to be observed for a more thorough understanding of the combustion mechanism. In this study, a slab motor was prepared. Four fuel types, polymethyl methacrylate (PMMA), glycidyl azide polymer (GAP) mixture polyethylene glycol (PEG) fuel (GP fuel), WAX, and low melting point thermoplastics fuel (LT fuel), were selected as inert, high energy material, and low melting point fuels. The Katazen Corporation developed special LTs for this study to lower the melting point to a hot water temperature range. Visible light was eliminated to easily observe the surface behavior. An infrared filter was employed that allowed a wavelength of 760 nm or above to penetrate. No droplets were observed in the PMMA and GAP mixture PEG fuel combustion tests or during the Wax and LT fuel combustion tests conducted at 0.1 and 2 MPa.