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A hybrid rocket is a rocket with a rocket motor which uses rocket propellants in two different phases. - one solid and the other either gas or liquid. The hybrid rocket concept can be traced back at least 75 years.〔(【引用サイトリンク】 GIRD-09 )〕 Hybrid rockets exhibit advantages over both liquid rockets and solid rockets especially in terms of simplicity, safety, and cost.〔(【引用サイトリンク】 Hybrid Rocket Propulsion Overview )〕 Because it is nearly impossible for the fuel and oxidizer to be mixed intimately (being different states of matter), hybrid rockets tend to fail more benignly than liquids or solids. Like liquid rocket motors, but unlike solid rocket motors, hybrid rocket motors can be shut down easily and the thrust can be controlled with a simple throttle. The theoretical specific impulse() performance of hybrids is generally higher than solid motors, and roughly equivalent to hydrocarbon-based liquid motors. as high as 400s has been measured in a hybrid rocket using metalized fuels.〔(【引用サイトリンク】 A Brief History of Hybrid Rocket Technology )〕 Hybrid systems are more complex than solid ones, but the significant hazards of manufacturing, shipping and handling solid rocket motors offset the system simplicity advantages. ==Basic concepts== In its simplest form a hybrid rocket consists of a pressure vessel (tank) containing the liquid propellant, the combustion chamber containing the solid propellant, and a valve isolating the two. When thrust is desired, a suitable ignition source is introduced in the combustion chamber and the valve is opened. The liquid propellant (or gas) flows into the combustion chamber where it is vaporized and then reacted with the solid propellant. Combustion occurs in a boundary layer diffusion flame adjacent to the surface of the solid propellant. Generally the liquid propellant is the oxidizer and the solid propellant is the fuel because solid oxidizers are problematic and lower performing than liquid oxidizers. Furthermore, using a solid fuel such as Hydroxyl-terminated polybutadiene (HTPB) or paraffin wax allows for the incorporation of high-energy fuel additives such as aluminium, lithium, or metal hydrides. Common oxidizers include gaseous or liquid oxygen or nitrous oxide. Common fuels include polymers such as polyethylene, cross-linked rubber such as HTPB or liquefying fuels such as paraffin wax. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hybrid rocket」の詳細全文を読む スポンサード リンク
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