Editing Hybrid-propellant rocket (section)

==Basic concepts==
[[File:Hybrids_big-tosvg.svg|thumb|300px|Hybrid rocket propulsion system conceptual overview]]

In its simplest form, a hybrid rocket consists of a [[pressure vessel]] (tank) containing the liquid [[Oxidizing agent|oxidizer]], the [[combustion chamber]] containing the solid [[rocket propellant|propellant]], and a mechanical device separating the two. When thrust is desired, a suitable ignition source is introduced in the combustion chamber and the valve is opened. The liquid oxidiser (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 extremely dangerous and [[rocket propellant#Advantages 2|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]].