Editing Hybrid-propellant rocket (section)

{{Short description|Rocket engine that uses both liquid / gaseous and solid fuel}}
{{Use mdy dates|date=August 2018}}
[[File:SpaceShipOne schematic.png|thumb|350px|Hybrid [[rocket motor]] detail of [[SpaceShipOne]]]]

A '''hybrid-propellant rocket''' is a [[rocket]] with a [[rocket motor]] that uses [[rocket propellants]] in two different phases: [[solid rocket propellant|one solid]] and the other either gas or [[liquid rocket propellant|liquid]]. The hybrid rocket concept can be traced back to the early 1930s.

Hybrid rockets avoid some of the disadvantages of [[solid rocket]]s like the dangers of propellant handling, while also avoiding some disadvantages of [[Liquid-fuel rocket|liquid rockets]] like their mechanical complexity.<ref>{{cite web |title=Hybrid rocket propulsion overview |publisher=Space Propulsion Group, Inc. |url=http://www.spg-corp.com/space-propulsion-group-resources.html}}</ref> Because it is difficult 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 engines, hybrid rocket motors can be shut down easily and the thrust is throttleable. The theoretical [[specific impulse]] (<math>I_{sp}</math>) performance of hybrids is generally higher than solid motors and lower than liquid engines. <math>I_{sp}</math> as high as 400&nbsp;s has been measured in a hybrid rocket using metalized fuels.<ref>{{cite web |title=A brief history of hybrid rocket technology |publisher=Space Propulsion Group, Inc. | url = http://www.spg-corp.com/News_12.php |url-status=dead |access-date=October 15, 2010 |archive-url=https://web.archive.org/web/20110716115139/http://www.spg-corp.com/News_12.php |archive-date=July 16, 2011}}</ref> Hybrid systems are more complex than solid ones, but they avoid [[PEPCON disaster|significant hazards]] of manufacturing, shipping and handling solid rocket motors by storing the oxidizer and the fuel separately.