Editing Rocket (section)

===Staging===
{{Main|Multistage rocket}}
[[File:Artistsconcept separation.jpg|thumb|Spacecraft staging involves dropping off unnecessary parts of the rocket to reduce mass]]
[[File:Ap6-68-HC-191.jpg|thumb|[[Apollo 6]] while dropping the interstage ring]]
Thus far, the required velocity (delta-v) to achieve orbit has been unattained by any single rocket because the [[propellant]], tankage, structure, [[guidance system|guidance]], valves and engines and so on, take a particular minimum percentage of take-off mass that is too great for the propellant it carries to achieve that delta-v carrying reasonable payloads. Since [[Single-stage-to-orbit]] has so far not been achievable, orbital rockets always have more than one stage.

For example, the first stage of the Saturn V, carrying the weight of the upper stages, was able to achieve a [[mass ratio]] of about 10, and achieved a specific impulse of 263 seconds. This gives a delta-v of around 5.9&nbsp;km/s whereas around 9.4&nbsp;km/s delta-v is needed to achieve orbit with all losses allowed for.

This problem is frequently solved by [[staging (rocketry)|staging]]—the rocket sheds excess weight (usually empty tankage and associated engines) during launch. Staging is either ''serial'' where the rockets light after the previous stage has fallen away, or ''parallel'', where rockets are burning together and then detach when they burn out.<ref name="NASAstaging">{{cite web |author=NASA |url=https://spaceflightsystems.grc.nasa.gov/education/rocket/rktstage.html |title=Rocket staging |access-date=2016-05-28 |publisher=NASA |work=Beginner's Guide to Rockets |year=2006 |url-status=dead |archive-url=https://web.archive.org/web/20160602123849/https://spaceflightsystems.grc.nasa.gov/education/rocket/rktstage.html |archive-date=2016-06-02 }}</ref>

The maximum speeds that can be achieved with staging is theoretically limited only by the speed of light. However the payload that can be carried goes down geometrically with each extra stage needed, while the additional delta-v for each stage is simply additive.