Editing Liquid rocket booster

{{Short description|Same as a solid rocket booster, but uses liquid instead of solid fuel}}
A '''liquid rocket [[booster (rocketry)|booster]]''' ('''LRB''') uses [[liquid fuel]] and [[oxidizer]] to give a [[Liquid-propellant rocket|liquid-propellant]] or [[hybrid rocket]] an extra boost at take-off, and/or increase the total payload that can be carried. It is attached to the side of a rocket. Unlike [[solid rocket booster]]s, LRBs can be throttled down if the engines are designed to allow it, and can be shut down safely in an emergency for additional escape options in [[human spaceflight]].{{citation needed|date=March 2017}}

==History==
By 1926, US scientist [[Robert Goddard]] had constructed and successfully tested the first rocket using [[liquid fuel]] at [[Auburn, Massachusetts]].{{citation needed|date=March 2017}}

[[File:Ariane4.jpg|thumb|right|Launch of [[Ariane 4]]4LP two [[solid rocket booster]] (smaller) and two liquid rocket boosters (larger, with no visible [[Plume (hydrodynamics)|plumes]])]]

For the Cold War era [[R-7 Semyorka]] missile, which later evolved into the [[Soyuz (rocket family)|Soyuz rocket]], this concept was chosen because it allowed all of its many rocket engines to be ignited and checked for function while on the [[launch pad]].{{citation needed|date=March 2017}}

The Soviet [[Energia (rocket)|Energia]] rocket of the 1980s used four [[Zenit rocket|Zenit]] liquid fueled boosters to loft both the ''[[Buran (spacecraft)|Buran]]'' and the experimental ''[[Polyus (spacecraft)|Polyus]]'' space battlestation in two separate launches.{{citation needed|date=March 2017}}

Two versions of the Japanese [[H-IIA]] space rocket would have used one or two LRBs to be able to carry extra cargo to higher geostationary orbits, but it was replaced by the [[H-IIB]].{{citation needed|date=March 2017}}

The [[Ariane 4]] space launch vehicle could use two or four LRBs, the 42L, 44L, and 44LP configurations.  As an example of the payload increase that boosters provide, the basic Ariane 40 model without boosters could launch around 2,175 kilograms into [[Geostationary transfer orbit]],<ref>{{cite web |url=http://www.astronautix.com/lvs/ariane4.htm |title=Ariane 4 |accessdate=2011-03-29 |url-status=dead |archiveurl=https://web.archive.org/web/20051125071728/http://www.astronautix.com/lvs/ariane4.htm |archivedate=2005-11-25 }} astronautix.com</ref> while the 44L configuration could launch 4,790&nbsp;kg to the same orbit with four liquid boosters added.<ref>{{cite web |url=http://www.astronautix.com/lvs/arine44l.htm |title=Ariane 44L |accessdate=2005-08-14 |url-status=dead |archiveurl=https://web.archive.org/web/20050728150931/http://www.astronautix.com/lvs/arine44l.htm |archivedate=2005-07-28 }} astronautix.com.</ref>

Various LRBs were considered early in the [[Space Shuttle]] development program and after the [[Challenger accident|''Challenger'' accident]], but the Shuttle continued flying its [[Space Shuttle Solid Rocket Booster]] until retirement.{{citation needed|date=March 2017}}

After the Space Shuttle retired, [[Pratt & Whitney Rocketdyne]] and [[Dynetics]] entered the "advanced booster competition" for NASA's next human rated vehicle, the [[Space Launch System]] (SLS), with a booster design known as "[[Pyrios]]", which would use two more advanced [[Rocketdyne F-1#F-1B booster|F-1B]] booster engines derived from the [[Rocketdyne F-1]] LOX/RP-1 engine that powered the [[S-IC|first stage]] of the [[Saturn V]] vehicle in the [[Apollo program]]. In 2012, it was determined that if the dual-engined Pyrios booster was selected for the SLS Block 2, the payload could be 150 metric tons (t) to Low Earth Orbit, 20&nbsp;t more than the congressional minimum requirement of 130&nbsp;t to LEO for SLS Block 2.<ref name=":32">{{cite news |url=http://www.nasaspaceflight.com/2012/11/dynetics-pwr-liquidize-sls-booster-competition-f-1-power/ |title=Dynetics PWR liquidize SLS booster competition |date=November 2012}}</ref> In 2013, it was reported that in comparison to the F-1 engine, the F-1B engine was to have improved efficiency, be more cost effective and have fewer engine parts.<ref>{{cite news |url=https://arstechnica.com/science/2013/08/dynetics-reporting-outstanding-progress-on-f-1b-rocket-engine/ |title=Dynetics reporting "outstanding" progress on F-1B rocket engine |publisher=[[Ars Technica]] |date=2013-08-13 |accessdate=2013-08-13}}</ref> Each F-1B was to produce {{convert|1800000|lbf|MN|abbr=on}} of thrust at sea level, an increase over the {{convert|1550000|lbf|MN|abbr=on}} of thrust of the initial F-1 engine.<ref>{{cite news |url=https://arstechnica.com/science/2013/04/new-f-1b-rocket-engine-upgrades-apollo-era-deisgn-with-1-8m-lbs-of-thrust/ |title=New F-1B rocket engine upgrades Apollo-era design with 1.8M lbs of thrust |author=Lee Hutchinson |publisher=[[Ars Technica]] |date=2013-04-15 |accessdate=2013-04-15}}</ref>

Many Chinese [[launch vehicle]]s have been using liquid boosters. These include China's man-rated [[Long March 2F]] which uses four liquid rocket boosters each powered by a single [[YF-20|YF-20B]] hypergolic rocket engine.<ref>{{Cite web|url=http://www.astronautix.com/c/changzheng2f.html|archive-url=https://web.archive.org/web/20161228023137/http://astronautix.com/c/changzheng2f.html|url-status=dead|archive-date=December 28, 2016|title=Chang Zheng 2F|website=www.astronautix.com|access-date=2017-01-10}}</ref> The retired [[Long March 2E]] variant also used similar four liquid boosters.<ref>{{Cite web|url=http://www.astronautix.com/c/changzheng2e.html|archive-url=https://web.archive.org/web/20161228002414/http://astronautix.com/c/changzheng2e.html|url-status=dead|archive-date=December 28, 2016|title=Chang Zheng 2E|website=www.astronautix.com|access-date=2017-01-10}}</ref> as did [[Long March 3B]]<ref>{{Cite web|url=http://spaceflight101.com/spacerockets/long-march-3be/|title=Long March 3B/E – Rockets|website=spaceflight101.com|access-date=2017-01-10}}</ref> and [[Long March 3C]] variants. China developed semi-cryogenic boosters for the [[Long March 7]] and [[Long March 5]], its newest series of launch vehicles as of 2017 .<ref>{{Cite web|url=http://spaceflight101.com/spacerockets/long-march-5/|title=Long March 5 – Rockets|website=spaceflight101.com|access-date=2017-01-10}}</ref>

==Current usage==
The [[Delta IV Heavy]] consists of a central [[Common Booster Core]] (CBC), with two additional CBCs as LRBs instead of the [[Graphite-Epoxy Motor|GEM-60]] [[solid rocket motor]]s used by the Delta IV Medium+ versions. At lift off, all three cores operate at full thrust, and 44 seconds later the center core throttles down to 55% to conserve fuel until booster separation.<ref name=d4ppg>{{cite web|title=Delta IV Payload Planner's Guide, June 2013|url=http://www.ulalaunch.com/uploads/docs/Launch_Vehicles/Delta_IV_Users_Guide_June_2013.pdf|website=United Launch Alliance|accessdate=July 26, 2014|archive-url=https://web.archive.org/web/20140710005717/http://www.ulalaunch.com/uploads/docs/Launch_Vehicles/Delta_IV_Users_Guide_June_2013.pdf|archive-date=July 10, 2014|url-status=dead}}</ref> The [[Angara (rocket family)#Angara A5|Angara A5V]] and [[Falcon Heavy]] are conceptually similar to Delta IV Heavy.<ref name="Capabilities & Services">{{cite web |url=http://www.spacex.com/about/capabilities |title=Capabilities & Services |author= |date=2012-11-28 |publisher=SpaceX |access-date=August 21, 2017 |archive-url=https://web.archive.org/web/20131007205105/http://www.spacex.com/about/capabilities |archive-date=October 7, 2013 |url-status=live }}</ref> The Indian [[Geosynchronous Satellite Launch Vehicle|GSLV]] also uses Four [[Geosynchronous Satellite Launch Vehicle#Liquid boosters|L40]] boosters that are attached to the [[S139 Booster|S139 stage]].<ref>{{Cite web |title=Indian Space Research Organisation |url=https://www.isro.gov.in/GSLV_CON.html |access-date=2025-02-09 |website=www.isro.gov.in}}</ref>

The Falcon Heavy was originally designed with a unique "propellant crossfeed" capability, whereby the center core engines would be supplied with fuel and oxidizer from the two side cores until their [[separation event|separation]].<ref name="nss201111">{{cite web |last=Strickland |first=John K. Jr. |title=The SpaceX Falcon Heavy Booster |date=September 2011 |url=http://www.nss.org/articles/falconheavy.html |publisher=National Space Society |access-date=November 24, 2012 |archive-url=https://web.archive.org/web/20130117112834/http://www.nss.org/articles/falconheavy.html |archive-date=January 17, 2013 |url-status=live }}</ref> Operating all engines at full thrust from launch, with fuel supplied mainly from the side boosters, would deplete the side boosters sooner, allowing their earlier separation to reduce the mass being accelerated. This would leave most of the center core propellant available after booster separation.<ref name="prop_cross">{{cite web |url=http://www.spaceref.com/news/viewpr.html?pid=33185 |title=SpaceX Announces Launch Date for the World's Most Powerful Rocket |publisher=SpaceX |date=April 5, 2011 |access-date=April 5, 2011 |archive-date=March 19, 2023 |archive-url=https://web.archive.org/web/20230319120607/https://spaceref.com/press-release/spacex-announces-launch-date-for-the-worlds-most-powerful-rocket/ |url-status=dead }}</ref> Musk stated in 2016 that crossfeed would not be implemented.<ref>{{cite tweet |user=elonmusk |author-link=Elon Musk |number=726561442636263425 |title="Does FH expendable performance include crossfeed?" "No cross feed. It would help performance, but is not needed for these numbers." |date=May 1, 2016 |access-date=June 24, 2017}}</ref> Instead, the center booster throttles down shortly after liftoff to conserve fuel, and resumes full thrust after the side boosters have separated.<ref name="sxfh">{{cite web |title=Falcon Heavy |url=http://www.spacex.com/falcon-heavy |publisher=SpaceX |access-date=April 5, 2017 |date=2012-11-16 |archive-url=https://web.archive.org/web/20170406182002/http://www.spacex.com/falcon-heavy |archive-date=April 6, 2017 |url-status=live }}</ref>

==See also== 
* [[Modular rocket]]
* [[Rocket launch]]

==References==
{{Reflist}}

[[Category:Boosters (rocketry)]]