Multirotor

{{Short description|Rotorcraft with more than two rotors}} [[File:DJI Phantom 1 1530564a.jpg|thumb|DJI Phantom, a quadcopter]]

A '''multirotor'''<ref>Early in helicopter development,"multi-rotor" was used to refer to helicopters with two rotor assemblies</ref> or '''multicopter''' is a rotorcraft with more than two lift-generating rotors separated horizontally. An advantage of multirotor aircraft is the simpler rotor mechanics required for flight control. Unlike single- and double-rotor helicopters which use complex variable pitch rotors whose pitch varies as the blade rotates for flight stability and control, multirotors often use fixed-pitch blades. They control vehicle motion by varying the relative speed of each rotor to change the thrust and torque produced by each. Some control the pitch of each rotor instead.<ref>{{Cite web |title=HeliQuads (Variable Pitch Multicopters) — Copter documentation |url=https://ardupilot.org/copter/docs/heliquads.html |access-date=2026-02-23 |website=ardupilot.org}}</ref>

Due to their ease of both construction and control, multirotor aircraft are frequently used in radio control aircraft and unmanned aerial vehicle (UAV) projects<ref>{{cite web|title=AeroQuad - The Open Source Quadcopter|url=https://santuy69.com/|access-date=2012-01-05|archive-url=https://web.archive.org/web/20120103092559/http://aeroquad.com/|archive-date=2012-01-03|url-status=dead}}</ref><ref>{{cite web|url=http://multicopter.org/wiki/Multicopter_Table|title=Multicopter Table|work=multicopter.org|access-date=30 June 2015|archive-date=6 November 2011|archive-url=https://web.archive.org/web/20111106071900/http://multicopter.org/wiki/Multicopter_Table|url-status=dead}}</ref><ref>{{cite web|url=http://uavp.ch/moin/FrontPage|title=FrontPage - UAVP-NG - The Open Source Next Generation Multicopter|work=uavp.ch|access-date=30 June 2015}}</ref><ref>{{cite web|url=http://ng.uavp.ch/|title=FrontPage - UAVP-NG - The Open Source Next Generation Multicopter|work=uavp.ch|access-date=30 June 2015}}</ref><ref>{{cite web|url=https://www.diydrones.com/|title=DIY Drones|work=diydrones.com|access-date=30 June 2015}}</ref><ref>[http://www.openpilot.org/ OpenPilot] {{webarchive|url=https://web.archive.org/web/20110527225811/http://www.openpilot.org/ |date=2011-05-27 }} Open source UAV autopilot for multirotors</ref> in which the names '''tricopter''', '''quadcopter''', '''hexacopter''' and '''octocopter''' are frequently used to refer to 3-, 4-, 6- and 8-rotor rotorcraft, respectively.<ref>{{cite web|url=https://www.kfx450central.com/members/frasacuan.1599218/#about|title=How to Pick The Best Multirotor Frame|work=My First Drone|access-date=30 June 2015|archive-url =https://web.archive.org/web/20140403153424/http://myfirstdrone.com/tutorials/best-multirotor-frame/|archive-date =3 April 2014}}</ref> There is also the X8 (also called ''octo-quad'') configuration that is similar to the quadracopter design, except that it has eight rotors; the lower of which have a reversed rotation direction.<ref>{{cite web|url=https://ardupilot.org/copter/_images/motororder-octoquad-x-2d.png|title=Octo Quad|work=ardupilot.org|access-date=30 December 2019}}</ref>

thumb|Hexacopter<ref>{{cite news|title=ALMA Filmed with Hexacopter|url=https://www.eso.org/public/announcements/ann13067/|access-date=6 September 2013|newspaper=ESO Announcement}}</ref>In order to allow more power and stability at reduced weight, coaxial rotors can be employed, in which each arm has two motors, running in opposite directions which cancels out rotational torque (one facing up and one facing down).<ref>{{cite web|url=http://www.coptercraft.com/multirotor-frame-configurations/|title=Multirotor Frame Configurations|work=Coptercraft|access-date=23 December 2015}}</ref> thumb|Lifting-wing multicopter Also possible is the addition of horizontal propellers.<ref>{{Cite web|url=https://www.unmannedsystemstechnology.com/company/deltaquad/|title=Hybrid VTOL Fixed Wing UAV - DeltaQuad Autonomous VTOL Drone|website= unmannedsystemstechnology.com}}</ref><ref>{{Cite web |url=http://px4.io/portfolio/quadranger-vtol/ |title=QuadRanger VTOL |access-date=2018-04-29 |archive-date=2018-11-06 |archive-url=https://web.archive.org/web/20181106145016/http://px4.io/portfolio/quadranger-vtol/ |url-status=dead }}</ref><ref>{{Cite web|url=https://newatlas.com/skyprowler-fixed-wing-quadcopter/36154/|title=SkyProwler combines a quadcopter and a fixed-wing airplane in one device|first=Ben|last=Coxworth|date=February 19, 2015|website=New Atlas}}</ref> These types of rotorcraft (which have just 4 vertical propellers) are called quadplanes.<ref>{{Cite web|url=https://ardupilot.org/plane/docs/quadplane-overview.html|title=QuadPlane Overview — Plane documentation|website=ardupilot.org}}</ref> It can also be possible by adding additional nonhorizontal wings, which are called lifting-wing multicopters.<ref>{{Cite book |last1=Xiao |first1=Kun |last2=Meng |first2=Yao |last3=Dai |first3=Xunhua |last4=Zhang |first4=Haotian |last5=Quan |first5=Quan |chapter=A Lifting Wing Fixed on Multirotor UAVs for Long Flight Ranges |date=2021-06-15 |title=2021 International Conference on Unmanned Aircraft Systems (ICUAS) |chapter-url=https://doi.org/10.1109/icuas51884.2021.9476859 |publisher=IEEE |pages=1605–1610 |doi=10.1109/icuas51884.2021.9476859|arxiv=2006.15579 |isbn=978-1-6654-1535-4 }}</ref><ref>{{Cite journal |last1=Zhang |first1=Haotian |last2=Tan |first2=Shaochang |last3=Song |first3=Ziming |last4=Quan |first4=Quan |date=June 2022 |title=Performance Evaluation and Design Method of Lifting-Wing Multicopters |url=https://doi.org/10.1109/tmech.2021.3090667 |journal=IEEE/ASME Transactions on Mechatronics |volume=27 |issue=3 |pages=1606–1616 |doi=10.1109/tmech.2021.3090667 |issn=1083-4435|url-access=subscription }}</ref><ref>{{Cite journal |last1=Quan |first1=Quan |last2=Wang |first2=Shuai |last3=Gao |first3=Wenhan |date=March 2025 |title=Lifting-Wing Quadcopter Modeling and Unified Control |url=https://doi.org/10.2514/1.g008134 |journal=Journal of Guidance, Control, and Dynamics |volume=48 |issue=3 |pages=689–699 |doi=10.2514/1.g008134 |arxiv=2301.00730 |bibcode=2025JGCD...48..689Q |issn=0731-5090}}</ref>

Most multirotors are small, with first-person view and battery power which limits their range, endurance, and payload.{{Citation needed|date=January 2026}}

==Manned examples== * de Bothezat helicopter - an American four-rotor helicopter that first flew on December 18, 1922, and was used for military evaluation. * Cierva Air Horse - a British three-rotor "heavy lift" helicopter first flying in 1948. Three rotors were used to give a large lift without compromising rotor strength.<ref>''Flight'' 14 April 1949 p427</ref> * Bensen B-12 - an American experimental ten-rotor personal helicopter first flown on November 2, 1961. The design was later changed to use eight rotors driven by sixteen motors * "eVTOL" projects: ** Airbus A³ Vahana - two American tiltwing octocopter prototypes. Development was ended in 2019 in favor of the CityAirbus project ** Airbus CityAirbus - a series of experimental multinational ducted X8 helicopters, and now hexacopters ** Boeing Passenger Air Vehicle - an American octocopter prototype fitted with a pusher propeller and three wings for horizontal flight ** Jetson One - a Swedish-Italian ultralight X8 helicopter, with four coaxial rotor booms fitted to a motorcycle-like cockpit ** Pivotal BlackFly - an American octocopter designed to fully rotate in orientation to transition between vertical and horizontal flight, much like more traditional tail-sitters ** Volocopter designs - a series of German prototype electric multicopters, many such as the 2X & Volocity with 18 rotors, the first electric multicopter in the world to achieve crewed flight.<ref>{{cite web|title=German multicopter makes first manned flight|date=1 November 2011|work=sUAS news|url=https://www.suasnews.com/2011/11/9691/german-multicopter-makes-first-manned-flight/|access-date=3 Nov 2011}}</ref><ref>{{cite web|title=Volocopter: 18-propeller electric helicopter takes flight|date=27 November 2013|work=CNN news|url=https://edition.cnn.com/2013/11/27/tech/innovation/volocopter-18-propeller-electric/index.html?iref=allsearch|access-date=2 Dec 2013}}</ref> The large number of low-cost motors make it economical, quiet and provide redundancy with ability to maintain control with up to four failed motors.<ref>{{cite journal|journal=Sport Aviation|title=New Aircraft Arises from Germany|date=January 2012|page=14}}</ref> [[File:OnyxStar XENA-8F coax foldable and pliable drone.jpg|thumb|OnyxStar XENA-8F coax foldable drone from AltiGator]]

==References== {{reflist}}

Category:Multirotor helicopters