Coaxial-rotor aircraft: Difference between revisions

'''CoaxialA rotors'''coaxial-rotor or aircraft'''coax rotors'''is arean a[[aircraft]] pair ofwhose [[helicopter rotor|rotors]]s are mounted one above the other on [[Concentric objects|concentric]] shafts, with the same axis of rotation, but turning in opposite directions ([[contra-rotating]]).

This rotor configuration is a feature of helicopters produced by the [[Russia]]n [[Kamov]] helicopter [[design bureau]].

The idea of coaxial rotors originates with [[Mikhail Lomonosov]]. He had developed a small helicopter model with coaxial rotors in July 19541754 and demonstrated it to the [[Russian Academy of Sciences]].<ref>Leishman, J. Gordon (2006). Principles of Helicopter Aerodynamics. Cambridge University Press. p. 8. {{ISBN|0-521-85860-7}}</ref>

[[File:Gyrodyne QH-50 DD-692 1967(cropped).jpg|thumb|A [[Gyrodyne QH-50 DASH|QH-50]] on board the USS ''Allen M. Sumner'' during a deployment to Vietnam, 1967]]

Having two coaxial sets of rotors provides symmetry of forces around the central axis for lifting the vehicle and laterally when flying in any direction. Because of the mechanical complexity, many helicopter designs use alternatealternative configurations to avoid problems that arise when only one main rotor is used. Common alternatives are single-rotor helicopters or [[Tandem rotors|tandem rotor]] arrangements.

[[File:OnyxStar HYDRA-12.jpeg|thumb|Coaxial hexacopter -– OnyxStar HYDRA-12 from [[AltiGator]]]]

[[Multirotor]] type [[unmanned aerial vehicle]]s exist in numerous configurations including duocopter,<ref>{{Cite web|title=DuoCopter, the perfect drone|url=https://www.research-drone.com/en/DuoCopter.html|access-date=2021-11-13|website=www.research-drone.com}}</ref> tricopter, [[quadcopter]], hexacopter and octocopter. All of them can be upgraded to coaxial configuration in order to bring more stability and flight time while allowing carrying much more payload without gaining too much weight. Indeed, coaxial [[multirotor]]s are made by having each arm carrying two motors facing in opposite directions (one up and one down). Therefore, it is possible to have ana quad-axis, octorotor looking like a quadcopterairframe thanks to coaxial configuration. Special Duocopters are characterised by two motors aligned in a vertical axis. The control is performed by the appropriate acceleration of a single rotor blade for targeted thrust generation during revolution. Having more lifting power for a greater payload explains why coaxial multirotors are preferred for nearly all professionallarge-payload commercial applicationapplications of [[Unmanned aerial vehicle|UAS]].<ref>{{cite web|url=http://www.coptercraft.com/multirotor-frame-configurations/|title=Multirotor Frame Configurations|work=Coptercraft|access-date=23 December 2015}}</ref>

The [[U.S. Department of Transportation]] has published a “Basic Helicopter Handbook”. One of the chapters in it is titled, “Some Hazards of Helicopter Flight'. Ten hazards have been listed to indicate what a typical single rotor helicopter has to deal with. The coaxial rotor design either reduces or completely eliminates many of these hazards. The following list indicates which:

[[File:Russian Air Force Kamov Ka-50.jpg|thumb|right|[[Russian Air Force]] Kamov [[Kamov Ka-50|Ka-5250]], a two-seat variant of the Ka-50.]]

[[File:A Russian Helix KA-27 (cropped).jpg|thumb|The[[Russian Navy]] Kamov [[Kamov Ka-27|Ka-3227]]]]

* [[KamovHiller KaXH-1044]] (1944)

* [[Kamov Ka-158]] (1947)

* [[Kamov Ka-1810]] (1949)

* [[Kamov Ka-2515]] (1953)

* [[Kamov Ka-2618]] (1955)

* [[Kamov Ka-2725]] (1963)

* [[Kamov Ka-5226]] (1965)

* [[Kamov Ka-126]] (1988)

* [[Kamov Ka-226]] (1997)

* [[Ingenuity (helicopter)|Mars helicopter ''Ingenuity'']] (2021)