Editing Vortex ring state (section)

=== Detection and correction ===
The signs of VRS are a vibration in the main rotor system<ref name=wayne>Johnson, Wayne. [https://books.google.com/books?id=SgZheyNeXJIC Helicopter theory] pp99+106, ''Courier Dover Publications'', 1980. Accessed: 25 February 2012. {{ISBN|0-486-68230-7}}</ref> followed by an increasing sink rate and possibly a decrease of [[Helicopter flight controls|cyclic]] authority.<ref name="AC 61-13B">Advisory Circular (AC) 61-13B, ''Basic Helicopter Handbook'', U.S. Department of Transportation, Federal Aviation Administration. 1978</ref>

In single rotor helicopters, the vortex ring state is traditionally corrected by slightly lowering the [[Helicopter flight controls#Collective|collective]] to regain cyclic authority and using the [[Helicopter flight controls#Cyclic|cyclic control]] to apply lateral motion, often pitching the nose down to establish forward flight. In tandem-rotor helicopters, recovery is accomplished through lateral cyclic or pedal input or both. The aircraft will fly out of the vortex ring into "clean air", and will be able to regain lift.<ref name="Helo" />

An alternative, the Vuichard Recovery Technique, reduces altitude loss and recovers more quickly.  Developed by Claude Vuichard, a [[Federal Office of Civil Aviation]] inspector in Switzerland, this recently popular technique uses thrust from the unaffected tail rotor<ref name=Vertical2021/> to [[Sideslip#Sideslip|sideslip]] (move sideways without rotating) the helicopter by at least one rotor diameter.  It can be thought of as maximizing sideways thrust from the tail rotor and balancing with the cyclic and collective to avoid rotation, but because the main rotor responds more slowly to the controls, it is actually performed in the opposite order: increase the collective to climb power, and apply cyclic in the direction of tail rotor thrust (as if turning opposite main rotor rotation) to a 15–20° bank angle, all while using the pedals to maintain heading (cross controls). Recovery is complete when the rotor disc reaches the upwind part of the vortex.<ref name="Helo"/><ref>{{cite web|last1=Tucker |first1=Tim |title=Flying Through the Vortex |url=https://www.rotorandwing.com/2015/09/01/flying-through-the-vortex/ |website=Rotor & Wing |date=September 2015 |publisher=Aviation Today |access-date=13 February 2016 |archive-url= https://archive.today/20220110230301/https://www.rotorandwing.com/2015/09/01/flying-through-the-vortex/ |archive-date= 10 January 2022 |url-status=live}}</ref><ref>Robinson R22/R44 Flight Training Guide, R22 Maneuver guide, Settling-With-Power/Vortex Ring State, Page 29, Revised: October 2013</ref><ref name=Vertical2021>{{cite web |title=Claude Vuichard & Tim Tucker tell the story behind the Vuichard Technique |url=https://verticalmag.com/features/claude-vuichard-tim-tucker-tell-the-story-behind-the-vuichard-technique/ |website=Vertical Mag |archive-url=https://web.archive.org/web/20210429170043/https://verticalmag.com/features/claude-vuichard-tim-tucker-tell-the-story-behind-the-vuichard-technique/ |archive-date=29 April 2021 |date=29 April 2021 |url-status=live}}</ref>