View source for Phugoid

==English==
{{was wotd|2024|March|8}}

===Etymology===
[[File:Phugoid8.png|thumb|400px|A diagram illustrating an [[aircraft]] undergoing phugoid [[motion#Noun|motion]] (''adjective sense'').]]

{{root|en|ine-pro|*bʰewg-|id=flee|*weyd-}}
The {{glossary|adjective}} is a {{lbor|en|grc|φῠγή|t=fleeing, flight; escape; retreat|nocap=1}} (ultimately from {{der|en|ine-pro|*bʰewg-|t=to flee}}) + [[w:English language|English]] {{m|en|-oid|pos={{glossary|suffix}} meaning ‘having the likeness of, resembling’, forming adjectives and nouns}}. The word was {{coinage|en|Frederick W. Lanchester|nat=the British|occ=aerodynamicist and engineer|nobycat=1|nocap=1}} (1868–1946) in his book ''Aerodonetics'' (1908),<ref>{{cite-book|author=[[w:Frederick W. Lanchester|F[rederick] W[illiam] Lanchester]]|chapter=Preface|title=Aerodonetics: Constituting the Second Volume of a Complete Work on Aerial Flight{{nb...|[...] With Appendices on the Theory and Application of the Gyroscope, on the Flight of Projectiles, etc.}}|location=London|publisher=[[w:Constable & Robinson|Archibald Constable & Co.]]{{nb...|Ltd., Orange Street, Leicester Square}}|year=1908|section=footnote 1|page=viii|pageurl=https://archive.org/details/aerodynamicscon00lancgoog/page/n16/mode/1up|oclc=1353621854|passage=From the Greek {{lang|grc|φ[υ]γη}} and {{lang|grc|ειδος}} (lit. ''flight-like'')}}.</ref> the author mistaking the meaning of {{m|grc||φῠγή}} to be “flight” in the sense of “the act of flying”:<ref name="OED">{{R:OED Online|pos=adj.'' and ''n|id=8778237945|date=July 2023}}</ref><ref>{{R:Collins English Dictionary|pos=adj}}</ref> see the quotations.

The {{glossary|noun}} is derived from the adjective.<ref name="OED"/>

===Pronunciation===
* {{IPA|en|/ˈfjuːɡɔɪd/|a=RP}}
* {{audio|en|LL-Q1860 (eng)-Vealhurl-phugoid.wav|a=Southern England}}
* {{IPA|en|/ˈfjuˌɡɔɪd/|a=GA}}
* {{audio|en|En-us-phugoid.oga|a=GA}}
* {{hyphenation|en|phug|oid}}

===Adjective===
{{en-adj|-}}

# {{lb|en|aeronautics|aviation}} Of the [[motion#Noun|motion]] of an [[aircraft]], [[missile]], or other [[flying#Adjective|flying]] [[object#Noun|object]]: [[continuously]] [[oscillate|oscillating]] in a [[vertical#Adjective|vertical]] [[plane#Noun|plane]] due to the object [[pitch#Verb|pitching]] up and [[climb#Verb|climbing]], thus [[slow down|slowing down]]; then pitching down and [[descend]]ing, thus [[speed up|speeding up]].
#* {{quote-book|en|author=[[w:Frederick W. Lanchester|F[rederick] W[illiam] Lanchester]]|chapter=The Phugoid Theory—The Equations of the Flight Path|title=Aerodonetics: Constituting the Second Volume of a Complete Work on Aerial Flight{{nb...|[...] With Appendices on the Theory and Application of the Gyroscope, on the Flight of Projectiles, etc.}}|location=London|publisher=[[w:Constable & Robinson|Archibald Constable & Co.]]{{nb...|Ltd., Orange Street, Leicester Square}}|year=1908|section=§&nbsp;18 (Introductory)|page=37|pageurl=https://archive.org/details/aerodynamicscon00lancgoog/page/n59/mode/1up|oclc=1353621854|passage=The '''Phugoid''' theory deals with the longitudinal stability, and the form and equations of the flight path of an aerodone.}}

====Translations====
{{trans-top|of the motion of an aircraft, missile, or other flying object: continuously oscillating in a vertical plane}}
* Finnish: {{t|fi|[[fugoidi]]-}}, {{t|fi|[[korkeus-nopeusheilahtelu]]n [[omainen]]}}
* Macedonian: {{t-needed|mk}}
{{trans-bottom}}

===Noun===
{{en-noun}}

# {{lb|en|aeronautics|aviation}} The [[motion#Noun|motion]] of an [[aircraft]], [[missile]], or other [[flying#Adjective|flying]] [[object#Noun|object]] [[continuously]] [[oscillate|oscillating]] in a [[vertical#Adjective|vertical]] [[plane#Noun|plane]] due to the object [[pitch#Verb|pitching]] up and [[climb#Verb|climbing]], thus [[slow down|slowing down]]; then pitching down and [[descend]]ing, thus [[speed up|speeding up]].
#* {{quote-book|en|author=[[w:Frederick W. Lanchester|F[rederick] W[illiam] Lanchester]]|chapter=The Phugoid Theory—The Flight Path Plotted|title=Aerodonetics: Constituting the Second Volume of a Complete Work on Aerial Flight{{nb...|[...] With Appendices on the Theory and Application of the Gyroscope, on the Flight of Projectiles, etc.}}|location=London|publisher=[[w:Constable & Robinson|Archibald Constable & Co.]]{{nb...|Ltd., Orange Street, Leicester Square}}|year=1908|section=§&nbsp;35 (The Time Period and Form of the Phugoid Path. Special Cases (continued).)|page=63|pageurl=https://archive.org/details/aerodynamicscon00lancgoog/page/n85/mode/1up|oclc=1353621854|passage=As the amplitude of the '''phugoid''' is increased beyond the limits of the semicircle, there is a rapid shortening of the time period as shown by the manner in which the ''time curve'' falls away almost immediately after that critical form of flight path is passed. {{...}} [I]f we select '''phugoids''' of greater and greater velocity, for a given aerodone the form of the tumbler curve approximates more and more closely to a circle of radius <math>=2H_n</math>.}}
#* {{quote-journal|en|author=Rob Taylor|title=Malaysia Airlines Flight 370 likely in steep dive before crash|journal={{w|The Wall Street Journal}}|archiveurl=https://web.archive.org/web/20230326230904/http://www.wsj.com/articles/malaysia-airlines-flight-370-likely-in-steep-dive-before-crash-1478048584|location=New York, N.Y.|publisher={{w|Dow Jones & Company}}|date=2 November 2016|issn=0099-9660|oclc=36098632|passage=As well as physical debris, the report drew on recent analysis by Australian defense scientists of burst frequency signals from Flight 370 to satellites that indicated the aircraft had been descending fast, likely in an automated series of swooping dives called '''fugoids'''.}}

====Alternative forms====
* {{alter|en|fugoid}}

====Translations====
{{trans-top|motion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane}}
* Arabic: {{t|ar|فوغويد|tr=fūgūyd}}
* Chinese:
*: Mandarin: {{t|cmn|起伏運動|tr=qǐfúyùndòng}}, {{t|cmn|週期運動|tr=zhōuqīyùndòng, zhōuqíyùndòng}}
* Finnish: {{t|fi|fugoidi}}, {{t|fi|fugoidiliike}}, {{t|fi|korkeus-nopeusheilahtelu}}
* French: {{t+|fr|phugoïde|f}}
* German: {{t+|de|Phygoide|f}}
* Italian: {{t|it|fugoide|?}}
* Japanese: {{t|ja|フゴイド運動|tr=フゴイドうんどう, fugoidoundō}}
* Korean: {{t|ko|푸고이드|tr=pugoidu}}
* Macedonian: {{t-needed|mk}}
* Romanian: {{t|ro|fugoidă|?}}
* Russian: {{t|ru|фуго́ид|m}}
* Spanish: {{t|es|fugoide|m}}
* Swedish: {{t|sv|phugoidrörelse|?}}, {{t|sv|fugoidrörelse|?}}
{{trans-bottom}}

===References===
<references/>

===Further reading===
* {{pedia}}

{{cln|en|terms suffixed with -oid}}