Editing Geodetic airframe

{{Short description|Type of aircraft structure}}
{{Use dmy dates|date=March 2017}}
{{Use British English|date=February 2022}}
[[File:Vickers Warwick geodesic fuselage.JPG|thumb|right|A section of the rear fuselage from a [[Vickers Warwick]] showing the geodetic construction in duralumin. On exhibit at the Armstrong & Aviation Museum at [[Bamburgh Castle]].]]

A '''geodetic airframe''' is a type of construction for the [[airframe]]s of [[aircraft]] developed by [[United Kingdom|British]] aeronautical engineer [[Barnes Wallis]] in the 1930s (who sometimes spelt it "geodesic"). Earlier, it was used by Prof. Schütte for the Schütte Lanz Airship SL 1 in 1909.<ref>{{cite book |last1=Nowarra |first1=Heinz J. |title=Deutsche Luftschiffe: Parseval - Schütte - Lanz - Zeppelin |date=1988 |publisher=Ponzun-Pallas-Verlag |location=Friedberg |isbn=978-3-7909-0332-4 |url=http://docplayer.org/9086308-Sandini-archiv-richlli.html |accessdate=2 December 2018 |language=German}}</ref> It makes use of a [[space frame]] formed from a spirally crossing basket-weave of load-bearing members.<ref name="Buttler93">Buttler, p.93</ref> The principle is that two [[geodesic|geodesic arcs]] can be drawn to intersect on a curving surface (the fuselage) in a manner that the [[Torsion (mechanics)|torsional load]] on each cancels out that on the other.<ref name="Buttler94">Buttler, p.94</ref>

==Early examples==
[[File:Constitutiondiagonalriders.gif|thumb|right|18th-century American warship's "Diagonal riders" in their construction]]

The "diagonal rider" structural element was used by [[Joshua Humphreys]] in the [[Original six frigates of the United States Navy|first US Navy sail frigates]] in 1794.<ref name=usc/> Diagonal riders are viewable in the interior hull structure of the preserved [[USS Constitution|USS ''Constitution'']] on display in Boston Harbor.<ref name=rbb>{{cite web |last1=Brooks |first1=Rebecca Beatrice |title=Construction of the USS Constitution |url=https://historyofmassachusetts.org/uss-constitution-construction/ |website=History of Massachusetts Blog |date=27 June 2017}}</ref><ref name=sf>{{cite conference |last1=Otton |first1=Patrick |title=USS Constitution Rehabilitation And Restoration |url=https://maritime.org/conf/conf-otton-const.htm |publisher=San Francisco Maritime Park Association |conference=Third International Conference on the Technical Aspects of the Preservation of Historic Vessels Conference Proceedings |date=1997}}</ref><ref name=usc>{{cite web |title=Keel Hauled |url=https://ussconstitutionmuseum.org/2016/09/09/keel-hauled/ |publisher=USS CONSTITUTION MUSEUM |date=September 2016}}</ref> The structure was a pioneering example of placing "non-[[Orthogonality|orthogonal]]" structural components within an otherwise conventional structure for its time.<ref name=sf/> The "diagonal riders" were included in these American naval vessels' construction as one of five elements to reduce the problem of [[hogging and sagging|hogging]] in the ship's hull, and did not make up the bulk of the vessel's structure, they do not constitute a completely "geodetic" space frame.{{citation needed|date=July 2019}}

Calling any diagonal wood brace (as used on gates, buildings, ships or other structures with cantilevered or diagonal loads) an example of geodesic design is a misnomer. In a geodetic structure, the strength and structural integrity, and indeed the shape, come from the diagonal "braces" - the structure does not need the "bits in between" for part of its strength (implicit in the name space frame) as does a more conventional wooden structure.

==Aeroplanes==
[[File:Vickers Wellington Mark X, HE239 'NA-Y', of No. 428 Squadron RCAF (April 1943).png|thumb|Wellington Mk.X ''HE239'' of [[No. 428 Squadron RCAF|No.428 Sqn.]] RCAF, illustrating the geodetic construction and the level of battle damage it could sustain and still return to base]]

The earliest-known use of a geodetic airframe design for any aircraft was for the pre-World War I [[List of Schütte-Lanz airships#SL1|Schütte-Lanz SL1]] rigid airship's envelope structure] of 1911, with the airship capable of up to a 38.3&nbsp;km/h (23.8&nbsp;mph) top airspeed.<ref>{{cite web |url=http://www.earlyaeroplanes.com/archive/airships01/1911.airship.SL1.framework.jpg |title=Archived copy |website=www.earlyaeroplanes.com |access-date=22 February 2022 |archive-url=https://web.archive.org/web/20131112025350/http://www.earlyaeroplanes.com/archive/airships01/1911.airship.SL1.framework.jpg |archive-date=12 November 2013 |url-status=usurped}}</ref>{{unreliable source?|date=February 2022}}

The [[Latécoère 6]] was a French four-engined biplane bomber of the early 1920s. It was of advanced all-metal construction and probably the first aeroplane to use geodetic construction. Only one was built.

[[Barnes Wallis]], inspired by his earlier experience with light alloy structures and the use of geodesically-arranged wiring to distribute the lifting loads of the gasbags in the design of the ''[[R100]]'' airship, evolved the geodetic construction method (although it is commonly stated, there was no geodetic ''structure'' in ''[[R100]]'').<ref>Murray, p.34 and p.44</ref> Wallis used the term "geodetic" to apply to the airframe; it is referred to as "Vickers-Wallis construction" in some early company documents.<ref name="barneswallisfoundation.co.uk">{{Cite web|url=https://www.barneswallisfoundation.co.uk/life-and-work/geodetic-aircraft-design/|title = Geodetic Aircraft Design – Barnes Wallis Foundation}}</ref> "Geodesic" is used in the United States for aircraft structures.<ref>https://archive.org/details/sim_journal-of-aircraft_january-february-2002_39_1, p.18</ref>

The system was later used by Wallis's employer, [[Vickers-Armstrongs]] in a series of bomber aircraft, the [[Vickers Wellesley|Wellesley]], [[Vickers Wellington|Wellington]], [[Vickers Warwick|Warwick]] and [[Vickers Windsor|Windsor]]. In these aircraft, the fuselage and wing were built up from [[duralumin]] alloy channel-beams that were formed into a large framework. Wooden battens were screwed onto the metal, to which the [[aircraft dope|doped]] [[linen]] skin of the aircraft was fixed. The Windsor had a woven metal skin.{{citation needed|date=September 2024}}

The metal lattice-work gave a light and very strong structure.<ref name="Buttler93"/> The benefit of the geodetic construction was larger internal volume for a given streamlined shape.<ref name="barneswallisfoundation.co.uk"/> Flight magazine described a geodetic frame as sheet metal covering in which diamond shaped holes have been cut leaving behind the geodetic strips.<ref>Flight magazine, 15 December 1938, p.548</ref> The benefit was offset by having to construct the fuselage as a complete assembly unlike aircraft using stressed-skin construction which could be built in sections. In addition, fabric covering on the geodetic frame was not suitable for higher flying aircraft that had to be pressurised. The difficulty of providing a pressurised compartment in a geodetic frame was a challenge during the design of the high altitude Wellington Mk. V. The pressure cabin, which expanded and contracted independently of the rest of the airframe, had to be attached at the nodal points of the structure.<ref>From Bouncing Bombs To Concorde, Robert Gardner 2006,{{ISBN|0 7509 4389 0}}, p.33</ref>

Geodetic wing and fin structures, taken from the Wellington, were used on the post-war [[Vickers VC.1 Viking]], but with a metal stressed-skin fuselage.<ref>{{citation |url=https://www.flightglobal.com/pdfarchive/view/1945/1945%20-%201005.html |archive-url=https://web.archive.org/web/20160604095942/https://www.flightglobal.com/pdfarchive/view/1945/1945%20-%201005.html |archive-date=4 June 2016 |date=24 May 1945 |work=Flight |title=Vickers Viking |first=C. B. |last=Bailey-Watson }}</ref> Later production Vikings were completely stressed-skin construction marking the end of geodetic construction at Vickers.<ref>From Bouncing Bombs To Concorde, Robert Gardner 2006,{{ISBN|0 7509 4389 0}}, p.65</ref>

==See also==
* [[Design principle]] 
* [[Figure of the Earth]]
* [[Geodesic dome]]
* [[Geodesic (disambiguation)]] 
* [[Geodetic system]]

==References==
===Inline citations===
{{reflist}}

===Sources===
* {{cite book |title= British Secret Projects: Fighters & Bombers 1935-1950 |last= Buttler |first= Tony |year= 2004 |publisher= Midland Publishing |location=Hinckley |isbn=978-1-85780-179-8  }}
* {{cite book
  | title = Bouncing-Bomb Man: the Science of Sir Barnes Wallis | first = Iain | last = Murray
  | publisher = Haynes | year = 2009 | isbn = 978-1-84425-588-7
  }}

{{DEFAULTSORT:Geodetic airframe}}
[[Category:Airship technology]]
[[Category:Structural system]]
[[Category:Aerospace engineering]]
[[Category:Vickers]]
[[Category:Barnes Wallis]]