{{Short description|Holes added to materials to make them lighter without reducing strength}} [[File:Bullied Firth Brown Boxpok wheel.JPG|thumb|right|Lightening holes in Bulleid Firth Brown (BFB) railway locomotive wheel]]
'''Lightening holes''' are holes in structural components of machines and buildings used by a variety of engineering disciplines to make structures lighter. The edges of the hole may be flanged to increase the rigidity and strength of the component.<ref name="Fournier, Ron"> {{cite book |first1=Ron |last1=Fournier |first2=Sue |last2=Fournier |publisher=HPBooks |year=1989 |title=Sheet Metal Handbook |url=https://books.google.com/books?id=ViUmhImu630C&dq=lightening+hole&pg=PA25 |page=25 |isbn=9780895867575 |accessdate=2012-06-08}} </ref> The holes can be circular, triangular, elliptical, or rectangular and should have rounded edges, but they should never have sharp corners, to avoid the risk of stress risers, and they must not be too close to the edge of a structural component.<ref name="Gerr, Dave"> {{cite book |first=Dave |last=Gerr |publisher=International Marine |year=2000 |title=The Elements of Boat Strength: For Builders, Designers, and Owners |url=https://archive.org/details/elementsofboatst00dave |url-access=registration |quote=lightening hole. |page=[https://archive.org/details/elementsofboatst00dave/page/322 322] |isbn=9780070231597 |accessdate=2012-06-08}} </ref><ref>{{cite web|url=https://www.oreilly.com/library/view/modeling-the-effect/9781119013211/c02.xhtml|title=Chapter 2: Holes - Modeling the Effect of Damage in Composite Structures: Simplified Approaches [Book]|website=www.oreilly.com}}</ref> <!-- uncited, not mentioned in the body Drilling out components was a popular way to lighten racing bicycle components in the 1970s. Eddy Merckx's hour record-winning bike has heavily drilled handlebars and chainring. Cyclists jokingly refer to the incorporation of "drillium" in the machine, as if it were an exotic metal which confers lightness. -->
==Usage== ===Aviation=== thumb|Aircraft manufacturing in Australia 1943. Note the circular lightening holes in the wing ribs. Lightening holes are often used in the aviation industry. This allows an aircraft to be as lightweight as possible, retaining the durability and airworthiness of the aircraft structure.<ref>{{cite web|url=https://patents.google.com/patent/US2423682A/en|title=Sheet metal structure}}</ref><ref>{{cite web |url=http://flysafe.raa.asn.au/scratchbuilder/ANC18_chapter_4.html |title=ANC-18 |publisher=Flysafe.raa.asn.au |date= |accessdate=2019-07-14 |archive-date=2019-03-23 |archive-url=https://web.archive.org/web/20190323123806/http://flysafe.raa.asn.au/scratchbuilder/ANC18_chapter_4.html |url-status=dead }}</ref>
===Maritime=== Lightening holes have also been used in marine engineering to increase seaworthiness of the vessel.<ref>{{cite web|url=https://forshipbuilding.com/ship-construction/midship/|title=Midship constructions|date=February 4, 2014}}</ref><ref>{{cite web|url=http://www.splashmaritime.com.au/Marops/data/less/Shipk/Shipasig/Seaworthconstassig.htm|title=SEAWORTHINESS ASSIGNMENT CONSTRUCTION|website=www.splashmaritime.com.au}}</ref><ref>{{cite web|url=https://www.marineinsight.com/naval-architecture/design-of-ships-bottom-structure/|title=Designing A Ship's Bottom Structure – A General Overview|date=July 13, 2015}}</ref>
===Motorsports=== thumb| Car chassis with lightening holes, circa 1935. Lightening holes became a prominent feature of motor racing in the 1920s and 1930s. Chassis members, suspension components, engine housings and even connecting rods were drilled with a range of holes, of sizes almost as large as the component.
{{Quote|style=font-size: 100%;|"[The] wisdom of the day was to make everything along the lines of a brick shithouse [...] and then drill holes in the bits to lighten them."|David Kelsey, Lotus Cars<ref name="Ludvigsen, Colin Chapman" >{{Cite book | title=Colin Chapman: Inside the Innovator | last=Ludvigsen | first=Karl | authorlink=Karl Ludvigsen | publisher=Haynes Publishing | year=2010 | isbn=978-1-84425-413-2 | ref={{harvid|Ludvigsen|Colin Chapman}} | page=150 }}</ref>}}
===Military=== Lightening holes have been used in various military vehicles, aircraft, equipment and weaponry platforms.{{citation needed|date=April 2017}} This allows equipment to be lighter in weight as well as increase the ruggedness and durability.{{citation needed|date=April 2017}} They are usually made by drilling{{citation needed|date=April 2017}} holes, pressed stamping or machining and can also save strategic materials and cost during wartime production.
===Architecture=== thumb|upright|Parsons House is an example of the use of lightening holes in architecture.{{citation needed|date=April 2017}} Lightening holes have been used on various architecture designs.<ref>{{cite web |url=http://metalstroi-s-g.com/en/company/innovations |title=INNOVATIONS - Metalstroi Stoianov & Georgiev Ltd. – Manufacturing and assembling metal constructions |publisher=Metalstroi-s-g.com |date= |accessdate=2019-07-14 |archive-date=2017-07-15 |archive-url=https://web.archive.org/web/20170715234227/http://metalstroi-s-g.com/en/company/innovations |url-status=dead }}</ref> During the 1980s and early 1990s, lightening holes were fashionable and somewhat seen as futuristic and were used in the likes of industrial units, car showrooms, shopping precincts, sports centres etc. Parsons House in London is a notable building that uses lightening holes since its renovation in 1988.<ref>{{Cite web |url=http://www.peterbellarchitects.co.uk/parsons.html |title=Peter Bell Architects: Peter Bell Architects |access-date=2017-04-05 |archive-url=https://web.archive.org/web/20150515011041/http://www.peterbellarchitects.co.uk/parsons.html |archive-date=2015-05-15 |url-status=dead }}</ref><ref>{{cite web|url=http://www.skyscrapernews.com/buildings.php?id=2077|title=Parsons House, London - Building #2077|website=www.skyscrapernews.com}}</ref> Ringwood Health & Leisure Centre in Hampshire is another notable example.<ref>{{cite web|url=http://www.pgparchitects.co.uk/ |title=Website Builder | Simple & Easy To Use | UK2 |publisher=Pgparchitects.co.uk |date= |accessdate=2019-07-14}}</ref><ref>{{cite web|url=https://c2.staticflickr.com/4/3742/9661374941_aef51b49d3_b.jpg |title=Photo |website=c2.staticflickr.com |format=JPG |access-date=2019-07-14}}</ref>
==See also== * Honeycomb structure * Hollow structural section * Isogrid * Truss * Fuller (groove) {{clear}}
==References== {{Reflist}}
==External links== {{Commons category|Lightening holes}} * [http://apps.dtic.mil/dtic/tr/fulltext/u2/a801086.pdf Tests Of Beams Having Webs With Large Circular Lightening Holes] {{Webarchive|url=https://web.archive.org/web/20201027183239/http://apps.dtic.mil/dtic/tr/fulltext/u2/a801086.pdf |date=2020-10-27 }}, by L. Ross Levin, National Advisory Committee for Aeronautics * [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093371_1993093371.pdf The Strength And Stiffness Of Shear Webs With And Without Lightening Holes], by Paul Kuhn, National Advisory Committee for Aeronautics * [http://apps.dtic.mil/dtic/tr/fulltext/u2/a801095.pdf The Strength And Stiffness Of Shear Webs With Round Lightening Holes Having 45° Flanges] {{Webarchive|url=https://web.archive.org/web/20220720171620/http://apps.dtic.mil/dtic/tr/fulltext/u2/a801095.pdf |date=2022-07-20 }}, by Paul Kuhn, National Advisory Committee for Aeronautics
Category:Mechanical engineering Category:Civil engineering Category:Structural engineering Category:Aerospace engineering Category:Marine engineering Category:Military engineering