# Nacelle

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This article is about aircraft nacelles. For wind turbine nacelles, see [Nacelle (wind turbine)](/source/Nacelle_(wind_turbine)). For other uses, see [Nacelle (disambiguation)](/source/Nacelle_(disambiguation)).

A **nacelle** (/nəˈsɛl/ nə-SEL) is a streamlined container for [aircraft](/source/Aircraft) parts such as [engines](/source/Aircraft_engine), fuel or equipment.[1] When attached entirely outside the airframe, it is sometimes called a pod, in which case it is attached with a [pylon](/source/Hardpoint#Pylon) or strut and the engine is known as a [podded engine](/source/Podded_engine).[2] In some cases—for instance in the typical "[Farman](/source/Farman_Aviation_Works)" type ["pusher" aircraft](/source/Pusher_configuration), or the [World War II](/source/World_War_II)-era [P-38 Lightning](/source/P-38_Lightning) or [SAAB J21](/source/SAAB_J21)—an aircraft cockpit may also be housed in a nacelle, rather than in a conventional [fuselage](/source/Fuselage).

## Etymology

Like many [aviation](/source/Aviation) terms, the word comes from [French](/source/French_language), in this case from a word for a small boat.[3]

## Development

The [Arado Ar 234](/source/Arado_Ar_234) was one of the first operational jet aircraft with engines mounted in nacelles. During its development, the four engines had four distinct nacelles. They once had their own landing gear wheel, but they were later combined to two nacelles with two engines each.

A visible feature on airliner nacelles is the chevron nozzle, a fan air/exhaust gas mixer for jet noise reduction.[4]

## Applications

### Multi-engined aircraft

Airliners install their engines in nacelles under the wing or on the sides of the rear fuselage.[5]

Engines may be mounted in individual nacelles, or in the case of larger aircraft such as the [Boeing B-52 Stratofortress](/source/Boeing_B-52_Stratofortress) (pictured right) may have two engines mounted in a single nacelle.[citation needed]

### Other uses

- The [generator and gearbox "shell"](/source/Nacelle_(wind_turbine)) – with rotator shaft – on a [horizontal-axis wind turbine](/source/Horizontal-axis_wind_turbine) (HAWT).[6]

- [Edward Turner](/source/Edward_Turner_(motorcycle_designer)) used the term to describe his styling device introduced in 1949 to tidy the area around the headlamp and instrument panel of his [Triumph Speed Twin](/source/Triumph_Speed_Twin), [Thunderbird](/source/Triumph_Thunderbird) and [Tiger 100](/source/Triumph_Tiger_100) motorcycles. This styling device was much copied within the British industry thereafter, although Czech motorcycle manufacturer [Česká Zbrojovka Strakonice](/source/%C4%8Cesk%C3%A1_Zbrojovka_Strakonice) was using it beforehand. Indeed, the [Royal Enfield Bullet](/source/Royal_Enfield_Bullet) still retains its version, the 'casquette', on its current models. The last Triumphs to sport nacelles were the 1966 models of the 6T [Triumph Thunderbird](/source/Triumph_Thunderbird) 650, 5TA [Triumph Speed Twin](/source/Triumph_Speed_Twin) 500, and 3TA [Triumph Twenty One](/source/Triumph_Twenty_One) 350.[7]
- [Harley-Davidson](/source/Harley-Davidson) refers to the streamlined headlamp and fork triple tree covering on the Milwaukee-Eight version of the [Harley-Davidson Fat Boy](/source/Harley-Davidson_Fat_Boy) as the "Headlamp Nacelle."[8] The replacement kit also refers to it as the "Fat Boy Nacelle Kit".
- A forward projection of a catamaran's bridgedeck designed to soften the impact of seas or make more space inside the cabin.[9]
- In the *[Star Trek](/source/Star_Trek)* franchise it is also used as a term for the housing containing coils that generate the warp field. This is separate to the engine that powers them.[10][11]

## Design considerations

The primary design issue with aircraft-mounted nacelles is streamlining to minimise [drag](/source/Aerodynamic_drag) so nacelles are mounted on slender pylons. This can cause issues with directing the needed conduits mounted within the nacelle to connect to the aircraft through such a narrow space. This is especially concerning with nacelles containing engines, as the fuel lines and control for multiple engine functions must all go through the pylons.[5] It is often necessary for nacelles to be asymmetrical, but aircraft designers try to keep asymmetrical elements to a minimum to reduce operator maintenance costs associated with having two sets of parts for either side of the aircraft.[5]

## References

1. The Cambridge Aerospace Dictionary, Bill Gunston,ISBN 0 511 33833 3

1. Wragg, David W. (1973). *A Dictionary of Aviation*. first ed. Osprey. p. 199. ISBN 9780850451634.

1. ["Online Etymology Dictionary"](http://www.etymonline.com/index.php?term=nacelle). Retrieved 5 December 2013.

1. 'JET NOISE REDUCTION TECHNOLOGY DEVELOPMENT AT GE AIRCRAFT ENGINES' [http://icas.org/icas_archive/ICAS2002/PAPERS/842.PDF](http://icas.org/icas_archive/ICAS2002/PAPERS/842.PDF)

1. Ilan Kroo, Professor of Aeronautics and Astronautics (April 13, 1999). ["Nacelle Design and Sizing"](https://web.archive.org/web/20010307121417/http://adg.stanford.edu/aa241/propulsion/nacelledesign.html). Aircraft Aerodynamics and Design Group at Stanford University. Archived from [the original](http://adg.stanford.edu/aa241/propulsion/nacelledesign.html) on March 7, 2001. Retrieved April 22, 2011.

1. [American Wind Energy Association (AWEA) video on construction of an individual wind turbine.](https://www.facebook.com/AmericanWindEnergyAssociation/videos/10152872502493775/)

1. Davies, Ivor *It's A Triumph*, p. 107. (Haynes Foulis 1980, 1990 edit.) ISBN 0 85429 182 2

1. ["2025 Fat Boy Motorcycle | Harley-Davidson USA"](https://www.harley-davidson.com/us/en/motorcycles/fat-boy.html). [Archived](https://web.archive.org/web/20250302003639/https://www.harley-davidson.com/us/en/motorcycles/fat-boy.html) 2 March 2025 at the Wayback Machine. Retrieved 2 March 2025.

1. *Cruising Catamaran Made Easy*. American Sailing Association. 2016. pp. 16, 31. ISBN 9780982102541.

1. Robinson, Ben; Riley, Marcus; Okuda, Michael (November 2010). *U.S.S. Enterprise NX-01, NCC-1701, NCC-1701-A to NCC-1701-E, Owners' Workshop Manual*. [Gallery Books](/source/Gallery_Publishing_Group). p. 97. ISBN 9781451621297.

1. Siegel, Ethan (15 October 2017). *Treknology: The Science of Star Trek From Tricorders to Warp Drive*. [Voyageur Press](/source/The_Quarto_Group). p. 11. ISBN 9780760352632.

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Adapted from the Wikipedia article [Nacelle](https://en.wikipedia.org/wiki/Nacelle) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Nacelle?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.