Anacelle (/nəˈsɛl/nə-SEL) is a streamlined container foraircraft parts such asengines, fuel or equipment.[1] When attached entirely outside the airframe, it is sometimes called a pod, in which case it is attached with apylon or strut and the engine is known as apodded engine.[2] In some cases—for instance in the typical "Farman" type"pusher" aircraft, or theWorld War II-eraP-38 Lightning orSAAB J21—an aircraft cockpit may also be housed in a nacelle, rather than in a conventionalfuselage.
The development of theArado Ar 234, merging the four nacelles into two
TheArado 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]
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 theBoeing B-52 Stratofortress (pictured right) may have two engines mounted in a single nacelle.[citation needed]
Harley-Davidson refers to the streamlined headlamp and fork triple tree covering on the Milwaukee-Eight version of theHarley-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 theStar 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]
The primary design issue with aircraft-mounted nacelles is streamlining to minimisedrag 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]
^abcIlan Kroo, Professor of Aeronautics and Astronautics (April 13, 1999)."Nacelle Design and Sizing". Aircraft Aerodynamics and Design Group at Stanford University. Archived fromthe original on March 7, 2001. RetrievedApril 22, 2011.
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