A nacelle is an enclosure on an aircraft for housing cargo, passengers or equipment such as an engine. The nacelle on a plane is typically a streamlined, elongated tubular shape. It is set perpendicular to the wing and parallel to the cabin.
Nacelles first began to appear on aircraft in the late 1920s and early 1930s as designers and manufacturers sought ways to cut drag on their planes. The advent of single-wing design, stronger lightweight materials, and the widespread use of wind tunnel testing aided in the process. The use of nacelles continued and accelerated with fighter aircraft design during World War II. The American P-38 fighter, for example, included three nacelles — one housing the cockpit and two others housing the plane's engines.
Several World War II bombers, both Allied and Axis planes, featured dual nacelles housing engines on either side of a central nacelle that housed the crew. Smaller gun nacelles were also used on some fighter-bomber craft. These detachable components were added to planes such as the American B-25 to make it a more powerful anti-ship, anti-tank or anti-personnel weapon. Nacelles of this period were made of a wide variety of materials, usually metal. The British de Havilland Mosquito, another plane with engine nacelles on either side of the central control nacelle, was made entirely of wood; the result was an extraordinarily fast airplane that was easy and quick to build even in factories with little or no aircraft manufacturing experience.
The world's first fighter jet, the German Me-262, developed at the end of World War II, also included two engine nacelles that hung below the plane's swept-back wing. Jet aircraft built by the Russians, Americans and other nations continued the use of nacelles to house their engines throughout the Korean and Vietnam war eras. Single-engine jets featuring the power plant in line behind the wings and cockpit also grew widely in use during the 1960s and 1970s.
As airplane builders continued to tinker with design over the years, they often found new uses for a nacelle or two. The Voyager airplane, which broke the world single-flight distance record in 1986, also featured a three-nacelle design reminiscent of the P-38 shape. The Voyager, made from lightweight composite materials, featured 17 fuel tanks balanced throughout the propeller-driver craft's body.
Nacelles are also in evidence on as of yet unbuilt ships of the future. Among the design elements of the Enterprise, the starship of television's "Star Trek" series in the 1960s, were two nacelles projecting from its main body. Other futuristic airplane and spaceship designs also have included a nacelle or two.