Fuselage

The fuselage (/ˈfjuːzəlɑːʒ/; from the French fuselé "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, and cargo. In single-engine aircraft it will usually contain an engine, as well, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage, which in turn is used as a floating hull. The fuselage also serves to position control and stabilization surfaces in specific relationships to lifting surfaces, which is required for aircraft stability and maneuverability.

737-700f
Fuselage of a Boeing 737 shown in brown

Types of structures

Fuselage Piper PA18
Piper PA-18 welded tube truss fuselage structure

Truss structure

This type of structure is still in use in many lightweight aircraft using welded steel tube trusses. A box truss fuselage structure can also be built out of wood—often covered with plywood. Simple box structures may be rounded by the addition of supported lightweight stringers, allowing the fabric covering to form a more aerodynamic shape, or one more pleasing to the eye.

Geodesic construction

Vickers Wellington Mark X, HE239 'NA-Y', of No. 428 Squadron RCAF (April 1943)
Geodesic airframe fuselage structure is exposed by battle damage

Geodesic structural elements were used by Barnes Wallis for British Vickers between the wars and into World War II to form the whole of the fuselage, including its aerodynamic shape. In this type of construction multiple flat strip stringers are wound about the formers in opposite spiral directions, forming a basket-like appearance. This proved to be light, strong, and rigid and had the advantage of being made almost entirely of wood. A similar construction using aluminum alloy was used in the Vickers Warwick with less materials than would be required for other structural types. The geodesic structure is also redundant and so can survive localized damage without catastrophic failure. A fabric covering over the structure completed the aerodynamic shell (see the Vickers Wellington for an example of a large warplane which uses this process). The logical evolution of this is the creation of fuselages using molded plywood, in which multiple sheets are laid with the grain in differing directions to give the monocoque type below.

Monocoque shell

Vans.rv-7.g-kels.arp
The Van's Aircraft RV-7 of semi-monocoque construction.

In this method, the exterior surface of the fuselage is also the primary structure. A typical early form of this (see the Lockheed Vega) was built using molded plywood, where the layers of plywood are formed over a "plug" or within a mold. A later form of this structure uses fiberglass cloth impregnated with polyester or epoxy resin, instead of plywood, as the skin. A simple form of this used in some amateur-built aircraft uses rigid expanded foam plastic as the core, with a fiberglass covering, eliminating the necessity of fabricating molds, but requiring more effort in finishing (see the Rutan VariEze). An example of a larger molded plywood aircraft is the de Havilland Mosquito fighter/light bomber of World War II. No plywood-skin fuselage is truly monocoque, since stiffening elements are incorporated into the structure to carry concentrated loads that would otherwise buckle the thin skin. The use of molded fiberglass using negative ("female") molds (which give a nearly finished product) is prevalent in the series production of many modern sailplanes. The use of molded composites for fuselage structures is being extended to large passenger aircraft such as the Boeing 787 Dreamliner (using pressure-molding on female molds).

Semi-monocoque

Fuselage-747
Sectioned fuselage showing frames, stringers and skin all made of aluminium

This is the preferred method of constructing an all-aluminum fuselage. First, a series of frames in the shape of the fuselage cross sections are held in position on a rigid fixture. These frames are then joined with lightweight longitudinal elements called stringers. These are in turn covered with a skin of sheet aluminum, attached by riveting or by bonding with special adhesives. The fixture is then disassembled and removed from the completed fuselage shell, which is then fitted out with wiring, controls, and interior equipment such as seats and luggage bins. Most modern large aircraft are built using this technique, but use several large sections constructed in this fashion which are then joined with fasteners to form the complete fuselage. As the accuracy of the final product is determined largely by the costly fixture, this form is suitable for series production, where a large number of identical aircraft are to be produced. Early examples of this type include the Douglas Aircraft DC-2 and DC-3 civil aircraft and the Boeing B-17 Flying Fortress. Most metal light aircraft are constructed using this process.

Both monocoque and semi-monocoque are referred to as "stressed skin" structures as all or a portion of the external load (i.e. from wings and empennage, and from discrete masses such as the engine) is taken by the surface covering. In addition, all the load from internal pressurization is carried (as skin tension) by the external skin.

The proportioning of loads between the components is a design choice dictated largely by the dimensions, strength, and elasticity of the components available for construction and whether or not a design is intended to be "self jigging", not requiring a complete fixture for alignment.

Materials

Fisher FP-202 Koala D-MKOA fuselage
Inside view of the wooden, fabric-covered fuselage of a Fisher FP-202.

Early aircraft were constructed of wood frames covered in fabric. As monoplanes became popular, metal frames improved the strength, which eventually led to all-metal-structure aircraft, with metal covering for all its exterior surfaces - this was first pioneered in the second half of 1915. Some modern aircraft are constructed with composite materials for major control surfaces, wings, or the entire fuselage such as the Boeing 787. On the 787, it makes possible higher pressurization levels and larger windows for passenger comfort as well as lower weight to reduce operating costs. The Boeing 787 weighs 1500 lb less than if it were an all-aluminum assembly.

Windows

Cockpit windshields on the Airbus A320 must withstand bird strikes up to 350 kt and are made of chemically strengthened glass. They are usually composed of three layers or plies, of glass or plastic : the inner two are 8 mm (0.3 in.) thick each and are structural, while the outer ply, about 3 mm thick, is a barrier against foreign object damage and abrasion, with often a hydrophobic coating. It must prevent fogging inside the cabin and de-ice from −50 °C (−58 °F), this was previously done with thin wires similar to a rear car window, but now is a transparent, nanometers thick coating of indium tin oxide siting between plies, electrically conductive and thus transmitting heat. Curved glass improves aerodynamics but sight criteria also needs larger panes. A cockpit windshield is composed of 4–6 panels, 35 kg (77 lb.) each on an Airbus A320. In its lifetime, an average aircraft goes through three or four windshields, and the market is shared evenly between OEM and higher margins aftermarket.[1]

Cabin windows, made from much lighter than glass stretched acrylic glass, consists of multiple panes: an outer one built to support four times the maximum cabin pressure, an inner one for redundancy and a scratch pane near the passenger. Acrylic is susceptible to crazing : a network of fine cracks appears but can be polished to restore optical transparency, removal and polishing typically undergo every 2–3 years for uncoated windows.[1]

Wing integration

"Flying wing" aircraft, such as the Northrop YB-49 Flying Wing and the Northrop B-2 Spirit bomber have no separate fuselage; instead what would be the fuselage is a thickened portion of the wing structure.

Conversely there have been a small number of aircraft designs which have no separate wing, but use the fuselage to generate lift. Examples include National Aeronautics and Space Administration's experimental lifting body designs and the Vought XF5U-1 Flying Flapjack.

A blended wing body can be considered a mixture of the above. It carries the useful load in a fuselage producing lift. A modern example is Boeing X-48. One of the earliest aircraft using this design approach is Burnelli CBY-3, which fuselage was airfoil shaped to produce lift.

Gallery

Airbus A340 Intérieur Fuselage Arrière

Interior rear-end of the main passenger level on an Airbus A340, showing the rear bulkhead as well as a doorway opening

Boeing 747 Le Bourget FRA 002

Rough Boeing 747 interior airframe

CubCrafters Fuselage

Fuselage of a CubCrafters Carbon Cub

Christen.eagle.2.g-ccyo.arp

The fuselage can be short, and seemingly unaerodynamic, as in this Christen Eagle

Glider fuselage schematic

Glider fuselage schematic

See also

References

  1. ^ a b Alex Derber (Nov 28, 2016). "What Passenger Cabin Windows Will Future Airliners Have?". Inside MRO. Aviation Week.

External links

Airbus A321

The Airbus A321 is a member of the Airbus A320 family of short- to medium-range, narrow-body, commercial passenger twin-engine jet airliners manufactured by Airbus. It was the first derivative of the baseline Airbus A320 aircraft. It represents a stretched-fuselage variant of the Airbus A320 and entered service in 1994 with Lufthansa, around six years after the original A320. The aircraft shares a common type rating with all other Airbus A320 family variants, allowing existing A320 family pilots to fly the aircraft without the need for further training.

In December 2010, Airbus announced a new generation of the A320 family, the A320neo (new engine option). The similarly lengthened fuselage A321neo variant offers new, more efficient engines, combined with airframe improvements and the addition of winglets, named Sharklets by Airbus. The aircraft delivers fuel savings of up to 15%. The A321neo carries up to 236 passengers, with a maximum range of 4,000 nmi (7,400 km; 4,600 mi) for the long-range version carrying onboard 206 passengers.Final assembly of the aircraft takes place in Hamburg, Germany, or Mobile, Alabama. As of 31 January 2019, a total of 1,850 Airbus A321 aircraft have been delivered, of which 1,827 are in service. In addition, another 2,241 airliners are on firm order (comprising 81 A321ceo and 2,160 A321neo). As of January 2019, American Airlines was the largest operator of the Airbus A321, operating 220 aircraft.

Airbus A350 XWB

The Airbus A350 XWB is a family of long-range, twin-engine wide-body jet airliners developed by European aerospace manufacturer Airbus. The A350 is the first Airbus aircraft with both fuselage and wing structures made primarily of carbon fibre reinforced polymer. Its variants seat 280 to 366 passengers in typical three-class seating layouts. The A350 is positioned to succeed the A340 and to compete with the Boeing 787 and 777.

The A350 was originally conceived in 2004 as a pairing of the A330's fuselage with new aerodynamics features and engines. In 2006, Airbus redesigned the aircraft in response to negative feedback from several major prospective customers, producing the "A350 XWB" (eXtra Wide Body). Development costs are estimated at €11 billion (US$15 billion or £9.5 billion). As of January 2019, Airbus had received 894 orders for A350s from 47 customers worldwide. The prototype A350 first flew on 14 June 2013 from Toulouse, France. Type certification from the European Aviation Safety Agency was received in September 2014 and certification from the Federal Aviation Administration two months later. On 15 January 2015, the A350-900 entered service with its launch operator Qatar Airways, and the A350-1000 on 24 February 2018 with the same airline.

Airbus Beluga XL

The Airbus Beluga XL (Airbus A330-743L) is a large transport aircraft due to enter into service in 2019. It is based on the A330 airliner, to be the successor to the Airbus Beluga. The XL has an extension on the fuselage top like the Beluga. It is being designed, built and will be operated by Airbus to move oversized aircraft components. The aircraft made its first flight on 19 July 2018.

Aircraft fairing

An aircraft fairing is a structure whose primary function is to produce a smooth outline and reduce drag.These structures are covers for gaps and spaces between parts of an aircraft to reduce form drag and interference drag, and to improve appearance.

Airplane

An airplane or aeroplane (informally plane) is a powered, fixed-wing aircraft that is propelled forward by thrust from a jet engine, propeller or rocket engine. Airplanes come in a variety of sizes, shapes, and wing configurations. The broad spectrum of uses for airplanes includes recreation, transportation of goods and people, military, and research. Worldwide, commercial aviation transports more than four billion passengers annually on airliners and transports more than 200 billion tonne-kilometres of cargo annually, which is less than 1% of the world's cargo movement. Most airplanes are flown by a pilot on board the aircraft, but some are designed to be remotely or computer-controlled.

The Wright brothers invented and flew the first airplane in 1903, recognized as "the first sustained and controlled heavier-than-air powered flight". They built on the works of George Cayley dating from 1799, when he set forth the concept of the modern airplane (and later built and flew models and successful passenger-carrying gliders). Between 1867 and 1896, the German pioneer of human aviation Otto Lilienthal also studied heavier-than-air flight. Following its limited use in World War I, aircraft technology continued to develop. Airplanes had a presence in all the major battles of World War II. The first jet aircraft was the German Heinkel He 178 in 1939. The first jet airliner, the de Havilland Comet, was introduced in 1952. The Boeing 707, the first widely successful commercial jet, was in commercial service for more than 50 years, from 1958 to at least 2013.

Bell P-39 Airacobra

The Bell P-39 Airacobra was one of the principal American fighter aircraft in service when the United States entered World War II. The P-39 was used by the Soviet Air Force, and enabled individual Soviet pilots to collect the highest number of kills attributed to any U.S. fighter type flown by any pilot in any conflict. Other major users of the type included the Free French, the Royal Air Force, the United States Army Air Forces, and the Italian Co-Belligerent Air Force.Designed by Bell Aircraft, it had an innovative layout, with the engine installed in the center fuselage, behind the pilot, and driving a tractor propeller via a long shaft. It was also the first fighter fitted with a tricycle undercarriage. Although its mid-engine placement was innovative, the P-39 design was handicapped by the absence of an efficient turbo-supercharger, preventing it from performing high-altitude work. For this reason it was rejected by the RAF for use over western Europe but adopted by the USSR where most air combat took place at medium and lower altitudes.

Together with the derivative P-63 Kingcobra, the P-39 was one of the most successful fixed-wing aircraft manufactured by Bell.

Bracing (aeronautics)

In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in compression or tension as the need arises, and/or wires, which act only in tension.

In general, bracing allows a stronger, lighter structure than one which is unbraced, but external bracing in particular adds drag which slows down the aircraft and raises considerably more design issues than internal bracing. Another disadvantage of bracing wires is that they require routine checking and adjustment, or rigging, even when located internally.

During the early years of aviation, bracing was a universal feature of all forms of aeroplane, including the monoplanes and biplanes which were then equally common. Today, bracing in the form of lift struts is still used for some light commercial designs where a high wing and light weight are more important than ultimate performance.

Bubble canopy

A bubble canopy is a canopy made without bracing, which attempts to provide 360° vision to the pilot. Bubble canopy designs vary. Some, like on later versions of the F4U Corsair, are built into the upper rear fuselage, while others, like the canopy of the P-51D Mustang and most modern fighter aircraft, are built flush with the fuselage, providing unobstructed rear visibility.

De Havilland Comet

The de Havilland DH 106 Comet was the world's first commercial jet airliner. Developed and manufactured by de Havilland at its Hatfield Aerodrome in Hertfordshire, United Kingdom, the Comet 1 prototype first flew in 1949. It featured an aerodynamically clean design with four de Havilland Ghost turbojet engines buried in the wing roots, a pressurised cabin, and large square windows. For the era, it offered a relatively quiet, comfortable passenger cabin and was commercially promising at its debut in 1952.

However, within a year of entering airline service, problems started to emerge, with three Comets lost within twelve months in highly publicised accidents, after suffering catastrophic in-flight break-ups. Two of these were found to be caused by structural failure resulting from metal fatigue in the airframe, a phenomenon not fully understood at the time. The other one was due to overstressing of the airframe during flight through severe weather. The Comet was withdrawn from service and extensively tested. Design and construction flaws, including improper riveting and dangerous concentrations of stress around some square openings in the fuselage, were ultimately identified. As a result, the Comet was extensively redesigned, with oval windows, structural reinforcements and other changes. Rival manufacturers meanwhile heeded the lessons learned from the Comet while developing their own aircraft.

Although sales never fully recovered, the improved Comet 2 and the prototype Comet 3 culminated in the redesigned Comet 4 series which debuted in 1958 and had a productive career of over 30 years. The Comet was also adapted for a variety of military roles such as VIP, medical and passenger transport, as well as surveillance. The most extensive modification resulted in a specialised maritime patrol variant, the Hawker Siddeley Nimrod, which remained in service with the Royal Air Force until 2011, over 60 years after the Comet's first flight.

Fixed-wing aircraft

A fixed-wing aircraft is a flying machine, such as an airplane or aeroplane (see spelling differences), which is capable of flight using wings that generate lift caused by the aircraft's forward airspeed and the shape of the wings. Fixed-wing aircraft are distinct from rotary-wing aircraft (in which the wings form a rotor mounted on a spinning shaft or "mast"), and ornithopters (in which the wings flap in a manner similar to that of a bird). The wings of a fixed-wing aircraft are not necessarily rigid; kites, hang gliders, variable-sweep wing aircraft and aeroplanes that use wing morphing are all examples of fixed-wing aircraft.

Gliding fixed-wing aircraft, including free-flying gliders of various kinds and tethered kites, can use moving air to gain altitude. Powered fixed-wing aircraft (aeroplanes) that gain forward thrust from an engine include powered paragliders, powered hang gliders and some ground effect vehicles. Most fixed-wing aircraft are flown by a pilot on board the craft, but some are specifically designed to be unmanned and controlled either remotely or autonomously (using onboard computers).

Floatplane

A floatplane (float plane or pontoon plane) is a type of seaplane, with one or more slender pontoons (known as "floats") mounted under the fuselage to provide buoyancy. By contrast, a flying boat uses its fuselage for buoyancy. Either type of seaplane may also have landing gear suitable for land, making the vehicle an amphibious aircraft. British usage is to call "floatplanes" "seaplanes" rather than use the term "seaplane" to refer to both floatplanes and flying boats.

Former

A former is a structural member of an aircraft fuselage, of which a typical fuselage has a series from the nose to the empennage, typically perpendicular to the longitudinal axis of the aircraft. The primary purpose of formers is to establish the shape of the fuselage and reduce the column length of stringers to prevent instability. Formers are typically attached to longerons, which support the skin of the aircraft.

The Former-and-Longeron technique was adopted from boat construction (also called stations and stringers), and was typical of light aircraft built until the advent of structural skins, such as fiberglass and other composite materials. Many of today's light aircraft, and homebuilt aircraft in particular, are still designed in this way.

Landing gear

Landing gear is the undercarriage of an aircraft or spacecraft and may be used for either takeoff or landing. For aircraft it is generally both. It was also formerly called alighting gear by some manufacturers, such as the Glenn L. Martin Company.

For aircraft, the landing gear supports the craft when it is not flying, allowing it to take off, land, and taxi without damage. Wheels are typically used but skids, skis, floats or a combination of these and other elements can be deployed depending both on the surface and on whether the craft only operates vertically (VTOL) or is able to taxi along the surface. Faster aircraft usually have retractable undercarriages, which fold away during flight to reduce air resistance or drag.

For launch vehicles and spacecraft landers, the landing gear is typically designed to support the vehicle only post-flight, and are typically not used for takeoff or surface movement.

Monoplane

A monoplane is a fixed-wing aircraft with a single main wing plane, in contrast to a biplane or other multiplane, each of which has multiple planes.

A monoplane has inherently the highest efficiency and lowest drag of any wing configuration and is the simplest to build. However, during the early years of flight, these advantages were offset by its greater weight and lower manoeuvrability, making it relatively rare until the 1930s. Since then, the monoplane has been the most common form for a fixed-wing aircraft.

Nacelle

A nacelle ( nə-SEL) is a housing, separate from the fuselage, that holds engines, fuel, or equipment on an aircraft. In some cases—for instance in the typical "Farman" type "pusher" aircraft, or the World War II-era P-38 Lightning—an aircraft's cockpit may also be housed in a nacelle, which essentially fills the function of a conventional fuselage. The covering is typically aerodynamically shaped.

Royal Air Force roundels

The air forces of the United Kingdom – the Royal Navy's Fleet Air Arm, the Army's Army Air Corps and the Royal Air Force use a roundel, a circular identification mark, painted on aircraft to identify them to other aircraft and ground forces. In one form or another, it has been used on British military aircraft from 1915 to the present.

Uruguayan Air Force Flight 571

Uruguayan Air Force Flight 571 was a chartered flight that crashed on a glacier at an elevation of 3,570 metres (11,710 ft) in the remote Andes. Among the 45 people on board, 28 survived the initial crash. Facing starvation and death, the survivors reluctantly resorted to cannibalism. After 72 days on the glacier, 16 people were rescued.

The flight carrying 19 members of a rugby team, family, supporters, and friends originated in Montevideo, Uruguay and was headed for Santiago, Chile. While crossing the Andes, the inexperienced co-pilot who was in command mistakenly believed they had reached Curicó, Chile, despite instrument readings indicating otherwise. He turned north and began to descend towards what he thought was Pudahuel Airport. Instead, the aircraft struck the mountain, shearing off both wings and the rear of the fuselage. The forward part of the fuselage careered down a steep slope like a toboggan and came to rest on a glacier. Three crew members and more than a quarter of the passengers died in the crash, and several others quickly succumbed to cold and injuries.

On the tenth day after the crash, the survivors learned from a transistor radio that the search had been called off. Faced with starvation and death, those still alive agreed that should they die, the others might consume their bodies in order to live. With no choice, the survivors ate the bodies of their dead friends. Seventeen days after the crash, 27 remained alive when an avalanche filled the rear of the broken fuselage they were using as shelter, killing eight more survivors. The survivors had little food and no source of heat in the harsh conditions. They decided that a few of the strongest people would hike out to seek rescue. Sixty days after the crash, passengers Nando Parrado and Roberto Canessa, lacking mountaineering gear of any kind, climbed from the glacier at 3,570 metres (11,710 ft) to the 4,670 metres (15,320 ft) peak blocking their way west. Over 10 days they trekked about 38 miles (61 km) seeking help. The first person they saw was Chilean arriero Sergio Catalán, who gave them food and then rode for ten hours to alert authorities. The story of the passengers' survival after 72 days drew international attention. The remaining 16 survivors were rescued on 23 December 1972, more than two months after the crash.The survivors were concerned about what the public and family members of the dead might think about their acts of eating the dead. There was an initial public backlash, but after they explained the pact the survivors made to sacrifice their flesh if they died to help the others survive, the outcry diminished and the families were more understanding. The incident was later known as the Andes flight disaster and, in the Hispanic world, as El Milagro de los Andes (The Miracle of the Andes).

Wide-body aircraft

A wide-body aircraft, also known as a twin-aisle aircraft, is a jet airliner with a fuselage wide enough to accommodate two passenger aisles with seven or more seats abreast. The typical fuselage diameter is 5 to 6 m (16 to 20 ft). In the typical wide-body economy cabin, passengers are seated seven to ten abreast, allowing a total capacity of 200 to 850 passengers. The largest wide-body aircraft are over 6 m (20 ft) wide, and can accommodate up to eleven passengers abreast in high-density configurations.

By comparison, a typical narrow-body airliner has a diameter of 3 to 4 m (10 to 13 ft), with a single aisle, and seats between two and six people abreast.Wide-body aircraft were originally designed for a combination of efficiency and passenger comfort and to increase the amount of cargo space. However, airlines quickly gave in to economic factors, and reduced the extra passenger space in order to maximize revenue and profits.Wide-body aircraft are also used for the transport of commercial freight and cargo and other special uses, described further below.

The biggest wide-body aircraft are known as jumbo jets due to their very large size; examples include the Boeing 747 ("jumbo jet"), Airbus A380 ("superjumbo jet"), and upcoming Boeing 777X ("mini jumbo jet"). The phrase "jumbo jet" derives from Jumbo, a circus elephant in the 19th century.Seven-abreast aircraft typically seat 160 to 260 passengers, eight-abreast 250 to 380, nine- and ten-abreast 350 to 480.Up to the end of 2017, nearly 8,800 wide-body airplanes had been delivered since 1969, peaking at 412 in 2015.

Wing root

The wing root is the part of the wing on a fixed-wing aircraft that is closest to the fuselage. On a simple monoplane configuration, this is usually easy to identify. On parasol wing or multiple boom aircraft, the wing may not have a clear root area.Wing roots usually bear the highest bending forces in flight and during landing, and they often have fairings (often named "wing fillets") to reduce interference drag between the wing and the fuselage.The opposite end of a wing from the wing root is the wing tip.

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