A hardpoint is a location on an airframe designed to carry an external or internal load. This includes a station on the wing or fuselage of a civilian aircraft or military aircraft where external jet engine, countermeasures, gun pods, targeting pods or drop tanks can be mounted. In aeronautics, the term station is used to refer to a point of carriage on the frame of an aircraft. A station is rated to carry a certain amount of payload, it is a design number which has taken the rated g-forces of the frame into account. Therefore, point loads on the structure from externally or internally mounted stores, equipment and payload are the weight of the item and any pylons, mounting brackets, etc. multiplied by the maximum load factor which the aircraft will sustain when these items are carried. In civilian aviation a station is used to carry an external engine or a fuel tank; as engines are a fixed installation, operators refer to them with the designation of the engine. Therefore, the term is being used for load points meant for non-fixed installation.
In the military, a station can be called weapons station. Unlike civilian aircraft, NATO aircraft frame strength is required to remain without detrimental deformations at 115 percent of the limit or specified loads, without structural failure at ultimate loads. Most stations on a military aircraft serve to carry weapons. A minor number of stations can serve to carry external fuel tanks; these stations are called a general aeronautic term referring to usage of fuel like wet thrust. The term wet is carried over to the adapters, such as a pylon. Wing stations require pylons to carry objects. Stations on the fuselage may not require a pylon, such as the fuselage stations on the McDonnell Douglas F-15 Eagle, while other aircraft need pylons for certain stations in order to provide clearance for the landing gear retraction sequence or to provide necessary item space. Swing-wing aircraft that mount pylons on the moving portion of the wing must include a mechanism for swiveling the pylon as the wing sweeps fore or aft, in order to keep the pylon and store facing directly forwards at all times.
The F-111's outermost pair of hardpoints do not swivel, can only be used while the wing is extended. This restricts the aircraft to subsonic flight only while these pylons are fitted fitted with fuel tanks during ferry flights; the pylons are automatically jettisoned if the wing sweep moves past 26 degrees, which would mean that the aircraft is accelerating towards transonic speeds. Stations may be numbered for reference or not at all; the numbering is not consistent and may originate from elsewhere like station 559 on the B-52. There is not an order in which numbers are assigned; the order can be for example from left to right or vice versa, or mirrored and from outboard to inboard. The unique centerline station is no exception. A pylon serves to connect the frame of an aircraft to an item or object, being carried; the use of a pylon is necessary to clear the carriage item of control surfaces as well as prevent undesired disturbance of the flow of air toward the wing. Pylons are designed to be aerodynamic to reduce air resistance.
There are many different forms and designs of pylons distinctly termed accordingly like a wedge adaptor or stub wing pylon. Stealth aircraft like the F-22 or F-35 can use jettisonable pylons to retain stealth and reduce drag. While most pylons are part of a modular system, compatible with numerous stores, certain weapons and aircraft can require special pylons or adapters to carry a specific load. For example, in the Vietnam War, the "Wild Weasel" defense suppression version of the F-105 Thunderchief, the F-105G, could carry the usual AGM-45 "Shrike" anti-radiation missile on a standard pylon and launcher, but the newly developed AGM-78 Standard ARM required a specially designed and unique "LAU-78/a" launcher, unique to that missile. NATO suspension equipment and stores are standardized in MIL-STD-8591. A military pylon provides carriage and the ability to jettison external stores – weapons, fuel tanks or other ordnance. Pylons have a modular bay to carry a wider variety of stores; these adaptors can be bomb racks, launchers or other types of support structures each with their own provisions for mounting all other assemblies.
Racks carry and release stores. Racks are either part of, or can be inserted into, the modular bay of a support structure such as a pylon. A rack can mount a store or another piece of suspension equipment, for example, numerous bombs being mounted onto a single pylon, such as was done on F-105 Thunderchief missions over Vietnam, or the large external pylons on the B-52 Stratofortress, which can carry 12 unguided bombs in four triple ejector racks mounted to a single pylon. Alternatively, using the same pylon, but different racks and adapters, 9 air-launched cruise missiles can be carried. Using modular racks and universal adapters makes it much easier to configure the desired load; the store is mounted by locking the store's lugs with L-shaped suspension hooks in the rack. Depending on the mass of the store there can be a single lug or a number of lugs on the store separated by a certain distance; the distances are standardized. For NATO there is the 14-inch suspension for a 30-inch suspension for heavier stores.
Depending on specific stores from 1000 lb upward
Polyethylene terephthalate abbreviated PET, PETE, or the obsolete PETP or PET-P, is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods, thermoforming for manufacturing, in combination with glass fibre for engineering resins. It may be referred to by the brand names Terylene in the UK, Lavsan in Russia and the former Soviet Union, Dacron in the US; the majority of the world's PET production is for synthetic fibres, with bottle production accounting for about 30% of global demand. In the context of textile applications, PET is referred to by its common name, whereas the acronym PET is used in relation to packaging. Polyester makes up about 18% of world polymer production and is the fourth-most-produced polymer after polyethylene and polyvinyl chloride. PET consists with repeating units. PET is recycled, has the number "1" as its resin identification code. Depending on its processing and thermal history, polyethylene terephthalate may exist both as an amorphous and as a semi-crystalline polymer.
The semicrystalline material might appear transparent or opaque and white depending on its crystal structure and particle size. The monomer bis terephthalate can be synthesized by the esterification reaction between terephthalic acid and ethylene glycol with water as a byproduct, or by transesterification reaction between ethylene glycol and dimethyl terephthalate with methanol as a byproduct. Polymerization is through a polycondensation reaction of the monomers with water as the byproduct. Plastic bottles made from PET are used for soft drinks. For certain specialty bottles, such as those designated for beer containment, PET sandwiches an additional polyvinyl alcohol layer to further reduce its oxygen permeability. Biaxially oriented PET film can be aluminized by evaporating a thin film of metal onto it to reduce its permeability, to make it reflective and opaque; these properties are useful in many applications, including flexible food packaging and thermal insulation. Because of its high mechanical strength, PET film is used in tape applications, such as the carrier for magnetic tape or backing for pressure-sensitive adhesive tapes.
Non-oriented PET sheet can be thermoformed to make packaging trays and blister packs. If crystallizable PET is used, the trays can be used for frozen dinners, since they withstand both freezing and oven baking temperatures. Both amorphous BoPET are transparent to the naked eye. Color-conferring dyes can be formulated into PET sheet; when filled with glass particles or fibres, it becomes stiffer and more durable. PET is used as a substrate in thin film solar cells. Terylene is spliced into bell rope tops to help prevent wear on the ropes as they pass through the ceiling. PET is used since late 2014 as liner material in type IV composite high pressure gas cylinders. PET works as a much better barrier to oxygen than earlier used PE. PET is used as a 3D printing filament, as well as in the 3D printing plastic PETG. PET was patented in 1941 by John Rex Whinfield, James Tennant Dickson and their employer the Calico Printers' Association of Manchester, England. E. I. DuPont de Nemours in Delaware, United States, first used the trademark Mylar in June 1951 and received registration of it in 1952.
It is still the best-known name used for polyester film. The current owner of the trademark is a partnership with a Japanese company. In the Soviet Union, PET was first manufactured in the laboratories of the Institute of High-Molecular Compounds of the USSR Academy of Sciences in 1949, its name "Lavsan" is an acronym thereof; the PET bottle was patented in 1973 by Nathaniel Wyeth. PET in its natural state is a semi-crystalline resin. Based on how it is processed, PET can be semi-rigid to rigid, it is lightweight, it makes fair moisture barrier, as well as a good barrier to alcohol and solvents. It is impact-resistant. PET becomes white when exposed to chloroform and certain other chemicals such as toluene. About 60% crystallization is the upper limit for commercial products, with the exception of polyester fibers. Clear products can be produced by cooling molten polymer below Tg glass transition temperature to form an amorphous solid. Like glass, amorphous PET forms when its molecules are not given enough time to arrange themselves in an orderly, crystalline fashion as the melt is cooled.
At room temperature the molecules are frozen in place, but, if enough heat energy is put back into them by heating above Tg, they begin to move again, allowing crystals to nucleate and grow. This procedure is known as solid-state crystallization; when allowed to cool the molten polymer forms a more crystalline material. This material has spherulites containing many small crystallites when crystallized from an amorphous solid, rather than forming one large single crystal. Light tends to scatter as it crosses the boundaries between crystallites and the amorphous regions between them; this scattering means that crystalline PET is white in most cases. Fiber drawing is among the f
Homebuilt aircraft known as amateur-built aircraft or kit planes, are constructed by persons for whom this is not a professional activity. These aircraft may be constructed from "scratch," from assembly kits. In the United States, Australia, New Zealand and South Africa, homebuilt aircraft may be licensed Experimental under FAA or similar local regulations. With some limitations, the builder of the aircraft must have done it for their own education and recreation rather than for profit. In the U. S. the primary builder can apply for a repairman's certificate for that airframe. The repairman's certificate allows the holder to perform and sign off on most of the maintenance and inspections themselves. Alberto Santos-Dumont was the first to offer for free construction plans, publishing drawings of his Demoiselle in the June 1910 edition of Popular Mechanics; the first aircraft to be offered for sale as plans, rather than a completed airframe, was the Baby Ace in the late 1920s. Homebuilt aircraft gained in popularity in the U.
S. in 1924 with the start of the National Air Races, held in Ohio. These races required aircraft with useful loads of 150 lb and engines of 80 cubic inches or less and as a consequence of the class limitations most were amateur-built; the years after Charles Lindbergh's transatlantic flight brought a peak of interest between 1929 and 1933. During this period many aircraft designers and pilots were self-taught and the high accident rate brought public condemnation and increasing regulation to amateur building; the resulting federal standards on design, stress analysis, use of aircraft-quality hardware and testing of aircraft brought an end to amateur building except in some specialized areas, such as racing. In 1946 Goodyear restarted the National Air Races, including a class for aircraft powered by 200 cubic inch and smaller engines; the midget racer class spread nationally in the U. S. and this led to calls for acceptable standards to allow recreational use of amateur-built aircraft. By the mid-1950s both the U.
S. and Canada once again allowed amateur-built aircraft to specified limitations. Homebuilt aircraft are small, one to four-seat sportsplanes which employ simple methods of construction. Fabric-covered wood or metal frames and plywood are common in the aircraft structure, but fiberglass and other composites as well as full aluminum construction techniques are being used, techniques first pioneered by Hugo Junkers as far back as the late World War I era. Engines are most the same as, or similar to, the engines used in certified aircraft. A minority of homebuilts use converted automobile engines, with Volkswagen air-cooled flat-4s, Subaru-based liquid-cooled engines, Mazda Wankel and Chevrolet Corvair six-cylinder engines being most common; the use of automotive engines helps to reduce costs, but many builders prefer dedicated aircraft engines, which are perceived to have better performance and reliability. Other engines that have been used include motorcycle engines. A combination of cost and litigation in the mid-1980s era, discouraged general aviation manufacturers from introducing new designs and led to homebuilts outselling factory built aircraft by five to one.
In 2003, the number of homebuilts produced in the U. S. exceeded the number produced by any single certified manufacturer. The history of amateur-built aircraft can be traced to the beginning of aviation. If the Wright brothers, Clément Ader, their successors had commercial objectives in mind, the first aircraft were constructed by passionate enthusiasts whose goal was to fly. Aviation took a leap forward with the industrialization that accompanied World War I. In the post-war period, manufacturers needed to find new markets and introduced models designed for tourism. However, these machines were affordable only by the rich. Many U. S. aircraft designed and registered in the 1920s onward were considered "experimental" by the CAA, the same registration under which modern homebuilts are issued Special Airworthiness Certificates. Many of these were prototypes, but designs such as Bernard Pietenpol's first 1923 design were some of the first homebuilt aircraft. In 1928, Henri Mignet published plans for his HM-8 Pou-du-Ciel.
Pietenpol constructed a factory, in 1933 began creating and selling constructed aircraft kits. In 1936, an association of amateur aviation enthusiasts was created in France. Many types of amateur aircraft began to make an appearance, in 1938 legislation was amended to provide for a Certificat de navigabilité restreint d'aéronef. 1946 saw the birth of the Ultralight Aircraft Association which in 1952 became the Popular Flying Association in the United Kingdom, followed in 1953 by the Experimental Aircraft Association in the United States and the Sport Aircraft Association in Australia. The term "homebuilding" became popular in the mid-1950s when EAA founder Paul Poberezny wrote a series of articles for the magazine Mechanix Illustrated where he explained how a person could buy a set of plans and build their own aircraft at home; the articles gained the concept of aircraft homebuilding took off. Until the late 1950s, builders had kept to wood-and-cloth and steel tube-and-cloth design. Without the regulatory restrictions faced by production aircraft manufacturers, homebuilders introduced innovative designs and construction techniques.
Burt Rutan introduced the canard design to the homebuilding world and pioneered the use of composite construction. Metal construction in kitplanes was taken to a new level by Richard VanGrunsv
The cruciform tail is an aircraft empennage configuration which, when viewed from the aircraft's front or rear, looks much like a cross. The usual arrangement is to have the horizontal stabilizer intersect the vertical tail somewhere near the middle, above the top of the fuselage; the design is used to locate the horizontal stabilizer away from jet exhaust and wing wake, as well as to provide undisturbed airflow to the rudder. Avro Canada CF-100 Canuck British Aerospace Jetstream 31/32 British Aerospace Jetstream 41 Britten-Norman Trislander Canadair CL-215 Cessna A-37 Dragonfly Cessna Citation - Excel and Latitude variants only Cessna T303 Crusader Cessna T-37 Tweet Consolidated PBY Catalina Dassault Falcon 10/100 Dassault Falcon 20/200 Dassault Falcon 50 Dassault Falcon 5X Dassault Falcon 7X Dassault Falcon 8X Dassault Falcon 900 Dassault Falcon 2000 de Havilland Canada DHC-3 Otter Dornier Do 335 Douglas A-4 Skyhawk Fairchild C-26 Metroliner Fairchild Swearingen Metroliner Gloster Meteor Handley Page Jetstream Hawker Hunter Ivanov ZJ-Viera Lake Buccaneer Lockheed JetStar McDonnell FH Phantom McDonnell F2H Banshee - early variants only Messerschmitt 262 Mikoyan-Gurevich MiG-15 Northrop YC-125 Raider Piccard Eureka PZL Bielsko SZD-50 Puchacz Republic F-84 Thunderjet Republic F-84F Thunderstreak/RF-84F Thunderflash Republic XF-84H Thunderscreech Roberts Cygnet Rockwell B-1 Lancer Rockwell Commander 112/114 Scaled Composites White Knight Two Stratos 714 Sud Aviation Caravelle Swearingen Merlin US Aviation Cumulus Westland Whirlwind Pelikan tail T-tail Twin tail V-tail
The fuselage is an aircraft's main body section. It holds crew and cargo. In single-engine aircraft it will 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 serves to position control and stabilization surfaces in specific relationships to lifting surfaces, required for aircraft stability and maneuverability. This type of structure is still in use in many lightweight aircraft using welded steel tube trusses. A box truss fuselage structure can 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 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 and rigid and had the advantage of being made 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 redundant and so can survive localized damage without catastrophic failure. A fabric covering over the structure completed the aerodynamic shell; 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. In this method, the exterior surface of the fuselage is the primary structure. A typical early form of this was built using molded plywood, where the layers of plywood are formed over a "plug" or within a mold. A 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.
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 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 molds 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; 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 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 disassembled and removed from the completed fuselage shell, fitted out with wiring 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 joined with fasteners to form the complete fuselage. As the accuracy of the final product is determined 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 is taken by the surface covering. In addition, all the load from internal pressurization is carried by the external skin; the proportioning of loads between the components is a design choice dictated by the dimensions 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.
Early aircraft were constructed of wood frames covered in fabric. As monoplanes became popular, metal frames improved the strength, which 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. Cockpit windshields on the Airbus A320 must withstand bird strikes up to 350 kt and are made of chemically strengthened glass, they are composed of three layers or plies, of glass or plastic: the inner two are 8 mm thick each and are structural, while the outer ply, about 3 mm thick, is a barrier against foreign object damage and abrasion, with a hydrophobic coating. It m
A former is an object, such as a template, gauge or cutting die, used to form something such as a boat's hull. A former gives shape to a structure that may have complex curvature. A former may become an integral part of the finished structure, as in an aircraft fuselage, or it may be disposable, being using in the construction process and discarded. Here, a former is a structural member of an aircraft fuselage, of which a typical fuselage has a series from the nose to the empennage 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 attached to longerons, which support the skin of the aircraft; the "former-and-longeron" technique was adopted from boat construction, 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, homebuilt aircraft in particular, are still designed in this way.
A former may instead be a temporary shape over which a structure is built, the former subsequently being discarded in whole or part, as follows: Strip-built boat construction uses formers over which thin plank strips are applied and glued. in some cases, some of the formers may be incorporated as structural ribs. In civil engineering, bridge building, architecture, arches may be built upon a wooden former, removed once the keystone is securely in place
A canard is an aeronautical arrangement wherein a small forewing or foreplane is placed forward of the main wing of a fixed-wing aircraft. The term "canard" may be used to describe the aircraft itself, the wing configuration or the foreplane. Despite the use of a canard surface on the first powered aeroplane, the Wright Flyer of 1903, canard designs were not built in quantity until the appearance of the Saab Viggen jet fighter in 1967; the aerodynamics of the canard configuration require careful analysis. Rather than use the conventional tailplane configuration found on most aircraft, an aircraft designer may adopt the canard configuration to reduce the main wing loading, to better control the main wing airflow, or to increase the aircraft’s maneuverability at high angles of attack or during a stall. Canard foreplanes, whether used in a canard or three-surface configuration, have important consequences on the aircraft’s longitudinal equilibrium and dynamic stability characteristics; the term “canard” arose from the appearance of the Santos-Dumont 14-bis of 1906, said to be reminiscent of a duck with its neck stretched out in flight.
The Wright Brothers began experimenting with the foreplane configuration around 1900. Their first kite included a front surface for pitch control and they adopted this configuration for their first Flyer, they were suspicious of the aft tail. The Wrights realised that a foreplane would tend to destabilise an aeroplane but expected it to be a better control surface, in addition to being visible to the pilot in flight, they believed it impossible to provide both control and stability in a single design, opted for control. Many pioneers followed the Wrights' lead. For example, the Santos-Dumont 14-bis aeroplane of 1906 had no "tail", but a box kite-like set of control surfaces in the front, pivoting on a universal joint on the fuselage's extreme nose, making it capable of incorporating both yaw and pitch control; the Fabre Hydravion of 1910 had a foreplane. But canard behaviour was not properly understood and other European pioneers—among them, Louis Blériot—were establishing the tailplane as the safer and more "conventional" design.
Some, including the Wrights, experimented with both fore and aft planes on the same aircraft, now known as the three surface configuration. After 1911, few canard types would be produced for many decades. In 1914 W. E. Evans commented that "the Canard type model has received its death-blow so far as scientific models are concerned." Experiments continued sporadically for several decades. In 1917 de Bruyère constructed his C 1 biplane fighter, having a canard foreplane and rear-mounted pusher propellor; the C 1 was a failure. First flown in 1927, the experimental Focke-Wulf F 19 "Ente" was more successful. Two examples were built and one of them continued flying until 1931. Before and during World War II several experimental canard fighters were flown, including the Ambrosini SS.4, Curtiss-Wright XP-55 Ascender and Kyūshū J7W1 Shinden. These were attempts at using the canard configuration to give advantages in areas such as performance, armament disposition or pilot view, but no production aircraft were completed.
The Shinden was ordered into production "off the drawing board" but hostilities ceased before any other than prototypes had flown. Just after the end of World War II in Europe in 1945, what may have been the first canard designed and flown in the Soviet Union appeared as a test aircraft, the lightweight Mikoyan-Gurevich MiG-8 Utka, it was a favorite among MiG OKB test pilots for its docile, slow-speed handling characteristics and flew for some years, being used as a testbed during development of the swept wing of the MiG-15 jet fighter. With the arrival of the jet age and supersonic flight, American designers, notably North American Aviation, began to experiment with supersonic canard delta designs, with some such as the North American XB-70 Valkyrie and the Soviet equivalent Sukhoi T-4 flying in prototype form, but the stability and control problems encountered prevented widespread adoption. In 1963 the Swedish company Saab patented a delta-winged design which overcame the earlier problems, in what has become known as the close-coupled canard.
It was built as the Saab 37 Viggen and in 1967 became the first modern canard aircraft to enter production. The success of this aircraft spurred many designers, canard surfaces sprouted on a number of types derived from the popular Dassault Mirage delta-winged jet fighter; these included variants of the French Dassault Mirage III, Israeli IAI Kfir and South African Atlas Cheetah. The close-coupled canard delta remains a popular configuration for combat aircraft; the Viggen inspired the American Burt Rutan to create a two-seater homebuilt canard delta design, accordingly named VariViggen and flown in 1972. Rutan abandoned the delta wing as unsuited to such light aircraft, his next two canard designs, the Long-EZ had longer-span swept wings. These designs were not only successful and built in large numbers but were radically different from anything seen before. Rutan's ideas soon spread to other designers. From the 1980s they found favour in the executive market with the appearance of types such as the OMAC Laser 300, Avtek 400 and Beech Starship.
Static canard designs can have complex interactions in airflow between the canard and the main wing, leading to issues with stability and behaviour in the stall. This limits their applicability; the development of fly-by-wire and artificial stability towards the end of the century opened the way for computerized controls to begin turning these complex effects fro