Pietenpol Air Camper
The Pietenpol Air Camper is a simple parasol wing homebuilt aircraft designed by Bernard H. Pietenpol; the first prototype that became the Air Camper was built and flown by Pietenpol in 1928. The Air Camper was designed to be built of plywood. One of Pietenpol's goals was to create a plane, affordable and easy to construct for home builders. Building an Air Camper requires basic woodworking skills and tools. Builders need to fabricate some metal fittings to attach the wooden parts together; some welding is required. The plans for the Pietenpol Aircamper were published in a four-part serial in the "Flying and Glider" Manual of 1932-33; the original model was flown using an Ace four cylinder water-cooled engine. The Model A Ford engine became the standard powerplant used. In the 1960s Bernard Pietenpol began to favor converted engines from Chevrolet Corvair automobiles; the Corvair flat six was higher horsepower and lighter, compared to the Model A, was similar to those available for general aviation use.
The length of a Pietenpol varies with the engine choices, as lighter engines needed to be mounted further forward for weight and balance reasons. Over the years over 30 different engines have flown in the Pietenpol Air Camper. Many modern Pietenpol builders prefer C85 or C90 air-cooled flat fours. Several examples of the Aircamper in 2012 were still flying. In the 1920s and 1930s, kits were available for the design, but there were none available again until 2015 when the Pietenpol Aircraft Company introduced a kit version of the Air Camper, with components supplied by Aircraft Spruce & Specialty; the kit includes all parts except the engine, fabric covering, hardware. Pietenpol Sky Scout BH Pietenpol designed and published plans for a single-seat version of the aircraft named the Pietenpol Sky Scout, smaller and was powered by the Ford Model T engine. During the late 1920s and early 1930s, this was less expensive than the Model A used in the Air Camper. UK LAA-approved Pietenpol Air Camper In some countries, civil aviation authority approval is required for each experimental aircraft design, in addition to the approval of each aircraft an individual makes, as in the US.
A variant of the Pietenpol Air Camper was designed by Mr. J. K. Wills, UK Light Aircraft Association approval was obtained for this variant. Grega GN-1 Aircamper A plans-only homebuilt design similar to the Air Camper using a Piper Cub wing. St Croix Pietenpol Aerial A biplane adaptation, designed by Chad and Charles Willie and produced by St Croix Aircraft of Corning, first flown in 1977. St Croix Pietenpol Aircamper An adaptation of the original design with more wingspan, longer fuselage and higher gross weight. Data from B. H. Pietenpol And Sons Air Camper Aircraft. "How to Build a Pietenpol Air Camper or Sky Scout Airplane". Retrieved May 14, 2013. General characteristics Crew: One pilot Capacity: One passenger Length: 17 ft 8 in Wingspan: 29 ft 0 in Height: 6 ft 6 in Wing area: 135 ft² Empty weight: 610 lb Loaded weight: 995 lb Max. Takeoff weight: 1080 lb Powerplant: 1 × Ford Model A automotive conversion engine, 40 hp Performance Maximum speed: 86 knots Stall speed: 30 knots Rate of climb: 500 ft/min Wing loading: 7 lb/ft² Aircraft of comparable role and era Aerotique Parasol Dormoy Bathtub Fisher FP-505 Skeeter Heath Parasol Letov Š 39 Loehle Sport Parasol Long Henderson Longster Pop's Props Cloudster Pop's Props Zing RagWing RW1 Ultra-Piet Smith Termite Related lists List of civil aircraft Pietenpol Airplanes in MNopedia, the Minnesota Encyclopedia Pietenpol family site Sky Camper history on AirVenture Museum site "The Pietenpol Story" by Chet Peek - Book covering the history of Bernard Pietenpol's Design Video of a Model A-engined Air Camper engine start and runup Walkaround and In-Flight Video of an original-style Air Camper HOT ROD Magazine's 2008 article on "Four-Cylinder Engine Build – Building A Better ‘Banger" for Ford Model A and B engines used to power Air Campers Flysquirrel.net's PDF-format article on different engine choices for Air Campers
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
Early flying machines
Early flying machines include all forms of aircraft studied or constructed before the development of the modern aeroplane by 1910. The story of modern flight begins more than a century before the first successful manned aeroplane, the earliest aircraft thousands of years before. From the earliest times there have been legends of men mounting flying devices or strapping birdlike wings, stiffened cloaks or other devices to themselves and attempting to fly by jumping off a tower; the Greek legend of Daedalus and Icarus is one of the earliest to come down to us. According to Ovid, Daedalus tied feathers together to mimic the wings of a bird. Other ancient legends include the Indian Vimana flying palace or chariot, Ezekiel's Chariot, the Irish roth rámach built by blind druid Mug Ruith and Simon Magus, various stories about magic carpets, mythical British King Bladud, who conjured up flying wings; some tried to build real flying devices birdlike wings, attempted to fly by jumping off a tower, hill, or cliff.
During this early period physical issues of lift and control were not understood, most attempts ended in serious injury or death when the apparatus lacked an effective horizontal tail, or the wings were too small. In the 1st century AD, Chinese Emperor Wang Mang recruited a specialist scout to be bound with bird feathers. In 559 AD, Yuan Huangtou is said to have landed safely following an enforced tower jump. In the seventeenth century, the Algerian historian Ahmed Mohammed al-Maqqari stated that the Andalusian scientist Abbas ibn Firnas made a jump in Cordoba, covering his body with vulture feathers and attaching two wings to his arms. No other sources record the event. Writing in the twelfth century, William of Malmesbury stated that the eleventh century Benedictine monk Eilmer of Malmesbury attached wings to his hands and feet and flew a short distance. Beyond those based on William's account, there are no other known sources documenting Eilmer's life. In 1496, a man named. In 1507, John Damian strapped on wings covered with chicken feathers and jumped from the walls of Stirling Castle in Scotland, breaking his thigh blaming it on not using eagle feathers.
Similar attempts continued with never more than partial success. Francis Willughby's suggestion, published in 1676, that human legs were more comparable to birds' wings in strength than arms, had only occasional influence. On 15 May 1793, the Spanish inventor Diego Marín Aguilera jumped with his glider from the highest part of the castle of Coruña del Conde, reaching a height of 5 or 6 m, gliding for 360 metres; as late as 1811, Albrecht Berblinger jumped into the Danube at Ulm. The kite was invented in China as far back as the 5th century BC by Mozi and Lu Ban; these leaf kites were constructed by stretching silk over a split bamboo framework. The earliest known Chinese kites were flat and rectangular. Tailless kites incorporated a stabilizing bowline. Designs emulated flying insects and other beasts, both real and mythical; some were fitted with whistles to make musical sounds while flying. In 549 AD, a kite made of paper was used as a message for a rescue mission. Ancient and medieval Chinese sources list other uses of kites for measuring distances, testing the wind, lifting men and communication for military operations.
After its introduction into India, the kite further evolved into the fighter kite. Traditionally these are small, unstable single line flat kites where line tension alone is used for control, an abrasive line is used to cut down other kites. Kites spread throughout Polynesia, as far as New Zealand. Anthropomorphic kites made from cloth and wood were used in religious ceremonies to send prayers to the gods. By 1634 kites had reached the West, with an illustration of a diamond kite with a tail appearing in Bate's Mysteries of nature and art. Man-carrying kites are believed to have been used extensively in ancient China, for both civil and military purposes and sometimes enforced as a punishment. Stories of man-carrying kites occur in Japan, following the introduction of the kite from China around the seventh century AD, it is said. In 1282, the European explorer Marco Polo described the Chinese techniques current and commented on the hazards and cruelty involved. To foretell whether a ship should sail, a man would be strapped to a kite having a rectangular grid framework and the subsequent flight pattern used to divine the outlook.
The use of a rotor for vertical flight has existed since 400 BC in the form of the bamboo-copter, an ancient Chinese toy. The bamboo-copter is spun by rolling a stick attached to a rotor; the spinning creates lift, the toy flies when released. The philosopher Ge Hong's book the Baopuzi, written around 317, describes the apocryphal use of a possible rotor in aircraft: "Some have made flying cars with wood from the inner part of the jujube tree, using ox-leather fastened to returning blades so as to set the machine in motion"; the similar "moulinet à noix" appeared in Europe in the 14th century AD. From ancient times the Chinese have understood that hot air rises and have applied the principle to a type of small hot air balloon called a sky lantern. A sky lantern consists of a paper balloon under or just inside. Sky lanterns are traditionally launched during festivals. According to Joseph Needha
The Malmö Flygindustri MFI-9 Junior was a light aircraft produced in Sweden in the 1960s. The aircraft was produced under license as the Bölkow Bo 208; the BA-7 was designed by Björn Andreasson and flown by him in prototype form on 10 October 1958. He built this first plane in his spare time while working for Convair in the United States, it was powered by an air-cooled Continental A-75 engine giving 56 kW driving a two-bladed variable-pitch propeller. The shoulder wings were forward swept to place occupants ahead of the spar for visibility. In 1960 Andreasson returned to Sweden and started working at Malmö Flygindustri where he designed an improved version of the BA-7 that went into production as the MFI-9 Junior. Changes included a larger cockpit and the powerplant was now a Continental O-200-A flat-four-cylinder air-cooled piston engine giving 75 kW. In 1963 it was followed by the MFI-9B Trainer and the MFI-9B Mili-Trainer; the MFI-9 uses a tricycle undercarriage. Between 1963 and 1971, 210 Bölkow Bo 208s were built under licence by Bölkow Apparatebau GmbH in Laupheim, Germany.
Many examples survive in private hands and are most found in Germany, the United Kingdom and Scandinavia. A limited number of airworthy examples can be found in New Zealand; the most produced variant of the Bo 208 is the Bo 208C, which used a Continental O-200-A flat-four-cylinder air-cooled piston engine giving 75 kW. A number of O-200 engines installed on Juniors were licence-built by Rolls-Royce in England. One variant of the MFI-9 which gained widespread fame was the MiniCOIN, a modification of the MFI-9B military trainer variant of the MFI-9, adapted to carry weapons; the name and concept originated with Carl Gustaf von Rosen, who realized that in a low intensity conflict a few small, minimally armed aircraft are capable of having a significant impact. Light aircraft are in any event more suitable for operation in the primitive conditions typical in such conflicts. Von Rosen was familiar with the military trainer version of the MFI-9, robust enough to be able to carry significant loads of ordnance suspended from hard points on the wings.
A number of MFI-9Bs had been constructed in hopes of a sale to the Swedish Air Force, but when the sale fell through, the aircraft became available at a low price. So in May 1969, von Rosen formed a squadron of five MiniCOINs to fight in the Nigerian Civil War on the side of the Biafrans in support of their effort to create an independent state. Von Rosen had the planes painted in camouflage colours and fitted with rockets from Matra, proceeded with a band of friends to form a squadron called Biafra Babies to strike at the airfields from which the federal Nigerian Air Force launched their attacks against the civilian population in Biafra. On 22 May 1969, over the next few days, Von Rosen and his five aircraft launched attacks against Nigerian airfields at Port Harcourt, Enugu and other small airports; the Nigerians were taken by surprise and a number of expensive jets, including a few MiG-17 fighters and three of Nigeria's six Ilyushin Il-28 bombers, were destroyed on the ground. The pilots included Lynn Garrison among a group of Biafran-born pilots.
Lynn Garrison co-ordinated the attacks destroying an Ilyushin Il-28 and a MiG-17 during the first raid on Port Harcourt. The MiniCOINs saw extensive service during most of the war, including the delivery of food aid drops. Garrison introduced a supply-dropping procedure learned in northern Canada. A bag of grain was enclosed in a larger bag before dropping. Many lives were saved through air drops using this simple concept. A total of 18 was supplied. MFI-9 – Two-seat primary trainer aircraft. 25 built. Bölkow Bo 208 – MFI-9 produced under licence by Bölkow in Germany. 200 built. MFI-9B Trainer – Two-seat sports, primary trainer aircraft. 43 built. Biafra Baby – Five MFI-9Bs armed with six French SNEB 68 mm unguided folding-fin rockets with armor-piercing warheads under each wing. MFI-9B Mili-Trainer – Two-seat primary trainer, light-attack aircraft. Two prototypes built. Ten aircraft leased by the Swedish Air Force 1966–68 for evaluation as a primary trainer only. BiafraUsed by the Biafran Air Force during the Biafran War.
SwedenTen MFI-9B Mili-Trainers evaluated by the Swedish Air Force. Data from Jane's All The World's Aircraft 1965–66General characteristics Crew: one pilot Capacity: 1 passenger Length: 5.85 m Wingspan: 7.43 m Height: 2.00 m Wing area: 8.70 m2 Empty weight: 340 kg Gross weight: 575 kg Powerplant: 1 × Continental O-200 A four-cylinder engine, 75 kW Performance Maximum speed: 236 km/h Cruising speed: 215 km/h Range: 800 km Service ceiling: 4,500 m Rate of climb: 4.3 m/s Armament Aircraft of comparable role and era ARV Super2 Saab Safari Notes BibliographyTaylor, John W. R.. Jane's All The World's Aircraft 1965–66. London: Samson Low, Marston. Taylor, Michael J. H.. Jane's Encyclopedia of Aviation. London: Studio Editions. P. 192. Simpson, R. W.. Airlife's General Aviation. Shrewsbury: Airlife Publishing. P. 85.'Fleas versus Falcons over Biafra' SAAB Trainers: Safir, SAAB 105, & Supporter
An amphibious aircraft or amphibian is an aircraft that can take off and land on both land and water. Fixed-wing amphibious aircraft are seaplanes that are equipped with retractable wheels, at the expense of extra weight and complexity, plus diminished range and fuel economy compared to planes designed for land or water only; some amphibians are fitted with reinforced keels which act as skis, allowing them to land on snow or ice with their wheels up. Floatplanes have floats that are interchangeable with wheeled landing gear however in cases where this is not practical amphibious floatplanes, such as the amphibious version of the DHC Otter, incorporate retractable wheels within their floats. Many amphibian aircraft are of the flying boat type; these aircraft, those designed as floatplanes with a single main float under the fuselage centerline, require outrigger floats to provide lateral stability so as to avoid dipping a wingtip, which can destroy an aircraft if it happens at speed, or can cause the wingtip to fill with water and sink if stationary.
While these impose weight and drag, amphibious aircraft face the possibility of these getting hit when operating from a runway. A common solution is to make them retractable as those found on the Consolidated Catalina however these are heavier than fixed floats; some aircraft may have the tip floats removed for extended use from land. Other amphibians, such as the Dornier Seastar use stub wings called sponsons, mounted with their own lower surfaces nearly with the ventral "boat-hull" shaped fuselage surface to provide the needed stability, while floatplane amphibians avoid the problem by dividing their buoyancy requirements between two floats, much like a catamaran; some non-amphibious seaplanes may be mistaken for amphibians which carry their own beaching gear - this is a wheeled dolly or temporary set of wheels used to move a flying boat or floatplane from the water and allow it to be moved around on land but can appear as a conventional undercarriage. These are not built to take the impact of the aircraft landing on them.
An amphibian can leave the water without anyone getting in the water to attach beaching wheels, yet a functional undercarriage is heavy and impacts the aircraft's performance, isn't required in all cases, so an aircraft may be designed to carry its own. An occasional problem with amphibians is with ensuring the wheels are in the correct position for landing. In normal operation, the pilot uses a checklist. Since amphibians can land with them up or down though, the pilot must take extra care to ensure they are correct for the chosen landing place. Landing wheels up on land may damage the keel, while landing wheels down on water will always flip the aircraft upside down, causing substantial damage. Amphibious aircraft are heavier and slower, more complex and more expensive to purchase and operate than comparable landplanes but are more versatile. If they cannot hover or land vertically, for some jobs they compete favorably with helicopters and do so at a lower cost. Amphibious aircraft can be much faster and have longer range than comparable helicopters, can achieve nearly the range of land based aircraft, as an airplane's wing is more efficient than a helicopter's lifting rotor.
This makes an amphibious aircraft, such as the Grumman Albatross and the Shin Meiwa US-2, useful for long-range air-sea rescue tasks. In addition, amphibious aircraft are useful as "Bushplanes" engaging in light transport in remote areas, where they are required to operate not only from airstrips, but from lakes and rivers. In the United Kingdom, traditionally a maritime nation, a large number of amphibians were built between the wars, starting from 1918 with the Vickers Viking and the early 1920s Supermarine Seagull and were used for exploration and military duties including search and rescue, artillery spotting and anti-submarine patrol; the most notable being the Short Sunderland which carried out many anti-submarine patrols over the North Atlantic on sorties of 8 – 12 hours duration. These evolved throughout the interwar period to culminate in the post World War 2 Supermarine Seagull, to have replaced the wartime Walrus and the Sea Otter but was overtaken by advances in helicopters. Starting in the mid-1920s and running into the late 1930s in the United States, Sikorsky produced an extensive family of amphibians that were used for exploration and as airliners around the globe, helping pioneer many overseas air routes where the larger flying boats could not go, helping to popularize amphibians in the US.
The Grumman Corporation, late-comers to the game, introduced a pair of light utility amphibious aircraft - the Goose and the Widgeon during the late 1930s for the civilian market. However, their military potential could not be ignored, many were ordered by the US Armed forces and their allies during World War II. Not coincidentally, the Consolidated Catalina was redeveloped from being a pure flying boat into an amphibian during the war. After the war, the United States military ordered hundreds of the Grumman Albatross and its variants for a variety of roles, like the pure flying boat was made obsolete by helicopters which could operate in sea conditions far beyond wh
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
Aspect ratio (aeronautics)
In aeronautics, the aspect ratio of a wing is the ratio of its span to its mean chord. It is equal to the square of the wingspan divided by the wing area. Thus, a long, narrow wing has a high aspect ratio, whereas a short, wide wing has a low aspect ratio. Aspect ratio and other features of the planform are used to predict the aerodynamic efficiency of a wing because the lift-to-drag ratio increases with aspect ratio, improving fuel economy in aircraft; the aspect ratio AR is the ratio of the square of the wingspan b to the projected wing area S, equal to the ratio of the wingspan b to the standard mean chord SMC: AR ≡ b 2 S = b SMC Roughly speaking, an airplane in flight can be imagined to affect a circular cylinder of air with a diameter equal to the wingspan. A large wingspan affects a large cylinder of air, a small wingspan affects a small cylinder of air. A small air cylinder must be pushed down with a greater power than a large cylinder in order to produce an equal upward force; this is because giving the same momentum change to a smaller mass of air requires giving it a greater velocity change, a much greater energy change because energy is proportional to the square of the velocity while momentum is only linearly proportional to the velocity.
The aft-leaning component of this change in velocity is proportional to the induced drag, the force needed to take up that power at that airspeed. The interaction between undisturbed air outside the cylinder of air, the downward-moving cylinder of air occurs at the wingtips and can be seen as wingtip vortices, it is important to keep in mind that this is a drastic oversimplification, an airplane wing affects a large area around itself. Although a long, narrow wing with a high aspect ratio has aerodynamic advantages like better lift-to-drag-ratio, there are several reasons why not all aircraft have high aspect wings: Structural: A long wing has higher bending stress for a given load than a short one and therefore requires higher structural-design specifications. Longer wings may have some torsion for a given load, in some applications this torsion is undesirable. Maneuverability: a low aspect-ratio wing will have a higher roll angular acceleration than one of high aspect ratio, because a high-aspect-ratio wing has a higher moment of inertia to overcome.
In a steady roll, the longer wing gives a higher roll moment because of the longer moment arm of the aileron. Low aspect ratio wings are used on fighter aircraft, not only for the higher roll rates, but for longer chord and thinner airfoils involved in supersonic flight. Parasitic drag: While high aspect wings create less induced drag, they have greater parasitic drag; this is. Due to the effects of Reynolds number, the value of the section drag coefficient is an inverse logarithmic function of the characteristic length of the surface, which means that if two wings of the same area are flying at equal speeds and equal angles of attack, the section drag coefficient is higher on the wing with the smaller chord. However, this variation is small when compared to the variation in induced drag with changing wingspan. For example, the section drag coefficient c d of a NACA 23012 airfoil is inversely proportional to chord length to the power 0.129: c d ∝ 1 0.129. A 20% increase in chord length would decrease the section drag coefficient by 2.38%.
Practicality: low aspect ratios have a greater useful internal volume, since the maximum thickness is greater, which can be used to house the fuel tanks, retractable landing gear and other systems. Airfield Size: Airfields and other ground equipment define a maximum wingspan, which cannot be exceeded, to generate enough lift at the given wingspan, the aircraft designer has to lower the aspect-ratio and increase the total wing area; this limits the Airbus A380 to 80m wide with an aspect ratio of 7.8, while the Boeing 787 or Airbus A350 have an aspect ratio of 9.5, influencing flight economy. Aircraft which approach or exceed the speed of sound sometimes incorporate variable-sweep wings; these wings a low aspect ratio at maximum sweep. In subsonic flow, steeply swept and narrow wings are inefficient compared to a high-aspect-ratio wing. However, as the flow becomes transonic and supersonic, the shock wave first generated along the wing's upper surface causes wave drag on the aircraft, this drag is proportional to the span of the wing.
Thus a long span, valuable at low speeds, causes excessive drag at supersonic speeds. By varying the sweep the wing can be optimised for the current flight speed; however the extra weight and complexity of a moveable wing mean that it is not used. The aspect ratios of birds' and bats' wings vary considerably. Birds that fly long distances or spend long periods