Aircraft fabric covering
Aircraft fabric covering is a term used for both the material used and the process of covering aircraft open structures. It is used for reinforcing closed plywood structures, the de Havilland Mosquito being an example of this technique, on the pioneering all-wood monocoque fuselages of certain World War I German aircraft like the LFG Roland C. II, in its wrapped Wickelrumpf plywood strip and fabric covering. Early aircraft used organic materials such as cotton and cellulose nitrate dope, modern fabric-covered designs use synthetic materials such as Dacron and butyrate dope for adhesive, this method is used in the restoration of older types that were covered using traditional methods; the purposes of the fabric covering of an aircraft are: To provide a light airproof skin for lifting and control surfaces. To provide structural strength to otherwise weak structures. To cover other non-lifting parts of an aircraft to reduce drag, sometimes forming a fairing. To protect the structure from the elements.
Pioneering aviators such as George Cayley and Otto Lilienthal used cotton-covered flying surfaces for their manned glider designs. The Wright brothers used cotton to cover their Wright Flyer. Other early aircraft used a variety of fabrics and linen being used; some early aircraft, such as A. V. Roe's first machines used paper as a covering material; until the development of cellulose based dope in 1911 a variety of methods of finishing the fabric were used. The most popular was the use of rubberised fabrics such as those manufactured by the "Continental" company. Other methods included the use of sago starch; the advent of cellulose dopes such as "Emaillite" was a major step forward in the production of practical aircraft, producing a surface that remained taut The air battles of World War I were fought with fabric-covered biplanes that were vulnerable to fire due to the flammable properties of the cloth covering and nitrocellulose dope. National insignia painted on the fabric were cut from downed aircraft and used as war trophies.
The German aircraft designer Hugo Junkers is considered one of the pioneers of metal aircraft. The flammable mixture of fabric and hydrogen gas was a factor in the demise of the Hindenburg airship. By the World War II era many aircraft designs were using metal monocoque structures due to their higher operating airspeeds, although fabric-covered control surfaces were still used on early mark Spitfires and other types; the Hawker Hurricane had a fabric covered fuselage, they had fabric covered wings until 1939. Many transports and trainers still used fabric, although the flammable nitrate dope was replaced with butyrate dope instead, which burns less readily; the Mosquito is an example of a fabric-covered plywood aircraft. The Vickers Wellington used fabric over a geodesic airframe which offered good combat damage resistance. An interesting case of ingenuity under wartime adversity was the Colditz Cock glider; this homebuilt aircraft, intended as a means of escape, employed prison bedding as its covering material.
With the development of modern synthetic materials following World War II, cotton fabrics were replaced in civil aircraft applications by polyethylene terephthalate, known by the trade-name Dacron or Ceconite. This new fabric could be glued to the airframe instead of sewn and heat-shrunk to fit. Grade A cotton would last six to seven years when the aircraft was stored outside, whereas Ceconite, which does not rot like cotton, can last over 20 years. Early attempts to use these modern fabrics with butyrate dope proved that the dope did not adhere at all and peeled off in sheets. Nitrate dope was resurrected as the initial system of choice instead, although it was supplanted by new materials too. One fabric system, developed by Ray Stits in the USA and FAA-approved in 1965, is marketed under the brand name Poly-Fiber; this uses three weights of Dacron fabric sold as by the brand name Ceconite, plus fabric glue for attaching to the airframe, fabric preparation sealer resin and paint. This system instead uses vinyl-based chemicals.
Ceconite 101 is a certified 3.5 oz/yd ² fabric. There is an uncertified light Ceconite of 1.87 oz/yd² intended for ultralight aircraft. This method requires physical attachment of the fabric to the airframe in the form of rib-stitching, rivets or capstrips, which are usually covered with fabric tapes. In addition to Poly-Fiber, a number of other companies produce covering processes for certified and homebuilt aircraft. Randolph Products and Certified Coatings Products both make butyrate and nitrate-based dopes for use with Dacron fabric. Superflite and Air-Tech systems use a similar fabric, but the finishes are polyurethane-based products with flex agents added; these finishes produce high gloss results. Falconar Avia of Edmonton, Canada developed the Hipec system in 1964 for use with Dacron fabric, it uses a special Hipec Sun Barrier that adheres fabric directly to the aircraft structure in one step, eliminating the need for the riveting, rib-stitching and taping used in traditional fabric processes.
The final paint is applied over the sun barrier to complete the process. Newer systems were developed and distributed by Stewart Systems of Cashmere and Blue River; these two systems use the same certified dacron materials as other systems, but do not use high volatile organic compounds, using water as a carrier i
In a fixed-wing aircraft, the spar is the main structural member of the wing, running spanwise at right angles to the fuselage. The spar carries the weight of the wings while on the ground. Other structural and forming members such as ribs may be attached to the spar or spars, with stressed skin construction sharing the loads where it is used. There may be more than one spar in a none at all. However, where a single spar carries the majority of the forces on it, it is known as the main spar. Spars are used in other aircraft aerofoil surfaces such as the tailplane and fin and serve a similar function, although the loads transmitted may be different from those of a wing spar; the wing spar provides the majority of the weight support and dynamic load integrity of cantilever monoplanes coupled with the strength of the wing'D' box itself. Together, these two structural components collectively provide the wing rigidity needed to enable the aircraft to fly safely. Biplanes employing flying wires have much of the flight loads transmitted through the wires and interplane struts enabling smaller section and thus lighter spars to be used at the cost of increasing drag.
Some of the forces acting on a wing spar are: Upward bending loads resulting from the wing lift force that supports the fuselage in flight. These forces are offset by carrying fuel in the wings or employing wing-tip-mounted fuel tanks. Downward bending loads while stationary on the ground due to the weight of the structure, fuel carried in the wings, wing-mounted engines if used. Drag loads dependent on airspeed and inertia. Rolling inertia loads. Chordwise twisting loads due to aerodynamic effects at high airspeeds associated with washout, the use of ailerons resulting in control reversal. Further twisting loads are induced by changes of thrust settings to underwing-mounted engines; the "D" box construction is beneficial to reduce wing twisting. Many of these loads are reversed abruptly in flight with an aircraft such as the Extra 300 when performing extreme aerobatic manoeuvers. Early aircraft used spars carved from solid spruce or ash. Several different wooden spar types have been used and experimented with such as spars that are box-section in form.
Wooden spars are still being used in light aircraft such as its relatives. A disadvantage of the wooden spar is the deteriorating effect that atmospheric conditions, both dry and wet, biological threats such as wood-boring insect infestation and fungal attack can have on the component. Wood wing spars of multipiece construction consist of upper and lower members, called spar caps, vertical sheet wood members, known as shear webs or more webs, that span the distance between the spar caps. In modern times, "homebuilt replica aircraft" such as the replica Spitfires use laminated wooden spars; these spars are laminated from spruce or douglas fir. A number of enthusiasts build "replica" Spitfires that will fly using a variety of engines relative to the size of the aircraft. A typical metal spar in a general aviation aircraft consists of a sheet aluminium spar web, with "L" or "T" -shaped spar caps being welded or riveted to the top and bottom of the sheet to prevent buckling under applied loads. Larger aircraft using this method of spar construction may have the spar caps sealed to provide integral fuel tanks.
Fatigue of metal wing spars has been an identified causal factor in aviation accidents in older aircraft as was the case with Chalk's Ocean Airways Flight 101. The German Junkers J. I armoured fuselage ground-attack sesquiplane of 1917 used a Hugo Junkers-designed multi-tube network of several tubular wing spars, placed just under the corrugated duralumin wing covering and with each tubular spar connected to the adjacent one with a space frame of triangulated duralumin strips — in the manner of a Warren truss layout — riveted onto the spars, resulting in a substantial increase in structural strength at a time when most other aircraft designs were built completely with wood-structure wings; the Junkers all-metal corrugated-covered wing / multiple tubular wing spar design format was emulated after World War I by American aviation designer William Stout for his 1920s-era Ford Trimotor airliner series, by Russian aerospace designer Andrei Tupolev for such aircraft as his Tupolev ANT-2 of 1922, upwards in size to the then-gigantic Maksim Gorki of 1934.
A design aspect of the Supermarine Spitfire wing that contributed to its success was an innovative spar boom design, made up of five square concentric tubes that fitted into each other. Two of these booms were linked together by an alloy web, creating a lightweight and strong main spar. A version of this spar construction method is used in the BD-5, designed and constructed by Jim Bede in the early 1970s; the spar used in the BD-5 and subsequent BD projects was aluminium tube of 2 inches in diameter, joined at the wing root with a much larger internal diameter aluminium tube to provide the wing structural integrity. In aircraft such as the Vickers Wellington, a geodesic wing spar structure was employed, which had the advantages of being lightweight and able to withstand heavy battle damage with only partial loss of strength. Many modern aircraft use carbon fibre and Kevlar in their construction, ranging in size from large airliners to small h
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, to improve appearance. On aircraft, fairings are found on: Belly fairing Also called a "ventral fairing", it is located on the underside of the fuselage between the main wings, it can cover additional cargo storage or fuel tanks. Cockpit fairing Also called a "cockpit pod", it protects the crew on ultralight trikes. Made from fiberglass, it may incorporate a windshield. Elevator and horizontal stabilizer tips Elevator and stabilizer tips fairings smooth out airflow at the tips. Engine cowlings Engine cowlings reduce parasitic drag by reducing the surface area, having a smooth surface and thus leading to laminar flow, having a nose cone shape, which prevents early flow separation; the inlet and the nozzle in combination lead to an isotropic speed reduction around the cooling fins and due to the speed-squared law to a reduction in cooling drag.
Fin and rudder tip fairings Fin and rudder tip fairings reduce drag at low angles of attack, but reduce the stall angle, so the fairing of control surface tips depends on the application. Fillets Fillets smooth the airflow at the junction between two components like the fuselage and wing, or the fuselage and fin. Fixed landing gear junctions Landing gear fairings reduce drag at these junctions. Flap track fairings Most jet airliners have a cruising speed between Mach 0.8 and 0.85. For aircraft operating in the transonic regime, wave drag can be minimized by having a cross-sectional area which changes smoothly along the length of the aircraft; this is known as the area rule. On subsonic aircraft such as jet airliners, this can be achieved by the addition of smooth pods on the trailing edges of the wings; these pods are known as anti-shock bodies, Küchemann Carrots, or flap track fairings, as they enclose the mechanisms for deploying the wing flaps. Spinner To cover and streamline the propeller hub.
Strut-to-wing and strut-to-fuselage junctions Strut end fairings reduce drag at these junctions. Tail cones Tail cones reduce the form drag of the fuselage, by recovering the pressure behind it. For the design speed they add no friction drag. Wing root Wing roots are faired to reduce interference drag between the wing and the fuselage. On top and below the wing it consists of small rounded edge to reduce the surface and such friction drag. At the leading and trailing edge it consists of much larger taper and smooths out the pressure differences: High pressure at the leading and trailing edge, low pressure on top of the wing and around the fuselage. Wing tips Wing tips are formed as complex shapes to reduce vortex generation and so drag at low speed. Wheels on fixed gear aircraft Wheel fairings are called "wheel pants", "speed fairings" or, in the United Kingdom, "wheel spats"; these fairings are a trade-off in advantages, as they increase the frontal and surface area, but provide a smooth surface, a faired nose and tail for laminar flow, in an attempt to reduce the turbulence created by the round wheel and its associated gear legs and brakes.
They have the important function of preventing mud and stones from being thrown upwards against the wings or fuselage, or into the propeller on a pusher craft. Bicycle fairing Motorcycle fairing Payload fairing
The Hanriot HD.14 was a military trainer aircraft produced in large numbers in France during the 1920s. It was a two-bay biplane with unstaggered wings of equal span; the pilot and instructor sat in tandem, open cockpits, the fuselage was braced to the lower wing with short struts. The main units of the fixed tailskid undercarriage were divided, each unit carrying two wheels, early production examples had anti-noseover skids projecting forwards as well. In 1922, production shifted to a much improved version, known as the HD.14ter or HD.14/23. This featured a smaller wing area, revised tail fin and cabane struts, fuselage cross-section; the landing gear track was narrowed in order to facilitate the aircraft's loading onto the standard army trailer of the day. Prolific, it was licence-produced by Mitsubishi in Japan, where another 145 were built, by the CWL and Samolot in Poland, where 125 and 120 were built. HD.14 - Original production version. Known as the HD.14 EP2. HD.14ter - Improved version of 1922.
Known as the HD.14/23. HD.14S - Air ambulance version HD.141 - Remanufactured ex-Army HD.14s for French aeroclub use H.410 - A 1928 development with Lorraine 5-cyl radial and revised undercarriage. H.411 - development of the HD.410 LH.412 - development of the HD.410 H.28 - Polish designation of license-produced modified HD.14/23 Ki 1 - Japanese Army designation of the Hanriot HD.14 BelgiumBelgian Air Force FranceAéronautique Militaire JapanImperial Japanese Army Air Force EstoniaEstonian Air Force PolandPolish Air Force Soviet UnionSoviet Air Force BulgariaBulgarian Air Force Mexico Spain General characteristics Crew: Two and instructor Length: 7.26 m Wingspan: 10.87 m Height: 3.00 m Wing area: 34.5 m2 Gross weight: 810 kg Powerplant: 1 × Le Rhône 9, 60 kW Performance Maximum speed: 110 km/h Range: 180 km Service ceiling: 4,000 m Armament Related lists List of Interwar military aircraft Taylor, Michael J. H.. Jane's Encyclopedia of Aviation. London: Studio Editions. P. 470. World Aircraft Information Files.
London: Bright Star Publishing. Pp. File 896 Sheet 11. Morgała, Andrzej. Samoloty wojskowe w Polsce 1924-1939. Warsaw: Bellona. ISBN 83-11-09319-9
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, is called a "star engine" in some languages; the radial configuration was used for aircraft engines before gas turbine engines became predominant. Since the axes of the cylinders are coplanar, the connecting rods cannot all be directly attached to the crankshaft unless mechanically complex forked connecting rods are used, none of which have been successful. Instead, the pistons are connected to the crankshaft with a master-and-articulating-rod assembly. One piston, the uppermost one in the animation, has a master rod with a direct attachment to the crankshaft; the remaining pistons pin their connecting rods' attachments to rings around the edge of the master rod. Extra "rows" of radial cylinders can be added in order to increase the capacity of the engine without adding to its diameter.
Four-stroke radials have an odd number of cylinders per row, so that a consistent every-other-piston firing order can be maintained, providing smooth operation. For example, on a five-cylinder engine the firing order is 1, 3, 5, 2, 4, back to cylinder 1. Moreover, this always leaves a one-piston gap between the piston on its combustion stroke and the piston on compression; the active stroke directly helps compress the next cylinder to fire. If an number of cylinders were used, an timed firing cycle would not be feasible; the prototype radial Zoche aero-diesels have an number of cylinders, either four or eight. The radial engine uses fewer cam lobes than other types; as with most four-strokes, the crankshaft takes two revolutions to complete the four strokes of each piston. The camshaft ring is geared to spin slower and in the opposite direction to the crankshaft; the cam lobes exhaust. For example, four cam lobes serve all five cylinders, whereas 10 would be required for a typical inline engine with the same number of cylinders and valves.
Most radial engines use overhead poppet valves driven by pushrods and lifters on a cam plate, concentric with the crankshaft, with a few smaller radials, like the Kinner B-5 and Russian Shvetsov M-11, using individual camshafts within the crankcase for each cylinder. A few engines use sleeve valves such as the 14-cylinder Bristol Hercules and the 18-cylinder Bristol Centaurus, which are quieter and smoother running but require much tighter manufacturing tolerances. C. M. Manly constructed a water-cooled five-cylinder radial engine in 1901, a conversion of one of Stephen Balzer's rotary engines, for Langley's Aerodrome aircraft. Manly's engine produced 52 hp at 950 rpm. In 1903–1904 Jacob Ellehammer used his experience constructing motorcycles to build the world's first air-cooled radial engine, a three-cylinder engine which he used as the basis for a more powerful five-cylinder model in 1907; this was made a number of short free-flight hops. Another early radial engine was the three-cylinder Anzani built as a W3 "fan" configuration, one of which powered Louis Blériot's Blériot XI across the English Channel.
Before 1914, Alessandro Anzani had developed radial engines ranging from 3 cylinders — early enough to have been used on a few French-built examples of the famous Blériot XI from the original Blériot factory — to a massive 20-cylinder engine of 200 hp, with its cylinders arranged in four rows of five cylinders apiece. Most radial engines are air-cooled, but one of the most successful of the early radial engines was the Salmson 9Z series of nine-cylinder water-cooled radial engines that were produced in large numbers during the First World War. Georges Canton and Pierre Unné patented the original engine design in 1909, offering it to the Salmson company. From 1909 to 1919 the radial engine was overshadowed by its close relative, the rotary engine, which differed from the so-called "stationary" radial in that the crankcase and cylinders revolved with the propeller, it was similar in concept to the radial, the main difference being that the propeller was bolted to the engine, the crankshaft to the airframe.
The problem of the cooling of the cylinders, a major factor with the early "stationary" radials, was alleviated by the engine generating its own cooling airflow. In World War I many French and other Allied aircraft flew with Gnome, Le Rhône, Bentley rotary engines, the ultimate examples of which reached 250 hp although none of those over 160 hp were successful. By 1917 rotary engine development was lagging behind new inline and V-type engines, which by 1918 were producing as much as 400 hp, were powering all of the new French and British combat aircraft. Most German aircraft of the time used water-cooled inline 6-cylinder engines. Motorenfabrik Oberursel made licensed copies of the Gnome and Le Rhône rotary powerplants, Siemens-Halske built their own designs, including the Siemens-Halske Sh. III eleven-cylinder rotary engine, unusual for the period in being geared through a bevel geartrain in the rear end of the crankcase without the crankshaft being mounted to the aircraft's airframe, so that the engine's internal working components (fully in
A fighter aircraft is a military aircraft designed for air-to-air combat against other aircraft, as opposed to bombers and attack aircraft, whose main mission is to attack ground targets. The hallmarks of a fighter are its speed and small size relative to other combat aircraft. Many fighters have secondary ground-attack capabilities, some are designed as dual-purpose fighter-bombers; this may be for national security reasons, for advertising purposes, or other reasons. A fighter's main purpose is to establish air superiority over a battlefield. Since World War I, achieving and maintaining air superiority has been considered essential for victory in conventional warfare; the success or failure of a belligerent's efforts to gain air superiority hinges on several factors including the skill of its pilots, the tactical soundness of its doctrine for deploying its fighters, the numbers and performance of those fighters. Because of the importance of air superiority, since the early days of aerial combat armed forces have competed to develop technologically superior fighters and to deploy these fighters in greater numbers, fielding a viable fighter fleet consumes a substantial proportion of the defense budgets of modern armed forces.
The word "fighter" did not become the official English-language term for such aircraft until after World War I. In the British Royal Flying Corps and Royal Air Force these aircraft were referred to as "scouts" into the early 1920s; the U. S. Army called their fighters "pursuit" aircraft from 1916 until the late 1940s. In most languages a fighter aircraft is known as hunting aircraft. Exceptions include Russian, where a fighter is an "истребитель", meaning "exterminator", Hebrew where it is "matose krav"; as a part of military nomenclature, a letter is assigned to various types of aircraft to indicate their use, along with a number to indicate the specific aircraft. The letters used to designate a fighter differ in various countries – in the English-speaking world, "F" is now used to indicate a fighter, though when the pursuit designation was used in the US, they were "P" types. In Russia "I" was used, while the French continue to use "C". Although the term "fighter" specifies aircraft designed to shoot down other aircraft, such designs are also useful as multirole fighter-bombers, strike fighters, sometimes lighter, fighter-sized tactical ground-attack aircraft.
This has always been the case, for instance the Sopwith Camel and other "fighting scouts" of World War I performed a great deal of ground-attack work. In World War II, the USAAF and RAF favored fighters over dedicated light bombers or dive bombers, types such as the Republic P-47 Thunderbolt and Hawker Hurricane that were no longer competitive as aerial combat fighters were relegated to ground attack. Several aircraft, such as the F-111 and F-117, have received fighter designations though they had no fighter capability due to political or other reasons; the F-111B variant was intended for a fighter role with the U. S. Navy, but it was cancelled; this blurring follows the use of fighters from their earliest days for "attack" or "strike" operations against ground targets by means of strafing or dropping small bombs and incendiaries. Versatile multirole fighter-bombers such as the McDonnell Douglas F/A-18 Hornet are a less expensive option than having a range of specialized aircraft types; some of the most expensive fighters such as the US Grumman F-14 Tomcat, McDonnell Douglas F-15 Eagle, Lockheed Martin F-22 Raptor and Russian Sukhoi Su-27 were employed as all-weather interceptors as well as air superiority fighter aircraft, while developing air-to-ground roles late in their careers.
An interceptor is an aircraft intended to target bombers and so trades maneuverability for climb rate. Fighters were developed in World War I to deny enemy aircraft and dirigibles the ability to gather information by reconnaissance over the battlefield. Early fighters were small and armed by standards, most were biplanes built with a wooden frame covered with fabric, a maximum airspeed of about 100 mph; as control of the airspace over armies became important, all of the major powers developed fighters to support their military operations. Between the wars, wood was replaced in part or whole by metal tubing, aluminium stressed skin structures began to predominate. On 15 August 1914, Miodrag Tomić encountered an enemy plane while conducting a reconnaissance flight over Austria-Hungary; the Austro-Hungarian aviator waved at Tomić, who waved back. The enemy pilot took a revolver and began shooting at Tomić's plane. Tomić fired back, he swerved away from the Austro-Hungarian plane and the two aircraft parted ways.
It was considered the first exchange of fire between aircraft in history. Within weeks, all Serbian and Austro-Hungarian aircraft were armed; the Serbians equipped their planes with 8-millimetre Schwarzlose MG M.07/12 machine guns, six 100-round boxes of ammunition and several bombs. By World War II, most fighters were all-metal monoplanes armed with batteries of machine guns or cannons and some were capable of speeds approaching 400 mph. Most fighters up to this point had one engine.
Hanriot 1909 monoplane
The Hanriot 1909 monoplane was an early French aircraft constructed by Rene Hanriot, a successful automobile racer. The Hanriot 1909 monoplane had an uncovered rectangular-section wire-braced wooden fuselage with cambered parallel-chord wings; the main undercarriage consisted of a pair of skids which carried a pair of independently sprung wheels mounted on a steel cross tube, the skids being carried on two pairs of struts which converged inwards, the aft pair being continued above the fuselage to form an inverted V cabane to which the wing bracing and warping wires were attached. The front struts terminated at the engine bearers, which were midway between the upper and lower longerons. Tail surfaces consisted of a tailplane and elevator mounted on top of the fuselage and a fixed fin mounted under the fuselage with the attached rudder underneath the horizontal tail surfaces; the aircraft was controlled with a pair of handwheels on either side of the cockpit operating wing warping and elevator, foot-pedals operating the rudder.
Two examples were shown at the Paris Aero Salon in October 1909 in an unfinished condition. One was powered by a (37 kW Buchet engine and the other by a 25 kW Hanriot engine. One was flown at Rheims in December 1909, first by Eugene Ruchonnet and afterwards by Rene Hanriot followed by his son Marcel aged 15; the two aircraft displayed at the 1909 Paris exhibition were the only examples manufactured. Flight refers to them as the Hanriot I and Hanriot II. By the time that they were first flown Hanriot and Ruchonnet had started work on a series of related monoplane designs, which were exhibited at the Salon d'Automobiles, d'Aeronautique, du Cycles et des Sports, which opened in Brussels on 16 January 1910. Data from General characteristics Crew: 1 Length: 9.4 m Wingspan: 9.16 m Wing area: 24 m2 Empty weight: 400 kg Powerplant: 1 × Buchet 6-cylinder inline piston engine, water cooled, 37 kW Opdycke, French Aeroplanes before the Great War. Atglen, PA: Schiffer, 1999 ISBN 0-7643-0752-5