A Townend ring is a narrow-chord cowling ring fitted around the cylinders of an aircraft radial engine to reduce drag and improve cooling. The Townend ring was the invention of Dr. Hubert Townend of the British National Physical Laboratory in 1929. Patents were supported by Boulton & Paul Ltd in 1929. In the United States it was called a "drag ring", it caused a reduction in the drag of radial engines and was used in high-speed designs of 1930-1935 before the long-chord NACA cowling came into general use. Examples of aeroplanes with Townend rings were the Boeing P-26 Peashooter, Douglas O-38, Vickers Wellesley, the Westland Wallace and the Gloster Gauntlet. Early claims portrayed it as a superior design to the NACA cowling, but comparisons proved aircraft performance using a Townend ring was inferior to that of a NACA cowling when flying at airspeeds above 217 kn; the Spotters Glossary North, J D, "Engine Cowling: With Special Reference to the Air-cooled Engine", The Aircraft Engineer, XXIV No. 6: 133–137 North, J D, "Engine Cowling", The Aircraft Engineer, IX No. 2: 174a–174f "Engine Cowling", Flight, XXVI No. 7: 157–158, 15 February 1934
A nacelle is a housing, separate from the fuselage, that holds engines, fuel, or equipment on an aircraft. In some cases—for instance in the typical "Farman" type "pusher" aircraft, or the World War II-era P-38 Lightning—an aircraft's cockpit may be housed in a nacelle, which fills the function of a conventional fuselage; the covering is aerodynamically shaped. Edward Turner used the term to describe his styling device introduced in 1949 to tidy the area around the headlamp and instrument panel of his Triumph Speed Twin and Tiger 100 motorcycles; this styling device was much copied within the British industry thereafter, although Czech motorcycle manufacturer Česká Zbrojovka Strakonice was using it beforehand. Indeed, the Royal Enfield Bullet still retains the ` casquette', on its current models; the last Triumphs to sport nacelles were the 1966 models of the 6T Triumph Thunderbird 650, 5TA Triumph Speed Twin 500, 3TA Triumph Twenty One 350. The generator and gearbox "shell" – with rotator shaft – on a horizontal axis wind turbine.
Spacecraft in the Star Trek franchise feature warp nacelles. Like many aviation terms, the word comes from French, in this case from a word for a small boat
A motorcycle fairing is a shell placed over the frame of some motorcycles racing motorcycles and sport bikes, with the primary purpose to reduce air drag. The secondary functions are the protection of the rider from airborne hazards and wind-induced hypothermia and of the engine components in the case of an accident. A motorcycle windshield will always be integrated into the design of the fairing; the major benefit of a fairing on sport touring and touring motorcycles is a reduction in aerodynamic drag, which allows for reduced fuel consumption and permits higher speeds at lower engine rpm, which in turn increases engine life. A motorcycle may have a rear fairing, a belly fairing, or any combination of these. Alternatively, a single fairing may or enclose the entire motorcycle, may enclose the rider; the importance of streamlining was known early in the 20th century, some streamlining was seen on racing motorcycles as early as the 1920s. Although motorcycles have a much higher power-to-weight ratio than cars, bikes – and the rider – are much less streamlined and the effects of aerodynamic drag on motorcycles are significant.
Any reduction in a motorcycle's drag coefficient pays dividends in improved performance. The term fairing came into use in aircraft aerodynamics with regard to smoothing airflow over a juncture of components where airflow was disrupted. Early streamlining was unsuccessful resulting in instability. Handlebar fairings, such as those on Harley-Davidson Tourers, sometimes upset the balance of a motorcycle, inducing wobble; the fairings were cowlings put around the front of the bike, increasing its frontal area. They became an integral part of the design. Modern fairings increase the frontal area at most by 5% compared to a naked machine. Fairings may carry headlights and other items. If the fairing is mounted on the frame, placing other equipment on the fairing reduces the weight and rotational inertia of the steering assembly, improving the handling; the BMW R100RS, produced from 1976 to 1984, was the first mass-market sport touring motorcycle to be offered with a full fairing as standard, marked the beginning of wider adoption of fairings on sports and touring types of motorcycles.
The integrated design included a development of the frame-mounted tail fairing at the rear of the removable dual seat accessing a storage compartment used on the BMW R90S from 1973 being the first example of a factory-fitted head fairing. A single piece, streamlined shell covering the front half of a motorcycle resembling the nose of an aircraft, sometimes referred to as torpedo fairing, it reduced the frontal drag, but it was banned by Fédération Internationale de Motocyclisme from racing in 1958, because it was thought that the frontal point of wind pressure made them unstable with small amounts of yaw. Other reasons cited for the ban were to ensure adequate steering stability in crosswinds. FIM regulations forbid streamlining beyond the wheel spindles and require the rider's arms and legs to be visible from the side. However, Peter Williams was permitted to give his 1973/74 JPS Norton a Peel-type fairing incorporating handlebar blisters which helped to reduce the drag coefficient to 0.39.
This was called so because, in early models, the front wheel mudguard streamlined with the rising windshield part of the fairing resembled the dolphin's snout from the side view. Further developments on this design became the norm. A full fairing is a large front-mounted fairing, should not be confused with cabin motorcycle or streamliner motorcycle fairings which or enclose the entire motorcycle. Full fairings cover both upper and lower portions of the motorcycle, as distinct from a half fairing, which only has an upper section, leaves the lower half of the motorcycle exposed; the fairing on a race or sport bike is meant as an aerodynamic aid, so the windscreen is looked through. If the rider is sitting up at speed he will be buffeted by his rapid progress through the air and act as a parachute, slowing the bike, while if the rider lies flat on the tank behind the windscreen he generates much less aerodynamic drag; the high windscreen and handlebar width of a touring fairing protect the upright rider from the worst of this, the windscreen is functional.
Full fairings can provide protection to the engine and chassis in the event of a crash where the fairings, rather than the engine covers and/or frame, slide on the road. Half fairings feature a windscreen and extend below the handlebars as far down as the sides of the cylinder block, but do not cover the sides of the crankcase or gearbox. Aftermarket kits –'lowers' – are available to extend some half fairings into full fairings. Due to the popularity of these kits, some motorcycle manufacturers have started to supply their own full fairing conversion kits and offer their half faired models new with a full factory-fitted kit. A windscreen and minimal fairing extending around the headlamp fixed to the triple clamp. Called a café fairing or bikini fairing, it stops well below the level of the rider's head, relying on air deflection to protect the rider's head and chest from the slipstream. Whereas the other types of fairing are all fixed to the main chassis of the bike and don't move, the handlebar fairing complete with screen is like an expanded/extended nacelle and is attached only to the forks/yokes, encompassing the headlight/s and clocks and varying amounts of the handlebars, it moves with them as the bars are turned and indicators move like on a naked bike instead of being fixed straight ahe
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
An engine or motor is a machine designed to convert one form of energy into mechanical energy. Heat engines, like the internal combustion engine, burn a fuel to create heat, used to do work. Electric motors convert electrical energy into mechanical motion, pneumatic motors use compressed air, clockwork motors in wind-up toys use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create forces and motion; the word engine derives from Old French engin, from the Latin ingenium–the root of the word ingenious. Pre-industrial weapons of war, such as catapults and battering rams, were called siege engines, knowledge of how to construct them was treated as a military secret; the word gin, as in cotton gin, is short for engine. Most mechanical devices invented during the industrial revolution were described as engines—the steam engine being a notable example. However, the original steam engines, such as those by Thomas Savery, were not mechanical engines but pumps.
In this manner, a fire engine in its original form was a water pump, with the engine being transported to the fire by horses. In modern usage, the term engine describes devices, like steam engines and internal combustion engines, that burn or otherwise consume fuel to perform mechanical work by exerting a torque or linear force. Devices converting heat energy into motion are referred to as engines. Examples of engines which exert a torque include the familiar automobile gasoline and diesel engines, as well as turboshafts. Examples of engines which produce thrust include rockets; when the internal combustion engine was invented, the term motor was used to distinguish it from the steam engine—which was in wide use at the time, powering locomotives and other vehicles such as steam rollers. The term motor derives from the Latin verb moto which means to maintain motion, thus a motor is a device. Motor and engine are interchangeable in standard English. In some engineering jargons, the two words have different meanings, in which engine is a device that burns or otherwise consumes fuel, changing its chemical composition, a motor is a device driven by electricity, air, or hydraulic pressure, which does not change the chemical composition of its energy source.
However, rocketry uses the term rocket motor though they consume fuel. A heat engine may serve as a prime mover—a component that transforms the flow or changes in pressure of a fluid into mechanical energy. An automobile powered by an internal combustion engine may make use of various motors and pumps, but all such devices derive their power from the engine. Another way of looking at it is that a motor receives power from an external source, converts it into mechanical energy, while an engine creates power from pressure. Simple machines, such as the club and oar, are prehistoric. More complex engines using human power, animal power, water power, wind power and steam power date back to antiquity. Human power was focused by the use of simple engines, such as the capstan, windlass or treadmill, with ropes and block and tackle arrangements; these were used in cranes and aboard ships in Ancient Greece, as well as in mines, water pumps and siege engines in Ancient Rome. The writers of those times, including Vitruvius and Pliny the Elder, treat these engines as commonplace, so their invention may be more ancient.
By the 1st century AD, cattle and horses were used in mills, driving machines similar to those powered by humans in earlier times. According to Strabo, a water powered mill was built in Kaberia of the kingdom of Mithridates during the 1st century BC. Use of water wheels in mills spread throughout the Roman Empire over the next few centuries; some were quite complex, with aqueducts and sluices to maintain and channel the water, along with systems of gears, or toothed-wheels made of wood and metal to regulate the speed of rotation. More sophisticated small devices, such as the Antikythera Mechanism used complex trains of gears and dials to act as calendars or predict astronomical events. In a poem by Ausonius in the 4th century AD, he mentions a stone-cutting saw powered by water. Hero of Alexandria is credited with many such wind and steam powered machines in the 1st century AD, including the Aeolipile and the vending machine these machines were associated with worship, such as animated altars and automated temple doors.
Medieval Muslim engineers employed gears in mills and water-raising machines, used dams as a source of water power to provide additional power to watermills and water-raising machines. In the medieval Islamic world, such advances made it possible to mechanize many industrial tasks carried out by manual labour. In 1206, al-Jazari employed a crank-conrod system for two of his water-raising machines. A rudimentary steam turbine device was described by Taqi al-Din in 1551 and by Giovanni Branca in 1629. In the 13th century, the solid rocket motor was invented in China. Driven by gunpowder, this simplest form of internal combustion engine was unable to deliver sustained power, but was useful for propelling weaponry at high speeds towards enemies in battle and for fireworks. After invention, this innovation spread throughout Europe; the Watt steam engine was the first type of steam engine to make use of steam at a pressure just above atmospheric to drive the piston he
A bonnet/hood scoop, sometimes called bonnet airdam/air dam, is an upraised component on the hood of a motor vehicle that either allows a flow of air to directly enter the engine compartment, or appears to do so. It is closed on all other sides, its main function is to allow a direct flow of air to the engine, hence the need for it to be upraised so as to channel air to the engine compartment. It may be closed, thus purely decorative, or serve to enhance performance in several possible ways. In most modern vehicles, internal combustion engines "breathe" under-hood air or air ducted from under the front bumper through plastic and rubber tubing; the high operating temperatures in the engine compartment result in intake air, 28°C or warmer than the ambient temperature, less dense. A hood scoop can provide the engine with denser outside air, increasing power. At higher road speeds, a properly designed hood scoop known as ram-air intake can increase the speed and pressure with which air enters the engine's intake, creating a resonance supercharging effect.
Such effects are only felt at high speeds, making ram air useful for racing, not street performance. Pontiac used the trade name Ram Air to describe its engines equipped with functional scoops. Despite the name, most of these systems only provided cool air, with little or no supercharging effect; some engines with turbochargers or superchargers are equipped with top mounted intercoolers to reduce the temperature and increase the density of the high-pressure air produced by the compressor. Channeling outside air to the intercooler increases its effectiveness, providing a significant improvement in power. To be effective, a functional scoop must be located at a high-pressure area on the hood. For that reason, some functional scoops are located at the rear of the hood, near the vehicle's cowl, where the curvature of the windshield creates such a high-pressure zone, may be placed so that their opening faces the windshield; the scoop will be most effective if it is either mounted high enough to clear the boundary layer or if it is a NACA duct, mounted below the surface and designed to draw the faster moving air outside of the boundary layer into the duct.
A shallow scoop, not a NACA duct may not admit a useful amount of air if it is open. Under the hood, an effective scoop must funnel air into the engine's intake in as short and direct a path as possible, preferably through a tube or channel, insulated against underhood heat. A scoop may be part of the hood, or may be part of the engine's air cleaner assembly, protruding through a hole cut into the bonnet; such a scoop is called a shaker hood, because the scoop vibrates noticeably when the engine is running under power. A hood scoop/top mounted intercooler can be beneficial during an off-road rally race. Rocks and debris can be kicked up by a car in front, those objects can damage a front-mounted intercooler. However, rock guards can be installed to prevent this problem
The NACA cowling is a type of aerodynamic fairing used to streamline radial engines for use on airplanes and developed by the National Advisory Committee for Aeronautics in 1927. It was a major advance in aerodynamic drag reduction, paid for its development and installation costs many times over due to the gains in fuel efficiency that it enabled; the NACA cowling enhanced speed through drag reduction while delivering improved engine cooling. The idea that the NACA cowling produced thrust through the Meredith effect is fallacious—although in theory the expansion of the air as it was heated by the engine could create some thrust by exiting at high speed, in practice this required a cowling designed and shaped to achieve the high speed exit of air required, in any case, at 1930s airspeeds, the effect is negligible; the cowling constitutes a circular airfoil, in contrast to the planar airfoil of wings. It directs cool air to flow through the engine where it is routed across the engine's hottest parts, that is, the cylinders and heads.
Furthermore, turbulence after the air passes the free-standing cylinders is reduced. The sum of all these effects reduces drag by as much as 60 percent; the test conclusions resulted in every radial-engined aircraft being equipped with this cowling, starting in 1932. The test aircraft, a Curtiss AT-5A Hawk biplane, featuring a Wright Whirlwind J-5 radial engine, reached an airspeed of 137 miles per hour equipped with the NACA cowling compared to 118 miles per hour without it. NACA duct Townend ring Aeronautic exhibit in Smithsonian Institution, Washington, D. C. Abstract of NACA TN 301 report and.pdf file Archive of NACA reports 1917-1958