The Bede BD-5 Micro is a series of small, single-seat homebuilt aircraft created in the late 1960s by US aircraft designer Jim Bede and introduced to the market in kit form by the now-defunct Bede Aircraft Corporation in the early 1970s. The BD-5 has a small, streamlined fuselage holding its semi-reclined pilot under a large canopy, with the engine installed in a compartment in the middle of the fuselage, a propeller-driving engine - or jet engine in the BD-5J variant - mounted to the rear of the cockpit; the combination of fighter-like looks and low cost led to the BD-5 selling over 5,000 kits or plans, with 12,000 orders being taken for a proposed factory-built, FAA-certified version. However, few of the kit versions were completed due to the company's bankruptcy in the mid-1970s, none of the factory built "D" models were produced, as a result of the failure to find a reliable engine for the design. In total, only a few hundred BD-5 kits were completed, although many of these are still airworthy today.
The BD-5J version holds the record for the world's lightest single-engine jet aircraft, weighing only 358.8 lb. Development of the "Micro" dates back as early as 1967, when Jim Bede was inspired by the Schleicher ASW 15. Along with his chief designer, Paul Griffin, they make preliminary designs of what would become the BD-5. At the time, Bede was working on the Bede BD-4. Serious work on the Micro started in 1970, with construction of the prototype starting in earnest late that year. While the BD-4 was conventional looking, the Micro was a radical design, it is an small one-seat design that looked more like a jet fighter than a typical general aviation aircraft, with the pilot sitting in a semi-reclined position under a large fighter-like plexiglas canopy only inches above the pilot's head. Behind the cockpit was a compartment housing a two-cylinder air-cooled 40 hp piston engine driving a pusher propeller. For improved performance the aircraft featured both a V-tail and retractable landing gear in order to reduce drag.
Calculated drag was so low that split flaps and spoilers were added to the wing in order to improve deceleration for landing. This was the first application of spoilers on a light aircraft; the low drag implied excellent performance. With the shorter "A" wing, 14 ft 3 in, it would be aerobatic and have a higher top speed. Builders could optionally buy both wings. In addition to being easy to fly, the BD-5 was intended to be easy to build and own; the fuselage was constructed from fiberglass panels over an aluminum frame, reducing construction time to only a few hundred hours. Although the early designs required some welding in the landing gear area, it was planned that this would be removed in the kit versions, so construction would require no special tooling or skills; the cost of operation would be low, offering fuel efficiency of 38 mpg‑US With the wings removed, the aircraft could be packed into a small custom trailer, allowing it to be towed away by car for storage in a garage, from there to any suitable flat area for takeoff.
Bede published an information booklet about the BD-5 in November 1970. Several positive magazine articles appeared at this point; the October 1971 issue of Science & Mechanics had the BD-5 on the cover, listing the price as $1,950. The associated article showed the construction of the original prototype, with numerous claims about how easy it was to construct; the August 1973 issue of Popular Science covered the aircraft, although it listed the price at $2,965 with the 40 hp engine. The "miniature fighter" generated intense demand; as one author put it, "Even before the plane first left the ground, thoughts of flying the sleek, bullet-shaped aircraft with its pusher prop stimulated the imagination of nearly everyone who had heard of the program."On February 24, 1971, the first $200 deposit to reserve a "place in line" to receive a kit was accepted, with the target shipping date being May 24, 1972. By August 1971, 800 deposits had been taken though the first BD-5 prototype had yet to complete high-speed taxi tests.
By the end of the year, the company had taken over 4,300 orders, making it one of the most popular general aircraft projects in modern history. The prototype, N500BD, flew on September 12, 1971, powered by a 36 hp Polaris Industries snowmobile engine; this was sixteen months. The stability of the aircraft with the original V-tail was marginal at best and needed a redesign. With the original fibreglass fuselage, this was a time-consuming process, so the decision was made to switch to an all-metal fuselage with the components incorporating compound curves produced using hydroformed aircraft-grade aluminum alloy; these could be modified with relative ease during the testing cycle. It made economic sense as the orders rolled in, the $30,000 in tooling would be spread over what was now a large order book. By December 1971, the tooling for the new fuselage was in development; the aircraft now featured a longer, more pointed nose, whereas the N500BD had been patterned on the ASW 15 and had a more rounded, egg-like shaping at the front.
While this work was in progress, Bede continued to experiment with modifications to the empennage abandoning the V-tail for a more conventional rudder and horizontal stabilizer layout with swept surfaces. Further testing o
A knot is an intentional complication in cordage which may be useful or decorative. Practical knots may be classified as hitches, splices, or knots. A hitch fastens a rope to another object. A knot in the strictest sense serves as a stopper or knob at the end of a rope to keep that end from slipping through a grommet or eye. Knots have excited interest since ancient times for their practical uses, as well as their topological intricacy, studied in the area of mathematics known as knot theory. There is a large variety of each with properties that make it suitable for a range of tasks; some knots are used to attach the rope to other objects such as another rope, ring, or stake. Some knots are used to constrict objects. Decorative knots bind to themselves to produce attractive patterns. While some people can look at diagrams or photos and tie the illustrated knots, others learn best by watching how a knot is tied. Knot tying skills are transmitted by sailors, climbers, cavers, rescue professionals, fishermen and surgeons.
The International Guild of Knot Tyers is an organization dedicated to the promotion of knot tying. Truckers in need of securing a load may use a trucker's hitch, gaining mechanical advantage. Knots can save spelunkers from being buried under rock. Many knots can be used as makeshift tools, for example, the bowline can be used as a rescue loop, the munter hitch can be used for belaying; the diamond hitch was used to tie packages on to donkeys and mules. In hazardous environments such as mountains, knots are important. In the event of someone falling into a ravine or a similar terrain feature, with the correct equipment and knowledge of knots a rappel system can be set up to lower a rescuer down to a casualty and set up a hauling system to allow a third individual to pull both the rescuer and the casualty out of the ravine. Further application of knots includes developing a high line, similar to a zip line, which can be used to move supplies, injured people, or the untrained across rivers, crevices, or ravines.
Note the systems mentioned require carabiners and the use of multiple appropriate knots. These knots include the bowline, double figure eight, munter hitch, munter mule, prusik and clove hitch, thus any individual who goes into a mountainous environment should have basic knowledge of knots and knot systems to increase safety and the ability to undertake activities such as rappelling. Knots can be applied in combination to produce complex objects such as netting. In ropework, the frayed end of a rope is held together by a type of knot called a whipping knot. Many types of textiles use knots to repair damage. Macramé, one kind of textile, is generated through the use of knotting, instead of knits, weaves or felting. Macramé can produce self-supporting three-dimensional textile structures, as well as flat work, is used ornamentally or decoratively. Knots weaken the rope; when knotted rope is strained to its breaking point, it always fails at the knot or close to it, unless it is defective or damaged elsewhere.
The bending and chafing forces that hold a knot in place unevenly stress rope fibers and lead to a reduction in strength. The exact mechanisms that cause the weakening and failure are complex and are the subject of continued study. Relative knot strength called knot efficiency, is the breaking strength of a knotted rope in proportion to the breaking strength of the rope without the knot. Determining a precise value for a particular knot is difficult because many factors can affect a knot efficiency test: the type of fiber, the style of rope, the size of rope, whether it is wet or dry, how the knot is dressed before loading, how it is loaded, whether the knot is loaded, so on; the efficiency of common knots ranges between 40—80% of the rope's original strength. In most situations forming loops and bends with conventional knots is far more practical than using rope splices though the latter can maintain nearly the rope's full strength. Prudent users allow for a large safety margin in the strength of rope chosen for a task due to the weakening effects of knots, damage, shock loading, etc.
The working load limit of a rope is specified with a significant safety factor, up to 15:1 for critical applications. For life-threatening applications, other factors come into play. If the rope does not break, a knot may still fail to hold. Knots that hold firm under a variety of adverse conditions are said to be more secure than those that do not. Repeated, dynamic loads will cause every knot to fail; the main ways knots fail to hold are: The load creates tension that pulls the rope back through the knot in the direction of the load. If this continues far enough, the working end fails; this behavior can worsen when the knot is strained and let slack, dragged over rough terrain, or struck against hard objects such as masts and flagpoles. With secure knots, slippage may occur when the knot is first put under real tension; this can be mitigated by leaving plenty of rope at the working end outside of the knot, by dressing the knot cleanly and tightening it as much as possible before loading. Sometimes, the use of a stopper knot or better, a backup knot can prevent the working end from passing through the knot.
Life-critical applications require backup knots to maximize safety. To capsize (or spil
Harley-Davidson, Inc. or Harley, is an American motorcycle manufacturer, founded in Milwaukee, Wisconsin in 1903. One of two major American motorcycle manufacturers to survive the Great Depression, the company has survived numerous ownership arrangements, subsidiary arrangements, periods of poor economic health and product quality, as well as intense global competition, to become one of the world's largest motorcycle manufacturers and an iconic brand known for its loyal following. There are events worldwide as well as a company-sponsored brand-focused museum. Noted for a style of customization that gave rise to the chopper motorcycle style, Harley-Davidson traditionally marketed heavyweight, air-cooled cruiser motorcycles with engine displacements greater than 700 cm³ and has broadened its offerings to include its more contemporary VRSC and middle-weight Street platforms. Harley-Davidson manufactures its motorcycles at factories in Pennsylvania. Construction of a new plant in Thailand is scheduled to begin in late 2018.
The company markets its products worldwide. Besides motorcycles, the company licenses and markets merchandise under the Harley-Davidson brand, among them apparel, home decor and ornaments, accessories and scale figures of its motorcycles, video games based on its motorcycle line and the community. In 1901, 20-year-old William S. Harley drew up plans for a small engine with a displacement of 7.07 cubic inches and four-inch flywheels. The engine was designed for use in a regular pedal-bicycle frame. Over the next two years and his childhood friend Arthur Davidson worked on their motor-bicycle using the northside Milwaukee machine shop at the home of their friend, Henry Melk, it was finished in 1903 with the help of Walter Davidson. Upon testing their power-cycle and the Davidson brothers found it unable to climb the hills around Milwaukee without pedal assistance, they wrote off their first motor-bicycle as a valuable learning experiment. Work began on a new and improved second-generation machine.
This first "real" Harley-Davidson motorcycle had a bigger engine of 24.74 cubic inches with 9.75 inches flywheels weighing 28 lb. The machine's advanced loop-frame pattern was similar to the 1903 Milwaukee Merkel motorcycle; the bigger engine and loop-frame design took it out of the motorized bicycle category and marked the path to future motorcycle designs. The boys received help with their bigger engine from outboard motor pioneer Ole Evinrude, building gas engines of his own design for automotive use on Milwaukee's Lake Street; the prototype of the new loop-frame Harley-Davidson was assembled in a 10 ft × 15 ft shed in the Davidson family backyard. Most of the major parts, were made elsewhere, including some fabricated at the West Milwaukee railshops where oldest brother William A. Davidson was toolroom foreman; this prototype machine was functional by September 8, 1904, when it competed in a Milwaukee motorcycle race held at State Fair Park. It was placed fourth; this is the first documented appearance of a Harley-Davidson motorcycle in the historical record.
In January 1905, small advertisements were placed in the Automobile and Cycle Trade Journal offering bare Harley-Davidson engines to the do-it-yourself trade. By April, complete motorcycles were in production on a limited basis; that year, the first Harley-Davidson dealer, Carl H. Lang of Chicago, sold three bikes from the five built in the Davidson backyard shed. Years the original shed was taken to the Juneau Avenue factory where it would stand for many decades as a tribute to the Motor Company's humble origins until it was accidentally destroyed by contractors cleaning the factory yard in the early 1970s. In 1906, Harley and the Davidson brothers built their first factory on Chestnut Street, at the current location of Harley-Davidson's corporate headquarters; the first Juneau Avenue plant was a 40 ft × 60 ft single-story wooden structure. The company produced about 50 motorcycles that year. In 1907, William S. Harley graduated from the University of Wisconsin–Madison with a degree in mechanical engineering.
That year additional factory expansion came with a second floor and with facings and additions of Milwaukee pale yellow brick. With the new facilities production increased to 150 motorcycles in 1907; the company was incorporated that September. They began selling their motorcycles to police departments around this time, a market, important to them since. In 1907 William A. Davidson, brother to Arthur and Walter Davidson, quit his job as tool foreman for the Milwaukee Road railroad and joined the Motor Company. Production in 1905 and 1906 were all single-cylinder models with 26.84 cubic inch engines. In February 1907 a prototype model with a 45-degree V-Twin engine was displayed at the Chicago Automobile Show. Although shown and advertised few V-Twin models were built between 1907 and 1910; these first V-Twins produced about 7 horsepower. This gave about double the power of the first singles. Top speed was about 60 mph. Production jumped from 450 motorcycles in 1908 to 1,149 machines in 1909. By 1911, some 150 makes of motorcycles had been built in the United States – although just a handful would survive the 1910s.
In 1911, an improved V-Twin model was introduced. The new engine had me
The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion. All parts rotate in one direction, as opposed to the common reciprocating piston engine, which has pistons and changing direction 180 degrees. In contrast to the more common reciprocating piston designs, the Wankel engine delivers advantages of simplicity, compactness, high revolutions per minute, a high power-to-weight ratio; this is because there are three power pulses per rotor revolution. In a two-stroke piston engine there is one power pulse per crankshaft revolution, with one in two revolutions in a four-stroke piston engine. Although at the actual output shaft of a rotary engine, there is only one power pulse per revolution, since the output shaft spins three times as fast as the actual rotor, as can be seen in the animation below, it makes it equivalent to a two-stroke piston engine of the same displacement; this is why the displacement only measures one face of the rotor, since only one face is working for each output shaft revolution.
The engine is referred to as a rotary engine, although this name is applied to other different designs, including both pistoned and pistonless rotary engines. The four-stage cycle of intake, compression and exhaust occur each revolution at each of the three rotor tips moving inside the oval-like epitrochoid-shaped housing, enabling the three power pulses per rotor revolution; the rotor is similar in shape to a Reuleaux triangle with the sides somewhat flatter. The design was conceived by German engineer Felix Wankel. Wankel received his first patent for the engine in 1929, he began development in the early 1950s at NSU, completing a working prototype in 1957. NSU subsequently licensed the design to companies around the world, who have continually added improvements; the engines produced are of spark ignition, with compression ignition engines having only been built in research projects. The Wankel engine has the advantages of compact design and low weight over the most used internal combustion engine employing reciprocating pistons.
These advantages have given rotary engine applications in a variety of vehicles and devices, including: automobiles, racing cars, aircraft, go-karts, jet skis, snowmobiles and auxiliary power units. The power-to-weight ratio has reached over one horsepower per pound in certain engines. In 1951, NSU Motorenwerke AG in Germany began development of the engine, with two models being built; the first, the DKM motor, was developed by Felix Wankel. The second, the KKM motor, developed by Hanns Dieter Paschke, was adopted as the basis of the modern Wankel engine; the basis of the DKM type of motor was that both the rotor and the housing spun around on separate axes. The DKM motor reached higher revolutions per minute and was more balanced. However, the engine contained more parts; the KKM engine was simpler. The first working prototype, DKM 54, produced 21 hp and ran on February 1, 1957, at the NSU research and development department Versuchsabteilung TX; the KKM 57 was constructed by NSU engineer Hanns Dieter Paschke in 1957 without the knowledge of Felix Wankel, who remarked "you have turned my race horse into a plow mare".
In 1960, NSU, the firm that employed the two inventors, the US firm Curtiss-Wright, signed a joint agreement. NSU was to concentrate on low and medium-powered Wankel engine development with Curtiss-Wright developing high-powered engines, including aircraft engines of which Curtiss-Wright had decades of experience designing and producing. Curtiss-Wright recruited Max Bentele to head their design team. Many manufacturers signed license agreements for development, attracted by the smoothness, quiet running, reliability emanating from the uncomplicated design. Amongst them were Alfa Romeo, American Motors Corporation, Citroën, General Motors, Mercedes-Benz, Porsche, Rolls-Royce and Toyota. In the United States in 1959, under license from NSU, Curtiss-Wright pioneered improvements in the basic engine design. In Britain, in the 1960s, Rolls Royce's Motor Car Division pioneered a two-stage diesel version of the Wankel engine. Citroën did much research, producing the M35, GS Birotor and RE-2 helicopter, using engines produced by Comotor, a joint venture of Citroën and NSU.
General Motors seemed to have concluded the Wankel engine was more expensive to build than an equivalent reciprocating engine. General Motors claimed to have solved the fuel economy issue, but failed in obtaining in a concomitant way to acceptable exhaust emissions. Mercedes-Benz fitted a Wankel engine in their C111 concept car. Deere & Company designed a version, capable of using a variety of fuels; the design was proposed as the power source for United States Marine Corps combat vehicles and other equipment in the late 1980s. In 1961, the Soviet research organization of NATI, NAMI, VNIImotoprom commenced development creating experimental engines with different technologies. Soviet automobile manufacturer AvtoVAZ experimented in Wankel engine design without a license, introducing a limited number of engines in some cars. Despite much research and development throughout the world, only Mazda has produced Wankel engines in large quantities. In Britain, Norton Motorcycles developed a Wankel rotary engine for motorcycles, based on the Sachs air-cooled rotor Wankel that powered the DKW/Hercules W-2000 motorcycle.
This two-rotor engine was included in the Commander and F1. Norton improved on the Sachs's air cooling. Suzuki made a production
A single-cylinder engine is a basic piston engine configuration of an internal combustion engine. It is seen on motorcycles, auto rickshaws, motor scooters, dirt bikes, go-karts, radio-controlled models, has many uses in portable tools and garden machinery; some single-cylinder automobiles and tractors have been produced, but are rare today due to developments in engine technology. Single-cylinder engines are simple and compact, will deliver the maximum power possible within a given envelope. Cooling is simpler than with multiple cylinders saving further weight if air cooling is used. Single-cylinder engines require more flywheel than multi-cylinder engines, the rotating mass is large, restricting acceleration and sharp changes of speed. In the basic arrangement they are prone to vibration - though in some cases it may be possible to control this with balance shafts. A variation known as the split-single makes use of two pistons which share a single combustion chamber. Single-cylinder engines are economical in construction.
The vibration they generate is acceptable in many applications in others. Counterbalance shafts and counterweights can be fitted but such complexities tend to counter the listed advantages. Components such as the crankshaft of a single-cylinder engine have to be nearly as strong as that in a multi-cylinder engine of the same capacity per cylinder, meaning that some parts are four times heavier than they need to be for the total displacement of the engine; the single-cylinder engine will inevitably develop a lower power-to-weight ratio than a multi-cylinder engine of similar technology. This can be a disadvantage in mobile operations, although it is of little significance in others and in most stationary applications. Early motorcycles and other applications such as marine engines all tended to be single-cylinder; the configuration remains in widespread use in motorcycles, motor scooters, dirt bikes, go-karts, auto rickshaws, radio-controlled models and is exclusively used in portable tools, along with garden machinery such as lawn mowers.
Lanz Bulldog tractors and several copies by the Polish company URSUS featured large horizontally mounted single cylinder engines. The bestselling motor vehicle of the world, the Honda Super Cub, has a fuel-efficient 49 cc single-cylinder engine; every scooter in the market has a single-cylinder engine. Many motorcycles with strong single-cylinder engines are available as well. There are sportbikes like the KTM 690 Duke R which has a 70 hp 690 cc single-cylinder engine, dual-sport motorcycles like the BMW G650GS, scooters like Gilera Fuoco 500 as well as classics like the Royal Enfield 500 Bullet with a long-stroke single-cylinder engine. Small engine Split single List of motorcycles by type of engine Images of several single-cylinder marine engines
Ultralight aviation is the flying of lightweight, 1- or 2-seat fixed-wing aircraft. Some countries differentiate between weight-shift control and conventional 3-axis control aircraft with ailerons and rudder, calling the former "microlight" and the latter "ultralight". During the late 1970s and early 1980s stimulated by the hang gliding movement, many people sought affordable powered flight; as a result, many aviation authorities set up definitions of lightweight, slow-flying aeroplanes that could be subject to minimum regulations. The resulting aeroplanes are called "ultralight aircraft" or "microlights", although the weight and speed limits differ from country to country. In Europe, the sporting definition limits the maximum take-off weight to 450 kg and a maximum stalling speed of 65 km/h; the definition means that the aircraft has a slow landing speed and short landing roll in the event of an engine failure. In most affluent countries, microlights or ultralight aircraft now account for a significant percentage of the global civilian-owned aircraft.
For instance in Canada in February 2018, the ultralight aircraft fleet made up to 20.4% of the total civilian aircraft registered. In other countries that do not register ultralight aircraft, like the United States, it is unknown what proportion of the total fleet they make up. In countries where there is no specific extra regulation, ultralights are considered regular aircraft and subject to certification requirements for both aircraft and pilot. In Australia, ultralight aircraft and their pilots can either be registered with the Hang Gliding Federation of Australia or Recreational Aviation Australia. In all cases, except for built single seat ultralight aeroplanes, microlight aircraft or trikes are regulated by the Civil Aviation Regulations. Paramotor and powered hang-glider pilots do not need a licence, provided the weight of the aircraft is not more than 75 kg, but they must obey the rules of the air. For heavier microlights the current UK regulations match the European ones, except that helicopters and gyroplanes are not included.
Earlier UK microlight definitions described an aeroplane with a maximum weight of 390 kg, a maximum wing loading of 25 kg per square metre. Other than the earliest aircraft, all two-seat UK microlights have been required to meet an airworthiness standard. In 2007, Single Seat DeRegulated, a sub-category of single seat aircraft was introduced, allowing owners more freedom for modification and experiments. By 2017 the airworthiness of all single seat microlights became the responsibility of the user, but pilots must hold a microlight licence. Ultralights in New Zealand are subject to NZCAA General Aviation regulations with microlight specific variations as described in Part 103 and AC103; the United States FAA's definition of an ultralight is different from that in most other countries and can lead to some confusion when discussing the topic. The governing regulation in the United States is FAR 103 Ultralight Vehicles. In 2004, the FAA introduced the "Light-sport aircraft" category, which resembles some other countries' microlight categories.
Ultralight aviation is represented by the United States Ultralight Association, which acts as the US aeroclub representative to the Fédération Aéronautique Internationale. There are several categories of aircraft which qualify as ultralights in some countries: Fixed-wing aircraft: traditional airplane-style designs. Weight-shift control trike: use a hang glider-style wing, below, suspended a three-wheeled carriage which carries the engine and aviators; these aircraft are controlled by pushing against a horizontal control bar in the same way as a hang glider pilot flies. Powered parachute: fuselage-mounted engines with parafoil wings, which are wheeled aircraft. Powered paraglider: backpack engines with parafoil wings, which are foot-launched. Powered hang glider: motorized foot-launched hang glider harness. Autogyro: rotary wing with fuselage-mounted engine, a gyrocopter is different from a helicopter in that the rotating wing is not powered, the engine provides forward thrust and the airflow through the rotary blades causes them to autorotate or "spin up" thereby creating lift.
Helicopter: there are a number of single-seat and two-place helicopters which fall under the microlight categories in countries such as New Zealand. However, few helicopter designs fall within the more restrictive ultralight category defined in the United States of America. Hot air balloon: there are numerous ultralight hot air balloons in the US, several more have been built and flown in France and Australia in recent years; some ultralight hot air balloons are hopper balloons, while others are regular hot air balloons that carry passengers in a basket. Advancements in batteries and motor controllers has led to some practical production electric propulsion systems for some ultralight applications. In many ways, ultralights are a good application for electric power as some models are capable of flying with low power, which allows longer duration flights on battery power. In 2007, the first pioneering company in this field, the Electric Aircraft Corporation, began offering engine kits to convert ultralight weight shift trikes to electric power.
The 18 hp motor weighs an efficiency of 90 % is claimed by designer Randall Fishman. The battery consists of a lithium-polymer battery pack of 5.6kWh which provides 1.5 hours of flying in the trike applicat
A swingarm, or "swinging arm" known as a swing fork or pivoted fork, is the main component of the rear suspension of most modern motorcycles and ATVs. It is used to hold the rear axle while pivoting vertically, to allow the suspension to absorb bumps in the road. Motorcycles had no rear suspension, as their frames were little more than stronger versions of the classic diamond frame of a bicycle. Many types of suspension were tried, including Indian's leaf spring suspended swingarm, Matchless's cantilevered coiled-spring swingarm. Before and after World War II, the plunger suspension, in which the axle moved up and down two vertical posts, became commonplace. In the latter, the movement in each direction was against coiled springs; some manufacturers, such as Greeves, used swingarm designs for the front forks, which were more robust than telescopic forks. In particular, sidecar motocross outfits use swing arm front forks; the swingarm has been used for the front suspension of scooters. In this case it aids in simplifying maintenance.
In motorcycles with shaft drive, such as the Yamaha XJ650 Maxim, the shaft housing forms the left side swingarm. Swingarms have come in several forms: Swinging fork - the original version consisting of a pair of parallel pipes holding the rear axle at one end and pivoting at the other. A pair of shock absorbers are mounted just before the rear axle and attached to the frame, below the seat rail. Cantilever - An extension of the swinging fork where a triangulated frame transfers swingarm movement to compress shock absorber/s mounted in front of the swingarm; the HRD-Vincent Motorcycle is a famous early form of this type of swingarm, though Matchless used it earlier, Yamaha subsequently. The Harley-Davidson Softail is another form of this swingarm, though working in reverse, with the shock absorbers being extended rather than compressed. Parallelogram Suspension was first introduced commercially in 1985 on the Magni "Le Mans". Magni called the system Parallelogrammo. Various parallelogram systems have been developed by other manufacturers.
Whereas a chain-driven bike would "squat" at the rear under acceleration, a shaft drive machine would do the opposite, causing the seat to rise upwards, a phenomenon known as "shaft-jacking". This anti-intuitive sensation can be disconcerting to riders, parallelogram suspensions seek to neutralize such unwelcome torque reactions. Paralever is BMW's version of the system, it allows the driveshaft to pivot along the same axis as the sprung rear frame due to the addition of a second link between the rear drive and transmission. The Paralever was introduced in 1988 R100GS motorcycles to combat shaft-jacking. Moto Guzzi has introduced a variant of the system, it named the Compact Reactive Drive Shaft system; the main difference is that the driveshaft is free to float into its structure, providing much softer feedback from transmission. Additionally, the upper arm of the Ca. R. C. is not part of the structure but just a guide to close the geometry of the suspension. Drag racing motorcycles will use longer swingarms to keep their center of gravity as forward as possible, which reduces the tendency to wheelie at the start.
A single-sided swingarm is a type of swingarm which lies along only one side of the rear wheel, allowing the rear wheel to be mounted like a car wheel. Single-sided swingarms are traditionally found on small motorcycles or scooters, where a robust chain case doubles as the swingarm linking the engine and rear wheel. Single-sided swingarms need to be much stiffer than the double-sided versions, to accommodate the extra torsional forces, as a result, they are heavier than double-sided arms. Having a single mounting point guarantees proper wheel alignment. Single-sided swingarms date from at least the late 1940s. In 1948, the Imme R100 produced by Norbert Riedel of Germany had both a single-sided front wheel suspension as well as a single-sided rear swingarm that doubled as the exhaust pipe. In 1950, Moto Guzzi introduced the Galletto, a large-wheel step-through scooter. In 1980, BMW introduced its first single-sided swingarm on the R80G/S, the "Mono-lever", superseded by the "Para-lever" used currently.
Honda features this style of swingarm on the Honda VFR. Ducati has created several models featuring single swingarms, most notably the Massimo Tamburini-designed 916 series. While Ducati abandoned this style for the 999, the company returned to it for the 1098 superbike in 2007, it survives in the current Ducati 1199; the Triumph Sprint ST and Speed Triple feature single-sided swingarms. "Squat" occurs. Shaft-jacking can be minimised by devices such as parallelogram swingarms. A practical way to minimise squat on a chain-drive bike is to locate the final drive sprocket as close as possible to the axis of the swingarm pivot. Bicycle suspension Suspension