In automotive design , an RMR , or rear mid-engine , rear-wheel-drive layout is one in which the rear wheels are driven by an engine placed with its center of gravity in front of the rear axle, and thus right behind the passenger compartment. Nowadays more frequently called 'RMR', to acknowledge that certain sporty or performance focused front-engined cars are also "mid-engined", by having the main engine mass behind the front axle, RMR layout cars were previously (until ca. the 1990) just called MR , or mid-engine, rear-wheel-drive layout ), because the nuance between distinctly front-engined vs. front mid-engined cars often remained undiscussed.
37-518: The Artega GT is a mid-engined, rear wheel drive 2-seat sports car produced by German automobile manufacturer Artega between 2009 and 2012. The GT was Artega's first model. A total of 153 units were produced. The two seater had an aluminum space frame and carbon fibre reinforced body for a light curb weight of 1,116 kg (2,460 lb). The engine was a Volkswagen -sourced direct injection 3.6 L VR6 rated at 296 bhp (221 kW; 300 PS) and 350 N⋅m (260 lb⋅ft) mated to
74-411: A Bundorf analysis . Great care must be taken to avoid conflating the understeer/oversteer behavior with the limit behavior of a vehicle. The physics are very different. They have different handling implications and different causes. The former is concerned with tire distortion effects due to slip and camber angles as increasing levels of lateral acceleration are attained. The latter is concerned with
111-510: A 6-speed DSG transmission. Acceleration from 0–100 km/h is tested to be at 4.6 seconds, with top speed estimated to be over 270 km/h (168 mph). In early 2011 GTspirit tested the Artega GT in Belgium and finished by saying that, Overall a superb handling sports car with not a single failure and that it had excellent performance not easily found elsewhere'' . The Artega GT
148-589: A given steady state operating condition by the Society of Automotive Engineers (SAE) in document J670 and by the International Organization for Standardization (ISO) in document 8855. Whether the vehicle is understeer or oversteer depends on the rate of change of the understeer angle. The Understeer Angle is the amount of additional steering (at the road wheels, not the hand wheel) that must be added in any given steady-state maneuver beyond
185-445: A handful of 2+2 designs . Additionally, some microtrucks use this layout, with a small, low engine beneath a flat load floor above the rear wheel-wells. This makes it possible to move the cab right to the front of the vehicle, thus increasing the loading area at the expense of slightly reduced load depth. In modern racing cars, RMR is a common configuration and is usually synonymous with "mid-engine". Due to its weight distribution and
222-531: A sign of greater things to come. The 718 followed similarly in 1958. But it was not until the late 1950s that RMR reappeared in Grand Prix (today's " Formula One ") races in the form of the Cooper - Climax (1957), soon followed by cars from BRM and Lotus . Ferrari and Porsche soon made Grand Prix RMR attempts with less initial success. The mid-engined layout was brought back to Indianapolis in 1961 by
259-531: A very favorable balance, with plenty of weight on the driven rear axle under acceleration, while distributing the weight fairly evenly under braking, thereby making optimal use of all four wheels to decelerate the car rapidly as well. The RMR layout generally has a lower tendency to understeer . However, since there is less weight over the front wheels, under acceleration the front of the car can be prone to lift and still have understeer . Most rear-engine layouts have historically been used in smaller vehicles, because
296-428: Is broken, they are relatively free to swing laterally. Under braking load, more work is typically done by the front brakes. If this forward bias is too great, then the front tyres may lose traction, causing understeer. Understeer gradient is one of the main measures for characterizing steady-state cornering behavior. It is involved in other properties such as characteristic speed (the speed for an understeer vehicle where
333-522: Is necessary to specify the speed and lateral acceleration whenever reporting understeer/oversteer characteristics. Many properties of the vehicle affect the understeer gradient, including tyre cornering stiffness, camber thrust , lateral force compliance steer, self aligning torque , lateral weight transfer , and compliance in the steering system. Weight distribution affects the normal force on each tyre and therefore its grip. These individual contributions can be identified analytically or by measurement in
370-409: Is taken to the grip limit of the tyres, where it is no longer possible to increase lateral acceleration, the vehicle will follow a path with a radius larger than intended. Although the vehicle cannot increase lateral acceleration, it is dynamically stable. When an oversteering vehicle is taken to the grip limit of the tyres, it becomes dynamically unstable with a tendency to spin . Although the vehicle
407-423: Is unstable in open-loop control, a skilled driver can maintain control past the point of instability with countersteering and/or correct use of the throttle or even brakes; this is done purposely in the sport of drifting . If a rear-wheel-drive vehicle has enough power to spin the rear wheels, it can initiate oversteer at any time by sending enough engine power to the wheels that they start spinning. Once traction
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#1732798046377444-399: Is what is happening when a car 'spins out'. A car susceptible to being loose is sometimes known as 'tail happy', as in the way a dog wags its tail when happy and a common problem is fishtailing . In real-world driving, there are continuous changes in speed, acceleration (vehicle braking or accelerating), steering angle, etc. Those changes are all constantly altering the load distribution of
481-639: The 1923 Benz Tropfenwagen . It was based on an earlier design named the Rumpler Tropfenwagen in 1921 made by Edmund von Rumpler , an Austrian engineer working at Daimler. The Benz Tropfenwagen was designed by Ferdinand Porsche along with Willy Walb and Hans Nibel . It raced in 1923 and 1924 and was most successful in the Italian Grand Prix in Monza where it stood fourth. Later, Ferdinand Porsche used mid-engine design concept towards
518-497: The Auto Union Grand Prix cars of the 1930s which became the first winning RMR racers. They were decades before their time, although MR Miller Specials raced a few times at Indianapolis between 1939 and 1947. In 1953 Porsche premiered the tiny and altogether new RMR 550 Spyder and in a year it was notoriously winning in the smaller sports and endurance race car classes against much larger cars –
555-605: The Cooper Car Company with Jack Brabham running as high as third and finishing ninth. Cooper did not return, but from 1963 on British built mid-engined cars from constructors like Brabham , Lotus and Lola competed regularly and in 1965 Lotus won Indy with their Type 38 . Rear mid-engines were widely used in microcars like the Isetta or the Zündapp Janus . The first rear mid-engined road car after WW II
592-464: The gearbox and differential . This represented an extremely innovative sportscar at a time when all of its competitors (aside from the rear-engined Porsches), from Ferraris to Aston Martins , were traditional front-engined, rear-wheel-drive grand tourers. The Pontiac Fiero was a mid-engined sports car that was built by the Pontiac division of General Motors from 1984 to 1988. The Fiero
629-596: The 2008 Detroit Auto Show that Artega was investing in a possible solar-powered concept vehicle to compete with the Tesla Roadster (2008) and Fisker Karma . Henrik Fisker, who also designed the Aston Martin V8 Vantage , contributed to the design of the Artega GT. The first produced Artega GT was reportedly sold to Steven Gregory Balboa, an Italian now residing in Rochester, New York. After
666-466: The Ackermann steer angle. The Ackermann Steer Angle is the steer angle at which the vehicle would travel about a curve when there is no lateral acceleration required (at negligibly low speed). The Understeer Gradient (U) is the rate of change of the understeer angle with respect to lateral acceleration on a level road for a given steady state operating condition. The vehicle is Understeer if
703-874: The Artega company filed for bankruptcy in July 2012, production has ceased and the company has been bought by German automotive supplier firm Paragon AG, which has offered all employees new jobs. Paragon AG will continue to supply owners with service, according to the Artega-website. On 30 September 2012 the production of the Artega GT was halted. There are currently no plans to resume production. Frame: Aluminum spaceframe. Rear module tubular space frame of high-tensile stainless steel Bodywork: Carbon fiber reinforced polyurethane compound material Dimensions (L X B X H): 3950 x 1880 x 1,180 mm (46.5 in) Kg/PS: About 3.6 kg/PS Engine: VR6 direct-injection engine in
740-610: The Renault-engined Lotus Europa , built from 1966 to 1975. Finally, in 1966, the Lamborghini Miura was the first high performance mid-engine, rear-wheel-drive road car. The concept behind the Miura was that of putting on the road a grand tourer featuring state-of-the-art racing-car technology of the time; hence the Miura was powered by a V12 transversely mounted between the rear wheels, solidal to
777-418: The center of mass is moved rearward, the understeer gradient tends to decrease. The shifting of the center of mass is proportional to acceleration and affected by the height of the center of mass. When braking, more of the vehicles weight (load) is put on the front tyres and an less on the rear tyres. Conversely, when the vehicle accelerates, the opposite happens, the weight shifts to the rear tires. Similarly, as
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#1732798046377814-586: The center of mass of the load is shifted from one side to the other, the inside or outside tyres traction changes. In extreme cases, the inside or front tyres may completely lift off the ground, eliminating or reducing the steering input that can be transferred to the ground. While weight distribution and suspension geometry have the greatest effect on measured understeer gradient in a steady-state test, power distribution, brake bias and front-rear weight transfer will also affect which wheels lose traction first in many real-world scenarios. When an understeering vehicle
851-489: The favorable vehicle dynamics it produces, this layout is heavily employed in open-wheel Formula racing cars (such as Formula One and IndyCar ) as well as most purpose-built sports racing cars . This configuration was also common in smaller-engined 1950s microcars , in which the engines did not take up much space. Because of successes in motorsport, the RMR platform has been commonly used in many road-going sports cars despite
888-404: The front tyres will keep the front of the vehicle on the desired path but the rear tyres will slip and follow a path with a greater radius. The back end will swing out and the vehicle will turn toward the inside of the curve. If the steering angle is not changed, then the front wheels will trace out a smaller and smaller circle while the rear wheels continue to swing around the front of the car. This
925-424: The fully rear-engine, rear-wheel-drive layout , the center of mass of the engine is in front of the rear axle. This layout is typically chosen for its favorable weight distribution . Placing the car's heaviest component within the wheelbase minimizes its rotational inertia around the vertical axis, facilitating turn-in or yaw angle . Also, a near 50/50% weight distribution, with a slight rear weight bias, gives
962-451: The inherent challenges of design, maintenance and lack of cargo space. The similar mid-engine, four-wheel-drive layout gives many of the same advantages and is used when extra traction is desired, such as in some supercars and in the Group B rally cars. The 1900 NW Rennzweier was one of the first race cars with mid-engine, rear-wheel-drive layout. Other known historical examples include
999-425: The lateral and longitudinal forces, a function of the normal force and coefficient of friction. If the lateral and longitudinal forces presented at the tyre during operations exceeds the tyre's available traction force then the tyre is said to be saturated and will loose its grip on the ground and start to slip. Push (plow) can be understood as a condition where, while cornering, the front tyres become saturated before
1036-406: The limiting friction case in which either the front or rear wheels become saturated first. It is best to use race driver's descriptive terms "push (plow) and loose (spin)" for limit behavior so that these concepts are not confused. Tyres transmit lateral (side to side) and longitudinal (front to back) forces to the ground. The total traction force (grip) available to the a tyre is the vector sum of
1073-409: The measurement methods. Results depend on the type of test, so simply giving a deg/g value is not sufficient; it is also necessary to indicate the type of procedure used to measure the gradient. Vehicles are inherently nonlinear systems , and it is normal for U to vary over the range of testing. It is possible for a vehicle to show understeer in some conditions and oversteer in others. Therefore, it
1110-409: The rear and slip first. Since the front tyres cannot provide any additional lateral force and the rear tyres can, the front of the vehicle will follow a path of greater radius than the rear and if there are no changes to the steering angle (i.e. the steering wheel stays in the same position), the vehicle's front will slide to the outside of the curve. If the rear tyres become saturated before the front,
1147-586: The rear mid Displacement: 3,597 cc (3.6 L; 219.5 cu in) Performance: 221 kW (300 PS; 296 hp) at 6,600 rpm Torque: 350 N⋅m (260 lb⋅ft) at 2,400 rpm Layout: Rear-wheel-drive Transmission: Six-speed direct-shift with Artega inverting stage (pat. appl.) Acceleration 0 - 100 km/h (62 mph): 4.6 seconds Speed: more than 273 km/h (170 mph) https://www.auto-motor-und-sport.de/test/artega-gt-im-supertest-wie-schlaegt-sich-der-deutsche-lotus/technische-daten/ RMR layout In contrast to
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1184-657: The understeer gradient is positive, Oversteer if the understeer gradient is negative, and Neutral steer if the understeer gradient is zero. Car and motorsport enthusiasts often use the terminology informally in magazines and blogs to describe vehicle response to steering in a variety of manoueuvres. Several tests can be used to determine understeer gradient: constant radius (repeat tests at different speeds), constant speed (repeat tests with different steering angles), or constant steer (repeat tests at different speeds). Formal descriptions of these three kinds of testing are provided by ISO. Gillespie goes into some detail on two of
1221-412: The vehicle, which, along with changes in tyre temperatures and road surface conditions are is constantly changing the maximum traction force available at each tyre. Generally, though, it is changes to the center of mass which cause tyre saturation and inform limit handling characteristics. If the center of mass is moved forward, the understeer gradient tends to increase due to tyre load sensitivity . When
1258-412: The weight of the engine at the rear has an adverse effect on a larger car's handling, making it 'tail-heavy', although this effect is more pronounced with engines mounted behind the rear axle. It is felt that the low polar inertia is crucial in selection of this layout. The mid-engined layout also uses up central space, making it generally only practical for single seating-row sports-cars, with exception to
1295-509: Was priced at approximately €75,000. The GT was built at a new factory in Delbrück , Germany with production starting in October 2008 and sales commencing in spring 2009. Production was claimed to be limited to roughly 500 units per year. First shown as a mock up at the 2007 Geneva Auto Show ; the Artega GT debuted a year later at the 2008 Geneva Auto Show. Klaus Dieter Frers announced at
1332-533: Was the 1962 (Rene) Bonnet / Matra Djet , which used the 1108cc Renault Sierra engine, mated to the transaxle from the FWD Renault Estafette van. Nearly 1700 were built until 1967. This was followed by the first De Tomaso, the Vallelunga , which mated a tuned Ford Cortina 1500 Kent engine to a VW transaxle with Hewland gearsets. Introduced at Turin in 1963, 58 were built 1964–68. A similar car was
1369-412: Was the first two-seater Pontiac since the 1926 to 1938 coupes, and also the first mass-produced mid-engine sports car by a U.S. manufacturer. Understeer and oversteer Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of the vehicle to changes in steering angle associated with changes in lateral acceleration. This sensitivity is defined for a level road for
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