Bristol 450
Encyclopedia
The Bristol Type 450 was a successful sports car racing
prototype model, designed in 1953 by Bristol Cars
and based on the abortive ERA
G-type Formula Two
car of 1952. Although most sources state that only three 450s were built, photographic evidence suggests that at least four were in existence at one point in time. The cars were constructed specifically to contest the prestigious 24 Hours of Le Mans
endurance race, at which they won both their class and the team prize in both and . In addition to its race victories, the Bristol 450 also took a number of outright speed records for the 2 litre class during trials at the Montlhéry circuit in 1953. Following the 1955 Le Mans disaster
, which killed Pierre Levegh
and 83 spectators, Bristol withdrew from direct involvement in motorsport and all but one of the 450s were broken up.
, and completed by his protégé and successor David Hodkin, as the chassis for the ERA G-type Formula 2 car, Leslie Johnson
's attempt to resuscitate the ERA name in 1952. The G-type was initially planned to run using a custom built ERA engine, but when funding became a problem the design was adapted to incorporate the popular Bristol straight-6
engine, also used with some success by Cooper
, Frazer Nash
and AC
. However, engine modifications made by Hodkin resulted in engine failure in all three of the G-type's Grand Prix outings, despite being driven by rising star Stirling Moss
. At the end of the 1952 season, out of money and in failing health, Johnson sold the project to the car manufacturing arm of the Bristol Aeroplane Company
.
front and de Dion tube
rear suspension were attached. The wheelbase was relatively long at 8 ft 1¼ in (247 cm), especially considering the car's narrow track of 4 ft 3 in (130 cm). Inboard brakes at the rear and an innovative hub/rim arrangement reduced unsprung weight
. These innovative wheels consisted of a large hub spider – through which driveshafts could be switched without needing to remove the wheels and brakes – to which a wheel consisting of little more than a rim was attached. For the 1955 Le Mans race, to save further time during pit stops, Bristol developed an equally innovative multi-barreled, powered spanner, which could remove all five wheel nuts simultaneously. In much the same way as for modern Formula One
wheel changes, the spanner would then retain the wheel nuts and allow precise reattachment of the new wheel to the car, applying the correct amount of torque to each nut.
The tall Bristol engine was mounted forward in the chassis, with drive passing along a propshaft directly under the cockpit to the four-speed gearbox mounted behind the driver. This arrangement, while requiring precise balancing of the engine-speed shaft, meant that weight distribution was as even as possible. Fuel was carried in two pannier cells behind the front wheels, in the position that Bristol road cars traditionally have battery and spare wheel compartments; their central position also resulted in minimal disturbance to the handling character of the 450, whether running on full tanks or empty. The sweet handling of the resulting car was commented on by driver Lance Macklin
, when he stated that the Bristol 450 "could be driven without hands".
In early 1954, modifications were made to the engine that raised power output from the original ~140 bhp to 155 bhp, raising top speed to over 140 mi/h with Le Mans gearing. With a kerb weight of only 1450 lbs (658 kg), the power-to-weight ratio was over 235 bhp/tonne, comparable with many modern high-performance sportscars.
The bodywork of the Bristol 450 was very advanced for the early 1950s. As a division of an aircraft manufacturer the Bristol design team had access to the company wind tunnel
and the car was designed to be as aerodynamically
efficient as possible. The cars first appeared with smooth basic shape, perhaps slightly over wide for the narrow track, but with the outline broken by lumpy, inelegant headlamp, spotlight and air intake bulges. The most striking features of the design were large twin stabilising fins running vertically down the rear of the small, enclosed cockpit, and down to the tip of the tail. The overall effect was far from pretty.
Following the team's first race outing both cars used returned to the factory in a damaged state. Alongside minor engine modification, during repair dramatic changes were made to the styling of the machines. The panelwork was smoothed even further, with the small front wings now completely gone and the roofline raised between the rear fins; the headlamps were set into deeply recessed, faired-in
conical tunnels; the spotlamps and indicator lights were set into more conventional faired recesses; and the engine air intake bulge was smoothed and tapered. At the same time the car's width was reduced, and cutout ducts were introduced behind the front wheels to improve cooling of the front brakes. All ancillary components were also removed from the airflow, either by fairing or by choosing alternative methods.
In 1955 a radical redesign of the cockpit was made, prior to that year's Le Mans outing. Further work in the Bristol wind tunnel had shown that, despite a slight increase in the Cd-value
, the reduction in frontal area as a consequence of removing the cockpit roof resulted in an overall reduction in the car's aerodynamic drag. Instead of the previously all-enveloping, twin-finned roof, a wrap-around screen and single large tailfin were employed, in a manner very similar to the 1955 Le Mans-winning Jaguar D-Type
cars. The compulsory second seat was still in place, but was covered by a solid tonneau
.
race. Two cars were entered, with a third held back as a spare. Unfortunately for Bristol, both were out before half distance with near-identical failures. In each case the balance weights became detached from the crankshaft. This caused the rear wheels to lock at high speed, in turn causing the cars to veer off the road and catch fire. However, in the laps that the cars had managed to complete, Jack Fairman
easily managed to post a new lap record for the 2 litre class. The cars were rebuilt at the factory, incorporating the revised aerodynamic bodywork, and only three weeks later, in early July, were entered into the 12h race at Reims
. The Reims track shared the high speed character of its French cousin at La Sarthe
and suited the Bristol's character well. Although one car again broke down, this time due to transmission failure on the first lap, the remaining car cruised to a class victory and finished fifth overall.
The cars returned to France in early October for a series of reliability speed record attempts at the Montlhéry circuit. All were successful, and on 6 October 1953 the Bristol team set six records for the 2 litre class, for endurance over a variety of distances and times: 200 miles (125.87 mph); 500 km (116.10 mph); 500 miles (112.25 mph); 1,000 km (115.49 mph); 3 hr (116.42 mph); and 5 hr (115.43 mph).
The cars did not race again until the 1954 Le Mans race
. This time three cars were entered, with uprated engines and the improved aerodynamic bodywork. In contrast with the previous year, and despite torrential rain, all three cars finished the race, coming home in first, second and third in their class and 7th, 8th and 9th overall. Their performance also earned Bristol the team prize. The 450s remained in France for the Reims race, and again demonstrated unblemished reliability, taking 2nd, 3rd and 4th in class, beaten only narrowly by a Ferrari
for the class victory.
Once again, Bristol was only interested in high-speed endurance racing and so the cars were put into storage until the 1955 24 Hours of Le Mans
. With the revised, open bodywork the cars repeated their dominance of the previous year. Again they finished 7th, 8th and 9th overall, 1st, 2nd and 3rd in class, and took the team prize. The lead car averaged over 100 mi/h for more than the first 12 hours – only slowing on team orders – and spent only 15 minutes in the pits during the entire 24 hour race!
However, despite this dominant victory record, the tragic accident during the race
and a corporate shift away from emphasis on their products' sporting credentials persuaded Bristol to withdraw from racing immediately following their 1955 Le Mans triumph. Their prize monies were quietly donated to the relief fund for victims of the disaster, and they withdrew from the 1955 Reims race. Rather than allow poorly financed and inexperienced privateer teams to run their cars in inappropriate events, on their return to the factory the best car was selected, built up using the best components from all chassis, and the remainder scrapped. This car was retained by Bristol Cars owner and former racing driver Tony Crook
for the next 30 years, on occasion loaning its engine to one of Crook's road-going saloons. In the late 1990s it was fully restored to 1955 specifications, and currently makes infrequent appearances at historic race meetings.
Sports car racing
Sports car racing is a form of circuit auto racing with automobiles that have two seats and enclosed wheels. They may be purpose-built or related to road-going sports cars....
prototype model, designed in 1953 by Bristol Cars
Bristol Cars
Bristol Cars is a manufacturer of hand-built luxury cars headquartered in Patchway, near Bristol, United Kingdom. Bristol have always been a low-volume manufacturer; the most recent published official production figures were for 1982, which stated that 104 cars were produced in that year...
and based on the abortive ERA
English Racing Automobiles
English Racing Automobiles was a British racing car manufacturer active from 1933 to 1954. Currently the ERA trademark is owned by a British kit-car manufacturer.-Prewar history:...
G-type Formula Two
Formula Two
Formula Two, abbreviated to F2, is a type of open wheel formula racing. It was replaced by Formula 3000 in 1985, but the FIA announced in 2008 that Formula Two would return for 2009 in the form of the FIA Formula Two Championship...
car of 1952. Although most sources state that only three 450s were built, photographic evidence suggests that at least four were in existence at one point in time. The cars were constructed specifically to contest the prestigious 24 Hours of Le Mans
24 Hours of Le Mans
The 24 Hours of Le Mans is the world's oldest sports car race in endurance racing, held annually since near the town of Le Mans, France. Commonly known as the Grand Prix of Endurance and Efficiency, race teams have to balance speed against the cars' ability to run for 24 hours without sustaining...
endurance race, at which they won both their class and the team prize in both and . In addition to its race victories, the Bristol 450 also took a number of outright speed records for the 2 litre class during trials at the Montlhéry circuit in 1953. Following the 1955 Le Mans disaster
1955 Le Mans disaster
The 1955 Le Mans disaster occurred during the 1955 24 Hours of Le Mans motor race, when a crash caused large parts of racing car debris to fly into the crowd. The driver was killed, as were 83 spectators. A further 120 people were injured...
, which killed Pierre Levegh
Pierre Levegh
Pierre Eugène Alfred Bouillin was a French sportsman and racing driver. He took the racing name Pierre Levegh in memory of his uncle, a pioneering driver who died in 1904...
and 83 spectators, Bristol withdrew from direct involvement in motorsport and all but one of the 450s were broken up.
Design history
The fundamental design of the Bristol 450 was laid down by Eberan von EberhorstEberan von Eberhorst
Professor Dr Robert Eberan von Eberhorst , was a noted Austrian engineer, who designed the Auto Union Type D Grand Prix racing car.-Life:...
, and completed by his protégé and successor David Hodkin, as the chassis for the ERA G-type Formula 2 car, Leslie Johnson
Leslie Johnson
Leslie George Johnson was a British racing driver who competed in rallies, hill climbs, sports car races and Grand Prix races.-Overview:...
's attempt to resuscitate the ERA name in 1952. The G-type was initially planned to run using a custom built ERA engine, but when funding became a problem the design was adapted to incorporate the popular Bristol straight-6
Straight-6
The straight-six engine or inline-six engine is a six-cylinder internal combustion engine with all six cylinders mounted in a straight line along the crankcase...
engine, also used with some success by Cooper
Cooper Car Company
The Cooper Car Company was founded in 1946 by Charles Cooper and his son John Cooper. Together with John's boyhood friend, Eric Brandon, they began by building racing cars in Charles' small garage in Surbiton, Surrey, England in 1946...
, Frazer Nash
Frazer Nash
Frazer Nash was a British sports car manufacturer and engineering company founded by Archibald Frazer-Nash in 1922. It produced sports cars incorporating a unique multi-chain transmission before World War II and also imported BMW cars to the UK. After the war it continued producing sports cars with...
and AC
AC Cars
AC Cars Group Ltd. formerly known as Auto Carriers Ltd. is a British specialist automobile manufacturer and one of the oldest independent car marques founded in Britain...
. However, engine modifications made by Hodkin resulted in engine failure in all three of the G-type's Grand Prix outings, despite being driven by rising star Stirling Moss
Stirling Moss
Sir Stirling Craufurd Moss, OBE FIE is a former racing driver from England...
. At the end of the 1952 season, out of money and in failing health, Johnson sold the project to the car manufacturing arm of the Bristol Aeroplane Company
Bristol Aeroplane Company
The Bristol Aeroplane Company, originally the British and Colonial Aeroplane Company, was both one of the first and one of the most important British aviation companies, designing and manufacturing both airframes and aero engines...
.
Chassis and running gear
In late 1952 Bristol made the surprise announcement that the car was to be redesigned as a two-seat sports car, for entry into the following year's Le Mans race. Over the following few months the G-type was comprehensively redesigned and rebuilt by Bristol's new motor sport department, with the design team led by David Summers. The chassis itself was founded on twin, oval-section rails running the length of the car, which were changed to simple circular-section members for the Bristol. To these, the G-Type's double wishboneDouble wishbone suspension
In automobiles, a double wishbone suspension is an independent suspension design using two wishbone-shaped arms to locate the wheel. Each wishbone or arm has two mounting points to the chassis and one joint at the knuckle. The shock absorber and coil spring mount to the wishbones to control...
front and de Dion tube
De Dion tube
A de Dion tube is an automobile suspension technology. It is a sophisticated form of non-independent suspension and is a considerable improvement over the alternative swing axle and Hotchkiss drive types. A de Dion suspension uses universal joints at both the wheel hubs and differential, and uses a...
rear suspension were attached. The wheelbase was relatively long at 8 ft 1¼ in (247 cm), especially considering the car's narrow track of 4 ft 3 in (130 cm). Inboard brakes at the rear and an innovative hub/rim arrangement reduced unsprung weight
Unsprung weight
In a ground vehicle with a suspension, the unsprung weight is the mass of the suspension, wheels or tracks , and other components directly connected to them, rather than supported by the suspension...
. These innovative wheels consisted of a large hub spider – through which driveshafts could be switched without needing to remove the wheels and brakes – to which a wheel consisting of little more than a rim was attached. For the 1955 Le Mans race, to save further time during pit stops, Bristol developed an equally innovative multi-barreled, powered spanner, which could remove all five wheel nuts simultaneously. In much the same way as for modern Formula One
Formula One
Formula One, also known as Formula 1 or F1 and referred to officially as the FIA Formula One World Championship, is the highest class of single seater auto racing sanctioned by the Fédération Internationale de l'Automobile . The "formula" designation in the name refers to a set of rules with which...
wheel changes, the spanner would then retain the wheel nuts and allow precise reattachment of the new wheel to the car, applying the correct amount of torque to each nut.
The tall Bristol engine was mounted forward in the chassis, with drive passing along a propshaft directly under the cockpit to the four-speed gearbox mounted behind the driver. This arrangement, while requiring precise balancing of the engine-speed shaft, meant that weight distribution was as even as possible. Fuel was carried in two pannier cells behind the front wheels, in the position that Bristol road cars traditionally have battery and spare wheel compartments; their central position also resulted in minimal disturbance to the handling character of the 450, whether running on full tanks or empty. The sweet handling of the resulting car was commented on by driver Lance Macklin
Lance Macklin
Lance Noel Macklin was a British racing driver from England. He participated in 15 Formula One World Championship Grands Prix, debuting on 18 May 1952....
, when he stated that the Bristol 450 "could be driven without hands".
In early 1954, modifications were made to the engine that raised power output from the original ~140 bhp to 155 bhp, raising top speed to over 140 mi/h with Le Mans gearing. With a kerb weight of only 1450 lbs (658 kg), the power-to-weight ratio was over 235 bhp/tonne, comparable with many modern high-performance sportscars.
Bodywork
Wind tunnel
A wind tunnel is a research tool used in aerodynamic research to study the effects of air moving past solid objects.-Theory of operation:Wind tunnels were first proposed as a means of studying vehicles in free flight...
and the car was designed to be as aerodynamically
Automotive aerodynamics
Automotive aerodynamics is the study of the aerodynamics of road vehicles. The main concerns of automotive aerodynamics are reducing drag , reducing wind noise, minimizing noise emission, and preventing undesired lift forces and other causes of aerodynamic instability at high speeds...
efficient as possible. The cars first appeared with smooth basic shape, perhaps slightly over wide for the narrow track, but with the outline broken by lumpy, inelegant headlamp, spotlight and air intake bulges. The most striking features of the design were large twin stabilising fins running vertically down the rear of the small, enclosed cockpit, and down to the tip of the tail. The overall effect was far from pretty.
Following the team's first race outing both cars used returned to the factory in a damaged state. Alongside minor engine modification, during repair dramatic changes were made to the styling of the machines. The panelwork was smoothed even further, with the small front wings now completely gone and the roofline raised between the rear fins; the headlamps were set into deeply recessed, faired-in
Fairing
A 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, and to improve appearance.-Types:...
conical tunnels; the spotlamps and indicator lights were set into more conventional faired recesses; and the engine air intake bulge was smoothed and tapered. At the same time the car's width was reduced, and cutout ducts were introduced behind the front wheels to improve cooling of the front brakes. All ancillary components were also removed from the airflow, either by fairing or by choosing alternative methods.
In 1955 a radical redesign of the cockpit was made, prior to that year's Le Mans outing. Further work in the Bristol wind tunnel had shown that, despite a slight increase in the Cd-value
Drag coefficient
In fluid dynamics, the drag coefficient is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment such as air or water. It is used in the drag equation, where a lower drag coefficient indicates the object will have less aerodynamic or...
, the reduction in frontal area as a consequence of removing the cockpit roof resulted in an overall reduction in the car's aerodynamic drag. Instead of the previously all-enveloping, twin-finned roof, a wrap-around screen and single large tailfin were employed, in a manner very similar to the 1955 Le Mans-winning Jaguar D-Type
Jaguar D-type
The Jaguar D-Type, like its predecessor the C-Type, was a factory-built race car. Although it shared the basic straight-6 XK engine design with the C-Type, the majority of the car was radically different...
cars. The compulsory second seat was still in place, but was covered by a solid tonneau
Tonneau
right|thumb|260px|1903 [[Ford Model A |Ford Model A]] rear-door TonneauTonneau cover , describes a hard or soft cover used to protect unoccupied passenger seats in a convertible, roadster, or for a pickup truck bed. Hard tonneau covers open by a hinging or folding mechanism while soft covers open...
.
Competition history
The Bristol 450 made its race debut at the 1953 24 Hours of Le Mans1953 24 Hours of Le Mans
The 1953 24 Hours of Le Mans was the 21st Grand Prix of Endurance, and took place on June 13 and 14 1953. It was also the third round of the World Sportscar Championship....
race. Two cars were entered, with a third held back as a spare. Unfortunately for Bristol, both were out before half distance with near-identical failures. In each case the balance weights became detached from the crankshaft. This caused the rear wheels to lock at high speed, in turn causing the cars to veer off the road and catch fire. However, in the laps that the cars had managed to complete, Jack Fairman
Jack Fairman
Jack Fairman was a British racing driver from England. He participated in 13 Formula One Grands Prix, debuting on 18 July 1953...
easily managed to post a new lap record for the 2 litre class. The cars were rebuilt at the factory, incorporating the revised aerodynamic bodywork, and only three weeks later, in early July, were entered into the 12h race at Reims
Reims-Gueux
Reims-Gueux was a triangular motor racing road course near Reims, France, which hosted 14 French Grands Prix.Reims-Gueux was first established in 1926 on the public roads between the small French villages of Thillois and Gueux. The circuit had two very long straights between the towns, and teams...
. The Reims track shared the high speed character of its French cousin at La Sarthe
Circuit de la Sarthe
The Circuit des 24 Heures, also known as Circuit de la Sarthe, located near Le Mans, France, is a semi-permanent race course most famous as the venue for the 24 Hours of Le Mans auto race. The track uses local roads that remain open to the public most of the year...
and suited the Bristol's character well. Although one car again broke down, this time due to transmission failure on the first lap, the remaining car cruised to a class victory and finished fifth overall.
The cars returned to France in early October for a series of reliability speed record attempts at the Montlhéry circuit. All were successful, and on 6 October 1953 the Bristol team set six records for the 2 litre class, for endurance over a variety of distances and times: 200 miles (125.87 mph); 500 km (116.10 mph); 500 miles (112.25 mph); 1,000 km (115.49 mph); 3 hr (116.42 mph); and 5 hr (115.43 mph).
The cars did not race again until the 1954 Le Mans race
1954 24 Hours of Le Mans
The 1954 24 Hours of Le Mans was the 22nd Grand Prix of Endurance, and took place on June 12 and 13 1954. It was also the fourth round of the World Sportscar Championship.-Official results:-Not Classified:...
. This time three cars were entered, with uprated engines and the improved aerodynamic bodywork. In contrast with the previous year, and despite torrential rain, all three cars finished the race, coming home in first, second and third in their class and 7th, 8th and 9th overall. Their performance also earned Bristol the team prize. The 450s remained in France for the Reims race, and again demonstrated unblemished reliability, taking 2nd, 3rd and 4th in class, beaten only narrowly by a Ferrari
Scuderia Ferrari
Scuderia Ferrari is the racing team division of the Ferrari automobile marque. The team currently only races in Formula One but has competed in numerous classes of motorsport since its formation in 1929, including sportscar racing....
for the class victory.
Once again, Bristol was only interested in high-speed endurance racing and so the cars were put into storage until the 1955 24 Hours of Le Mans
1955 24 Hours of Le Mans
The 1955 24 Hours of Le Mans was the 23rd Grand Prix of Endurance, and took place on June 11 and 12, 1955. It was also the fourth round of the World Sportscar Championship....
. With the revised, open bodywork the cars repeated their dominance of the previous year. Again they finished 7th, 8th and 9th overall, 1st, 2nd and 3rd in class, and took the team prize. The lead car averaged over 100 mi/h for more than the first 12 hours – only slowing on team orders – and spent only 15 minutes in the pits during the entire 24 hour race!
However, despite this dominant victory record, the tragic accident during the race
1955 Le Mans disaster
The 1955 Le Mans disaster occurred during the 1955 24 Hours of Le Mans motor race, when a crash caused large parts of racing car debris to fly into the crowd. The driver was killed, as were 83 spectators. A further 120 people were injured...
and a corporate shift away from emphasis on their products' sporting credentials persuaded Bristol to withdraw from racing immediately following their 1955 Le Mans triumph. Their prize monies were quietly donated to the relief fund for victims of the disaster, and they withdrew from the 1955 Reims race. Rather than allow poorly financed and inexperienced privateer teams to run their cars in inappropriate events, on their return to the factory the best car was selected, built up using the best components from all chassis, and the remainder scrapped. This car was retained by Bristol Cars owner and former racing driver Tony Crook
Tony Crook
Anthony Crook is a former racing driver from England. He was born in Manchester. He participated in 2 World Championship Formula One Grands Prix, debuting on 19 July 1952. He scored no championship points. He also participated in several non-Championship Formula One races...
for the next 30 years, on occasion loaning its engine to one of Crook's road-going saloons. In the late 1990s it was fully restored to 1955 specifications, and currently makes infrequent appearances at historic race meetings.