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Joakim Bonnier 1966 in the Chaparral 2D
during practice at the Nürburgring.
Mike Spence 1967 in the Chaparral 2F
during practice at the Nürburgring.

Chaparral Cars was a United States automotive company which built prototype race cars from the 1960s through the early 1970s. Chaparral was founded by Jim Hall, a Texas oil magnate with an impressive combination of skills in engineering and race car driving. Throughout the 1960s and 1970s, Chaparral's distinctive race cars experienced strong success in both American and European racing circuits. Despite winning the Indy 500 in 1980, the Chaparrals left motor racing in 1982. Chaparral cars also featured in the SCCA/CASC CanAm series and in the European FIA Group 7.

Chaparral was the first to introduce effectively designed air dams and spoilers ranging from the tabs attached to the earliest 2 model to the driver-controlled high wing 'flipper' on the astoundingly different looking 2E, all the way through to Hall's most idealistically inspired creation, the 2J, the car that would forever be known as the 'vacuum cleaner'. The use by Jim Hall of a semi-automatic transmission in the Chaparral created flexibility in the use of adjustable aerodynamic devices.

The development of the Chaparral chronicles the key changes in race cars in the '60s and '70s in both aerodynamics and tires. Jim Hall's training as an engineer taught him to approach problems in a methodical manner and his access to the engineering team at Chevrolet as well as at Firestone changed aerodynamics and race car handling from an art to empirical science. The embryonic data acquisition systems created by the GM R&D group aided these efforts. An interview with Jim Hall by Paul Haney [1] illustrates many of these developments.

Contents

Models

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1

The Chaparral 1 was the first car to carry the Chaparral name and marked the transition of Jim Hall from an entrant to a constructor. Built by Troutman and Barnes, the Chaparral 1 was a conventional front-engined car, a development of the Scarab sport car first built for Lance Reventlow in 1957. Jim Hall raced it successfully through 1961, 1962 and 1963 while he created the design for Chaparral 2. As it was not a design owned by Jim Hall, other cars were sold to cut costs. It was the only Chaparral to be raced by someone other than Chaparral cars.

2

The Chaparral 2-Series was designed and built to compete in the United States Road Racing Championship and other sports car races of the time, particularly the West Coast Series that were held each fall. Following the lead of innovators like Bill Sadler from Canada and Colin Chapman who introduced rear engined cars to Grand Prix cars in Europe (where Jim Hall had raced in Formula 1), its basic design concept was a rear engined car.

First raced in 1963, it was developed into the dominant car in the series in 1964 and 1965. Designed for the 200 mile races of the sports car series, it was almost impossible to beat. It proved that in 1965 by winning the 12 Hours of Sebring on one of the roughest tracks in North America.

As the car was being developed, Jim Hall took the opportunity to implement his theories on aerodynamic force and rear wheel weight bias.

In addition, the Chaparral 2-Series featured the innovative use of fiberglass as a structural element. Hall also developed 2-Series cars with conventional aluminum chassis.

It is very difficult to identify all iterations of the car as new ideas were being tested continually. There are three generally accepted variants:

  • The 2A is the car as originally raced, featuring a very conventional sharp edge to cut through the air. It also featured a square tail with a concave tail reminiscent of the theories of Dr Kamm. Almost immediately an issue with the front end being very light at speed with a consequent impact on steering accuracy and driver confidence. The first aerodynamic appendages began to appear on the 2A.
  • The 2B was the name applied to the cars with the full package of “aero tweaks”, chin spoilers, fender slots and rear spoiler.
  • The 2C was the name applied to the car with the first in-car adjustable rear wing which was designed to be flat on the straight and tipped up to add rear downforce under braking and in corners. This was a direct benefit of the automatic transmission which kept the left foot free to operate the wing mechanism. The 2C was based on a Chevrolet designed aluminum chassis and was a much smaller car in every dimension than the 2A. Without the natural non-resonant damping of the fiberglass chassis, Jim Hall nicknamed it the EBJ, “Eye Ball Jiggler.”

Coincidental with the development of aerodynamics was Hall's development of race tires. (This is a complex subject that should have a separate article.) Jim Hall owned Rattlesnake Raceway adjacent to his race shop; that proximity allowed him to participate in much of Firestone's race tire development.

A two-article series in "Car and Driver" magazine featured Jim Hall's design theories. The article turns speculation about vehicle handling into applied physics. It was the precursor to the elaborate data collection and management of current racing teams. Hall's methodology was probably the first documented approach to measuring and managing the properties of race cars.

2D

The 2D was a closed cockpit variant of the 2 series (which were all open cockpit designs), designed for endurance racing in 1966. It won at 1000 km Nürburgring in 1966 with Phil Hill and Joakim Bonnier driving. It also competed in the 1966 24 Hours of Le Mans, withdrawing after 111 laps.

2E

The 2E was based on the Chevrolet designed aluminum 2C chassis and presented Jim Hall's most advanced aerodynamic theories to the racing world in the 1966 inaugural Can Am championship. The 2E established the paradigm for virtually all racing cars built since. It was startling in appearance, with its radiators moved from the traditional location in the nose to two ducted pods on either side of the cockpit and a large wing mounted several feet above the rear of the car on struts. The wing was the opposite of an aircraft wing in that it generated downforce instead of lift and was attached directly to the rear hubs, loading the tires, for extra adhesion while cornering. A ducted nose channeled air from the front of the car up, creating extra downforce as well. By depressing a pedal that was in the position of the clutch pedal on a car with a manual transmission, Hall was able to feather, or flatten out, the angle of the wing when downforce was not needed, such as on a straight section of the track, to reduce drag and increase top speed. In addition, an interconnected air dam closed off the nose ducting for streamlining as well. When the pedal was released, the front ducting and wing returned to their full downforce position. It was a brilliant design. But the moveable-wing was banned by the FIA so Jim Hall had to make do with a fixed-wing which was not adjustable by the driver during the race. Within two years every sports racing car as well as formula one car had wings on tall struts, although many were not as well designed as Hall's and the resulting accidents from their failures caused the high wings to be outlawed by the sanctioning bodies.

The 2E scored only one win in Laguna Seca with Phil Hill driving, but the reason for this may have been the larger engines the other competitors were using. Hall stuck to an aluminum 5.3 liter Chevrolet engine in his lightweight racer while the other teams were using 6 and sometimes 7 liter iron engines, trading weight for power.

The 2E was a crowd favorite and remains Jim Hall's favorite car.

2F

Hall applied the aerodynamic advances of the aluminum 2E to the older fiberglass chassis closed-cockpit 2D for the 1967 racing season. A movable wing, on struts, loaded the rear tires while an air dam in the front released pressure to keep the suspension from compressing at high speeds, and the radiators were moved to positions next to the cockpit. An aluminum 7 litre Chevrolet engine replaced the 5.3 litre engine of the 2D. While always extremely fast, the extra power of the larger engine was too much for the automatic transmission to handle and it broke with regularity. When a solution was finally found to the transmission problems, the 2F scored its only win on 30 July 1967 in the BOAC 500 at Brands Hatch with Phil Hill and Mike Spence driving. After this race, the FIA changed its rules, outlawing not only the 2F but the Ford Gt Mark 4 (winner at LeMans) and the Ferrari P4 (winner at Daytona, 2nd at LeMans) as well.

As with the 2D, the 2F raced wearing Texas license plates.

2G

The 1967 2G was a development of the 2E. It featured wider tires, and a 427 aluminum Chevy engine. While on par with his competitors in terms of power, the lightweight 2C chassis was stretched to the limit and it was only Hall's driving skill that kept the car competitive. For the 1968 Can Am series, still larger tires were added when the 2H was not ready to race.

Jim Hall's racing career was effectively ended in a savage crash at the Stardust Grand Prix, although he did drive in the 1970 Trans Am series while fielding a team of Chaparral Camaros .

2H

Never one to be complacent, Jim Hall noted that the increasing downforce also created enormous drag. Seeking a competitive edge, the 2H was built in 1969 as the replacement for the 2G to minimize drag rather than maximize downforce. However, the anticipated gains in speed were more than offset by the reduced cornering speeds and the car was consistently slower than anticipated.

Generally deemed a failure, it eventually sprouted a huge wing.

2J

The Chaparral 2J at the Goodwood Festival of Speed.

The most unusual Chaparral was the 2J. In addition to a powerful 700 hp engine, and a three-speed semi automatic transmission, the back of the 2J housed two 17-inch fans driven by a single 45 hp snowmobile engine. The Can Am Series had no engine size limit, so the snowmobile engine wasn't affected by an engine displacement maximum. The purpose of the fans was to 'suck' air from under the car to provide downforce. This gave the car tremendous gripping power and enabled greater maneuverability at all speeds, which cannot be achieved by simpler aerodynamic devices such as diffusers and wings. Since it created the same amount of vacuum under the car at all speeds, down-force did not decrease at lower speeds. With other aerodynamic devices, down-force decreases as the car slows down or achieves too much of a slip angle, both of which were not problems for the 'sucker car'. It also had ground effect Lexan-plastic skirts to keep air from leaking in, a technology that would appear in Formula One several years later.

The 2J competed in the CanAm series and often qualified at least a couple of seconds quicker than the next fastest car, but was not a success because it was plagued with mechanical problems. It ran for only one racing season in 1970 after which it was outlawed by the SCCA (even though it was approved by the SCCA prior to the car's first race). The SCCA succumbed to pressure from other teams, McLaren in particular, who argued that the fans constituted 'movable aerodynamic devices' which were outlawed by the international sanctioning body FIA (which was first applied against the 2E's adjustable-wing). There were also complaints from other drivers saying that whenever they drove behind it the fans would throw stones at their cars. McLaren argued that if the 2J was not outlawed, it would likely kill the CanAm series by totally dominating it - ironically, something McLaren had been doing for years[1]. A similar suction fan was used in Formula 1 eight years later for the 1978 Swedish Grand Prix, by the Brabham BT46B but was banned soon after.

2K

Rutherford's 2K on display in the Indianapolis Motor Speedway Hall of Fame Museum.

The 2K was a USAC ground effect car which was designed by Briton John Barnard. It won the 1980 Indianapolis 500 with Johnny Rutherford.

Museum

In 2005 a wing of the Permian Basin Petroleum Museum in Midland, Texas was dedicated to the permanent display of the remaining Chaparral cars and the history of their development by Midland native Jim Hall.

Tributes

References

  1. ^ CHAPARRAL Complete History of Jim Hall's Chaparral Race Cars 1961 -1970 by Richard Falconer and Doug Nye, 1992 Motorbooks

External links


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