The BT49 was created in 1979 as a short-notice replacement for the team’s Alfa Romeo-engined BT48, after Brabham team owner Bernie Ecclestone decided to end his relationship with the Italian engine manufacturer. The BT48 had not been a great success, and Ecclestone was concerned about being overshadowed by Alfa Romeo’s own Formula One efforts. Motorsport author Alan Henry writes that Ecclestone did not want his team to take second place to an Alfa Romeo works team, and that the team designing Alfa Romeo's cars was drawing on Brabham knowledge. The design shift coincided with a growing emphasis on aerodynamic ground effect, pioneered by the Lotus 78, over pure engine power. To focus on aerodynamics, the Brabham team reverted to the reliable and widely used Ford Cosworth DFV engine, which they had last used in 1975. Three BT49s were designed and built in only six weeks for the Canadian Grand Prix.
The BT49 features a monocoque chassis constructed from sheet aluminium alloy reinforced with carbon fibre composite panels, making it one of the first Formula One chassis to incorporate carbon fibre structurally. The chassis is slightly longer than that of the BT48, with a revised design from the cockpit back, including modified sidepods and a reduced fuel tank capacity—from 45 to 38 imperial gallons (205 to 173 L)—to match the lower fuel consumption of the DFV engine compared to the Alfa Romeo. This resulted in a weight reduction of 35 pounds (15.9 kg) and 95 lb (43.1 kg) when fully fuelled.
The underside of the BT49 is shaped to generate downforce through ground effect, accelerating air beneath the car to reduce pressure and increase tyre grip. This provides higher cornering speeds with less drag than conventional wings. Initially, the reduced pressure area was sealed with sliding skirts that moved with the car’s suspension to prevent air leakage. Gordon Murray stated that the car's aerodynamics were its greatest strength: "It had more [downforce] than any other car and it all came from the ground effect. We ran the car with no front wing at all and scarcely any at the back."
The suspension uses double wishbones front and rear, with springs and dampers mounted out of the airflow and activated by pullrods. Anti-roll bars are fitted at both ends. Disc brakes are mounted outboard within the wheel hubs and activated by four-piston calipers. While initially using conventional steel brakes, the car was later fitted with lighter carbon-carbon discs and pads, a technology Brabham had introduced to Formula One in 1976. The wheels are 13 inches (330 mm) in diameter, occasionally using 15-inch (381 mm) wheels at the front. The car initially used Goodyear tyres, but switched to Michelin’s radial tyres for part of the 1981 season when Goodyear temporarily withdrew from Formula One.
The BT49 is powered by the Ford Cosworth DFV, a 2,993 cc (183 cu in) naturally aspirated V8 engine producing around 500 brake horsepower (373 kW) at 11,000 rpm. The engine is fully stressed, forming a structural component of the car. The car uses a six-speed gearbox designed by Brabham, with internal components from Hewland and a casing cast by Alfa Romeo.
The BT49’s racing career began at the 1979 Canadian Grand Prix following Niki Lauda’s sudden retirement. The car showed early promise, with Nelson Piquet running third before a broken gearbox forced retirement. In 1980, Piquet secured his first Formula One win at the United States Grand Prix West, leading the race from pole position. He also won at the Dutch and Italian Grands Prix, but lost the championship to Williams driver Alan Jones after an engine failure while leading the Canadian Grand Prix. The team finished third in the constructors’ championship.
In 1981, the BT49C was introduced, featuring a lighter chassis and a controversial hydropneumatic suspension system designed to exploit a loophole in the regulations regarding ride height. This system allowed the car to lower itself at speed to increase downforce. Frank Williams protested the system at the Argentine Grand Prix, objecting to the flexibility of the skirts, leading to a rule clarification from FISA. Despite the challenges, Piquet secured the 1981 World Championship, winning races in Argentina and San Marino.
The 1982 season saw the introduction of the BT49D, with a still lighter chassis. Piquet won the Brazilian Grand Prix but was later disqualified for running underweight due to the use of water-cooled brakes. The team, along with other DFV-powered teams, protested this decision and boycotted the subsequent race. Piquet and Riccardo Patrese secured further podium finishes, with Patrese winning the Monaco Grand Prix in a BT49.
The hydropneumatic suspension system used on the BT49C in 1981 prompted scrutiny from the sport’s governing body, FISA. Following protests and clarifications, the regulations were tightened to limit the exploitation of ground effects and ensure consistent ride heights. The 60 mm ground clearance rule was removed for the 1982 season, but the fixed skirts and very stiff suspension remained.
The Brabham BT49’s innovative use of carbon fibre and its focus on ground effect aerodynamics influenced subsequent Formula One car designs. The BT49 also served as a testbed for BMW’s turbocharged engine, which would power the BT50 and later cars. Since 1995, BT49s have competed regularly in the FIA Historic Formula One Championship, demonstrating the car’s enduring design and performance. Christian Glaesel won the 2005 FIA Historic Formula One Championship driving a BT49D, and Joaquin Folch won the 2012 championship in a BT49C.
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