Brabham BT55

Racing car


Category = Formula One | Car_name = Brabham BT55
Constructor = Motor Racing Developments Ltd. | Team = Brabham
Designer = Gordon Murray
Drivers = Riccardo Patrese,
Elio de Angelis,
Derek Warwick
Test drivers = -
Chassis = Carbon fibre composite/Kevlar monocoque
Front suspension = Pullrod double wishbone
Rear suspension = Pushrod double wishbone
Engine position = mid-mounted
Engine name = BMW,
Capacity = 1.5 litre
Turbo/NA = turbocharged,
Configuration = straight-4 (non-structural),
Gearbox name = Weissman
Gears = 7-speed
Differential =
Type = manual
Tyres = Pirelli
Fuel =
Debut = 1986 Brazilian Grand Prix
Races = 16
Cons_champ = 0
Drivers_champ = 0
Wins = 0
Poles = 0
Fastest_laps =
Last_season = 1986
The Brabham BT55 was a Formula One racing car designed by Gordon Murray and David North for the Brabham team owned by Bernie Ecclestone. It used a BMW four cylinder turbocharged engine tilted over on its side to allow a clear supply of air to the rear wing. The car competed during the 1986 Formula One season. It was not successful and its introduction coincided with the end of Brabham's time as a competitive team. Murray's next car, McLaren's MP4/4, is usually claimed to be based on the same principles and won 15 of 16 races in 1988.

Concept

In the early 1980s, Formula One design had become dominated by ground effect, an aerodynamic effect which sucked cars down onto the track at high speed, giving them increased grip and allowing them to go round corners faster. The effect was created by shaping the underside of the car. The Fédération Internationale de l'Automobile mandated that cars must have flat undersides from the 1983 season onwards to eliminate ground effect and reduce speeds. Brabham's first attempt to meet the new regulations, the BT52, had been very effective, winning the drivers' title for Nelson Piquet in 1983. The BT53 and BT54 which followed were developments of the same aerodynamic concept, but by 1985 the team had reached the limit of aerodynamic development of the design. The 1985 car won only one race, and Murray decided that a radical approach was needed.

A conventional straight four engine, like the BMW Brabham was using, is tall relative to other engine configurations like 'vee' or 'boxer' where the cylinders are tilted away from the vertical. In order to create a large amount of downforce by other means, Murray came up with the concept of a 'lowline' car, with very low bodywork over a tilted over engine, which would allow a large supply of air to reach the rear wing undisturbed. A similar approach of laying down a tall engine to reduce cross sectional area was used in 1950s Championship Car roadsters by the American Kurtis-Kraft and Epperly racing car constructors and by Colin Chapman in the 1958 front-engined Formula One Lotus 16. [Bamsey (1988) p.65] [Hodges (1990) p.143] In order to achieve this, the driver was placed in a lying down position and BMW designed a special version of their four cylinder turbocharged engine with the tall engine block, normally positioned vertically in the car, tilted almost horizontally (18° from horizontal) to reduce the overall height of the unit. Drivers had been placed in the reclining position by Lotus in the early 1960s, but were sitting more upright again by the 1980s.

Chassis and suspension

The car was also Brabham's first fully composite monocoque. Although the team had been the first in Formula One to make use of carbon fibre composite panels in the structure of the car in 1978, Murray had been reluctant to design a fully composite car until he understood how it would perform in a crash: he eventually persuaded Ecclestone to finance a fully instrumented crash test of a BT49 chassis. [Howard (2006) p.52] He was not happy to employ a two piece composite chassis, preferring to develop a technique which produced a seamless monocoque of carbon fibre/kevlar composite over a nomex honeycomb. This structure was reinforced, like his earlier designs, by machined aluminium bulkheads. [Bamsey (1988) p.70]

Engine and transmission

At Murray's request, BMW designed a special version of their M10 inline four engine. Differences from the standard upright unit were few, mainly concerning the oil scavenging system and the cradle in which the unit was mounted. Like the upright version the unit was not a stressed component. Mounting the engine on its side meant that the power takeoff from the unit, previously at the bottom, was offset to one side. A special gearbox from American gearbox specialists Weissman was produced to deal with this.

Racing history

The aerodynamic concept worked, in that the car produced plenty of downforce. However, this was matched by an unexpectedly high level of drag which limited the performance of the car. The tilted over engine and specially designed gearbox also produced many reliability problems. The team scored just two points all season, both by driver Riccardo Patrese.

The team's other driver, Elio de Angelis, was the first driver to die in a works Brabham when he was killed in an accident while testing at the Circuit Paul Ricard in France. The car survived the accident relatively intact and de Angelis had only minor injuries. There were very few track marshals at the circuit and he was trapped in the car and killed by oxygen deprivation due to a fire before they arrived. He was replaced by Derek Warwick, reportedly the only driver who did not call team owner Bernie Ecclestone to ask about the drive.

Aftermath

Murray has since summarised the reasons for the car's failure:"...I was much too ambitious in how much we lowered it. The rather tall BMW had to lie down so far it produced a heavily offset crank needing a special gearbox and drivetrain, and what I did wrong was to try to do it in the time available.

Secondly, the engine never worked properly in the lay down position. The exhaust and turbo system was a nightmare and it had incurable oil surge and drain problems in corners. One way it was OK, but not the other.

The weight distribution gave dynamic centre of gravity movements that messed up the traction.

And then Bernie [Ecclestone, owner of the team] who is totally non-technical and had always left that side completely to me, started to get involved on the technical side. We had had 16 years with never a cross word until then, and things were changing with his deeper and deeper involvement in [the Formula One Constructors Association] . Then McLaren made approaches to me and I just felt it was the end of the road at Brabham." [Stanniforth (1988, 1994) pp.168–169]

Murray left the team at the end of the year to join rivals McLaren. His 1988 car, the McLaren MP4/4 is usually said to have been based on the BT55 concept, although McLaren team manager Jo Ramirez has downplayed Murray's involvement in the design of the MP4/4. The lying down driver position has again become the standard in Formula One since 1988.

Brabham regrouped with the much more conventional BT56, but had to re-use the tilted over BMW engine and gearbox as the German manufacturer, already reducing its involvement in Formula One, had sold the supply of conventional engines to Megatron for use by other teams. BMW pulled out of Formula One altogether at the end of 1987, and the Brabham team missed the 1988 season.

Footnotes

References

;Books
* cite book
last = Bamsey
first = Ian
coauthors = Benzing, Enrico; Staniforth, Allan; Lawrence, Mike
title = The 1000 BHP Grand Prix cars
publisher = G T Foulis & Co Ltd
date = 1988
id = ISBN 0854296174
*cite book
last = Hodges
first = David
coauthors =
title = A-Z of Formula Racing Cars 1945-1990
publisher = Bay View books
date = 1998
id = ISBN 1-901432-17-3
*cite book
last = Ramirez
first = Jo
coauthors =
title = Memoirs of a Racing Man
publisher = Haynes Group
date = 2005
id = ISBN 1-84425-238-8
* cite book
last = Staniforth
first = Allan
coauthors =
title = Competition Car Suspension
publisher = Haynes
date = 1988, 1994
id = ISBN 0-85429-956-4;Magazines
* cite news
last = Howard
first = Keith
title = Carbon fibre
page = 52
language =
publisher = Motorsport
date = June 2006