Brabham-BMW BT55 (aborted in June 2011)

On 29th of April 2011, I started another car, namely the Brabham-BMW BT55, beside my Red Bull RB7. On 12th of June, I aborted the manufacturing of that car and concentrated on the RB7.

The Brabham-BMW BT55, went into history as the most powerfull F1 car ever built. In 1984 and ’85, the successful times were over for the Brabham Team after the two world championship titles of “their” driver Nelson Piquet. The BT52 to BT54 series was at the end of its development. The aerodynamical concept of the 1983 championship winning BT52 wasn’t already a stroke of genius. In 1984 it was even enough for two wins and in ’85 only the win in France was at the credit side of the Brabham Team. Gordon Murray, chief designer of Brabham, recognized, that it was time for a radical change in car design. He tried to get the bodywork of the car as low as possible, to get a much cleaner airflow to the important rear wing. BMW helped in delivering Brabham with a modified engine whose cylinder axis was tilted 72° to the vertical, to get the bodywork lower. In qualifying trim, these engines reached a power of almost 1010kW (1370hp). With this engine, the side pods top edge of the car were only about 360mm above the reference plane. For comparison, at current F1 cars, the top edge of the side pods are lying on a level of the cockpit area, which is 550mm above the reference plane (lowest not suspended part). The highest part of the car, except rear wing and roll over hoop, was about 600mm above the ground.

Sadly, the BT55 proved not to be a top car. Even it was maybe the most elegant car of the middle 80’s, the BT55 was only be able to secure two points and the 9th place at the 1986 constructors championship. Too less for the requirements of Gordon Murray. He left Brabham at the end of the season in direction of McLaren. His concept earned glory in shape of the McLaren MP4-4 which won 15 of 16 races in 1988. But that’s another story.

That's my BT55 at aborton state in June 2011.

That’s my BT55 at abortion state in June 2011. Because I wanted to concentrate on the RB7, I decide to defer the manufacturing of the this car. I guess, I’ll never finish this car. But who knows, maybe some day…


A front view of the car. At that times, the maximum width of the cars was 2150mm (compared to the 1800mm of todays cars). The front wing was 1500mm wide (today 1800mm).


The front area. You can see the three pedals (semi-automatic clutch was introduced somewhere in the early 90s ) and the three fluid reservoirs (front and rear brake circuit and clutch fluid).


Front suspension in typical mid 80’s layout. Double wishbones with pull rod activated inboard spring damper unit and a track rod. At the front wing you can see a gurney flap across the whole width of the adjustable flap.


Front suspension viewed from behind. Don’t ask me why Brabham gave the lower suspension arms an aerodynamical profile and the upper ones not. The uprights aren’t very detailed. Today I would do that better.


The driver’s seat. My very first carbonized part ever. 🙂 In my point of view, it’s unique, to have a separation of the driver’s feet area as it is at this car. You can see the separation on the front cockpit bulkhead.


The BMW engine was a not fully stressed member of the car. That was one of the disadvantageous aspects of the four-cylinder engine. At the engines front end, you can see the aluminium bulkhead, which is the main part of the frame around the engine. Of course the gearbox was a fully stressed member.


The BMW M12 M-Power engine was the most powerfull F1 engine ever. In qualifiying trim, it reached a power of over 1000kW (1370hp). Paul Rosche, chief engineer at BMW, said: “…we are at about 1400hp. For sure there are more, 1450 maybe 1500, but the bench had reached its limit at 1400.”


I’ve never finished the M12 engine. The whole water-and oil circuit is missing. Also the turbo charger and the exhaust system. Also the gearbox is far away from finish.


Top view of the car in abortion state.


The moncoque was Brabhams first full carbon fibre shell. Gordon Murray was always sceptical on the static strenght of the pure carbon fibre. So he reinforced every car befor with an aluminium core.


Brabham and the american specialist Weissmann developed a gearbox to handle the enormous loads that came from the turbo charged BMW engine.


Developed out of a production engine, this machine was used in Formula 2 and touring cars before it was upgraded for F1 use. Out of this resulted the problems the engine had by producing more and more power.


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About paulsf1

My name is Paul Bischof. I’m a student in mechanical engineering at the Technical University of Graz in Austria, expected finishing in February 2016. Since I was eight years old, I am building model planes out of paperboard. Since 2004 I scratch (that means building without an assembling set) Formula 1 and sportscars in 1:10th scale. The average time I need for such a car is around 400 to 700 hours within 4 to 8 months. One car has around 3500 up to 5000 single components. On this blog, you can take a look on my work and later, after my studies, hopefully you can see me in Formula 1.

4 responses to “Brabham-BMW BT55 (aborted in June 2011)”

  1. SuperSwede says :

    I would REALLY like to see you finish this build. But even in this state it is a very interesting “show piece”. I´m a BIG Formula 1 fan but an even BIGGER BMW fan. What Paul Roche did with the M10 based M12/13 is fantastic. So if you decide that you don´t want to finish the complete car, you can perhaps finish the engine. It would be a great piece in itself.

    Cheers & keep up the FANTASTIC work. 🙂


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