Lotus Mk VIII, Mk IX and Mk X aerodynamic sports racing car 1955

Lotus Mk IX proposed by Bonhams Auction at 2009 Retromobile in Paris. The car was sold for 80.500 Euros.

Colin Chapman's emergent Lotus series of ever-more sophisticated competition cars featured cycle mudguard or open-wheeled trials special-type design until what proved to be his landmark design for the Lotus Mark VIII series.

Lotus Mk VIII exhibited by Movendi at 2016 Retromobile in Paris

These sports-racing cars were the first to feature fully wheel-enveloping aerodynamic bodywork conceived and designed by De Havilland Aircraft aerodynamicist Frank Costin. His brother Michael was one of Colin Chapman's closest and most influential collaborators, and would become technical director of the growing Lotus Engineering Company before joining engineer Keith Duckworth in partnership as the 'Cos' of Cosworth.

Lotus Mk VIII exhibited by Movendi at 2016 Retromobile in Paris

It was during the winter of 1953 that Colin Chapman began design study for such a car, for which detail chassis design and stress calculation was completed by Peter Ross and Gilbert 'Mac' Mackintosh. The result was a  fully triangulated multi-tubular spaceframe chassis

Manufactured by Dave Kelsey and John Teychenne's Progress Chassis Company in Edmonton, North London, the chassis frame was welded together from 1¼-inch 20-gauge tubing.

Lotus Mk VIII exhibited by Movendi at 2016 Retromobile in Paris

Once fitted with the Frank Costin-designed aerodynamic body, fashioned in 20-gauge aluminium sheet by specialist Williams & Pritchard, also of Edmonton, the completed chassis/body unit for the Mark VIII weighed less than a set of five wheels and tyres. The frame alone scaled barely 35lbs. But the original chassis design proved a nightmare in practical terms, for its complex triangulation prevented engine removal in less than 12 hours, and replacement a further 24! Even then the engine had to be largely dismantled in the process.

Lotus Mk IX at 2018 Classic Le Mans -Photo Philippe Girardon

The following Lotus Mk IX and Mk X were evolution of the first aerodynamic Lotus. According to sources, seven to nine Mk VIII , 32 models Mk IX and seven Mk X sports cars were produced, making it quite exclusive an automobile . The cars used mechanical components from large production popular British automobiles of the moment, like Ford, MG. A few models were equiped with specialized engine like Connaught, Coventry Climax or Bristol.

Lotus Mk IX at 2018 Classic Le Mans- Photo Philippe Girardon

The Mark IX was slightly shorter than the 1954 Mark VIII model and featured tall, thicker and shorter-chord rear fins – which were at that time something of a Frank Costin trademark. The driver was fared into place behind a fully wrapped-around perspex windscreen moulding, with a tonneau covering the passenger seat area beside him. The chassis used some of the lightest-gauge tubing yet employed by Colin Chapman. With the entire upper half of the forward bodywork being removable, access was greatly improved compared to the Mark VIII and a tail lid exposed the final-drive and inboard Alfin drum or later Girling disc brakes.

Lotus Mk IX proposed by Bonhams Auction at 2009 Retromobile in Paris. The car was sold for 80.500 Euros.

Early examples used specially-cast elektron finned brake drums but these were soon replaced by new Girling discs. Ford steering was used or in at least one of the cars a rack-and-pinion system modified to suit the Lotus front suspension. Colin Chapman and Ron Flockhart participated with a Lotus Mk IX,  propelled by a Coventry Climax FWA engine, at 1955 Le Mans 24 Hours but did not finish. The Mark IX had, however, lapped the Sarthe circuit at over 97mph – the fastest lap by any competing car relative to engine size and horsepower.

The exquisitely proportioned, beautifully compact little Lotus-Climax Mark IX was one of the most popular and widely successful small-capacity sports-racing cars of its contemporary period in 1954-55 not only in the United Kingdom but also in the U.S.A.; two Lotus Mk IX prototypes were entered at the Sebring 12 Hours in 1955.

Notable racing drivers who excelled in Mark IXs include Peter Ashdown and Peter Lumsden. John Bolster of 'Autosport' magazine track-tested both the works' Mark IXs, with alternative MG and Climax power, the latter being the faster, achieving a measured maximum speed of over 127mph and accelerating from 0-60mph in 7.8 seconds.

Lotus Mk X exhibited by Galerie des Damiers at 2019 Retromobile in Paris

one Lotus Ford Mk IX aerodynamic sports car was sold for 80,500 Euros at Bonhams Auction during 2009 Retromobile in Paris. the car is registered 'WFF 747' in the article's illustrations. It is powered by the 1172cc Ford Ten side-valve engine.

Lotus Mk X exhibited by Galerie des Damiers at 2019 Retromobile in Paris

one 1955 Lotus Bristol Mk X was sold for 110,400 Euros at 2006 Bonhams Auction at Goodwood United Kingdom. This Lotus Mk X was based on original Mk VIII chassis N°108.

Lotus Mk X exhibited by Galerie des Damiers at 2019 Retromobile in Paris

one 1955 Lotus Climax Mk IX two seater sports racing car was sold for 149,171 Euros at 2012 Bonhams Auction at Goodwood United Kingdon.

Lotus Mk X exhibited by Galerie des Damiers at 2019 Retromobile in Paris

source: Bonhams Auction Archives

Wallpapers of Lotus Mk VIII, Mk IX and Mk X aerodynamic sports racing car 1955(click on image to enlarge)