THE SHARPESTT

In the 1920s, Razor Blade took Aston Martin hunting for speed records. Now it takes John Simister to his limits

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Aerodynamic drag. The less of it a moving object has, the faster it will go on a given amount of power. So if you want to break a speed record, reduce the drag.

That drag is the product of a shape’s drag coefficient (the 'Cd' much vaunted by many a maker after Audi displayed 'Cd 0.30' on the rear side windows of its third-generation 100 in the early 1980s) multiplied by the frontal area. A 1920s open-wheeled racing car is unlikely to score well on the Cd bit, detail smoothing notwithstanding, but there were exciting possibilities with the 'A' part. The car you see here, hailed as the thinnest racing car ever made, is the result.

Seen from above, it resembles a blade. If you view it from the rear against a light background, you might not even notice the body at first. This is the Aston Martin Razor Blade.

This very sharp-looking car’s reason for its 1922 creation was to break the record for the highest speed maintained over an hour in a ‘light car’ – one with an engine of no more than 1500cc. Brooklands was the obvious British venue for such an attempt, 100 miles or more in the hour the aim, but Aston Martin was being harried in this quest by rival AC. The pressure was on.

At the front, the new car's chassis (numbered 1915) was much like that of 1921’s A3, the third Aston Martin to be built and nowadays the oldest survivor of the marque. But this chassis width was reduced sharply aft of the engine, as a body just 18.5in wide and the very narrow rear track show. That body was shaped and built by de Havilland, with obvious aeronautical expertise featuring a smooth undertray and a vertical slot in the tail’s extremity to allow the escape of air from inside the Razor Blade and make it act less like a windsock.