The Railton Special, later rebuilt as the Railton Mobil Special, is a one-off motor vehicle built for John Cobb's successful attempts at the land speed record.
It was powered by two supercharged W12-block Napier Lion VIID (WD) aircraft engines. These engines were the gift of Betty 'Joe' Carstairs, who had previously used them in her powerboat Estelle V. Multiple engines weren't a new technique, having already been used by the triple-engined White Triplex and the Railton Special's contemporary rival, Captain Eyston's twin-engined Thunderbolt. With the huge powers thus available, the limitation was in finding a transmission and tyres that could cope. Reid Railton found a simple and ingenious solution to this by simply splitting the drive from each engine to a separate axle, giving four wheel drive.
On 15 September 1938, the Railton Special took the land speed record from Thunderbolt at 353.30 mph (568.58 km/h), also being the first to break the 350 mph (560 km/h) barrier. Eyston re-took the record within 24 hours, holding it again until Cobb took it a year later on 23 August 1939 at a speed of 369.70 mph (594.97 km/h).
After World War II, further development and sponsorship by Mobil Oil led to re-naming as the 'Railton Mobil Special'. It was the first ground vehicle to break 400 mph (640 km/h) in a measured test. On September 16, 1947 John Cobb averaged 394.19 mph (634.39 km/h) over the measured mile in both directions to take the world land speed record.
It weighed over 3 tonnes and was 28' 8" long, 8' wide and 4'3" high. The front wheels were 5'6" apart and the rear 3'6". It was designed by Reid Railton and is currently on display at the Thinktank museum in Birmingham, England.
A truck was used to push-start the Railton on September 15, and Cobb climbed through the truck to avoid stepping on the slim four-hundredweight aluminium shell and dropped into his cockpit after walking over planks placed on the hull. Cobb's car would go on to hold the land speed record until 1963, a remarkable 16 year run, and remains to this day a fitting tribute to both designer and driver. Reid Railton used many unorthodox methods to achieve his result. He started with an S-shaped backbone chassis, and used two second-hand 1928 Napier Lion aero engines from a motor boat, but set them at an angle, one driving the front wheels and the other the rear wheels. The special lightweight body shell was made in one piece and had to be taken off for re-fuelling and tyre changes between the two runs necessary for the record. The whole body, less its undershield, could be lifted off by six men. Cooling was also by a novel method, no radiator being used, but an ice-tank which was repacked between runs. The melted ice was also used to take heat away from the drum brakes, before being ejected from the non-circulatory system.