Thunderbolt (car)

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Thunderbolt
Captain Eyston's Thunderbolt, 1938 (Our Generation, 1938).jpg
Overview
Manufacturer Bean Cars of Tipton
Production1
Body and chassis
Body style land speed record car
Layout twin steering front axles, single driven rear axle with twin-wheels
Powertrain
Engine Twin Rolls-Royce R V-12 aero engines
Transmission Coupled gearbox and single final drive
Dimensions
Kerb weight 7 tons

Thunderbolt was a British Land Speed Record holder of the 1930s, driven by Captain George E.T. Eyston.

Contents

Records held

Between 1937 and 1939, the competition for the Land Speed Record was between two Englishmen: Captain Eyston and John Cobb. Thunderbolt's first record was set at 312.00 mph (502.12 km/h) on 19 November 1937 on the Bonneville Salt Flats. Within a year Thunderbolt returned with improved aerodynamics and raised its record to 345.50 mph (556.03 km/h) on 27 August 1938. [1]

Bonneville Salt Flats densely packed salt pan in Tooele County in northwestern Utah

The Bonneville Salt Flats is a densely packed salt pan in Tooele County in northwestern Utah. The area is a remnant of the Pleistocene Lake Bonneville and is the largest of many salt flats located west of the Great Salt Lake. The property is public land managed by the Bureau of Land Management and is known for land speed records at the "Bonneville Speedway". Access to the flats is open to the public.

This record only stood for a matter of weeks before John Cobb's Reid-Railton broke the 350 mph (560 km/h) barrier and raised it to 353.30 mph (568.58 km/h) on 15 September 1938, as Eyston watched. This inspired him to take Thunderbolt to a new record of 357.50 mph (575.34 km/h). Cobb had held the record for less than 24 hours.

<i>Railton Special</i> land speed record-breaking car

The Railton Special, later rebuilt as the Railton Mobil Special, is a one-off motor vehicle designed by Reid Railton and built for John Cobb's successful attempts at the land speed record in 1938.

Eyston and Thunderbolt held the record for almost a year, until Cobb took it again at a speed of 369.70 mph (594.97 km/h) on 23 August 1939. This was the last record attempt before the outbreak of the Second World War. Although Cobb returned after the war and further developed his car to exceed 400 mph (640 km/h), Thunderbolt never attempted the record again.

Design

The leading Land Speed Record cars of the period had taken two approaches to obtaining power; using either the latest and most sophisticated aero-engines available or combining multiple engines. Thunderbolt used both techniques to produce an unprecedentedly powerful car. In its day, terms like "leviathan" and "behemoth" were commonly used to describe the 7-ton car, over twice the weight of its competitors.

The engines were a pair of Rolls-Royce R-type V-12 aero engines, as previously used singly in Malcolm Campbell's Blue Bird of 1933. In fact, one of Eyston's spare engines for the record attempts was on loan from Campbell. There were so few of these engines built (around 20) that many of them had illustrious careers over several different records. One of the Thunderbolt's had already powered the Schneider Trophy winner. Each engine was of 36.5 litres capacity, supercharged, and had an individual output power of 2,350 bhp (1,752 kW; 2,383 PS). Handling all this power through a single driven axle required great innovation in metallurgy and in manufacturing the geartrain, as well as water-cooling the completed transmission.

Rolls-Royce R

The Rolls-Royce R was a British aero engine designed and built specifically for air racing purposes by Rolls-Royce Limited. Nineteen R engines were assembled in a limited production run between 1929 and 1931. Developed from the Rolls-Royce Buzzard, it was a 37-litre capacity, supercharged V-12 capable of producing just under 2,800 horsepower (2,090 kW), and weighed 1,640 pounds (770 kg). Intensive factory testing revealed mechanical failures which were remedied by redesigning the components, greatly improving reliability.

V12 engine piston engine with 12 cylinders in vee configuration

A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders each, usually but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft. Since each cylinder bank is essentially a straight-six which is by itself in both primary and secondary balance, a V12 inherits perfect primary and secondary balance no matter which V angle is used, and therefore it needs no balance shafts. A four-stroke 12 cylinder engine has an even firing order if cylinders fire every 60° of crankshaft rotation, so a V12 with cylinder banks at 60° or 180° will have even firing intervals without using split crankpins. By using split crankpins or ignoring minor vibrations, any V angle is possible. The 180° configuration is usually referred to as a "flat-twelve engine" or a "boxer" although it is in reality a 180° V since the pistons can and normally do use shared crankpins. It may also be written as "V-12", although this is less common.

Malcolm Campbell English racecar driver and speed record holder

Major Sir Malcolm Campbell was a British racing motorist and motoring journalist. He gained the world speed record on land and on water at various times during the 1920s and 1930s using vehicles called Blue Bird, including a 1921 Grand Prix Sunbeam. His son, Donald Campbell, carried on the family tradition by holding both land speed and water speed records.

The chassis and bodyshell were built at the Bean works in Tipton. [2] There were three axles and eight tyres. The two leading axles steered and were of different track, so that each tyre ran on a clean surface rather than following a rut. The driven rear axle used twin tyres to reduce the load on them, a technique already used by Bluebird. Separate panels of polished silver Birmabright, a new aluminium alloy, clad the chassis. The body never had the aerodynamic refinement of the Railton Special and was distinctly blocky in appearance. At the rear was a large triangular tailfin, flanked by a pair of hydraulically activated air brakes. [3]

Bean Cars brand

Bean Cars was a brand of motor vehicles made in England by A Harper Sons & Bean, Ltd at factories in Dudley, Worcestershire, and Coseley, Staffordshire. The company began making cars in 1919 and diversified into light commercial vehicles in 1924. For a few years in the early 1920s Bean outsold Austin and Morris.

Tipton town in the borough of Sandwell, West Midlands, England

Tipton is a town further northwest of Birmingham in the borough of Sandwell, West Midlands, England. Historically within Staffordshire, with a population of around 38,777 at the 2011 UK Census. It is a part of the Black Country, located about halfway between Birmingham and Wolverhampton, in the West Midlands conurbation. It is 9 miles northwest of Birmingham. Most of the town is now in the borough of Sandwell, with the western fringes – including the Foxyards estate and the site of the former Tipton Town Hall – in the borough of Dudley.

Birmabright is a trade name of the former Birmetals Co. for various types of lightweight sheet metal in an alloy of aluminium and magnesium. The alloy was introduced by the Birmid Group in 1929 and was particularly noted for its corrosion resistance. Birmal Boats was created in 1930 for the building of light-alloy boats. Birmetals Ltd was formed in 1936 and during the war produced both copper bearing aluminium alloys and the Birmabright magnesium bearing alloys, mainly for aircraft production.

Design changes

When first built there was a large eight-sided cooling air intake at the front, replaced by a smaller oval intake for the 1938 season. Another improvement for this second attempt was to paint a matt black arrow onto the side of the car. During the first attempts, the new photo-electric timing equipment had failed to detect the polished aluminium car body against the brilliant white salt. [4]

For the 1939 attempts, the streamlining was increased further. Cooling was now by a tank of melting ice rather than a radiator (as used first by Golden Arrow ). A rounded nose now filled the previous radiator air intake and the stabilising fin was removed, all leading to an appearance more like Cobb's Railton.

Thunderbolt today

Thunderbolt was displayed in the British Pavilion at the New Zealand Centennial Exhibition in 1939-40, it also toured New Zealand during the Second World War, but is thought to have been destroyed by a fire in a Rongotai warehouse.

Another surviving engine can be seen in the Science Museum in London.


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References

  1. Holthusen, Peter J.R. (1986). The Land Speed Record. ISBN   0-85429-499-6.
  2. "Captain George Eyston's 'Thunderbolt' car, 1937". (commercial photo gallery)
  3. "George Eyston: The Empire Club of Canada Speeches 1938-1939". includes some images of Thunderbolt
  4. "Wolverhampton History and Heritage". The Bean. Retrieved 10 March 2014.

See also