World's Greatest Cars, Part 1

This article was first published in 2006.

The Bluebird, driven by Donald Campbell, is one of the most exciting cars ever made. Not only did it set a Land Speed Record of 403.1 mph (649 km/h) in 1964, but it did so driving all four wheels.... This article is based on a publicity pamphlet issued in 1963, just prior to the record attempts taking place.

In addition to excellent technical detail, it shows clearly the pride that British companies took in being part of the record-breaking attempt.

The Bristol Siddeley Proteus

Donald Campbell and his team realized from the start that the new Bluebird would have to be powered by a turbine and the obvious unit was the Bristol Siddeley Proteus which had already established itself as a world beater.

It was the first large turbo-prop to be approved for use in commercial aircraft and is one of the most powerful turbo-prop engines in international airline service. Ten airlines make world wide use of the Proteus in Bristol Britannia aircraft which are also used by RAF Transport Command. Well over 2 million flying hours have been accumulated.

In 1959 a pocket power station big enough to supply all the electrical needs of a town of 10,000 people was commissioned in the West of England. Since then four more have been built. The alternators are Proteus powered.

It was also in 1959 that a new class of fast patrol boats was commissioned by the Royal Navy. They were and still are the fastest warships in the world with a top speed of over 50 knots. Three Proteus engines power each ship. Since then the navies of Denmark, Italy, Germany, Sweden and USA have ordered Proteus engines for marine application.

The advantages of the Proteus for the world's land speed record car are its high power to weight ratio and small size. It is a high compression engine featuring the free power turbine principle with the second two stage free turbine driving the front and back wheels.

Proteus drives all four road wheels and, at full throttle, delivers almost 5,000 brake horsepower.

Chassis and Body Structure

The Bluebird was built by Motor Panels (Coventry) Ltd. The designers devised a structure which combines maximum strength and rigidity with very light weight; this was achieved through the use of a special light alloy foil formed into a ''honeycomb'' sandwich ¾ inch thick and faced on either side with high duty aluminium alloy sheeting, the whole being bonded together by a special process using heat and pressure.

The main beams of the frame run the entire length of the vehicle from front to rear. High stress points were reinforced by inserts, stiffeners and diaphragms. The beams were joined by four cross-members forming separate compartments - the cockpit, engine gearboxes and wheels. This structure was covered with a stressed skin of aluminium alloy to form the body.

The whole was a completely hand made structure measuring 30 feet long and 8 feet wide; manufacturing tolerances were expressed in ten thousandths of an inch. High precision components, machined brackets and special very high tensile nuts and bolts were produced at Darlaston by another member of the Owen family of companies, Rubery Owen & Co. Ltd, who worked closely with Motor Panels.

Bluebird was constructed by an extension of a method employed in the aircraft industry. Absolute accuracy was paramount; to achieve this Motor Panels evolved a technique whereby the car was built over a heavy steel base plate mounted in concrete.

Four jacking points, one just inside each wheel, carried the body whilst it was being assembled, and formed the main rig and datum. Wooden formers were made to maintain close limits and uniformity on individual panels. These formers were used for shaping and flanging the alloy sheets. Where panels had to be shaped to match the outer contour of the car, wooden ''egg box'' jigs were employed.

The problem of skinning was solved by hand-forming the outer panels to the diaphragms and stiffeners already in position. After fitting, the individual skins were riveted into position. Particular care was given to the smoothness of the surface to avoid unnecessary air turbulence while the car is travelling at high speeds.

Bluebird's shape is of advanced aerodynamic design, evolved from a long series of wind tunnel experiments at the Imperial College of Science & Technology in London.

Transmission

The power turbine of the Proteus Engine drives two special David Brown gearboxes through Dowty Rotol jack shafts and barrel couplings, at a maximum input speed of 12,000 rpm.

Each gearbox weighs only 380 lbs, and has to transmit 2,500 hp. At full engine power they generate heat equivalent to 40 kilowatts. The two gearboxes have a fixed reduction ratio of 3.6 to 1 and drive all four road wheels through Birfield constant velocity couplings and floating half shafts.

This arrangement has the great advantage of ensuring even torque to all four wheels. There is no clutch, for the transmission is automatic through the gas stream between the primary and power turbine stages, there being no mechanical link or connection between these two turbines.

The Proteus is started and the compressor run up to a predetermined speed with the car held on the brakes. The brakes are then released and the vehicle accelerates according to throttle opening.

The power turbine absorbs the excess energy from the gas eflux from the primary stage. Full power cannot be applied until the Bluebird has reached 400 mph, at any lower speed it would result in drastic and catastrophic wheelspin.

The transmission layout is in the simplest form and although differentials are incorporated in the system, they are normally locked. A free-wheel arrangement operates with the front drive shaft since, during braking, the weight of the car moves forward and has the effect of decreasing the radium of the front wheels, thus causing them to rotate faster than the rear wheels. This action could lead to the breaking of the half shafts, which is prevented by the use of the free-wheel system.

Wheels and Tyres

No tyre had ever before been made to withstand the stresses imposed at the speeds envisaged for the Bluebird. At 450 mph these are just 100 times greater than on the Railton Special at 394 mph. The Dunlop Rubber Co undertook the formidable task of solving the many problems involved. Their underground test plant, specifically designed and constructed for this purpose, alone cost 150,000 pounds Stirling.

After exhaustive trials, Fort Dunlop produced a tyre with an outer coating of 1/50 inch natural rubber covering multiple layers of rayon cord. The tyre and tube (also of natural rubber) weighs 50lb and is inflated with nitrogen at over 100 psi. The diameter is 52 inches.

The Dunlop Rim and Wheel Co developed steel wheels, using ultra high quality forgings. The wheels, which will rotate at nearly 3,500 rpm, must be very accurately balanced. The tyre and wheel assembly weighs 245 lbs, and the Dunlop Company developed special hydraulic equipment to facilitate rapid wheel changing during the short period available for turn-round during a world record attempt.

Brakes

The Bluebird is equipped with special power-operated Girling disc brakes, fitted outboard on each side of the two gearboxes. At a full power stop the Ferodo pads or linings on these disc brakes will run at a peak temperature of 2,200 degrees Fahrenheit, in fact practically at white heat.

The Bluebird weighs 9,600 lb, and to stop the car from 450 mph in five miles means dissipating 76 million foot pounds of energy in 60 seconds.

The Girling disc brakes, with their Ferodo pads, will have to deal with 36 million foot pounds of this total; braking power equivalent to stopping 400 fully laden saloon cars from 40 mph.

Weight is a critical factor and Girling met the challenge by developing twin caliper discs. Each caliper, made of magnesium alloy to save weight, consists of three pairs of brake linings, acting on either side of each of the rotating discs. There are 24 pairs of linings in all. The discs are keyed into the driving hubs so that they can slide along towards the fixed linings as wear takes place. They are power operated with compressed air.

The brakes are actuated by a duplicated electro-pneumatic system devised by Electro-Hydraulics Ltd in conjunction with Girlings & Norris Brothers.

The brake linings themselves, made and developed by Ferodo, required the development of a special friction material. The result is a pad which has withstood more severe and continual punishment on inertia dynamometer tests than any other brake lining in the world.

In addition to the Girling discs, aerodynamic or air brakes are incorporated for use above 400 mph - in this case two flaps open on either side of the rear of the car in order to provide greatly increased air drag. They are actuated by a pneumatic hydraulic system developed by Electro-Hydraulics Ltd.

Instruments

It is imperative that the pilot should have continuous knowledge of both the speed of Bluebird and the rate of acceleration while, at the same time, keeping his eyes on the course during the record bid. For the first time in any vehicle, the readings from speedometer and accelerometer will be projected on to the windscreen and focused on the horizon ahead of the car so that Campbell will not have to move his eyes or change their focus.

Smiths Motor Accessories Ltd developed this new instrument display through the use of a collimating lens - a lens that bends the light rays to make the object appear to be at a distance. The new system is now being applied to high speed aircraft.

Campbell will see two dials - the lower, the speedometer, the upper, the accelerometer. The speed dial revolves against a fixed pointer and it is calibrated from zero to 500 mph. The accelerometer dial remains stationary and a pointer moves over its figures: 1, 3, 4, 5, R. When the car is travelling at 100 mph, the pointer must not exceed the figure 1. At 200 mph it must be midway between 1 and 3; at 400 mph it must not exceed 4 and so on.

A constant balance must be accurately maintained between speed and acceleration since there is a limit to tyre adhesion. The faster the vehicle is traveling, the less the maximum permissible acceleration. The letter ‘R’ on the accelerometer represents the highest permissible rate of deceleration or braking.

The Bluebird's behaviour during the course of each trial run will be recorded on a special electronic instrument carried within the vehicle. Smiths scientists developed special transducers which send the information to the central brain. This will record such factors as power, ground speed, acceleration, rate and degree of roll, yaw, and the rate and degree of movement of the steering and suspension - thus engineers will have a complete record of actual performance to match against the computed figures and wind-tunnel data.

Control and Hydraulic Systems

The Bluebird is 30 feet long, 8 feet wide, with an overall height of 4 feet 9 inches. The wheelbase is 13 feet 6 inches, the track 5 feet 6 inches. The top of the aerodynamic fin when fitted stands 7 feet 8½ inches from the ground.

The steering is manual and in no way power-assisted. The primary movement on the steering wheel is transmitted through a bevel gear box, duplex chain and sprockets, to a special Burman recirculating ball system connected directly to the track rod. The road wheels have a maximum movement of 4 degrees either way.

Suspension is fully independent with wishbones and Girling Oleo pneumatic integral spring and damper units permitting a vertical wheel movement of 2 inches. Units are inflated with nitrogen and the spring rate is variable in accordance with the pressure used.

The disc brakes are operated by a duplicated electro-pneumatic system devised and installed by Electro-Hydraulics Ltd, another member of the Owen family of companies. Movement of the brake pedal progressively opens a valve admitting compressed air from high pressure storage bottles through a network of lines and shuttle valves to the disc brake units. In the event of failure, the pilot is immediately able to turn to the emergency system through the operation of a selector valve in the cockpit.

The parking brakes form a third and completely independent system; they also are pneumatically operated from a separate set of high pressure storage bottles and are controlled by a lever valve from the cockpit. The parking brakes are either full on or full off.

The air brakes are hydraulically operated and controlled by the pilot through a system developed by Electro-Hydraulics in association with Norris Bros; these aerodynamic flaps are opened by two pneumatically-actuated hydraulic jacks, one of which displaces the other to prevent any risk of a flap opening on one side only.

The chassis incorporates an integral jacking system to facilitate handling and rapid wheel changing during a record attempt. An Electro-Hydraulic jack is built into each of the four wheel bays and these are actuated by an external Dowty hydraulic power pack, which is plugged into the control panel; the jacks may be operated independently or together.

Fuel and Lubricants

Donald Campbell will use BP fuel and lubricants as he has done in all previous record attempts. Two special fuelling vehicles were built by BP for the Bonneville Salt Flats and they will also be used in Australia to carry the Aviation Turbine fuel which powers the Proteus.

Bluebird's fuel consumption is about one gallon a mile at top speed, and in order to refuel after each run, the fuelling vehicles will be positioned at either end of the course.

Apart from fuel, BP is supplying seven different lubricants and greases for the engine, gearboxes, steering, wheels, brakes and general greasing.

Some of these products had to be specially developed to meet the severe stresses at high speeds, stresses far beyond anything encountered with ordinary cars. The most difficult problem was formulating a lubricant for Bluebird's two gearboxes, where the load is as much as 4,000 pounds per inch of gear tooth width. The lubricant had to be thin enough to provide lubrication and yet not break down under extreme stress. At first it was thought that a castor base oil such as that used for racing cars would be suitable, but even this was not strong enough to stand up to the enormous pressures. After much testing a suitable oil was found, basically an engine oil but containing special additives.

Specifications

Country of Manufacture: Great Britain

Engine: Bristol-Siddeley Proteus 705 gas turbine aircraft engine (modified to have driveshaft at each end), Compressor 12 axial-flow stages, 1 centrifugal stage, 8 combustion chambers 2 two stage turbines. Maximum Power, 5,000bhp at 11,000-11,800 power turbine rpm and 11,800 compressor rpm, plus 1,000lb approx. exhaust thrust at standstill diminishing with speed

Axles: spiral bevel at front and rear

Type of drive final drive 3.6 to 1

Chassis: Aeroweb sandwich 2 skins 0.048 inch thick light alloy spaced ¾ inch apart by resin bonded ¼ inch mesh honeycomb of 0.002 inch thick light alloy

Suspension: independent by ball-jointed transverse wishbones

Shock Absorbers: Girling oleo-pneumatic suspension struts with rubber rebound buffers

Steering: Gear Burman recirculating ball quick-thread mechanism as centre section of 3-piece track rod, operated by bevel gear and chains from steering wheel

Brakes: Girling disc brakes, inboard mounted, with duplicated operation from compressed air reservoirs. Discs 16 3/8 inch external diameter and 10 3/8 inch internal diameter. Air brakes to rear. In all three separate brake systems.

Wheels: Dunlop split-rim disc wheels

Tyres: Dunlop 7.8 inch section 52 inch external diameter

Dimensions: Wheelbase 13ft 6in., Track front 5ft 6in., Track rear 5ft 6in., Length 30ft, Weight 3.5 - 4.2 tons

Body Manufacturer: Motor Panels Ltd., material aluminium