LAND SPEED RECORD.

Auckland Star, Volume LXII, Issue 4, 6 January 1931, Page 15

LAND SPEED RECORD.

"WIZARD" SMITH'S ATTEMPT.

DESCRIPTION OF THE CAR,

CAPABLE OF 310 MILES AN HOUR?

The Napier engined motor car which is being constructed by Messrs. Harkness and Hillier to enable Norman (Wizard) Smith to attack the late Sir Henry Segrave's land speed record on the Ninety Mile Beach, North Auckland, in March, is now nearing completion. As far as the engine is concerned, very little information is permitted. It is a Napier Schneider Cup aero engine with 12 cylinders arranged in three banks of four each and develops 1700 h.p. Beyond this, no details may bo disclosed, the engine being lent under a pledge of strict secrecy by the British Government.

Special racing tyres whose rubber treads are only 1 -04fcli of an inch thick, are being provided, and it is stated by the makers that these arc superior to those supplied to the late Sir Henry Segrave. The frame of the car consists of two channel section side members each 13 inches deep, which run the whole length with stiff cross members at intervals, running through its length. Owing to the fact that the same type of engine is being used as that in the Golden Arrow, the ' same general lines will be observed. The tests carried out with the Golden Arrow showed that to overcome head resistance at 250 m.p.li., some 462 li.p. was absorbed, but the designer, Captain J. Irving, calculated that this was increased to 555 m.p.h. by modifications incorporated to ensure the driver's safety. The frontal area of the new car is only 83 per cent of that of the Golden Arrow, and Norman Smith will have approximately 1700 h.p. at his command. The new car will be geared tp attain a speed of 100 miles an hour in iiist gear, 200 miles an hour in second, and 300 miles in third. Another interesting mechanical feature will be the transmission from the engine to the back wheels.- There will bo a cJpuMe clutch, consisting essentially of a friction clutch

capable of transmitting up to 400 h.p. while the machine is gathering speed; positive dogs will be engaged for the higher speeds. This type of drive has been adopted to minimise the possibility of clutch slip and possible ''seizure." The crankshaft of the engine enters the gearbox, but at the rear of the box, the drive is split, being taken by two parallel propeller shafts. provided with metal type enclosed universal joints at each end. These drive shafts are enclosed in armour-plated tunnels of metal J-inch thick, to protect the driver, who sits between them, in case of failure of either or both of thorn. There is no differential, but final drive to the back wheels will be taken by a crown wheel and pinion attached to the drive shaft from the gearbox. All gears and pinions are wherever possible forged and machined integral with their shafts. Two separate gear ratios are being provided for the final drive, one to do 300 miles an hour, and the other for a slightly lower speed. The steering gear consists of a direct coupling to each of the front wheels by drag links and steering arms from a specially designed box, located behind the engine. The front wheels are also coupled by a track rod in case of failure of the independent steering. The steering wheel is 16 inches in diameter; the steering column is disposed horizontally, and operates through worm and wheel mechanism. Springs are quarter eliptics, with a very limited movement, Only about 2J inches being allowed to eliminate danger of rolling of the chassis at high speeds. Both front and rear axles are held rigidly in position by radius rods to prevent axial movement, but may move vertically within fixed limits since the ends of tiie springs are free.

Wheels. Wheels will be 37in in diameter, and fitted with 7in specially built racing tyres, guaranteed capable of running at a" speed of 310 miles ah hour. They will be inflated to a pressure of 1401b to the square inch. The rubber tread, with that between the 12 piles of cotton cords, is specially compounded to avoid overheating. The wheel spokes will be streamlined by solid steel discs. Mechanically operated brakes on the back wheels only will be fitted; they will be of as large dimensions as the size of the wheels will allow. The front axle will consist mainly of a hollow forging, with 9in flanges for the attachment of the iip-turned stub-axle ends. The three pieces will be spigoted and bolted together. Cooling will be effected by a special system designed by Mr. Harkness. which will contain about 20 gallons of water. To reduce the resistance of "drag"' to a minimum, and, at the same time make provision for an aero-dynamic down load, which will assist the deadweight in holding the car to the ground, and maintain traction at speed, the nose of -the body has been sloped downwards. Directional stability will be increased bv the two fins at the back. The Golden Arrow had only one such stabiliser. The width of the bcdv lias been reduced to 19 inches at the widest part: the total length of the car will be 2Gft, with a Avlieelbase of 13ft 4in and track of oft. The whole mechanism will be protected by an inider-pau of armour plate; it will have a ground clearance of inches. The maximum height of the car from the ground will be 3ft Sin.