WHERE’S GEORGE ? FINAL TRIUMPH OF G. FT. E Y STON ON THE BONNEVILLE SALT FLATS. ” THUNDERBOLT 11 REACHES 319 M.P.H.
WHERE’S George ? At one moment he was at one end of a measured kilometre on the Bonneville Salt Flats, Utah, U.S.A. Seven seconds later he was at the other end, having travelled in his ” Thunderbolt ” at no
less than :319.11 m.p.h. Then he was back again, this time averaging 305.59 m.p.h. A new world’s land speed record had been set up, the mean of the two runs representing 312.20 m.p.h. !
Only slightly slower were the speeds over the Measured mile. In one direction Eyston averaged 317.74 m.p.h., and in the other 305.34 m.p.h., giving a mean speed over this distance of 311.42 m.p.h.
The record rims took place in the early morning, and the light was by no means good. So dark was it, in fact, that Capt. Eyston on one of his runs was unable to note the distinguishing marks at the start of the measured distance, but had in any case, after a flying start of about five miles, attained sufficient speed for the record. He was further handicapped by his goggles blowing out of place just as he entered the measured distance on his fastest run. Quite unperturbed, Eyston removed one hand from the wheel at 320 m.p.h., and pulled the goggles straight again. The surface at the Salt Fiats has not this year been at its best. It is only for a few months during the year that the surface is ever really dry, and this year the water took longer than usual after the
seasonal rains to evaporate. In consequence, Eyston had some poor conditions to overcome, especially on his earlier test runs. On the day of the record he was fortunate in finding the surface a little drier, after a short spell of fine weather, but it was not as good as one has reason to expect at this time of the year. The whole record was a fight against time, for it must be appreciated that the “
Thunderbolt” incorporated many novri features of design, and there had been no opportunity to test the car as a coi-r plete unit before leaving England. Eystor arrived at the Salt Flats at the beginning of October, and found the salt crust still too soft to support his seven-ton car.
It was not until October 28th that a test run was possible over the ten-mile course, and on this occasion 309.6 m.p.h. was attained in one direction—a speed well above the old record set up by Six Malcolm Campbell at 301.13 m.p.h. On the return rim, however, the clutch gave trouble, and no time was recorded.
While this trouble was being attended to, George Eyston took out his other car, “Speed of the Wind,” and using a circular course instead of the straight eleven miles traversed by the “Thunderbolt,” captured several long-distance records, including the world’s 12-hour record at 163.08 m.p.h. On November 6th, ” Thunderbolt ” was ready again, and this time reached 310.685 m.p.h. But again the terrific power from the two Rolls-Royce engines was too much for the clutch. The clutch was of interesting design, which must not be condemned merely through failure
in initial experiments. The power was first transmitted by friction plates, which, after the principle of a synchromesh gear, synchronised the speeds of the dutch Shaft and the crankshaft, and allowed spring-loaded dogs to engage and give the effect of a solid drive.
The trouble was, not occurring in the friction part of the clutch, where the Ferodo linings stood up well, but in the rest of the novel principle involved. Capt. Eyston, who, while the car was being built at the Bean works at Tipton, Staffs., had personally supervised the whole operation, now showed his mettle as a designer, as well as a driver, by sitting down and redesigning the clutch. The drawings were rushed off by aeroplane, and new parts were made. On the final runs, when the world’s record was broken no further trouble was experienced. The car itself was built in under seven months. Its two supercharged RollsRoyce engines, of Schneider Trophy type, have a total capacity of over 73
litres, and develop 5,000 h.p. The engines are set side by side amidships, and there is a three-speed gearbox. Eyston attained 100 m.p.h. in bottom gear, and accelerated up to 220 m.p.h. before changing into top !
Although the car is a six-wheeler, only the rear pair of wheels are driven. Both pairs of front wheels, however, are connected to the steering, while the driver sits just in front of the engines. All six wheels are independently sprung. The steering gear was of Burman-Douglas type, and the steering layout was built by the Wolseley company. The road Springs were made by Jonas Woodhead, the well known Leeds firm which has supplied 80 many racing drivers Andre shock absorbers were used, and Moseley Float-on-Air upholstery. The tyre manufacturers deserve especial credit. It is only by the unflagging research of the Dunlop technicians that such speeds have become possible at all . one must remember that this is only the second time that the Salt Flats have been used for the land speed record, and that fresh calculations were necessary on the change-over from Daytona Sands to Utah, with a surface of an en
tirely different character. So great is the centrifugal force at 320 m.p.h. at the tyre diameter increases by no less than 1 in.! For this reason extremely thin treads are necessary, or the rubber would be flung right off. In spite Of the five Mile stretches for acceleration before entering the measured distance and for pulling up, both these operations require great skill, with the gigantic forces involved. It will be remembered when the late Sir Henry Segrave attained 200 m.p.h. for the first time, the brake shoes actually melted, and Sir Henry had to run into the Sea to pull up. It is estimated that the stored eiwrgy to be dissipated at the end of WHERE’S GEORGE ?—continued
each run, converted into heat, would be enough to raise one cwt. of water from freezing to boiling point in 40 seconds. The air brakes originally designed for the car were not used, and Eyston relied upon the friction brakes alone. These
were of interesting design, for instead of the usual internal expanding type, disc brakes, similar to a plate clutch, were used. None of the brakes was on the wheels, for in order to keep the unsprung weight as low as possible, cardan shafts ran from the second pair of front wheels to the centre of the chassis, just in front of the driver’s seat: while, at the rear, the brakes were mounted on the end of the propeller shaft, behind the rear axle. The brake operation was on the Lockheed hydraulic system, the stationary friction plates were manufactured by Borg and Beck, while the rotating spinners, also made by Borg and Beck, were lined with Ferodo, in which firm’s laboratories the whole brake layout was tested. It was found that temperatures
between 800 and 1,000 F. were developed, which means that the braking surfaces actually reached dull red heat. Special B.P. Ethyl was used for the record, and the two engines burnt eight gallons a minute! It is fortunate that at maximum speed Capt. Eyston took only just over 11 secs. to cover a mile’ The oil was Castrol, circulated by the pump on each engine at the rate of eight gallons
a minute. Some ingenious person has also calculated that at 310 m.p.h a cylinder wall area of 2. acres pzr minute had to be covered by lubricant.
Forty-eight Lodge sparking plugs, and B.T.H. magnetos, supplied the ignition. The delicate instruments needed were by Smith and Negretti and Zambra, and, as in. previous record attempts, a T.T.N. steering stabiliser was fitted. The body, interesting in that all wheels were totally enclosed, as on the original 200 m.p.h. Sunbeam, was made of Birmabright metal, to Capt. Eyston’s own design.
Eyston is expected back in. England on the Aquitania, arriving on December 14th.
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