EYSTON’S R.A.E. LECTURE
Recently, lectures on motor sporting subjects seem to have been cropping up in the most unexpected places. The latest being the Royal Aircraft Establishment Technical Society which, following a lecture on the Metropolitan Water Board, invited Capt. G. E. T. Eyston to talk on record-breaking. It was encouraging indeed to find nearly a thousand people anxious to pay for admission, and they all appeared to appreciate the show.
Starting with his smallest cars, Capt. Eyston showed pictures of the M.G. “Magic Midget” at various stages of its career. Referring to the use of a transmission system running diagonally across the car, he said that the principle worked out excellently on a variety of cars, but sundry propeller shaft failures caused by imperfect balancing occurred—very near the driving seat ! This car was usually run with discs on the rear wheels only, although at Montlhery it was just possible to retain control with discs on the front wheels also.
Passing fairly quickly over various other cars which he had used for attacks on class records, Capt. Eyston dealt with his diesel-engined car Flying Spray,” showing photographs of the engine unit which was so shrouded in secrecy at the time. As was widely assumed, this was a converted Rolls-Royce “Kestrel,” but in the conversion process Ricardo had fitted it with sleeve valves.
Most of the same chassis components figured in “Speed of the Wind as in “Flying Spray,” and the engine was again a “Kestrel.” This was virtually obtained “over the wall,” even being passed back when a new crankcase proved essential for adequate ground clearance. In order to avoid pressmen, the first tests of this car were made on Heath Row Aerodrome, followed by trials on Brooklands at very early hours. Incidentally, the silencing system needed just for these Brooklands tests cost a matter of £50.
The front-wheel-drive chassis of these ears was very successful on the salt flats, coping with potholes, 4 in. deep, worn in the track during record runs. In order to ease the strain of perpetual cornering, however, a sort of rudder was fitted above the nose of the car, which could be turned through up to 150 by the driver.
For the World’s Land Speed Record, Capt. Eyston originally planned a fairly small single-engined car. But when the tyre folk insisted on eight wheels, things began to grow, till ” Thunderbolt ” was evolved. This had its two sets of front wheels, the forward pair with reduced track to aid streamlining and prevent anything being thrown on to the other tyres. Twin rear wheels were used on a single axle, since the complication of two driving axles threatened to be too great.
The bolt-on wheels used had duralumin rims and steel centres.
At Utah, recurring trouble arose with the clutches, which were arranged to link the two engines positively together after the initial getaway, and redesign was necessary. A special wheelspin recorder was made and fitted, showing the difference between front and rear wheel r.p.m., but thanks to generous weight it registered nothing whatever.
Tyre troubles were apparently associated less with the violent application of 4,000 h.p. during acceleration than with the high-frequency flexing of the casing under the weight of the car. A tyre pressure of 120 lb./sq. in. was used, while Cobb probably gained 10 m.p.h. by using 150 lb./sq. in., the rolling resistance on such a car being roughly equal to the wind resistance.
Sundry questions from the audience, filling an interval while the projector for some films was tuned up, brought forth a good deal of further interesting ” gen.” The salt of Utah did not cause much corrosion trouble during the dry autumn weather when the record runs were made—but by the time the car reached home again it was in a terrible state. A motor-cycle-type of positivestop ratchet gear-change was used, with an indicator showing which of the three ratios was engaged-2nd gear gave 240 m.p.h., while top was about 1.5 to 1.
For the 1939 record attempts the car was lightened by a ton, at a cost of £1 per lb. removed. This result was obtained by such changes as the use of coil springs instead of leaf, and light-alloy members in the independent wheel springing linkages.
Apparently, when the war broke out in 1939, a new rig for the high-speed testing of tyres was half completed, and valuable results were expected from it. Capt. Eyston thinks the Land Speed Record will be raised a lot higher yet, discretion suggesting progress by 20 or 30 m.p.h. stages. Incidentally, it appears that at the end of the 1939 record-blitz, during an attempt to make ” Thunderbolt ” do six miles a minute, things “came to pieces,” causing it to motor on its belly for abouit three miles! Finally, there was a film show covering the Utah record runs of ” Thunderbolt ” and “Speed of the Wind.” Partly photographed in colour, the films gave a
very fine impression of the difficulties of motoring on salt, of the speed of “Thunderbolt,” and of the actual beauty of that monstrous device in its black-painted form.—J. L.