RUMBLINGS, June 1935

Power-Weight NOT many years ago one of the principal differences

between driving a racing car and a tourer was the amount of gear-changing which had to be done on the former to obtain the best performance: Nowadays with 14 cwt. racing cars fitted with engines developing 250 h.p. and more, the lowest ratio of a four-speed gear-box is scarcely ever used, and at Monaco this year many of the drivers were using only third and top, in spite of the twisty nature of the course.

Under the circumstances, therefore, three speeds are sufficient for almost everything, and on the three-litre Alfa-Romeos only three ratios are provided, whereas four were used in the older 2.6-litre cars. The extra space has made it possible to fit stouter gear-wheels, overcoming a weakness revealed when the engine capacity was first increased.

Speeds on Brooklands

The International Trophy was the first occasion on which the Grand Prix cars built under the new formula have been ” let out ” on the outer circuit. Shuttleworth, who of course has one of the latest 3-litre Alfas, told me that he was getting 145 m.p.h. on the Railway Straight, even though he had to ease up his foot coming off the Byfleet Banking, and was only prevented from going faster by fear of over-revving.

The final ratio on the Monopostos can be changed in under an hour by unbolting the casing at the back of the gear-box and changing the pinions driving the two propellor shafts, and with a higher ratio he reckons to get at least 150 m.p.h.

Briar Lewis’s Bugatti was also reaching this figure, and looked very much steadier coming off the Byfleet. Almost more striking was the speed of the new M.G. Midgets which, with a capacity of only 750 c.c., were doing close on 130 m.p.h. The drivers reported that with the new suspension they were having quite a ” boulevard-ride,” rather a contrast from the old Montlherys which laid the foundation of M.G. fast motoring.

Independent Suspension Problems

The last word has definitely not been spoken on independently sprung wheels, though now the racing fraternity have adopted them much valuable information should be gained in a short time. The principal snag about many of the lay-outs is that the track alters as the car heels over, an effect which must disturb the tvre-grip considerably when a fast corner is being negotiated. The front suspension of the Auto-Unions, in which the wheels can only move vertically is free from this objection, while on the Bimotore AlfaRomeos the problem is tackled in a different way. The twin propellor shafts are retained, but the two bevel casings and their half-axles are no longer connected but move independently on either side of the rear engine, with radius rods to ensure that they work vertically up and down.

The Man from Middlesbrough

Freddie Dixon certainly deserves his title of being the toughest man of all, and has practically recovered from his aeroplane accident in March, when he received cuts about the head, lost all his teeth but one, and was soaked in petrol from head to foot. When I spoke to him before the International Trophy, he said he intended just to keep going steadily, as he did not feel that he had quite got back his old flair.

As it happened, of course, driving gently was the best plan he could have adopted, fot the fastest runners soon fell out. After securing second place in this way, I hope we shall see him full of vim in the Isle of Man.

Work on the Silver Bullet has been discontinued during the past three months, but everything had been planned out before the accident, and Dixon hopes to have the car ready to take to the United States in September, which will allow him to return to England in time for the Five Hundred Miles Race.

What a Wagon I •

• Like a good many people, I have always wondered why the Silver Bullet was not successful when Kaye Don took it to Daytona in 1929. It was fitted, you will remember, with two twelve-cylinder aero engines giving a total capacity of about 48 litres, and as Fred remarked, ” if they had worked as well as any lorry

you see running about the street, unsupercharged and running on petrol from the pump, the car would have taken the record. It only stood then at a little over 200 m.p.h., and 1, too h.p. would have been quite enough to do the trick.” When the car was orginally designed, it was intended to fit Roots-type blowers for each engine, but Coatelen was approached by some inventor who was pushing the centrifugal supercharger, and was won over to his opinion. Unfortunately thiS meant a single blower at the rear of the engines feeding to a central distributing box, and the total length of induction pipe to the rear cylinders, which were only a few inches from the-blower-casing, was no less than twelve feet. Each cylinder received a mixture of a different strength, and the car rarely if ever fired on all twenty

fcur. This and the failure of the blower-casing during tests in America rapidly showed those in charge that the car was not going to work, and it was brought back from Daytona after a short trial. Dixon will use two superchargers, and considers that with quite simple tuning he should be able to get 3,000 h.p. The single Rolls-Royce engine fitted to the ” Blue Bird ” gives the splendid figure of 2,350 h.p., but power will tell, and Dixon reckons that the odd

six or seven hundred should more than counter-balance the less efficient streamlining of the older car. ” I’m not saying anything more about the Bullet till we’ve rebuilt it,” concluded Freddy, who hates advance publicity above everything, but from what has been said, it seems that the old Sunbeam-engined car may yet take its place on the roll of Land Speed Record holders.

A Ten-Litre Car

Dixon’s ambi:ion lies deeper than simply to challenge the record of another English driver. For some years now he has been planning an attack on the Record with what he calls “a normal motor-car,” that is to say, one with an engine of moderate size specifically built for fitting to a car. He favours one of about 10-litres capacity, probably a 16-cylinder engine in order to get cylinders of an efficient size. He ,x)nsidered it was possible to get a power output of close on i,o0o h.p., and with an engine of this size it should be possible to make a car with a minimum of frontal area, and one which should be faster than the mighty aero-engined monsters which have held the record for the past ten years. No such engine exists at the present day, though the cylinder dimensions would approximate to those of the 4.9-litre Bugatti. However, if the Silver Bullet

does its stuff, Dixon will be in a position to think about building the car of his dreams, so you can see why he has thought fit to challenge Campbell’s position as Speed King.

Donington Steps Out

On the occasion of the opening of the MercedesBenz showrooms in London last month, Herr Werlin, one of the directors of the parent company in Stuttgart, put a question which must have been asked by all of us at one time or another : “Why is there no British Grand Prix ? ” What may well be the answer to this plea has been furnished by the Donington authorities, who have decided to run their International fixture on October 5th under the 750 kg. regulations. Really big prize-money is to be offered, and the organisers. hope to secure entries from the Auto-Union and Mercedes factories. At present there are three Bugattis and one Alfa-Romeo in this country which have been built to conform with the formula, but most of the older 2.3s can be modified to bring their weight below the limit. The E.R.A.s, of course, have about Oscwt. in ha nd.

Contemporaneous with this comes the rumour that Auto-Union are building another batch of rear-engined racing cars, which will be sold to all and sundry. Perhaps this will tempt Whitney Straight out of retirement; meanwhile he is busy with aeroplanes, and will be running trips to the Isle of Man, Lc Mans and Dieppe.