ON THE TREND of RACING-CAR DESIGN
ON THE TREND of RACING-CAR DESIGN
As the racing-car of to-day becomes the sporting-car of the not far distant future, and as we observed last month that not only is the sports-car now widely used for fast everyday travel under quite ordinary conditions but that additionally, its design exerts a beneficial influence upon the merely utility car, there seems sufficient excuse for dwelling for a few thousand words on design tendencies. It is, at once, a simple and a difficult task ; simple because the field to be covered is relatively small, difficult because, though racing cars are no longer stored within moated monasteries guarded by men of arms, or bred in heavily-padlocked works, certainly full details of their specifications, and the changes that are made therein in the course of a single year, are extremely difficult to access. It is a source of great pleasure to be able to record that, more than ever before, the racing-car remains a highly specialised piece of machinery, which could not normally be evolved by the utility eardesigner and certainly could not be maintained in efficient order by even very capable, very knowledgeable mechanics from production-car factories. This advanced engineering practice, moreover, if it is usually the expression of an artist-craftsman, has a far greater mission to fulfil than the mere satiafaction it gives to a man in control of the finished product, the thrill it provides to hundreds of persons who watch the car in action or follow its fortunes through the medium of the motor papers ; a mission, indeed, greater than the spur it may provide to the Advertising Manager of the firm responsible. For the old proverb that the racing-car of to-day is the touring car of to-morrow, if due for reconstruction, is fundamentally as sound as ever it was. This rather prosy Opening must be excused on the score that the writer was once severely frowned upon for daring to hope that motorracing would not become purely the National Sport. By that he had no wish to imply that he did not want to see gate-records broken at new road-racing meetings, or that he had an aversion to public back'ng of an English Grand Prix car. But what was in his mind was that racing would for most of us suffer a severe blow if it were ever reduced to a series of spectacular contests with starting, prize and gate-money the be-all and end-all in the minds of car-designers, entrants and drivers, with standardised cars running in innumerable events at more or less predetermined average speeds. I believe that it is a fact that racily-, motorcycle engines are punished far harder on the cinders than they are round Brooklands or over the I.O.M. course, but because the dirt-track engine is built for artificial functions, from whi ch no lessons of value are likely to be handed on to motor-cyclists as a whole, our more eminent designers, engineers and scientists are not greatly interested in them, or are interested only because of commercial obligaf ions imilarIv, racing in America seems to lose value because even the more serious cars which run at Indianapolis bear tancy names and appear to be largely standardised designs, run as an advertisement for some firm or individual. Consequently, it is indeed good to reflect that the racingcars which compete in the International Grand Prix races are more than ever
before extremely specialised. very costly productions, involving the highest technique of the engineer, metallurgist, chemist and mathematician—and, let us add, demanding the highest skill in their effective driving under contest conditions. As a bearing on this statement. the 0.1). Mercedes-Benz costs around L8,000. Iii the same way, the cars that run in our own races at Donington, Brooklands, in Ireland, at Ulster, and in the I.O.M. are real engineering productions that tend to become ever -more the care of specialists. Which is good : I do not foresee car cinder-track racing influencing this happy state of affairs to the slightest extent, however rosy its own future may be. There is a possibility that some of the proposed new road-eir -nits, it they materialise, may be productive ot low average speeds and that if sufficient starting money is forthcoming certain young men, whose primary association with motor-racing is that of dicing into the limelight with no great personal danger, may iorsake the dirt and co-operate in stunt events over such circuits with any kind of cars. But if this happens, and if huge flocks of people attend regularly to the detriment of the local cinema, I feel sure that ever greater numbers of true enthusiasts will journey to those venues where thoroughbred racing-cars compete seriously. One has only to contemplate the atmosphere of the club hill climb or speed trial, where competing cars are, one and all, honest efforts to hot-up standard motors, to demonstrate absolutely standard motors, or to evolve suitable special ears, to appreciate that the foregoing is no fantastic picture, and that in this country we do take our racing very seriously, and as a technical study. And over and above everything the eminent automobile designers of the world, who are not engaged on a fulltime job in breeding utility vehicles. will continue to grapple with the problems of racing-car evolution, that the world's motorists may ultimately reap the benefit. The most remarkable feature of the 750 kg. maximum weight limit has been the manner in which light alloy construction and extreme weight conservation has permitted the use of power-units of great size, with resultant maximum speeds that a few seasons ago were entirely
unassociated with road-racing cars. When the new formula was introduced most engineers pictured a capacity of 3 to 4litres as the maximum practical under the circumstances. Vet we have seen Alfa-Romeo. increase their engine size from 2.9-litres to 3.2-litres, 3.8-litres and finally to 4.2-litres. Bugatti, mainly employing a :3.3-litre unit, has produced a 3.8 and toyed with a 4.7-litre. Mercedes-Benz has increased from 2.0-litres to 4.1, 4.5 and then to 4.9-litres, and now has a new 5.6-litre engine on the stocks, though this is believed to be over the weight limit. The Auto-Union started as a 3.1-litre and was progressively stepped up to 4-litres, 5.3-litres and 5.8-litres, and Maserati has contrived to use 4.4-litres of motor and get within formula impositions. So that the engines used in these extremely light Grand Prix cars are actually larger than the engines commonly in use for track and sprint work. In this connection it should be borne in mind that the new formula which comes into force in 1938 limits the capacity to 3.1-1itres, so that the recent trend towards larger engines is misleading as a prophecy of future development, and the reader is referred to an informative article published in MOTOR
SPORT last August, which likely developments arising from the new formula were discussed at Some length. The multi-cylinder engine is universal for G.P. cars, Bugatti and Maserati employing eight-cylinder units, the former in line, the latter a V8 in its latest form, Mercedes-Benz has recently forsaken. the in-line-eight for a V12, Alfa-Romeo changed from in-line-eight to VI 2 at Tripoli last season, after experimenting with the " bimotore," and Auto-Union has used a V16 cylinder engine ever since passing beyond the experimental stage. On the other hand the engine of fewer " pots " is not defunct in racing circles, for our own E.R.A., Riley and M.G. Magnettes are six-cylinder cars, and Maserati is concentrating on this type of unit for limited capacity racing, after having built larger racing engines with this number of cylinders. And the 750
Austins, and M.G.s and the 1,100 c.c. 1 I-litre and 2-litre Altas have fourcylinder units, while Riley last season used this class of engine in 11-litre form. In spite of the turbulence debate that occupies scientific delvers into combustionchamber happenings, the inclined valve, hemispherical cylinder-head is in general use, and quite apart from flame flow considerations, this form of head allows for adequate port areas, the maximum employment of gas velocities for filling and scavenging, the best arrangement of water-jacketing, and valve cooling, and the smallest surface/volume ratio. Apart from Alfa-Romeo, Bugatti, Maserati, and Mercedes-Benz, the little Austin Seven appeared last year with a twin camshaft head. Alta has always used this layout, Riley and E.R.A. have inclined valves, albeit operated by pushrods, and if the majority of M.G.s have single-camshaft pent-roof heads, it is a significant fact that early last year Laurence Pomeroy, Junr., and the Bellevue Garage, in combination, turned out three R-type M.G.s with twin-cam heads, to defeat previous retirements
through cracked heads, and with extreme supercharging in view. The Auto-Union is a notable exception, having a central camshaft and short vertical push-rods operating valves inclined in one plane. Although advocates of simplicity point out that push-rod actuation is satisfactory up to _extremely high rates of revolution, the need for heavy valve-spring pressures to overcome valve-gear inertia is liable to impose unwelcome stresses not only on the valves themselves, but upon the operating mechanism, _apart from the possibility of distortion in large lightalloy construction engines adversely affecting a form of valve actuation embracing sixteen or twenty-four separate push-rods. The use of 00 valve inclination also points to double oh, camshaft Operation, and camshaft drive is nearly said to employ modreratepressures and in 1934 the Alfas were supercharged to 81 lb. and the :Witte Maserati to 111 lb., and the 1,500. c.c. Maserati to approximately 11 lb. Mercedes-Benz blow air through the carburetter, which is believed to be productive of better pick-up and which facilitates charge cooling. For racing the Roots-pattern blower is almost universal, though the " R "-M.G.s have Zoller-vane compressors, as has Appleton's special Riley, and at the end of last season Raymond Mays was experimenting with an outsize in this make of vane compressor on the 11-litre E.R.A. It will be recalled that M.G. reverted to the Roots blower-of Marshall make—for its road-racing cars, presumably on account of oiling-up difficulties. The supercharger is, generally speaking, easier to apply to the
.always by shaft Or gear-train for racing purposes, Alfa-Romeo deeming it desirable to take the drive from the crankshaft centre. Four valves per cylinder, handed on from vat-time aeronautical practice to the racing-car engine, would have died a natural death at the hand of the supercharger, had not increased crankshaft speeds developed by limited capacity racing shown that volumetric efficiency is impaired by excessive gas induction velocities and variations. Naturally supercharging is almost universal in present-day racing, though it is doubtful if extreme pressures are employed to the same extent as in the days of the limited capacity ruling, in spite of improved fuels and the advancement of forced-induction technique. Probably the reliability factor is the reason, because the present state Of things under the maximum weight ruling should certainly not of itself tone down blower boosts. Accurate figures are hard to come by for the G.P. cars. Amongst British racingcars the new Austins are blown at 20 lb. per sq. in., the " R "-type M.G. at 22-28 lb., while the Appleton-Riley is given 25 lb. The first E.R.A. was blown at 15 lb., while compression ratios are generally kept in the region of 6 to 1 with supercharged units. It is not easy to access the position with the G.P. cars, but the Auto-Union and Mercedes-Benz are
racing than to the utility engine, which may to some extent explain its lack of headway in the latter field. Ribbing is largely made use of to dissipate heat and there is every reason to believe that in spite Of forced induction great attention is paid to intake arrangements. AlfaRomeo used to take great pains over the efficient delivery of the mixture from the double Roots blowers, and MercedesBenz used four blow-off valves on a manifold of complicated formation. Amongst unsupercharged racing-cars the Riley deserves special mention, the works entries and the examples driven by those eminent free-lancers, F. W. Dixon and H. G. Dobbs, having performed extremely creditably, largely on account of Riley's high volumetric efficiency, aided by their adaptability to multicarburetter layouts and their good com bustion chamber formation. Dixon's 132 m.p.h. lap speed from an unblown 2-litre of conservative streamline form and proven reliability is a measure of
Riley efficiency. Incidentally, the marque has occasionally run in blown form. To-day plain Main and big-end bearings are common for racing-engines, though Seaman's Delage, as a representative of the old school, has rollers throughout. The E.R.A.'s central main bearing is of roller-type, and the in-line Maserati
eights had roller, ball and plain bearings supporting the crankshaft.
Lubrication systems of the true dry sump type are popular, as are external oil-coolers, which began to be a general trend in 1925. E.R.A. and Austin have used large cylindrical type coolers, and the Austin has a triple and the E.R.A. a double oil-pump. The ability of presentday racing-cars to run through a race non-stop gives no opportunity for sump replenishment, and alloy construction sorely tries sump-storage systems. Ignition is mainly by magnetos of the older pattern, and the 14 m.m. plug plays its Part.
Light alloy construction is an interesting study. The latest racing Austin Seven has wet .cylinder liners in a block of R.R. alloy, with a detachable head and the upper portion of the liners finned and in direct contact with the cooling water. The older M.G.s have cast-iron blocks and detachable heads, and E.R.A. uses a steel block in unit with the upper half of the crankcase, and an aluminium head. Alta uses separate Cast-iron wet liners in a light alloy crankcase and water-jacket, with a detachable alloy head having screwed in aluminium-bronze valve seats. The old 1k-litre Delage and the Bugattis have fixed heads.
Mercedes-Benz favour a light alloy sump, and steel cylinders in very thin welded-steel water-jackets, Which they believe to be a better method of weight conservation than the use of liners in an alloy block. Alfa-Romeo employ a light alloy sump and block, with steel cylinder liners, while Auto-Union and Maserati are believed to use wet liners in alloy blocks. Water cooling is nearly always pump assisted, and Alta extends watercooling to the main bearings, while E.R.A. has salt-filled exhaust valves. Engine speeds seem to centre around 5,000 to 9,000 r.p.m., and although the
E.R.A. peaks at about 7,500 r.p.m. this is no advance on the 7,0008,000 or higher r.p.m. of the better 1litre cars of a decade earlier. On the other hand the new Austin of 750 c.c. is built for sustained engine speeds up to 12,000 r.p.m. The present G.P. engines are remarkable in their ability to tick over at about 500 r.p.m. without oiling up their racing plugs and to pick up cleanly at all times.
The h.p. per litre of the modern G.P. cars ranges from about ninety to one hundred, giving 0. maximum b.h.p. of upwards of 400 in Some instances, in cars weighing under 14; cwt., which, with the low interference drag of monoposto bodywork. results in road speeds of upwards of 200 m.p.h.
Turning to the chassis, last season proved the practicability of the unconventional tubular-frame rear-engined Auto-Union which is a Dr. Porsche design of true genius. Weight is saved by light alloy construction and extensive drilling of chassis members and components, which method is adopted also by MercedesBenz.
Where speeds of 200 m.p.h. and more are realised in road contests, with one car passing another at only slightly diminished paces, independent suspension is a vital necessity, from the viewpoint of accurate steering and absolute control, apart from the need to obtain maximum wheel adhesion for acceleration and braking and to diminish tyre stresses. Mercedes-Benz adopted coil-spring independent suspension, all round at first, and now at the front only.
Auto-Union uses swinging links controlled at the front by torsion bars and at the rear by a single transverse leaf spring. Bugatti has remained faithful to normal suspension, retaining, of course, his famous reversed quarter-elliptics at the back, but I understand he has independent layouts in hand.
Alfa-Romeo adopted the coil-spring and fluid-damped Dubonnet independent layout at the front, with reversed quarterelliptics at the back after experimentation with independent rear systems, finally employing an independent arrangement all round for the V12. Maserati has employed chassis with torsion bar front and freely shackled half-elliptic rear independent suspension. In this country only M.G. has produced a fully independently sprung racing chassis, but Riley has used it for the front wheels, and Alta and E.R.A. may have similar developments for 1037. I feel that independent rear spring for racing-cars must come, if only to reduce unsprung weight. Racing technique has of recent years undergone a complete change, and the gearbox is not nearly so frequently used as formerly in road contests. Most of the
Alfa-Romeos have three-speed in place of the former four-speed boxes, and AutoUnion, starting with five speeds, now uses four. For the smaller cars the Wilson sell-change box is popular though it would be interesting to know how much attention is needed between races. Seaman had five speeds on the Delage, for which a Wilson box was formerly used. AlfaRomeo and 'Mercedes-Benz combine the gearbox with the back axle, which is interesting in view of the fact that the latter now has a rigid axle suspended on transverse quarter-elliptic springs. It is interesting that Austin favour synchromesh for sprint work.
Bugatti excepted, all the modern G.P. cars have hydraulic brake actuation, as has Seaman's Delage, and the problem of making brake shoes stand up to the extremely arduous conditions now prevailing has been satisfactorily solved. Our leading racing men pin their faith to Ferodo linings. Provision is made for taking up wear while in motion, which is often necessary three of four times during a race, and Alfa-Romeo use a tap-control to .alter the braking-power between front and rear wheels. E.R.A. use Girling actuation. Amongst the smaller cars large fuel tanks add avoirdupois that kills performance and a pretty problem arises, particularly as it is no easy matter to make a big lightweight tank withstand the stresses involved. It will be recalled that .Seaman's veteran Delage scored over the E.R.A.s last season in certain races, largely because it did not require to visit the pits to refuel. Incidentally, the amazing performances of this car, which beat all comers in the 200-Mile Race emphasises the measure of progress made since 1025, for the Delage is not radically modified, albeit modern fuels and a reduction of weight are important factors in
this connection. The 11-litre E.R.A. has made most creditable progress. Steering is now far lower geared than in former times. The monoposto roadracing body seems well adapted to roadracing, provided vision and drivingroom is studied, and a return to two-seater types is unthinkable. Sitting above the transmission provides an excellent driving position and -appears to keep the occupant immune from the ill-effects of exhaust heat and fumes. This form is becoming
widely used for lesser road events, track and sprint work. Its streamlining reaches a high standard, as is evident by the 228 m.p.h. record of the 6-litre MercedesBenz, with a coupe top addition. In this particular instance part of the weight of the car was lifted from the tyres by the wind pressure, which I should say is a very modern development, with distinct possibilities. Tail-fins for directional stability appear to have made little headway, probably because their advocates have now been forced to realise that a racing-car, unlike an aeroplane, is subject to the action of severe cross-currents
of air. With modern G.P. bodywork formation it seems likely that losses due to parasite and interference drag are now not much higher than those for which skin-friction is alone responsible. It is unfortunate that even aeronautical engineers know very little of the latter problem. The importance of correct streamlining in modern road-racing is shown up by the 8 to 10 m.p.h. speed increase obtained by Mercedes-Benz when they incorporated a slightly lower bonnet in the new, lower, short-wheelbase car.
So far as the ultimate speed record is concerned, it is significant that 300 m.p.h. has been surpassed with an open cockpit and 2,600 h.p. transmitted through a single pair of wheels. It may yet be that the fastest car-speed record will exceed that of the fastest air-speed record. Huge powers are likely to be employed for forthcoming attempts, but Fred Dixon is known to be toying with the idea of attacking Campbell's figure with a 10-litre motor, and although the recent, certainly astonishing, Auto-Union and Mercedes-Benz records must not be taken as indicative that such a task is now fairly certain of accomplishment, it would seem that 250 m.p.h. with this capacity may be realised quite soon. The late Frank Lockhart exceeded 200 m.p.h. on 3-litres of Stutz Special nine years ago. Unconventional racing designs are not much in prominence, but Count Trossi's radial nine-cylinder two-stroke frontdrive car must not be overlooked, and
George Eystott deserves every credit for using front drive and independent front suspension for long-distance records at Utah at very high speeds with a minimum of teething troubles.
New material in the field of amateurbuilt special cars is regrettably sparse, but the Appleton-Riley is an ambitious effort with which good results have been obtained ; and in sprint events R. A. Waddy's twin-engined four-wheel drive Fuzzi Nine is a meritorious creation.
Diesel records have been mainly confined to F,yston's high-speed exploits with the big 'bus-type A.E.C. unit and one would like to see a growing interest in class records for this type of power-unit and more attention given to developing racing editions of small capacity production types, as when R. Munday demonstrated the Perkins engine in the old " flat-iron " Thomas-Special at Brooklands. In sprint events, which are growing in popularity and importance, road-racing cars have mainly predominated, though the veteran Vauxhill-Villiers has been a match. The racing cycle-car of G.N. foundation has by no means disappear,ed, possibly because the Akela V-twin engine of this make gives a b.h.p. equivalent to that of the earlier blown racing Austin Seven units, with only mild tuning and without the weight which water-cooling and supercharging involves. I am not convinced that the road-racing type need have things all its own way in this class of competition, and increased " purses " for these events may result in striking developments, though along what lines I certainly do not pretend to foresee. Incidentally, Instone and Sumner have applied their hands to supercharging the V-twin, in which sphere of research I believe H. B. Showell pioneered. Brooklands racing has developed mainly into a parade of road-racing and modified sports-cars, with the true track car almost defunct, though the new Austin Seven, the unblown Rileys and the monoposto Shelsley Frazer-Nash have proved useful outer-circuit cars. The
140 m.p.h. Barnato4lassan with 8-litre .ix-cylinder twenty .four-valve Bentley engine in a very slim frame, with ultra faired body, and the 41-litre Bentleyen.gined Pacey-Hassan-Special are almost the only modern representatives of the true Brooklands car, but the 4i-litre I,agonda's run in the 500-Mile Race may draw attention to the possibilities of the modern sports chassis for this class of high-speed motoring.
A recent development has been the employment of aeroplane motors in modern chassis for attacks on longdistance class records, with no eye to raising the ultimate land-speed figure— G. E. T. Eyston's Schneider Rolls-Royce engined car and the Napier-Railton being the cars in mind.
Tyres are something of a problem in modern G.P. racing, but evidence that rapid progress is still being made is to be had by comparing the tyre changes in the 1935 500-Mile Race with those made during the same race of 1936. It is difficult to foresee the outcome of the 1938 formula, but smaller engines may be more highly supercharged and run faster, which in turn might result in gearedtogether crankshafts—as in the last racing Fiats—to case bearing loadings and big-end stresses on multi-cylinder units. Certainly the 11-litre engine size will be extremely evident this year, E.R.A., Riley, Alta, Maserati, Delage, AutoUnion, Merce.Ides and Ferrari being likely followers of limited capacity racing, and horse-powers Of around 200 are to be expected from engines of this capacity. Wheel-spin is a source of worry in spite of the adoption of cam-type differentials, and with weight-conservation of less moment four-wheel drive might well figure on G.P. cars. Sports-car racing will benefit from recently introduced rulings to obviate the entry of G.P. cars lightly disguised and buying prosperity renders the T.T. and Le Mans especially important.
Motor scribes, like the racing motorist, are apt to be defeated by time and space, on which note I will end this article. With the doodle-bug I am not concerned.