THE TREND OF DESIGN (PART 2)
An article dealing with the progress that has been made in the design and production of racing cars during the past twelve months.
THER. is not a great deal to be written about racing-car design tendencies, because the subject was rather thoroughly dealt with exactly a year ago in MOTOR SPORT and as 1937 was the last year under the maximum weight formula, and as very few races will be eligible to oldformula cars from now on, development in the Grand Prix field has not unnaturally eased up. There still remains the very satisfactory knowledge that modern road-racing calls for the highest scientific technique and extremely skilful drivingtactics. It is a most thrilling and absorbing spectacle, as was brought home to the majority of enthusiasts in this country for the first time on the occasion of the Auto-Union and Mercedes-Benz visitation to Donington last October. Nevertheless, that such racing is a first-rate spectacle is entirely incidental ; indeed, the Formula in use up to last season actually aimed, unsuccessfully it is true, at making the cars slower than formerly. The very opposite rules in cinder-track racing and our opposition to this kind of racing lies in the futility of endangering
life in what is a pure circus. Staged solely to amuse a certain public, doodledicing can be an excellent institution, provided it does not have to endanger drivers’ lives to attain its ends. But that it can. ever hope to attain the status of, and ultimately oust, road-racing as it has been practised ever since motor racing began, we just cannot accept, in spite of Mr. Cecil Kimber’s view. We are, as a matter of fact, by no means certain that the future prospects of doodledicing, within its own limitations, are as bright as the fans imagine. Turning to the happier subject of proper racing, whatever may be said about its having become too specialised to hand down any lessons of value to the utility car designer, certainly valuable publicity still results for entry in classic events,
as Messrs. Auto-Union Sales Ltd. and
Mercedes-Benz Ltd. would testify. All credit is therefore due to Lord Austin and Victor Riley for their continued interest in racing and, of course, to E.R.A. Ltd., the last-named in particular, on their entry into unlimited Formula racing this coming season. Multi-cylinders rule supreme. Mer cedes-Benz have used an ” eight ” of 5,660 c.c.—cylinders in line, Auto-Union their 75 x85 nun. 6,006 c.c. 450 V16, while Alfa-Romeo produced another V12 of 5-litres, and the rumoured 3-litre E.R.A. is to be a V12. Moreover, most of the new G.P. cars will have multi-cylinder engines, 24 cylinder units being in the wind, and the Delahaye, of course, is a 41-litre V12. Mercedes-Benz actually contrived to get the 8-cylinder 5.6-litre car within the 750 kg. maximum, in spite of using a new lengthened chassis to improve roadholding, though their 12-cylinder record breaking car of this capacity was outside the limit. And Auto-Union rose from 5.8 to just over 6-litres under the Formula, though employing a shorter wheelbase. itilaserati has produced both four and sixcylinder iflitre cars, the latter with cylinders cast in pairs. Modern G.P. engines are of short stroke and give around 90 b.h.p. per litre, consuming roughly 0.7 lb. of alcohol fuel per b.h.p. per hour, or about 5 m.p.g. at racing speed. The complete cars weigh about $f to 4 lb. per h.p. with driver aboard. Fully inclined o.h. valves operated by twin o.h. camshafts are general, exceptions being E.R.A.’s push-rod actuation from highlevel camshafts each side of the block and the single camshaft of the Auto-Union, which operates the inlet vales via rockers and the exhaust valves via push-rods and bell-cranks. Mercedes-Benz use an oil-cooler and Auto-Union a large separate oil reservoir before the driver and an oil-radiator. Light alloy construction Is popular, on a variety of different systems. Auto-Union use R.R. alloy, and Mercede.s-Benz steel liners in an alloy block, while the 1938 E.R.A.s will have many castings of elektron, as have the 1-litre Maseratis. Supercharging is universal, the blower pressures being around 5 to 6 lb. per square inch on G.P. cars. The racing Austin Sevens are blown at 16 to 18 lb. and the Murray-Jamieson blowers on the 1k-litre E.R.A.’s deliver
at 22 to 25 lb. ” Bira’s ” old 3-litre Maserati and I flitre Delage have about 12 lb. boost and the six-cylinder 1,493 c.c. Maseratis are blown at 15 lb. The record-breaking 1,100 c.c. M.G. of Major Gardner’s is believed to be blown at around 40 lb. per square inch. The Roots supercharger is the most popular for racing work, but E.R.A. have this year been using large Zoller vane compressors set behind the power-unit, sucking from twin S.U. carburetters. An experimental layout using an Arnott vane compressor has been applied to Connell’s fl -litre E.R.A. by the Monaco Eng. Co., employing an increased boost. E. W. W. Pacey also experimented with a vane compressor on a Bentley engine linered down to 3-litres, for track work, but reverted to the unblown unit for the 500 Kilometre Race. Mercedes-Benz abandoned their through-thecarburetter system, used ever since they introduced supercharging for touring cars just after the War, adopting the conventional layout for the German Grand
Prix. Alfa-Romeo apparently retain their familiar double Roots blowers on the new V12. Concerning power outputs, naturally figures are difficult to come by and cannot be guaranteed accurate, but G.P. cars seem to give around 90 b.h.p. per litre in 4-6-litre form and about 75 b.h.p. per litre in 3-litre size, if one disregards the opinions ruling in certain quarters as to the optimism of Italian and German bench-testers. The 11-litre six-cylinder Maseratis give approximately 120 b.h.p’ per litre at 6,080 r.p.m. and ” Bira’s” old 3-litre Maserati 100 b.h.p. per litre at just below 6,000 r.p.m. The older 11-1itre E.R.A. is believed to develop about 125 b.h.p. per litre and the racing twin cam Austin Sevens about 160 b.h.p. per litre. 200 b.h.p. per litre from small units is in sight, especially for sprint runs, and is probably attained now by some engines—such as the recordbreaking M.G. Magnette and Zoller-blown 1,100 c.c. E.R.A. By the use of 80 per cent. alcohol content in the fuel, very large fuel lines and float chambers, piston crowns as thick as 10 mm., and the use of mineral lubricating oils, together with great attention to design details, compression pressures and crankshaft
speeds continue to rise. It is usual to increase supercharge boost before raising the mechanical compression ratio, which remains at around 6 to 1—-10 to 1 in consequence. A future step would seem to be elimination of the exhaust valve heat zone, by adoption of rotary or sleevevalves ; the Gnyot racing-cars of 1925 had Burt McCallum single-sleeve valves, and sleeve-valves have been used by Panhard and Voisin, while H.R.G. installed a Cross rotary valve engine in one Of their cars for a few events last year. Alcohol fuels are virtually knock-proof, but detonation occurs if pre-ignition takes place, and the cooling of exhaust valves by big guide-areas, salt-filled stems (used by E.R.A.), and water flow round the seating,s, is nearing the limit. It is interesting that commercial brand oil is frequently used in modern racing engines. while Capt. Eyston used commercial B.P. for his world’s 12-hour record with the Rolls-Royce engined ” Speed of the Wind.” Suspension has undergone considerable change. Mercedes-Benz use independent coil suspension at the front, like that on their standard chassis, including the famous Type 540K. At the rear they use torsional bars, but we believe that a light beam now ties the wheels, so that an independent action is not obtained. Apparently the object is to obviate any tendency to roll when cornering, and using a light cross-axle and a gearbox mounted with the final drive on the frame still results in low unsprung weight and consequent improved wheel adhesion. The scrubbing _action _inherent with a rigid axle is of little moment, as acceleration and braking calls for frequent tyre
changes. Separate steering arms are used.
Auto-Union modified their front axle and brake layout last season. They use torsional suspension front and back, said to be fully independent all round, though it is probable that the tied rear wheel method has recently been used, as with Mercedes. E.R.A. adopted front independent suspension at *the beginning of the 1937 season, with marked success. The front wheels swing on two arms held in bearings on the frame, these arms extending rearwards parallel to each other. They are controlled by torsion bars engaging each lower arm, the upper arms engaging friction shock-absorbers, and to accommodate the torsion members the wheelbase actually varies slightly each side. This suspension is rumoured to have been designed for E.P.A. by Dr. Porsche,. the Auto-Union designer, and it was applied to two works Li-litre cars and to the 1,100 c.c. and the 2-litre. Earl Howe’s E.R.A. was fitted with De Ram shockabsorbers, retaining the normal halfelliptic springing, these wonderful shockabsorbers having been described exclusively in MOTOR SPORT when M. Bugatti adopted them for his 3.3-litre G.P. ears. Geoffrey Taylor evolved a system of all-round independent suspension for the racing Altas, using vertical guides and coil springs, and we believe that two cars have been built with this suspension and it has been applied at the front only to a third Alta by Bellevue Garage (Racing) Ltd. ” Bira.’s ” 11-litre Delage was fitted with front independent suspension employing a transverse leaf spring and transverse swinging links above the stub axles, designed by Delahaye but built in this country, and the Conan-Doyle’s 2-litre Delage was given a somewhat similar system, incorporating a divided tubular axle, but neither car was extensivCiy raced. Riley have not developed their coil independent system, but E.R.A. are experimenting with independent rear springing for their Formula cars. Maserati used quarter-elliptic rear springing on one of the new four-cylinder Cars, getting better road-.holding than on the six-cylinder cars with half-elliptic rear springs. Maserati front independent snspension is by wishbone links and torsion
arms beside the frame. Independent suspension seems universally to be appreciated, both as an aid to faster corner work and more comfortable riding. It was used for the first time for ultra-high speed work on ” Thunderbolt,” on all three axles. Mercedes-Benz and Auto-Union have tubular frames. The new V12 AlfaRomeo has a very low frame and independent suspension that does not appear to be of the Dubonnet layout formerly used by this marque. Mere. have the gearbox as virtually part of the rear axle, mounted on the frame, and Auto-Union drive the wheels direct from the gearbox engine rear-mounted power-unit. The Auto-Union has a short right hand gear lever. Hydraulic brake actuation is almost universal, with provision for varying the braking effect and balance from the cockpit. E.R.A. have adopted Lockheed application working Girling plungers, the ribbed drums well exposed to the air stream, and at first experienced teething troubles. Bodies seem to have settled down to -a fairly standard form, and AllaROmeO used a Mercedes shape body for the new V12. Driving vision is more important than absolute minimum head resistance, though Mercedes-Benz used offset transinission to obtain low seating on the record-breaking twel e-cylinder car. For record work almost enclosed cockpits have been used by Auto-Union and Mercedes, with enclosed wheels. For racing at Avus slots in the cockpit sides were used to provide a view of the tyres. Short distance standing start records are now taken at such high speeds that streamlining is now necessary in this field of activity and offsets the weight Of the fairing.. George Eyston’s ” Thunderbolt ” had an ” enclosing-everything ” body when it achieved nearly 320 m.p.h., as had the Sunbeam that first exceeded 200 m.p.h., after isolated radiators, pencil leading-edges and cooling tanks between the wheels, snub-noses and surface radiators, and ice-cooling to permit of snub-noses, have all been used for this ultra-high speed work. We shall have to publish an article on the streamline question when space permits. AutoUnion and Mercedes-Benz use winch tunnels to determine body forms, as did Sunbeam when building the V12 4-litre car for Segrave to attack the flying mile and kilo records in 1926—though they only evolved a slightly advanced edition of the road-racing body of that period. That racing carries research a stage further than theory was convincingly demonstrated during the German Record Week, when Mercedes-Benz were unable to participate effectively on account of their body design causing the front wheels to lift at about 248 m.p.h. This, however, lends strength to the rumour that they have previously used bodies for record work that made use of upward windpressure to reduce the load carried by the tyres. Our last year’s contention, that parasitic and interference drag is now not much greater than that of skinfriction is borne out by the varnished exterior of the bodywork of the Mercedes that tried for records during the Record Week. Mercedes-Benz, on their road-racing cars, shamelessly use circular intakes in the leading cowling to admit air to the carburetter and oil-cooler. In sports-car races advanced streamlining has been evident, from the tank-like 3.3 Bugatti to the Delahaye, Talbot and Riley cars having wings with faired ” boxes ” behind the wheels and faired tails. Wings are ever an evil factor in racing and Delahaye have used inspection slots through which cool air can reach the front tyres. It is interesting that the completely closed cockpit makes no headway, though cockpits are given very large windscreens and streamlined head rests, and the sides are well enclosed. Even Eyston used an open top on his 320 m.p.h. runs. It Would seem that on short distance flying start record work an enclosed cockpit would be beneficial, as the large screens now necessary to deflect pressure from the driver’s head add considerably to the parasitic drag. For this work Mercedes-Benz and Auto-Union use slots in the nose to admit air to the radiator, and as cowlings are considerably distorted by wind pressure difficult problems arise. For standing start records Auto-Union used a more normal nose cowl. Mercedes carry out preliminary wind-tunnel tests on 1 : 2,5 scale wood models at the Stuttgart technical school, with wool flaps to show up eddy points. Auto-Union do wind-tunnel experiments with half full-size wood models at the Priedrichschafen aeroplane works, though. formerly they used the big tunnel at Berlin airport. Complete enclosure pays and Major Gardner estimates that his M.G. Magnette would reach 170 m.p.h. with enclosed wheels, etc. Modern streamlining is a compromise between the two old schools of thought—razor blade narrowness or ” fiat-iron ” low build. For Brooklands work variations of the original simple radiator cowling are popular, as on the Pacey-Hassan, Barnato THE TREND OF DESIGN—continued
Hassan, Dunham’s Alvis, and BowlerHofman, etc. In 1936 E.R.A. were handicapped by having to stop to refuel their 11-litre cars in the 200-Mile Race, but have since used larger tanks. The problem is not so much a matter of increased weight, for often the tank constitutes part of the tail, but centres round loss of performance in the early stages of a race owing to weight of fuel and the difficulty of rendering large light tanks reliable under racing con ditions. Modern G.P. cars give about 5 m.p.g. and smaller-engined racing-cars rather less. Modern classic races are usually contested Over a distance of slightly more than 200 miles, so that over 40 gallons of fuel will be required to ensure a non-stop run. This represents about 15 per cent. of the total weight of a Formula car, and about 20 to 25 per cent. of the total weight of cars under 11-litres Another aspect is the effect on roadholding as weight diminishes towards the -end of •a race and here Auto-Union contrive to use a centrally-located tank, thanks to their rear-engined construction.Even so, they appear to start with these 50 gallon tanks less than half full. Stops are in any case necessitated for change of tyres every 100 to 150 miles at racing speed on courses such as Nitrburg and Donington, and refuelling need cause no additional delay with modern pressure apparatus. E.R.A. have evolved a very high-speed system for 1938. With. smaller cars the problem is :a considerable one, as tyres will last through a 200-mile road race. If there is any prospect of the car needing to stop, such as for brake adjustment, or topping up of oil or water, it may pay to start with 20 instead of 40 gallons Of fuel, using smaller tanks and saving some 3 cwt. Tyres progress fully in keeping with conditions, and our own Dunlops compare very favourably with foreign makes. Germany has tried synthetic rubber, in accordance with her Four Year Plan, but did not do so at
Donington. Record runs at over 300 m.p.h. would be impossible but for research undertaken at Fort Dunlop. Interest still centres around the 1litre class, though such cars can compete reasonably in Formula races in future. Very large rear covers were popular at Avus. E.R.A. are generally accepted to be leaders in this class, being victorious last season in the South African G.P.. Rand (..P., British Empire Trophy, Cot( t ion Trophy, A vusrennen, R.A.C. I.O.M. Light Car Race, Nuffield Trophy, Picardy G.P., Albi G.P., London G.P., J.C.C. International Trophy, Berne G.P., 200-Mile Race, Phcenix Park Scratch Race and Imperial Trophy Race. It seems probable that the 1937 11-litre cars were heavier than the original 14-litres, which weighed about 13 cwt., as larger blowers were subsequently used. Lockhart’s Miller still holds the flying mile 11-litre record at 164.01 m.p.h., but E.R.A. may
attack it this year. Major Gardner’s one-way run with the 1,-100 c.c. M.G. at 150 m.p.h. was a distinct high-light of last season, likewise Auto-Union’s 2541 m.p.h. with a 6-litre engine. Sprint records are becoming fantastic, Auto-Union taking the standing start mile at 138 m.p.h. N’llieelspin is a real problem, as wind-pressure cannot be employed to assist adhesion at the start, when it is most needed, and with enclosed wheels and almost enclosed cockpits a driver finds it difficult to judge his throttle movements—we foresee long mirrors lining the side of the road by the starting line at Frankfurt next year Eyston used twin -aero motors for his 320 m.p.h. run and it is significant that an open cockpit and rear-wheel drive were once again employed for this class of work though the eight-wheel chassis was revolutionary enough. Fotir-witeel drive must come and is likely to figure in the Napier-engined Reid Railtondesigned car which Cobb is taking to Utah next September. Prodigious as is the cost of attacking over 300 m.p.h. records, the use of aero-motors in monster
frames is undoubtedly cheaper and more certain than developing smaller cars, as F. W. Dixon has in view and as Dr. Porsche is rumoured to have completed,
on his drawing board. There is likely to be renewed activity in this sphere of endeavour very soon, as .Eyston is modifying his car and America is said to be interested. Eyston used a positive clutchengagement, an idea suggested in correspondence on the subject of Land Speed Record cars by the present writer over ten years ago. The difference between 250 and 320 m.p.h. is apt to be underestimated.
Wheelspin is now a serious factor in G.P. racing, offset to some extent by the use of automatically locking differentials. It will be interesting to see whether fourwheel drive will he exploited with increased weight allowances under the new Formula, though this seems unlikely. Engines will probably run faster and he more highly boosted than formerly, with 3-litre units perhaps peaking at nearer 7,000 than 6,000 r.p.m. and giving upwards of 350 h.p. In view of the interest occasioned by E.R.A. successes, it is significant to note that use was made of Wilson pre-selector gearboxes, Aero piston rings, Hartford shock-absorbers, Ashby steering wheels, Bosch plugs, Burman gears, Ferodo clutch and brake linings, Latex upholstery, Girling and Lockheed braking, Scintilla magnetos. Shell-Mex and B.P. fuel, Smith instruments, Specialloid pistons, Tecalemit lubricators, alloys by High Duty Alloys Ltd., Dunlop tyres, and constructional work by Thompson it Taylor Ltd., Vauxhall Motors Ltd., and Riley (Co vent ry ) Ltd. Premises were opened at Brooklands and the chief works are
at Bourne. The 11-litre class will not be hampered by the new formula, as few cars are yet .down to the imposed weight minima. E.R.A.s will continue active therein and Maserati will modify the existing 11-litre sixes. Briefly surveying things in general., Rileys have done very well with unblown racing engines, Maclure’s Crystal Palace achievements being outstanding, the engine’s cylinder capacity having been
very materially increased throughout the season. Capt. Eyston has taken world’s long-distance records with his RollaRoyce aero-engined front-drive ” Speedof-the-Wind” which was remarkably free front teething troubles from the commencement. At Brooklauds the usual miscellaneous entry has broken all records. In spite of the pessimists, outer-circuit work has not been entirely neglected, Major Gardner’s M.G., the Duesenberg, Richard Marker’s Bentley (with new chassis), Cobb’s Sunbeam, the Pacey-Hassan, Napier-Railton and Graham-Paige reappearing, while the Barnato-Hassan also reappeared to win a short handicap at over 128 m.p.h. and the Bentley engined Bowler-Hofman is a newcomer amongst track cars. Harvey-Noble concentrated exclusively on outer-circuit work and broke the Class 1-1 lap record at 122.4 m.p.h. with a specially streamlined single-seater M.G. The B.A.R.C. will continue to hold track races next season and there is Scope for new cars built for the job. with low-speed engines, cockpits faired in more than is desirable for roadracing, and long-wheelbase chassis to secure good track-holding qualities. The valve of the aero-motor in this field Was again demonstrated by the Napier Railton. Continued on page 97 Home brewed racing cycle-cars have rather surprisingly shown their ability to hold their own With multi-cylinder jobs in sprint events, notably J. V. Bolster’s twin J.A.P. mined ” Mary ” and J. G. Fry’s V-twin Blackburnengined Freikaisenvagen, with Morgan
independent front springing. Development of such cars ceased about 1924 as G.P. cars took the field, and they were thereafter purchased cheaply by youthful enthusiasts and regarded mainly as a joke. More recently much good money has been spent on them, with very beneficial results.
Diesel records are recognised in a general diesel category, but much good should result from the institution of diesel class records, to encourage development of the smaller units, the Perkins engine used by R. J. Munday in 1936 for record work being ” hotted” to give increased output just as is a petrol engine, as outlined in an interesting booklet issued by the makers. Perhaps the R.A.C. will make a deputation to the A.I.A.C.R. ? In the 750 c.c. class the o.h.v. Austin Sevens were outstanding in sprint, track and roadcircuit contests, and. Gordon Brettell’s very light Cozette blown Austin Seven, supercharged at about 9 lb: and built largely of R.R. 66 alloy, was well to the fore. It was constructed by the Monaco Motor and Eng. Co. of Watford. Bellevue Garage (Racing) Ltd. developed a K3 M.G. Magnette to lap at 124 m.p.h. Special cars have been built in considerable numbers for sprint work, notably Semmence’s .A.C.,engined job. The Appleton-Special, Eccles-Special and Brooke’s M.G.-Rile-y have run in important racing -events. Frazer-Nash-B .M.W. have competed successfully at Brooklands with fully-equipped Type 328 Frazer-Nash-B.3,1.W. sports two-seaters and a team of T-type M.G. Midgets won the Donington 12-Hour Sports-Car Race, modified in respect of larger Luvax shockabsorbers, Duplex Hartfords on the front
axles, 7.25 to 1 compression ratios flexible external oil-pipes, and aluminium bonnet panels. On the whole, therefore, the past racing season has not been a slack one and much of value has been contributed to the world’s automobile engineering know
ledge. The majority of us probably prefer to follow racing in general, with particular interest attaching to the fortunes of certain individual marques or drivers, but, even so, a once-yearly survey of the purely technical outlook does not, we hope, come amiss. Those readers who are particularly interested in this aspect of motor sport are advised to study the foregoing information in conjunction with the article on the same subject which we published in January 1937. Next January it will be extremely interesting to look back on the developments resulting from the first season’s activity under the new Formula, possible trends of which have already been discussed in MOTOR SPORT.
Reviews, February 2006
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