THE TREND OF DESIGN

THE TREND OF DESIGN

Once again the time has come to survey, as concisely as possible, the progress that has been made in the design and production of high-performance cars during the past twelve months (TO BE PUBLISHED IN TWO PARTS)

I. SPORTS-CARS

FiRsT and foremost, the distinction between sports and utility cars continues to narrow and not a single newly-introduced sports-car, no

matter how high its maximum speed, or how varied its general performance, that does not possess very many of the sober characteristics of the more ordinary vehicle. The under 1-litre class is the only one in which this rule does not apply Strictly and even small-engined sportscars now largely attain their performance with power-units which would drop quite readily into closed-car chassis without embarrassing the owner by reason of noise, roughness, or the need for delicate handling and frequent servicing. Actually, the racing-class Of sports-car is not defunct, but today it is a definitely specialised production, built in limited numbers for enthusiasts, by concerns like Alta, Bugatti, Atalanta, Alfa-Romeo, FrazerNash and Rapier and, even so, Bugatti and Alfa are at more than the transitional stage, exhibiting racing-car aspects in their specifications rather than in their road behaviour. The conventional sort of power-unit holds undisputed sway in the general spOrts-car field, and recent newcomers are nearly all in this ca.tegory. These new sports models are sparse in point of numbers, but individually notable. Alvis have the 1.8-litre four-cylinder, a sturdy extremely sound quality car, which emphasises the modern trend by being available only in closed form. The same well-established British concern has, however, introduced the open short-chassis edition of their 4.3-litre model. The Atalanta is a new marqtte with advanced s pecification, embracing a blower operatable at will and an o.h. camshaft, 12 valve, four-cylinder, 11-litre engine. The Invicta has reappeared, based on Delage designs with electric gearshift, and the Lea-Francis is shortly to be reintroduced as a high-grade mediumpriced quality car with distinctive valve gear. S.S. have introduced the intensely interesting 31-litre S.S. ” 100,” which is a car of careful but quite normal design that contrives to offer extremely high performance, including a maximum speed in the region of, if not appreciably exceeding, 100 m.p.h., at a distinctly Moderate list-price. Definitely this car represents a land-mark in progress, as combining the performance once associated with -expensive advanced supersports cars with design features belonging to the medium-price class. Talbot announces another example of the big modern ..side-valve engined car of really presentable performance, while FrazerNash-B.M.W. has a short-chassis edition of the big 2-litre introduced early last year. That is about the sum total of new sports-cars on the British market for 1038, though that is not to say that other makers have not effected useful and extensive improvements. Prices have tended to increase, but generally the

sports-car market has not suffered extensively and in many cases beneficial alterations or equipment additions have been incorporated with no change in prices. Bentley Motors Ltd. :continue the .4ilitre Bentley, which represents the highest conception of British sports-car technique and is a car which has experienced thoroughly satisfactory sales-success ever since its inception in 3k-litre form four years ago. M.G. have found it quite unnecessary to make any change in their 11 and 2-litre cars, and the T-model

M.G. Midget also continues as before. The ” Phantom Ill ” Rolls-Royce, however emphatically it is pronounced as not a sports-car, offers truly exceptional performance allied to such accuracy of control and refinement of design and construction that it is in demand the world over amongst those Who can purchase ears in this price-class. The wonderful Type 328 Frazer-Nash-B.M.W,, possessed of perhaps the highest allround performance in relation to engine capacity of _any push-rod production sports-car, is now very popular amongst amateur sportsmen, and British-Salmson are in active product ion with their sports Six.” The ” lions ” amongst Continental marques, Bugatti, Alfa-Romeo, Merc6des-Benz and Dclailave, find a ready following amongst c

spacious bodywork. Georges Roeseh’s beautiful Straight-eight Sunbeam seems to be in abeyance. temporarily, we hope. Turning to design details, as we have said, the conservative type of engine rules supreme in point of numbers. The o.11. . type is the more popular, with actuation by push-rods and rockers. But side-valve engines are now notably efficient and, apart from the high-performance American m akes responsible for a quite serious invasion of our market, Talbot has introduced a sports s.v. 3-litre, and the RaiIton, Lammas-Graham, J ensen, and Brough-Superior represent versions of U.S.A. designs modified to con form to British ideals. The medi UM-sized Mereedes-Benz is an outstanding example of really high-performance side valve car and 0.M., curiously, offers both s.V. and o.h.v. engines of identical capacity in two sizes. Amongst smaller ears Morgan use an o.h. inlet, side

exhaust engine and the Talbot Ten, in much improved form, and the new 1,267 c.c. Railton, are semi-sporting s.v. types. Vauxhall Motors, Ltd., have done much research on the subject of controlled carburation and wide-gap ignition to obtain better fuel economy from small engines and. their new o.h.v. Ten saloon does 60 tu.p.h. and 40.m.p.g., and Talbot employ similar methods on the revised Ten, which uses .032″ plug-gaps. The 75 m.p.h. 35 m.p.g. sports job is consequently in sight. Much of the present efficiency of s.v. engines is attributable to the use of high-compression ratios, which average around 6 to 1 with alloy head, the 10 h.p. Railton using a ratio of 6.5 to I. Combustion chamber research and the excellence of modern commercial brands of leaded or alcohol fuel, such as B.P. Ethyl, are responsible. The b.h.p. per litre of the average s.v. sports engine is around 28, or 37 if supercharged, and that of the average s.v. American unit approximately 25. Naturally the flat or pentroof head is dominant amongst o.h.v. operation, because of push-rod actuation, and here again excellent fuels and improved understanding of combustion conditions results in knock-free high power output. The b.h.p. litre of the average engine of this type is roughly 34. On the other hand, the hemispherical head has a great deal to recommend it, even though compression ratios are no higher than those employed with vertical valves. Better filling results, due to excellent port shapes, combustion is more complete and heat-loss is reduced. Moreover, such head-design renders an engine capable of greater development, not only on account of the ability to operate at really high compressionratios, but because ports polish more easily and valves remain unstressed at higher speeds. The greater turbulence may give rise to knocking, but ignition adjustments can cope with this sufficiently to satisfy a skilful driver. Inclined valve heads are used by A.C., Alfa-Romeo, Alta, A utovia, British-Salrnson, Bugatti, Darracq, Frazer-Nash, Frazer-NashB.M.W., Lancia. Aprilia, Lea-Francis, Rapier and Riley. They average about 87 b.h.p. per litre, taking such figures as are available. Thus it is seen that the use of inclined valves is equivalent in power output per litre to supercharging a side-valve unit, with the important qualification that most of the o.h.v. engines used to obtain this average will not be working at maximum compressionratios and so will be less prone to knocking and detonation than blown s.v. units and capable of greater development. Alfa, Bugatti, Alta, British-Salmson, Frazer-Nash Six and Rapier use twin o.h, camshafts, as is permissible on highgrade cars where rapid owner service is not essential and care can be given to details of lubrication and drive. Riley, Lea-Francis, and Autovia have the ingenious system of push-rods each side of the block, which simplifies servicing. The Type 328 Frazer-Nash-B.M.W. has a single camshaft which operates the distant valves via rockers and horizontal push-rods. Another example of hemispherical head with push-rod valve actuation is found in the Competition 4-litre Darracq, and this model develops 25 b.h.p. more than the corresponding pentroof head model, and is allowed to run up to 200 r.p.m. higher, while it uses a compression-ratio of 7.4 to 1, against 6.3 to 1 of the other model. This operation of inclined valves by push-rods is a noteworthy development of 1937. A.C., Frazer-Nash Four and Lancia use single o.h. camshaft operation, in many ways the most practical layout. Naturally, modern engine speeds prohibit the inclined system with recessed cams and a single push-rod and rocker for two valves, as used on many pre-war aero-engines and for a time by Salmson. Modern o.h.v. engines employ very high-compression-ratios, a notable example being the new 3f-litre S.S., where very careful cooling permits a ratio of 7.2 to 1. Some designers use a single o.h. camshaft to operate vertical or semi-vertical valves, obtaining direct cam contact with the stems, or using very short rockers, a practice followed by Mercedes-Benz, V12 Lagonda, Buick and Singer. Camshaft drive is usually by the silent chain, perfected of recent years, but Alfa, Bugatti, British-Saltnson, and MercedesBenz use shaft or gear-train drives. Aston-Martin have a single o.h.. camshaft head with special valve location and Atalanta has a three valve head with actuation by single o.h. eight-cam chaindriven camshaft. In engines having ports on opposite sides of the block hot-spotting is usually obviated by use of multicarburetters, but the Lea-Francis has a contact hot-spot for its single instrument by means of a passage through the block and in some inclined valve engines the ports emerge on the same side, as on the 1k-litre Riley. The rotary-valve type still only exists in experimental form and sleeve-valves are practically defunct. Citroen, however, now list a diesel-engined

car as standard. It has a capacity of 1,750 c.c. and a speed range of 8508,500 r.p.m., giving 40 b.h.p. and costing as a saloon 975. More recently a 2,245 c.c. Tippeu diesel, having a speed range of 800-3,600 r.p.m. producing 42 b.h.p. at 3,000 r.p.m., has been tested in a Lanchester Eighteen saloon. Big four-cylinder engines show a tendency to return, thanks to the evolution of satisfactory flexible mountings, and the 2Flitre Riley and 1.8-litre Alvis are high-performance examples. Otherwise the six is popular as an in-line type, with the U.S.A. still producing the bulk of straight-eights, abetted by Bugatti, Delage and Renault in France, Mercedes-Benz and Horch in Germany, Minerva in Belgium, Alfa-Romeo in Italy and Daimler in this country. In spite of the complications of crankshaft design and accessibility, the V form of construction is tempting in point of compactness and good fuel distribution. In eight-cylinder types, Antovia, Cadillac, Ford, Horch, Jensen, La Salle, Riley and Standard employ the V formation and all the twelve-cylinder cars—Delahaye, Hispano Suiza, Lagonda, Lincoln and Rolls-Royce—are V types, though M. Voisin has contrived to build a straighttwelve. Constructional methods remain normal, with A.C. using wet-liners, Lancia employing light-alloys extensively and other makers using steel liners in alloy blocks in isolated cases. Cylinderwear is being combated by numerous means and has been the subject of extensive research. Thin steel-backed bearings, manufactured to very fine limits and strictly interchangeable, have come into use for journals and big-ends, notably those of Messrs. Vsndervell Products Ltd., used by Alvis, S.S. and Talbot, etc. Crankshaft design has improved out of all knowledge and balanced stiff shafts in rigid crankcases have rendered the highest output engine smooth at all rates ot revolution. The use of one carburetter per pair of cylinders continues to be popular, possibly because in this age of Belisha-lamps rapid pickup is essential and designers are loth to rarefy the mixture by hot-spotting, more especially as accurate hot-spot control in accordance with exhaust volume

is not easy to ensure. Supercharging makes no appreciable headway. The new Atalanta has an Arnott vane-type compressor which can be disengaged by operation of a cockpit lever, a method used by Stutz when a blower was applied to the ” Bearcat.” Mercedes-Benz retain their famous clutch-controlled Roots system on the 5.4-litre straight-eight engine, Alfa-Romeo still use their double Roots blower on the sports 2.9-litre chassis. and Frazer-Nash use twin Centric vane compressors on the 1f-litre ” Shelsley ” job. As the Mercedes-Benz comfortably exceeds 100 m.p.h. with closed bodywork and the ” Spyder ” Alfa does over 110, and the ” Shelsley ” Frazer-Nash is probably the highest performance production-model 1 flitre in the world, forced induction has its merits. But the ordinary car used will not tolerate the increased fuel consumption, often occasioned by the very inefficiency of the engines to which proprietary layouts are tacked. Marshall Roots and Centric and Arnott vane-type superchargers are still available as proprietary articles and we believe A.C. are interested in the application of the latter type to their cars. Auburn, Cord, Brough-Superior, Lammas, and Lammas-Graham are available with low-pressure centrifugal boosters, and 0.M., Rapier and Alta list blown models. Jensen now fit a turbo-impeller to their larger V8 model for L45 extra cost. The Type 540K Mercedes-Benz, father of all production supercharged cars, gains 65 b.h.p. by reason of the boost, with no increase in engine speed, which its clutch system of control makes available for acceleration as well as speed increase. It is in many ways the ideal form of forced-induction application. Otherwise the supercharger-outlook is stagnant and even Mr. Geoffrey Taylor, who has been making his own Roots blowers for the racing and super-sports Altas, contemplates introducing a range of unsupercharged cars. Lubrication systems now cope adequately with bearing loadings, and naturally pressure-feed is universal, though that essentially reliable high-performance car, the Railton, uses a modern version of splash-feed. Dry sump lubrication makes no headway, even Aston-Martin having dropped it for all save their Speed Model of the 2-litre range. Base chambers are frequently ribbed, but all too Often tucked away behind dumb-iron aprons and fancy fronts, though increased capacity seems to look after cooling well enough in most instances. Some makers ve developed a horrible habit of omitting an oil-gauge from amongst the facia instruments, and that is a pity, because an oil-gauge has so many tales to impart to a knowledgeable driver. Ignition is universally by coil, which doesn’t seem to matter so much now that the system is generally understood and modern batteries are so excellent, and there is the consolation that if there is insufficient juice to energise the plugs there would be precious little for operating other vitals, such as lights, fuel-feed and even, in some cases, gear shift, if one could get going, anyway. But some makers carry such philosophy a trifle far and

omit. any provision for hand-starting, as, for instance, Opel. which makes it almost essential to turn the car into a service depot for major overhauls. At last suction as well as centrifugal ignition-timing control has arrived, though naturally a sports-car driver likes to have a hand override, and hand control only is desirable on cars specially sensitive to ignition advance, except where sold to a class of person who would never use a minor hand control–even direction indicator switches are forgotten to-day. 14 nnn, sparking plugs assist in conserving space in o.h.v. combustion chambers, and the 12 mm. size may become quite common ere long. Cooling systems if anything seem to overcool engines, but thermostatic regulation is general, applied to the water-flow, as nothing has come of automatic control of fan or radiator shutters. It is distinctly sad that even marques like Alfa-Romeo now employ radiator grilles and concealed filler-caps, with the proviso that the old-style radiator is certainly a very weighty component. Very considerable progress has been made in the matter of cylinder and head cooling, largely on account of the improved castings now possible, and when use is made of this factor to diminish the hot-exhaust-valve bugbear, astonishingly high compression-ratios can be employed with normal head design and commercial fuels. Outstanding examples are the new 31-litre and litre S.S. cars, in which water is pumped at high velocity over the exhaust ports, exhaust-valve guides, and around the plugs, leaving the head via three largebore take-off pipes, enabling 7.2 to 1 compression-ratios to be used. There continues to be a general simplification of component drives, and belt-drive is widely used for auxiliaries, including water-impellers and even water-pumps. Alvis do all their own iron and alloy foundry work, and the old weathering process of cylinder hardening is made use

of. Detail design still varies very materially, make by make, as, for instance, the nine springs per valve used by Alvis against a single spring and leaf tappetadjuster of the S.S. valve-gear. Unfortunately in a brief survey such as this we must now pass to the chassis. Clutches, in spite of the abuse they frequently are called upon to withstand, function astonishingly well. Flexible mounting of power-units is apt to result in a sense of vagueness of operation unless the pedal linkage is well designed and this portion of the withdrawal mechanism can be too flimsily constructed. Thesingleplate class of clutch is universal and Ferodo is a much-used lining. Synchromesh gear-change has engulfed us, but fortunately it has improved considerably all round during the past year and double declutching is now usually possible for those who prefer, without the dogs tying themselves in knots, while remotecontrol can safely be employed without the short lever movement resulting in a speed of manipulation able to defeat the synchro part of the mesh. And there is no doubt that a well-placed rigid remote-control adds enormously to the pleasure Of handling. One can hardly forgive the designer of a L700 car who, in providing it. gets his lever movements reversed and still omits to fit a reverse catch, however. The open gate change we have to mourn, unless we drive an B.R.G., the Moss gearbox of which has an excellent remote gated change. Actually, sonic makers do still pay their clients the compliment of using quite ” plain” gearboxes, including Bianchi, B.S.A.., Bugatti, D.K.W., H.R.G., Jowett, Opel, Lancia, the larger Railtons, and Terraplane. Nor does the change need to be difficult, given stiff shafts and pro perly-ground gears. The disadvantage lies in the inability to use silent, pinions, but from what we have heard with some so-called silent boxes, this May apply More in theory than in practice. Bugatti actually uses silent pinions, but has a dog-clutch engagement calling for normal handling methods, and II.R.G. likewise has a dog-engaged silent third. The famous Wilson pre-selector box, proved thoroughly in racing, is found on Alta, Antovia, Cord, Darracq, Rapier, and Riley sports Models. Mere4des-Benz have a special box on the Type 540K, which has been fully described in MOTOR SPORT and the 2-litre Frazer-Nash13.M.W.s have an automatic free-wheel operating on the two higher ratios, per mitting foolproof changes. Otherwise the free-wheel is used only by Rover and D.K.W. amongst cars of note. Electric change is found on Atalanta, Delage, Delahaye, Invicta. and Hudson, and certain sports-cars are available with Wilson epicyciic boxes as an extra. FrazerNash retain their famous all-chain transmission of many merits. Synchro-mesh for all ratios figures On Alvis, HumberHillman and Talbot productions. Gear levers, as we have said, are often remotecontrol type On sports and semi-sporting cars, but, just as thereis a subtle difference between the external aspect of the thoroughbred’s engine and that of massproduced cars, so the layout of remote controls varies considerably. The aristocratic right-hand lever is found on the 41-litre Bentley, and both RollsRoyce models, and Rapier has right-hand conventional lever control of a Wilson box. Lockheed have introduced, a useful ” hill-holder ” which should be universally fitted judging by the number of persons who run back when restarting on hills., and in view of the weird places modern designers put equally weird hand brakes. A possible development is a system of pre-selection with a synchromesh box.. Overdxives are found on some American cars and used by Mercedes Benz, Riley, Atalanta and Jensen, It will probably prove essential for Auto bahn use. The Type 320 MercedesBenz, with a maximum of over 90 in.p.h„ and a sustained cruising speed of 82 m.p.h. in closed form, portrays the influence of A ullbah Front-drive features on the B.S.A. in this country, the excellent French Citroen, and the Hotchkiss, the Adler, Audi and D.K.W. from Germany, and the Cord in America, after practical pioneering by Alvis and Tracta. It exhibits its full advantages combined with a flat

platform frame or backbone chassis. The B.S.A. Co. have recently stated that their cars restart happily on greasy 1 in 4 grades and our own experience suggests that lack of grip is not a major disadvantage, except, perhaps, on mud surfaces. Normal transmission is by open shaft, now well balanced and with thoroughly reliable universals, to a spiral-bevel rear axle. Dipstick oil-level indicators gain ground, and steel banjo axle-casings hold the fort, with rubber effectively used to deaden sounds. Too many inexpensive 1937 cars developed noisy axles very early in life. Frame design has passed through a multitude of stages and now boxmembers are popular for obtaining stiffness, with less accentuation on cruciform centre sections for this purpose. Very stiff frames make for ” dead” riding. Skilful use is made of electric flash, spot and oxy-acetylene welding, but if stiffness is gained, weight reduction seldom follows. The revolutionary Hotchkiss Alpax onepiece construction gives appetising food

for thought. One-piece construction, introduced ages ago by Lagonda and Lancia, or backbone frames are future developments, but limited to large-output construction and single body styles in the former instance, hence the recent Aprilia Lancia change. Lockheed hydraulic, Bendix semiservo’ and Girling direct-action brakes fight a continued battle amongst pro prietary systems. From data recently included in a contemporary’s road-tests it appears that the mechanical systems impart the lightest pedal pressures, though it is early to quote :without com prehensive figures. Generally, modern brakes are very excellent indeed. Bentley and Rolls-Royce alone retain servomotor actuation ; a particularly excellent piece of detail design, incidentally. We prefer hand-levers between the front seats, where benches are not fitted, to dash-placed pistols. Steering is varied. Sometimes five turns are required, lock to lock, and the Minister of Transport might well enforce a maximum of three turns. The Frazer-Nash-B.M.W. remains the finest modern steering we have tried, though its fascinating smoothness of action is being wooed by others, usually with lower gearing and seldom the same accuracy. We believe two-speed steering has arrived—in America. Automatic chassis lubrication figures on Alvis, Autovia, Brough-Superior, Daimler, LeaFrancis, Rover and Triumph cars, and the same effect by one-shot layout is found on the large Alvis, Audi, Bentley, Darrac:q, Delage, Frazer-Nash-B.M.W., Horch, Invicta, Lagonda, Mercedes-Benz, Riley and Rolls-Royce. Lea-Francis have a propeller-shaft in two sections, with a bearing on the frame, like the Austin Seven. Permanent jacking, so appreciated by sports-car users, is standard on A.C., Alvis, Aston-Martin, Autovia, BritishSalmson, Brcaigh, Darracq, Hansa, Lagonda, Lammas, Lea-Francis, M.G., and Rolls-Royce chassis. And so we come to that very important matter, suspension. Independent suspension, even on quite inexpensive utility cars, makes good headway. For steering accuracy, maximum acceleration and braking adhesion, and greater comfort, both by reason of more level riding and the possibility of employing softer springs, there is a great deal to be said for independent suspension all round. The criticism that this gives rise to rolling is hardly serious, and the reason that only a limited number of makers independently suspend the rear wheels is attributable to the extra complication of hinged drive-shafts. Those who do comprise Adler, Alfa-Romeo, Austro-Daimler, Buick, Hansa, Hotchkiss Ten, Imperia, Lancia Aprilia, MercedesBenz, Steyr, and Wanderer. Horch uses jointed shafts but ties the wheels with a light axle to prohibit rolling, as on the forward drive D.K.W. Front independent suspension only gives vastly improved riding over bad roads and definitely increases steering accuracy, while, well carried out, very supple springs can be employed with perfect road adhesion, as instanced by the behaviour of all Frazer Nash-B.M.W. models. The following British makers have adopted front independent suspension (we include utility types) :—Alvis, Atalanta, BritishSalmson, B.S.A., Dahnler, Hillman, Humber, Invicta, Lagonda, Lanchester, Morgan, Rolls-Royce, Talbot and VallXhail. It is in the same stage of development that front brakes were in. around 1923-4 and divers systems are in use. Wishbone layouts allow the wheels to

move in an arc and court gyroscopic motions unless very carefully designed, swinging arm systems alter the wheelbase with wheel movement, and Lancia and Morgan alone use vertical sliding guides. Similarly, there is much variation of springing methods, Alvis, British-Salmson, B.S.A., Hillman, Humber, and Talbot favouring transverse leaf springs, Atalanta, Rolls-Royce, Daimler, Lanchester, and Morgan coil springs, and Lagonda a torsional method, while the Vauxhall has the Dubonnet system. The fact has to be faced that well designed conventional layouts give extremely good roadholding, instanced particularly by Bugatti, Bentley, M.G., Aston-Martin, S.S., and.

Frazer-Nash. Bentley, Aston-Martin and M.G. use cables or arms to steady the front axle, and Bentley, Rolls-Royce and Lagonda have driver-controlled shockabsorbers of Luvax manufacture. Here we must leave this very big subject. If this survey has been less interesting than that of the previous year and rather more a tabulation of makers’ tastes than a story of startling engineering innovations, we must plead lack of space and the fact that design has progressed steadily rather than in revolutionary jerks emphasised by individual exploitation of advanced ideas. This is as it should be, for thereby does a much wider public enjoy the benefits of engineering and constructional advance ment. We can congratulate ourselves on the excellence and variety of the sports and semi-sporting models, in particular those of British manufacture, and remind, ourselves that utility types have exhibited very little progress since about 1032 in respect of improved performance, because every increase in engine-power has been cancelled by increased weight resulting from larger bodywork or multi

plication of equipment. Designers of high-performance cars must guard against such a trend in the future. Those who are interested in this question of design trend should read this article in conjunction with that published in our issue of December 1986, because a year’s development hardly allows a b road appreciation to be obtained. Part II, dealing with racing design, will appear in next month’s issue;