Geo. Roesch on post-war design

Many people are wondering if we are devoting sufficient attention to post-war design, in view of the export market struggle which will be the industry’s main concern following the armistice. So many designs were rushed out in 1919 only to prove, in many cases, commercially impracticable that during this war it would seem a good thing to look to the future. We shall not go back to the state of affairs which existed in 1919, when one of the ways of regaining the road was to build a cycle-car in your cellar with the aid of a small lathe and a stock of raw materials – The Model Engineer published instructions for so making the “D” Ultra in May, 1919. Competition for world markets will be intense and the call will be for sound cars of good performance and complete dependability. Consequently interest attaches to the paper which Geo. Roesch, the famous Talbot designer, now chief engineer to David Brown Tractors, Ltd., read before the I.A.E. in London on April 21st, entitled “Post-War Automobile Design.” Geo. Roesch opened by suggesting that new cars, more scientifically designed than their predecessors, would appear after the war to cater for new needs. Larger outputs and lower costs to suit post-war economy could be expected and less will be sacrificed to conventionality and fashion, more attention being paid to utility and performance in relation to total cost to the user. Safer cars are required, because by that is meant also cars with better performance. Smoother and more silent vehicles are demanded, because they make for quicker travel from point to point with less fatigue. The constantly increasing pace of living must be catered for. Values of performance, expressed by speed, acceleration and deceleration, can only be fully assessed when compared to other characteristics, such as visibility, stability, silence, smoothness, comfort, appearance, road conditions and cost.

The author expressed the opinion that weight reduction would depend on whether aluminium or other lighter metals will be available after the war at a cost which will justify their extensive use in popular cars. On more expensive ones full advantage will be taken of the opportunity thus provided to improve performance by this means. The material question will underlie any advance contemplated in design. The size and weight of the mechanism could be reduced by first choosing the smallest and lightest wheel for the size of car and then cutting down the two axles to minimum dimensions, and so on. The lighter the unsprung weight the easier the problem becomes, because low weight cannot be obtained without good supple suspension – here the author quotes modern racing cars. It is claimed that the experimental Ford plastics car weighs 1,000 lb. less than the corresponding car made of steel. A complete change of proportions has produced the result. It was the same design treatment which brought out the Model-T Ford and, later, the Austin Seven.

The author went on to define the merits of front-wheel drive and said that the design and manufacture of the Citroen have shown a way to good performance and low cost. Objections to f.w.d. include reduced tractive adherence of the front wheels, employment of four universal joints, heavy steering and possibly increased car length, with consequent added weight. In other respects it gives a degree of road-worthiness only found in the best orthodox-construction vehicles, and with modern silent gears and universals the front transmission is unnoticed. Lack of adhesion is offset by a forward, low c. of g., and satisfactory universal joints are now obtainable. Careful design, eliminating friction, lightens the steering and length adds to appearance. Modern conditions have improved the prospect of the f.w.d. car, but not to the point of making it the ideal form of utility vehicle; it is attractive for a special market.

Roesch next praised the practical aspect of the early rear-engined de Dion Bouton, with radiator in front and engine under the seats ahead of the axle, particularly characterising the use of a small, compact engine. Roesch considers that sitting the drive alone between the front wheels, as in the Rumpier and more recent Dubonnet, is not a commercial proposition. Success with rear engine location depends on using a small, light engine, and air cooling to get the weight down is found in the German “people’s car” and in the V8 Tatra, the noise of which would be unacceptable in this country. In the author’s opinion the advantages of rear engine location were more illusory than real. Progress here will depend upon light air-cooled power units much quieter in operation than now, and this type of car will not easily win favour again. Of conventional layout the author remarks that it is the result of 50 years’ development and gives the designer the opportunity to be original in further improving the best that has so far been produced. To reduce weight, chassis and body must be considered as one. The tendency has been to go over to chassisless construction; the author prefers the separate frame. After dealing with bodywork in some detail, the author considers the engine, quoting the Trojan and D.K.W. as examples of two-stroke construction and the Rover Eight and the Franklin as exponents of air-cooling. He does not believe either will become general, but, after disposing of the two-stroke as firing unevenly at low speeds and wasting fuel, says of the D.K.W. that it is the exception confirming the rule. Solid-injection c.i. does not yet show promise for car use, but supercharging increases its prospects in the distant future. Roesch suggests that now that Ford has introduced a six-cylinder-in-line motor, the V engine will recede further into the background. [Rolls Royce and Lagonda should contribute to the discussion here. – Ed.] Small bores do not allow two rods on one crankpin in a V engine unless the engine is specially lengthened, and Roesch once produced a 4.5-litre straight eight which was nearly 6 in. shorter than a certain V12 of similar capacity. He criticises the small V-construction still used in Italy, with its extra width, balance, greater complications and manufacturing difficulties. [Yet Lancia built its great reputation on this type. – Ed.] The present orthodox four or six-cylinder engine will satisfy the need of most cam.

Sleeve valves in an aluminium cylinder seem most attractive, but although the Burt-McCollum single-sleeve principle has been adopted on certain aero engines, unfortunately car conditions of application and working are different. No change from poppet valves can safely be foreseen, but these can be improved, particularly by better cooling. The need of a very stiff and stable combined cylinder block and crankcase was emphasised, and integral counterweights and hollow pins for cast crankshafts will give better balance and durability and reduce bearing wear, so that main bearings can be narrower and will absorb less friction. [Talbot crankshafts were fine pieces of work. – Ed.] The importance of adequate oil filters and fillers and of cylinder lubrication on starting and rapid heating up of the lubricant were emphasised. Fuel injection will have to be tried. The author favoured pump cooling, with fan and thermostatically controlled draught. The author considered that for a long time to come only expensive cars of high performance will use superchargers, remarking that, after all, a 12-h.p. engine will for a long time to come be cheaper and more reliable than a blown 8 h.p. [Certainly the Talbot in racing guise has been one of the most outstanding of unsupercharged cars of moderate capacity. – Ed.] Transmission systems were reviewed, with a good word for the friction-type clutch, and then, discussing suspension, the author shows a preference for a solid rear axle, even with f.w.d., and prefers parallel i.f.s. to the swing axle. A plea is put out for a two-spoke steering wheel – [as on the old Rover Eight. – Ed.] – and brakes needing no more pressure than the accelerator and adequate on the steepest hills with the gear lever in neutral, are called for. Disc brakes are a possible development. Altogether a most valuable paper, from which we are able to quote only very briefly.