Anthony Heal, the Sunbeam historian, traces the career of this great engineer, who was born at Concarneau one hundred years ago.
Louis Herve Coatalen, MIAE, was born on September 11th 1879 at Concarneau, Finisterre, the second son of hotelier François Marie Coatalen and Louise le Bris. He was educated first at the Lyceé de Brest and then took the strenuous three year engineering course at the Ecole des Arts et Metiers at Cluny. After doing this military training he got a job in the drawing office of the pioneer motor manufacturing firm of De Dion Bouton et Cie, Puteaux, Seine, going on from there to Clement & Cie, at Levallois Perret and to Panhard et Levassor. Seeing greater opportunities for young men in the motor industry in England, he came to this country in 1900. For a few months he worked for the Crowden Motor Car Co. at Leamington Spa and then, at the age of 21, he joined Humber Ltd. at Coventry as chief engineer. He designed two new models, the 8/10 h.p. and the 10/12 h.p. The success of the latter, a 4-cylinder medium-sized car selling for £300, restored the fortunes of the Humber Company. The demand entailed increased production, to the extent that the cars were being completed in the street. Coatalen was not content just to be a backroom designer. The Chairman, Edward Powell, said “We cannot keep him at his desk. He will get out on the road and drive a car”. In the 1906 Tourist Trophy race he drove a Coventry Humber into sixth place, averaging 32.1 m.p.h.
In 1907 he entered into a partnership with William Hillman of Coventry to produce The Hillman-Coatalen. He designed a 25 h.p. 4-cylnider car which he drove in the Tourist Trophy race that year. He put up the fastest lap at 37.5 m.p.h. but crashed at Quarter Bridge. Two new cars with 4-cylinder (4” x 5”) engines were built for the race in 1908. Coatalen drove one, the other being handled by Kenelm Lee Guinness, who was later to become famous not only as a racing driver but also as the maker of KLG sparking plugs. He retired with a broken chassis. Coatalen finished 9th having been delayed by a leaking petrol pipe.
On the recommendation of Thomas Cureton, managing director of the Sunbeam Motor Car Co. of Moorfields, Wolverhampton, Coatalen was engaged as Chief Engineer in February 1909. His first product was the 16/20 h.p. 4-cylinder Sunbeam which competed in numerous hill-climbs and reliability trails, and distinguished itself by its performance in the Scottish Six Days Trial. This success encouraged the company to launch a smaller 12/16 h.p. model (80 x 120 mm.) with T-head and pressure lubrication. The factory had to be extended and production facilities were expanded to meet the demand. In the following year Coatalen married Olive Mary Bath, daughter of Henry James Bath, consulting engineer and director of the Sunbeam Motor Co. They had two sons, Hervé Louis (b. 1913) and Jean Louis (b. 1916). Coatalen believed that the saying “Racing improves the Breed” was as true of motor cars as of horses. He drove “hotted up” standard Sunbeam cars with success at Brooklands track and in 1910 appeared with a special streamlined single seater “Nautilus”. Its 4-cylinder 92 x 160 mm. engine had 16 overhead valves operated by pus rods and rockers. The radiator was mounted behind the drive and, not surprisingly, the engine suffered from overheating. In 1911 a more advanced design, with 8 inclined valves, operated by an overhead camshaft, was produced. Fitted with a narrow single-seater body and known as “Toodles II”, this 3,217 c.c. racing car won three races at Brooklands during the season and set up a new 16 h.p.-Class Short Record (½ mile) at 86 m.p.h.
In the same year, Coatalen re-designed the engine of the successful 12/16 h.p. Sunbeam, giving it a Monobloc cylinder casting with L-head. Noe was entered in the Coupé de l’Auto Voiturette race at Boulogne, the Sunbeam company’s first entry in a race abroad. Driven by T. Richards, he was lying 7th when he was forced to retire on the 8th lap due to a broken steering connection.
Before the introduction of his new 25/30 h.p. 6-cylinder model at the Motor Show of 1911, Louis Coatalen subjected it to a severe test, thereby giving a convincing demonstration of its speed, stamina and reliability. One of the new chassis, fitted with a single-seater body, was driven at Brooklands for 12 hours, the engine running non-stop for the whole period. Driven by the designer and T. H. Richards, the Sunbeam averaged 75.66 m.p.h., setting up 15 worlds records from 4 hours to 12 hours. During the 1911 season Sunbeam cars competed in numerous hill-climbs, speed trials and races at Brooklands with considerable success, winning nearly 50 cups and prizes and setting up 15 Worlds Records.
The dynamic influence of Louis Coatalen was felt throughout the Moorfield works. New automatic machinery was installed and production was increased. He not only designed the cars but organised the factory, engaged fresh talent, and in 1912 was elected a Director of the Company. His colleagues, however, impressed on him that it would be better if in future other people drove the cars in competitions!
The Coupe de l’Auto Voiturette race in 1912 was held at Dieppe simultaneously with the Grand Prix of the Automobile Club de France. Four slightly modified 12/16 h.p. (80 x 149 mm.) cars were prepared for the two day 956-mile event. The Sunbeams took the first three places in the 3-litre race and astonished everybody by finishing 3rd, 4th and 5th in the Grand Prix, being beaten only by a Peugeot with an engine more than twice their size and by a Fiat nearly five times as large. The combination of high efficiency with outstanding reliability, resulting from high speed development at Brooklands, had triumphed.
One of these side-valve 3-litre cars, driven by R. F Grossman and D. Resta, later in the season, set up 19 Class E Records and 6 Worlds Records at Brooklands from 50 miles to 1,000 miles, (76.1 m.p.h.). The fastest lap was at 86.77 m.p.h. A couple of weeks later Resta took the Class E record for the kilometre at 100.94 m.p.h. A team of 4 ½ -litre 6-cylinder cars with side-valve engines were prepared for the Grand Prix at Amiens in 1913. J. Chassagne finished 3rd and Resta 6th, being beaten by Georges Boillot and Jules Goux on 5.6-litre Peugeots. Towards the end of the season, Coatalen produced a new Sunbeam racing car designed for track racing and World Record attempts. Driven at Brooklands by Jean Chassagne, it lapped at over 117 m.p.h. and set up 8 World Records, including 1 Hour at 107.95 m.p.h. The 9-litre 12-cylinder engine comprised a pair of Grand Prix type 6-cylinder blocks mounted on the crankcase in V formation at 60 degrees.
But the days of the side-valve engine in Grand Prix racing were numbered, for in 1913 the Peugeot cars, designed by the Swiss engineer Ernest Henry, with their twin-overhead-camshafts and sixteen valves, were invincible. They won both the Grand Prix and the Coupe de l’Auto races, beating the Sunbeams into third place in both events. Coatalen was quick to respond to the challenge. One of the 3-litre Peugeots was procured and taken to Wolverhampton where it was closely studied. Not surprisingly, the Sunbeam cars which competed in the French Grand Prix and Tourist Trophy races in 1914 bore more than a slight resemblance to the designs of Ernest Henry. The latter race was won by K. Lee Guinness’s Sunbeam, but in the Grand Prix both Peugeot and Sunbeam were defeated by the new Mercedes racing cars.
Following the death of Thomas Cureton in 1914, Coatalen was appointed Joint Managing Director of Sunbeam’s with Mr. W. M. Iliff, who had joined the Board some months earlier.
Some time before the outbreak of war in August 1914, the Sunbeam company had a 150 h.p. 8-cylinder aero engine already in production. Coatalen had purchased a Farman bi-plane in 1913 to which this engine had benefitted and on its early test flights the machine had been piloted by John Alcock, who later made the first Transatlantic flight, for which he received a knighthood. Known as the “Crusader” this engine had side-valves but the ever increasing demands of the services for more power caused the company to apply some of the lessons learned in building their racing car engines. Twin overhead camshafts and the four valves per cylinder were adopted for several Sunbeam-Coatalen aero-engines. Over 20 types were produced and power output rose from 150 to 900 h.p. Sunbeam engines were supplied to the Royal Air Force and the Royal Naval Air Service, as well as to the French and Russian air services, and five 275 h.p. 12-cylinder “Maori” type engines were fitted to the British rigid airship R34 which made the first out and home flight across the Atlantic in 1919.
Sunbeam-Coatalen engines were also fitted to the Short seaplanes of RNAS that gave the Higher Command information about the disposition of the enemy’s ships in the Battle of Jutland. In an obituary notice Lord Sempill wrote “As one who served in the RNAS and was closely concerned with the technical side, I am sure that a sincere tribute is due to Louis Coatalen, designer of the engines which powered the large majority of our seaplanes and airships. As a designer he was ahead of his time”. The French Government showed its appreciation of his service to Allied aviation by nominating him Chevalier of the Legion d’Honneur.
Although the Sunbeam Motor Car Co. Ltd. was busy turning out a wide variety of engines for aeroplanes, airships and coastal motor boats, and airframes of Short seaplanes, Louis Coatalen nevertheless managed to design and produce a couple of 4.9-litre 6-cylinder racing engines on the lines of those used for the 1914 Grand Prix. Using aluminium pistons, they developed 156 b.h.p. and were fitted into two Grand Prix chassis. Josef Christiaens and Frank Bill took them to the USA where they competed in several track events during the 1916 season. At Indianapolis, Christiaens after some tyre trouble, finished fourth. He had to hold the engine speed down to 2,900 r.p.m. owing to a vibration period at 3,000 r.p.m. Louis Chevrolet drove one of the Sunbeams in a 20-mile race at Indianapolis later in the season. In overtaking Hughie Hughes’ Duesenberg he took the engine up to 3,200 r.pm. only to have a connecting rod come through the side of the crankcase.
Soon after the Armistice in November 1918, Coatalen started to prepare for the return to motor-car production again. Revised versions of the pre-war 16 h.p. and 24 h.p. cars were announced. He took the first post-war 24.hp 6-cylinder car on an extended test run over the war damaged roads of France. The long straight Routes Nationales provided opportunities to prove the car’s speed and stamina and the Alpine mountain roads tested its power and the efficiency of its cooling in a way that was not possible in England.
Following the merger of the Sunbeam, Talbot and Darracq companies in 1920, Louis Coatalen was appointed Chief Engineer and announced his intention of opening a drawing office and experimental department in Paris in addition to the one in Wolverhampton. With the re-opening of Brooklands and the revival of motor racing in France there was plenty of scope for him to embark on an extensive racing programme. The two 4.9-litre Indianapolis Sunbeams had been rebuilt with shorter chassis and returned to the USA for the first post-war 500-mile race in 1919, but they were withdrawn as it was alleged that the engines exceeded the capacity limit of 300 cubic inches which the race regulations stipulated. At Brooklands, however, these cars were immediately successful, driven by H. G. Hawker, G. L. Geach, and by André Boillot who lapped at 111 m.p.h.
The 12-cylinder car with which J. Chassagne had taken the one-hour record in 1913 had been sold in the United States, where Ralph de Palma had won a match race with it at the Sheepshead Bay Speedway, Long Island at 113.7 m.p.h. It was also driven at other tracks by Hughie Hughes and came to an untimely end in a 100-mile race at the Kalamazoo dirt-track when it skidded right across the track and eight cars ran into it. It had been Coatalen’s intention to produce a luxurious touring car using the V12 engine but the outbreak of war in 1914 prevented him from realising his ambition of marketing the first 12-cylinder car. The Packard company bought the 12-cylinder Sunbeam and produced a 12-cylinder racing car of their own, which was the prototype for their 12-cylinder “Twin Six” production model.
To replace it Coatalen designed and built a new car for Brooklands races and Worlds records. It had a specially-built 350 h.p. V12-cylinder engine in a narrow chassis frame with a single-seater body. It made an inauspicious start to its racing career. In June 1920, when driven by H. G. Hawker, a tyre burst on the banking and despite his great efforts to hold it the Sunbeam went through the corrugated iron fence along the Railway Straight. No great damage was done and in October the big car was taken to Gaillon in France where Réné Thomas succeeded in setting up a new record for the hill at 108.6 m.p.h. To comply with the regulations for this event a second seat was cantilevered from the near side of the single-seater body and a simple wind shield was fixed in front of it. With this adaptation the scrutineers accepted the car as a two-seater!
A limit of 3-litres was agreed internationally for Grand Prix events in Europe and for the Indianapolis 500-mile race in USA. This provided Coatalen with an opportunity to produce a team of new racing cars of the latest design. They had 8-cylinder engines with very light aluminium cylinder blocks and followed the practice pioneered by Ernest Henry of four valves per cylinder operated by two overhead camshafts. The dimensions, 65 x 112 mm., were also in line with Henry’s latest design for Ballot, but Coatalen used plain bearings, which resulted in a rather lengthy crankshaft. The low chassis frame was upswept over the both front and back axles and to achieve a low centre of gravity the line of the transmission sloped downwards towards the front. Cable-operated brakes on all four wheels, which could be adjusted while the car was in motion, were an innovation. These cars had to represent the three marques, Sunbeam, Talbot and Talbot-Darracq. This was achieved by fitting different radiators. Two Sunbeams and a Talbot Darracq ran at Indianapolis. The latter retired early in the race but the American driver, Ora Haibe, took his Sunbeam into fifth place at 83.86 m.p.h. Réné Thomas was lying third until shortly before the finish when he was forced to retire due to a broken water connection.
Coatalen planned a mass attack for the first post-war Grand Prix de l’Automobile Club de France which was to be held at Le Mans in July 1921. No less than even 3-litre straight-eights were entered, two Sunbeams, two Talbots and three Talbot-Darracqs. It was too ambitious a programme for the Racing Department to fulfil. As a result the two Sunbeam entries were withdrawn but K. Lee Guinness and H. O. D. Segrave, who were to drive the Talbots, exerted all their powers of persuasion on Louis Coatalen to allow their cars to start. For Segrave the whole of his future career as a member of the team depending on putting up a good performance in this, his first Grand Prix. A less determined person might well have given up. The road surface disintegrated and flying stones made a hole in the oil tank, pierced the steel cowl in front of the driver, knocked his mechanic Moriceau unconscious and caused continual tyre trouble. During the race Segrave and Moriceau changed wheels 14 times and had to re-time the ignition by the roadside. Guinness had his troubles too. Despite everything, three out of the four cars finished the race, André Boillot in fifth place, K. Lee Guinness eighth, and Segrave ninth.
In contrast to the not very successful début of the new Grand Prix cars, Coatalen’s 1½-litre Talbot-Darracqs scored an immediate success in the Coupe Internationale des Voiturettes held on the Grand Prix course at Le Mans in September 1921. René Thomas, K. Lee Guinness and H. O. D. Segrave finished one, two, three and a similar success was achieved in the 200 mile race at Brooklands a month later, Segrave winning followed by Guinness and Malcolm Campbell.
These neat little cars had 4-cylinder engines that were virtually half the Grand Prix straight-eights, 65 x 113 mm, with 16-overhead valves operated by two overhead camshafts driven by a train of gears at the front. The rear axle had no differential.
All the Sunbeam models announced for 1922 were equipped with new overhead valve engines. The 16 h.p. and the 24 h.p. 6-cylinder were continued in improved form and a new smaller 14 h.p. car was added to the range.
The racing season started off with some encouraging successes at Brooklands. Seagrave was successful with one of the Indianapolis cars and J. Chassagne and Guinness both won races with the 350 h.p. 12-cylinder Sunbeam. At the May meeting, Guinness set a new lap record at 123.39 m.p.h. and later, Worlds Records for the mile and the kilometre at 129.17 and 133.75 m.p.h. He was timed over a half-mile during this record attempt at 140.51 m.p.h. Malcolm Campbell took the big car to Saltburn Sands and achieved 138 m.p.h. over a kilometre.
The RAC revived the Tourist Trophy race in the Isle of Man after a lapse of eight years. There were two classes: 3-litres and 1½-litres. Three 3-litre straight-eight Sunbeams and three 1 ½ -litre Talbot-Darracqs were entered. Sir Algernon Guinness won the voiturette race for Talbot-Darracq and Jean Chassagne the 3-litre race for Sunbeam. H. O. D. Segrave put up the fastest lap.
This was the last International motor race run on the 3-litre formula, for the AIACR had already decided on a 2-litre limit for Grand Prix races in 1922. As a result, Coatalen had to build a team of new racing cars. Influenced perhaps by the success of the 16-valve 1½-litre Talbot Darracqs and the 4-cylinder 2-litre Ballot he commissioned Ernest Henry to design a car to the new formula. Despite Henry’s experience of the 8-cylinder engines of 4.9-litres and 3-litres capacity he had designed for Ballot, he decided on a 16-valve 4-cylinder with the inlet valves much larger than the exhaust valves.
The dimensions, 68x 136 mm., gave a 2 to 1 stroke/bore ratio which compared unfavourably with 1.54 of the winning Fiat. The system of servo brake operation, which Henry had used successfully on the 3-litre Ballots, was adopted for the Sunbeams. The cars lacked the speed of the 6-cylinder Fiats and in the Grand Prix at Strasbourg all three retired due to broken inlet valves. Just as Ernest Henry’s 16-valve Peugeots had dominated Grand Prix racing 10 years earlier, so the new Italian cars now eclipsed his latest design. Despite the failure of the new 2-litre Sunbeam cars in the Grand Prix, the 1 ½ -litre Talbot-Darracqs continued to be invincible in voiturette races in France and Spain, as well as at Brooklands and the Isle of Man. To conclude the 1922 season, which had started so successfully, Sunbeam cars won three out of the four classes for which they were eligible at the Brooklands Speed Championship Meeting.
If his Sunbeam and Talbot-Darracq cars had achieved success Coatalen’s private life was not running smoothly. He worked mostly in Paris and was seen only occasionally at the works in Wolverhampton. His marriage to Olive ended in divorce in 1922 and in the following year he married Mrs. Enid Florence (Iris) van Raalte (née Graham).
Just as in 1914 Coatalen had realised that his early designs were outdated, so in 1922 it was clear that Ernest Henry’s design had been superseded by those of the Italian engineers. Coatalen’s response to the challenge was to engage the services of Vincent Bertarione who had worked with Fornace and Cappa to produce the successful 2-litre 6-cylinder Fiats. Bertarione started work on a new 2-litre 6-cylinder engine with two valves per cylinder set at 96 degrees. The cylinders were fabricated with welded-on water jackets. Split-race roller bearings were used for both mains and big ends. With 7.4 to 1 compression the new engines have 108 b.h.p. at 5,000 r.p.m., nearly 25% more power than the 1922 design. They were mounted in the same chassis that ran at Strasbourg, but the bodywork followed the lines of the successful Fiats.
In the Grand Prix de l’ACF at Tours, the strongest opposition to the new Sunbeams was provided by the eight-cylinder Fiats which were using superchargers for the first time in Grand Prix racing. They proved to be the fastest cars in the race, but all three retired with engine trouble. The Sunbeam proved to be both fast and reliable, finishing first, second and fourth. Segrave’s car won the race at 75.3 m.p.h., the first Englishman and the first British car to win the Grand Prix since its inception in 1906. Later in the season, the Sunbeams were again successful at the Boulogne meeting and in the Spanish grand Prix at the new Sitges Autodrome.
Bertarione also produced a new 8-valve 4-cylinder engine for the Talbot-Darracq voiturettes and these cars continued their invincible career. Segrave won at Boulogne and Divo carried of both the Coupe des Voiturettes at Le Mans and the Grand Prix de la Penya Rhin at Barcelona.
For 1924 the Sunbeam Company introduced three new models with overhead valve engines in unit with the gearbox, torque tube transmission, cantilever rear springs and four-wheel brakes on all but the 12/30 h.p., the smallest and cheapest car in the range. The latter was discontinued after two years but the six-cylinder 20/60 h.p. model continued, with periodic modifications, for several years.
The speed of the supercharged Fiat cars at Tours caused Louis Coatalen to start experiments with forced induction. The Wittig vane type supercharger had not been successful in the Grand Prix, but after adopting the Roots type of blower Fiat had been victorious in the Italian Grand Prix. Following their example, the Sunbeam Experimental Department increased the output of their successful Grand Prix engine using a Roots-type blower driven at crankshaft speed. Like Fiat, the supercharger forced air though the carburettor to the engine. Experiments were then made with the supercharger drawing mixture from the carburettor and discharging it into the induction manifold. This arrangement increased the power output from 115 b.h.p. to 138 b.h.p. at 5,000 r.p.m. Bertarione designed a new lower chassis with wheelbase increased by 4” to accommodate the longer engine and supercharger unit. The transmission was revised, incorporating a new multi-plate clutch, four-speed gearbox and torque tube. The brake-servo introduced on the 1922 racing cars and the three-piece front axle were the only vestigial features which remained of Ernest Henry’s influence on Sunbeam design.
It was evident that the Sunbeam team had the fastest cars on the Grand Prix circuit at Lyons in 1924 and even the Alfa Romeo team with their new supercharged eight-cylinder cars readily acknowledged this before the race. But if Sunbeam had won in 1923 through the misfortunes of Fiat, now in 1924 they lost the race as a result of their own bad luck. Segrave led for the first three laps and put up the fastest lap at 76.25 m.p.h., but was then slowed by persistent misfiring. Plugs were changed but to no avail and he could do no better than finish fifth. New magnetos had been fitted to the Sunbeams, on the advice of the Bosch representative, the night before the race. On examination afterwards some of the windings were found to be broken. When the old magnetos were fitted again the misfiring disappeared.
Two Sunbeams ran in the Spanish Grand Prix at San Sebastian driven by K. Lee Guinness and H. O. D. Segrave. The former took the lead at the outset, but Segrave decided to start gently and to watch the opposition, which included Bugattis two 12-cylinder Delages and Count Masetti driving a Mercedes. This was the first Grand Prix since the 1914-18 War in which German cars had been permitted to take part. The course was not in good condition and clay had been spread on some corners instead of sand, which added to the dangers. Guinness took the lead but on the wet clay on one of the corners his car went straight on up a steep bank and overturned three times. Both he and his mechanic Barratt were thrown out. The mechanic was killed and Guinness suffered severe injuries.
The sight of his team mate’s crashed car caused Segrave to drive with the great caution, lying second behind Masetti’s Mercedes until the latter stopped to refuel. The Sunbeam then took the lead and Masetti, in trying to catch Segrave, went off the road, leaving him to win the race, with Constantini’s Bugatti in second place followed by the Delages of Morel and Divo.
Bertarione had also redesigned the 1 ½ -litre Talbot-Darracqs with superchargers and they continued to be unbeatable in their class. Guinness and Resta were first and second in the Swiss Voiturette Grand Prix at Geneva at 70 m.p.h. In the 200 Mile Race at Brooklands the cars finished in team order, first, second and third, Guinness, Duller and Segrave, averaging 102 m.p.h., and in the 1 ½ -litre race at Montlhèry, Scales, Segrave and Bourlier repeated the same result at 100.5 m.p.h.
At Brooklands in September, Dario Resta, with Bill Perkins and his mechanic, set up several short distance International Class E records, from 1 kilometre (f.s.) at 121.18 m.p.h. to 5 miles at 114.23 m.p.h. As the result of a tyre leaving the rim the Grand Prix Sunbeam crashed through the fence on the Railway Straight. Resta was killed and Perkins severely injured. Later in the same month Malcolm Campbell took the 350 h.p. car to Pendine where he achieved a World Record for the kilometre at 146.16 m.p.h., the mean of runs in both directions of the course.
Despite the disappointment in the Grand Prix at Lyons, the new supercharged cars had shown themselves to be fully competitive with the Italian and French machines and Coatalen must have been well pleased with their achievements. To add to his satisfaction a daughter, Marjorie, was born during the year.
In March 1924, W. O. Bentley wrote a lengthy letter, which was published in the correspondence columns of The Autocar, in which he challenged the often repeated and commonly accepted statements that “racing improves the breed” and “the racing car of today is the touring car of tomorrow”. He maintained that the specially-designed racing car has nothing in common with the standard touring car and that the racing of a “standard car” is the only way in which its weaknesses can be exposed so that its design may be steadily improved. This attack on the specially designed racing car as the instrument of progress naturally enough produced a spirited reply from Louis Coatalen in which he cited several features of current automobile design which had been developed by racing. These included high-speed engines, dry-sump lubrication, nickel-chrome cranskshafts, special steel for valves, unit construction of engine and gearbox, torque tube transmission, quickly detachable wheels and four-wheel brakes. “In my opinion,” he said “the production of special racing cars for experimental purposes is absolutely necessary if progress in touring car design is to be made quickly . . . “ “Sunbeam touring cars are very closely related to the racing designs from which they have been conscientiously developed.”
Credibility was added to the latter statement by a somewhat premature announcement early in May that a new 3-litre Super Sports Sunbeam with a twin overhead camshaft 6-cylinder engine was being developed. The hard-hitting but courteously phrased correspondence between the two leading automobile engineers continued until the end of May, when Coatalen had the final word. “The burden of my argument was simply that racing car practice accelerated development . . . The Sunbeam Company enters races and builds special cars because it is seeking justification for its future designs . . . just as the Bentley is a modification of accepted old-time racing practice, the new 3-litre Sunbeam is a modification of modern racing practice. My object in racing is primarily the very great research value that is obtained. The production of racing cars is amply justified by the results.”
The 24-Hour Race at Le Mans, which had been run for the first time in 1923, was won in 1924 by a 3-litre Bentley driven by J. F. Duff and F. C. Clement at 53.8 m.p.h. Coatalen considered the Bentley as a development of the typical 1914 racing car design and, no doubt, felt that ten years later a rather more sophisticated and up-to-date design could not fail to be successful. Vincent Bertarione was therefore commissioned to design a 3-litre 6-cylinder engine with twin overhead camshafts and dry sump lubrication with an eye to achieving success in the 24 Hour Race.
If the engine was an up-to-date design, the chassis in which it was mounted was basically that of an ordinary Sunbeam touring car. Two of these 3-litre Sunbeams were entered for the 1925 Grand Prix d’Endurance, one to be driven by Segrave and George Duller, the other by Jean Chassagne and S. C. H. Davis. After the chassis frames had been strengthened at the Talbot works in Paris, the cars started the race without much testing in the practice period. Nevertheless they achieved a creditable result. Segrave led the race for the first 11 laps, engaging in a hard fought duel with Kensington Moir on the leading Bentley which resulted in the latter running out of fuel. The Sunbeam was later forced to retire with clutch trouble. Chassagne and Davis finished in second place despite a rear axle badly damaged when the Sunbeam was forced off the road by another competitor. They covered 1,343 miles, 52 miles more than Duff’s Bentley achieved in 1924. Coatalen had successfully demonstrated the superiority of his 3-litre car over the Bentley, which had been the object of the exercise, and the Sunbeam Sales Department began to receive public demand for such a car to be put on the market. After the main weaknesses of the prototype had been remedied, the 3-litre Super Sports Car was added to the range of Sunbeam models offered in 1926.
Early in 1925, one of the supercharged Grand Prix cars driven by H. O. D. Segrave and J. G. P. Thomas had attacked the 12 Hour Record at Montlhèry but the attempt had to be abandoned because of engine trouble and a snowstorm. Nevertheless new Worlds Records for 3 Hours and 500 Kilometres were set up at 102 m.p.h. Segrave later put up the fastest time at the Kop Hill and at Shelsley Walsh hill-climbs, and Malcolm Campbell set up new Worlds Records for the mile and the kilometre at Pendine with the now ageing 350 h.p. Sunbeam. His mean average speed of runs in both directions was 150.87 m.p.h.
The Grand Prix cars ran again in the French Grand Prix at Montlhèry in much the same form as the previous year. Count Masetti finished third behind the 12-cylinder Delages of Benoist and Wagner. Segrave and Count Conelli both retired due to mechanical troubles. After the race, Masetti took Conelli’s car to Switzerland where he put up fastest time and a new record for the course at the Klausen Pass hill-climb beating A. Divo, driving the 10-litre Delage, by 16 seconds. The Spanish Grand Prix, in which Masetti retired at half distance, was the last International Grand Prix in which the Sunbeam Motor Car Company’s supercharged 2-litre cars were officially entered. For 1926 Grand Prix racing was to be restricted to cars of 1,500 c.c. The Talbot-Darracq voiturettes, in their last season, continued to be unbeatable in their class. Duller, Conelli and Segrave took the first three places in the Grand Prix de l’Ouverture at Montlhèry and Segrave and Masetti were first and second in the 200 Mile Race at Brooklands. The marque enjoyed an invincible superiority in voiturette racing for five consecutive seasons.
This achievement was going to be much harder to maintain with the 1 ½ -litre class becoming the arena for International Grand Prix racing. New cars of the most advanced design would be needed. Coatalen commissioned Bertarione to produce a worthy successor to the successful 4-cylinder voiturettes. The new cars had 8-cylinder roller-bearing engines with superchargers driven off the front of the crankshaft, which produced 145 b.h.p. at 6,500 r.p.m. Very low frontal area was achieved by off-setting the engine and gearbox so that the driver sat between the torque tube and the 10” deep chassis frame. The front and rear axles passed through slots in the side members. The whole car had a striking, workmanlike appearance. Early in the season they suffered from teething troubles with their brakes and front axle breakages but these were overcome before the end of the racing season. Segrave and Divo were first and second in the 200 Mile Race at Brooklands, and the first three places in the Grand Prix due Salon were taken by Divo, Segrave and Moriceau.
At the Sunbeam works a new 12-cylinder 4-litre racing car was completed early in 1926. It comprised two 2-litre Grand Prix cylinder blocks mounted at 75° on a common crankcase with a large Roots supercharger driven off the front of the crankshaft. This engine, which gave 306 b.h.p. at 5,000 r.p.m., was fitted into a chassis 3 ½” longer than that of the Grand Prix cars. The whole car weighed only 18 cwt. Despite some trouble with the large supercharger, Segrave set up a World’s Record on the sands at Southport, covering a kilometre at a mean speed of 152.3 m.p.h. for runs in both directions. Two smaller superchargers were later substituted for the large one, which overcame the trouble experienced with cracked casings. In July the 4-litre car was sent to San Sebastian to compete in the Spanish Grand Prix. Segrave led for the first four laps but had to retire when the front axle broke. After a new axle had been fitted at the works, Segrave drove the car again in the 6 km. Speed Trial at Boulogne where he put up the fastest time and won the Coupe Crouty with a speed of 140.6 m.p.h. Driving the 18 cwt. car at this speed on a highly cambered Route Nationale resulted in Segrave admitting that, for the first time in his life, he had been really frightened in a motor car. The Sunbeam was loaded into a railway van and consigned to Milan where it was to run in the Italian Grand Prix. When Segrave got there the car had not arrived. He was missing an opportunity to practice on the Monza circuit and was getting anxious. The Sunbeam was only located in a railway siding after he had personally made a search of the goods yard.
Segrave, after his first practice, was disappointed at his lap time, despite making every effort, but after watching the Italian drivers on the banked circuit he followed their example, using the top of the banking. As a result, he set up a record lap at 110.5 m.p.h. In the race itself he led for 20 laps but then had to retire due to loss of oil from the gearbox.
The record set up by the 4-litre Sunbeam at Southport earlier in the year had, meanwhile, been broken by J. G. Parry Thomas with his 500 h.p. Liberty aero-engined monster known as “Babs”, which had achieved over the 170 m.p.h. Coatalen and Segrave agreed that even with its two superchargers the 4-litre Sunbeam could not be delayed to exceed this speed. It was evident that considerably more power would be required to regain the record.
Financial considerations would make the design and construction of an entirely new machine impossible. Nevertheless, they devised a scheme which was ingenious, practicable, and not impossibly expensive. Two old Sunbeam “Matabele” aero-engines, which had been modified for use in the racing motor boat “Maple Leaf VII” in the 1921 Championship of the Sea in USA, were to be mounted fore and aft of a specially constructed chassis frame, coupled together, driving through a three speed gearbox and a bevel driven countershaft, with final drive by outside chains to the rear wheels. The detailed design was undertaken by Captain J. S. Irving with great skill. The engines were stripped and rebuilt and the chassis was assembled and tested by coupling the rear hubs directly to Heenan and Froude dynamometers. In this manner the car was run satisfactorily at the equivalent of 210 m.p.h. The body shape was evolved by wind-tunnel tests. Dunlop designed, made and tested special tyres which would transmit 1,000 h.p., each tyre carrying a weight of over one ton, at 200 m.p.h. for 3 ½ minutes.
H. O. D. Segrave and K. Lee Guinness took the car to Daytona in March 1927. Arrangements were made with the FIA to check the timing mechanism. The test runs at moderate speed were made over the course but these gave misleading results due to spectators crossing the timing strips. The final-drive ratio was altered to improve the car’s acceleration and on March 29th all was set for the record attempt. Segrave drove to the south end of the course, turned the car and made his northward timed run. He turned again, made his southward run with the wind, and returned to the timing stand. After the timekeepers had checked the times for each run his average speed was announced: one Kilometre – 202.98 m.p.h. One mile – 203.79 m.p.h. Five Kilometres – 202.67m.p.h. thus beating the previous record by no less than 29 m.p.h. On his return to England a luncheon was held at the RAC in honour of Segrave and the Sunbeam, with members of the British Motor Industry and other distinguished guests. Many other dinners and receptions were held in his honour both in London and Wolverhampton in the weeks that followed.
The advantage from the safety angle of the diesel engine for aircraft use had occupied Coatalen’s mind and he had designed a 9-litre Sunbeam-Coatalen diesel engine with this purpose in mind. In 1929 an engine had been built and development work was in hand. Coatalen’s name was displayed prominently on the side of the engine. Some members of the STD Group were opposed to the scheme as they felt that it was beyond the resources of the Group to finance the successful development of such an engine. Coatalen entered into negotiations with the makers of Indian motorcycles. The negotiations were abortive as the company changed hands and the new owners dropped the idea. Coatalen now seldom visited Wolverhampton. He had his drawing office in Paris and as the result of ill-health he spent much of his time at his villa in Capri.
Towards the end of 1929 work was started on a new record-breaking Sunbeam. The two supercharged 12-cylinder engines were largely of light alloy and were said to be intended eventually for use in aeroplanes. With the cubic capacity of 24-litres each engine was expected to develop 2,000 h.p. Two overhead camshafts on each bank of cylinders operated four valves per cylinder. Split-race roller bearings were used for both the main crankshaft and big-end bearings. The two engines were mounted tandem fashion at the front of the chassis. They were coupled by a countershaft running at 2.3 times engine speed. From the three-speed gearbox two parallel, contra-rotating propeller shafts transmitted the drive to the rear axle. The driver’s seat was positioned between the two shafts. It was originally intended to use multiple Roots type superchargers but a large centrifugal blower mounted between the engines was eventually used instead. The slim body terminated in two large fins with a pivoted flap mounted between them which could be used as an air-brake. Little testing had been possible before the car, known as the “Silver Bullet”, was shipped, early in 1930, to Daytona. Kaye Don was chosen to drive it.
The record attempt was like a Greek tragedy. Nothing went as planned, the beach was not in good condition, the car was not as fast as expected. There was friction between Coatalen and the driver. Some blamed Don for not “putting his foot down” and others said the engines did not deliver the power required. The only record achieved was a local one, five miles at 151.62 m.p.h. The highest speed recorded was 186 m.p.h. The continued delays were costly and after six weeks the expedition returned ignominiously home.
The accusation that Kaye Don was afraid to drive the “Silver Bullet” to its limits was belied by the courageous way he drove the 4-litre 12-cylinder Sunbeams “Tiger” and “Tigress” at Brooklands. He three times held the lap record, finally gaining the Daily Herald Trophy when he broke Birkin’s record with a lap at 137.38 m.p.h.
With Coatalen’s influence removed and in the difficult economic conditions of the time, the affairs of the STD Group were in decline and in 1935 Motor Industries Ltd (a subsidiary of Rootes Securities Ltd) acquired the assets and goodwill of the Sunbeam Motor Car Co. Coatalen had, meanwhile, acquired from Gustave Baehr the Lockheed Hydraulic Brake Co. in Paris and had launched KLG Sparking Plugs in France. His marriage to Mrs. Van Raalte came to an end and he married Ellen Amy Bridson in 1935. Development work on diesel aero engines continued. An Hispano Suiza engine was converted to diesel operation, using Coatalen’s special injection pump which worked at very high pressure. The fuel pipes from the pump to the injection nozzles were the Achilles heel of the system as they started to leak after 30n to 35 hours of continuous test running.
The German invasion in 1940 caused the evacuation of the Lockheed Brake Co. to Bordeaux until the total occupation of France, when the company returned to Paris. Much of the plant was lost or damaged during the war and the advent of the jet engine put a stop to the development of the diesel aero engine.
In 1953 Louis Coatalen was elected President of the Societe des Ingenieurs de l’Automobile. He was still actively engaged in the affairs of the Lockheed Brake Co. at the time of his death in Paris on May 19th, 1962. The French mint, in 1974, struck a bronze commemorative medal, bearing a bas-relief portrait by Lhoste and the inscription Louis Coatalen 1879-1962 – ses moteurs vainqueurs sur terre, sur l’eau, dans les airs”, and the date 1923, the year of the Sunbeam victory in the Grand Prix de l’A.C.F. It is for his work for the Sunbeam Motor Co. and for the successes they achieved that Louis Coatalen will be chiefly remembered.