Louis Coatalen

The brief partnership was dissolved in 1909 and Coatalen moved from Coventry to Wolverhampton to join Sunbeam. He was appointed joint managing director (with William M Iliff) in 1914.[4]

1913 Sunbeam 12-16 sports

His first design was one of the outstanding light car designs of its day. In 1912 three 12-16s took the first three places in Dieppe's Coupe de l'Auto 2-day race for 3-litre cars. The first of the three cars was also third in the race for Grand Prix cars. But his designs rapidly became less innovative and he seemed to copy Peugeot developments rather than use his own.[2]

Sunbeam cars won the Tourist Trophy races in 1914 and 1922. The Sunbeam cars that took the first three places in the 1923 French Grand Prix were said to have owed much to Fiat designs.[2]

Coatalen's streamlined Nautilus in 1910

During World War I he designed aircraft engines for Sunbeam. On his death in 1962 Lord Sempill wrote to The Times to point out that Coatalen was one of the three leading designers of engines for aircraft and airships used by the RNAS in the First World War. The other two, he said, were W O Bentley and Sir Henry Royce.[5]

Sunbeam produced a greater variety of aero engines than any other business during the war. W O Bentley said this was "in part because Coatalen was so good at selling ideas to the Admiralty and War Office."[3]

He was appointed a director of STD Motors when in 1920 Sunbeam joined with Clément-Talbot and Darracq to form STD Motors Limited, but he remained chief engineer of Sunbeam.[6] He was later put in charge of the technical and designing staffs of all STD subsidiaries.[7]

With the success of 1.5-litre Talbot-Darracq cars, his main interest became racing cars. Their wins catapulted Sunbeam to the highest echelons of international competition from the legendary success at the 1912 Coupe de l’Auto to winning the 1914 and 1922 Tourist Trophy and 1923 and 1924 Grand Prix. Coatelen collaborated with the industry foremost designer Ernest Henry on the 1922 Grand Prix Sunbeams and had some of the most respected drivers of the period – Henry Segrave, Jean Chassagne and Kenelm Lee Guinness driving his Sunbeam cars.

In 1926, Sunbeam's racing activities were taken into the STD company and moved to Suresnes near Paris in France and although Coatalen continued working part-time in Wolverhampton, he spent most of his time in Paris.

On his direction, Sunbeam was among the first British manufacturers to provide front wheel brakes.[2] Coatalen's innovations included balancing the wheels (a technique also claimed by Sig Haugdahl) and putting the oil pump in the sump, and he was an early advocate of shock absorbers.[8]

Sunbeam became heavily involved in land speed record attempts including the successful 1000HP car of 1927 and the failed 'Silver Bullet' of 1930. Louis Coatalen designed the engines for the first car to exceed 150 miles per hour and the first car to exceed 200 miles an hour, the 1000 horsepower Sunbeam driven by Henry Segrave.[2]

Sunbeam 350 horsepower Campbell's Bluebird, first car to exceed 150 mph

Sunbeam 1000 horsepower first car to exceed 200 mph

Sunbeam Silver Bullet 4000 horsepower failed to reach 250 mph

Louis Coatalen married four times: in 1902 to Annie Ellen Davis (divorced 1906), in 1910 to Olive Bath (daughter of a Sunbeam director, Henry J Bath), in 1923 to Iris van Raalte, née Graham, and in 1934 to Ellen Bridson known to family as Dickie. There is no record of a marriage to a member of the Hillman family.