Roy Fedden - Cosmos Engineering and The Jupiter

Cosmos Engineering and The Jupiter

During this period the aviation portions of Brazil Straker were purchased by Cosmos Engineering, where work on the designs continued. Both were ready for testing in 1918, but there seemed to be little interest at first. In September, however, a Mercury was experimentally fitted to a Bristol Scout, and it dramatically improved performance, easily beating the competing Sunbeam Arab. Bristol then decided to try the Jupiter in their new Badger design, finding that it too completely outperformed the competing ABC Dragonfly. Production of both designs for Bristol was to start immediately, but the war ended only days later and the contract was cancelled.

With the ending of the war, Cosmos had no production designs, and their repair work was quickly dwindling. The company was soon insolvent. Convinced of the quality of the Cosmos designs, the Air Ministry "made it be known" that they would be rather happy if the company were purchased by Bristol, which eventually took place in 1920. Sir George White later noted that they acquired Mercury design and seven engines, all the assets of Cosmos, along with Fedden and his design team, all for just £15,000. Even then most sources suggest they only did so after being forced to by the Air Ministry, which is perhaps not surprising given the fragile economy of the era.

Bristol soon found a role for the larger design, which entered production at Bristol's new engine plant in Filton as the Bristol Jupiter. The Jupiter became a commercial success and was widely used around the world, resulting in Fedden becoming one of the most highly paid engineers in Europe.

By the late 1920s, the Jupiter design was no longer competitive, and Fedden and Butler started work on a pair of new designs. Both would use a supercharger to provide boost even at ground level, at that time a new-fangled idea, and thereby deliver similar power as the Jupiter's from a much smaller engine. Re-using their earlier name, this design emerged as the Bristol Mercury, while a more powerful design at the same size as the original Jupiter became the Bristol Pegasus.