Roy Fedden

Sir Roy Fedden * 1885; † 1973) was an engineer who designed most of Bristol Engine Company's successful aircraft engine designs.

Fedden was born in the Bristol area to fairly wealthy and influential parents. Fedden's family was the first in the area to own a car, an interesting parallel with Harry Ricardo's. This early influence almost certainly led to his future career. Fedden attended Clifton College, but did not do well scholastically and was known primarily for sports. After graduation, he declined to enter the Army, the "normal route" for students at Clifton, and announced he would apprentice as an engineer.

His apprenticeship was completed in 1906, and he immediately designed a complete car. He managed to convince the local firm of Brazil Straker to hire him, and the design was produced as the successful Shamrock. He remained at Brazil Straker over the following years, and he was particularly influential in convincing company management to take on the repair of various aircraft engines when World War I started. The company's role soon expanded to producing Rolls-Royce Hawk and Falcon engines, as well as major parts of the famous Rolls-Royce Eagle. Henry Royce offered Fedden a senior position with his company, but Fedden declined.

In 1915, Fedden started the design of his own aero engine, along with his draughtsman Leonard Butler. The two were inseparable for the next twenty years, and most of their designs were stamped "FB" to indicate the shared credit. They designed two engines during WW1: the 14-cylinder radial Mercury, notable for the cylinders being arranged helically instead of in two rows, and the larger, more conventional, two-row Jupiter design of about 400 hp.

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.

In 1925 and 1926, Harry Ricardo wrote a series of seminal papers at the RAE claiming that the poppet valve system was already operating at its peak capability, and that any future engines would have to use sleeve valves instead. Fedden and Butler immediately turned to such a design, adapting the Mercury to become the Bristol Aquila, and the Pegasus as the Bristol Perseus. However, both of these engines quickly found themselves at the "low end" of the power spectrum as ever-larger aircraft designs demanded ever-larger engines to power them.

To solve this problem, the two designs were quickly adapted to two-row configurations, resulting in the Bristol Taurus and the superb Bristol Hercules. Not one to rest on his laurels, Fedden then started adapting the Hercules into a two-row 18-cylinder design as the Bristol Centaurus.

The Taurus was in service when World War II started in 1939, but the Hercules was still in testing. Work on the Centaurus was suspended while the final problems with Hercules production was worked out. The entire Bristol sleeve-valve range would see widespread service throughout the war on a wide variety of designs. They were so successful that the Air Ministry forced a reluctant Bristol to help with the high-power Napier Sabre project that had bogged down due to problems with their sleeves.

With Hercules production in full swing in 1941, Fedden returned to the Centaurus. Production was able to start in 1942, but at the time there were few aircraft that could be adapted to a 2,500 hp engine. Newer designs intended to mount engines of this size appeared near the end of the war, notably certain versions of the Hawker Tempest, taking over from the Sabre in that design.

For his role in creating some of the most successful aircraft engines of the era, Fedden was knighted in 1942.

The stress of wartime production needs had taken its toll on Leonard Butler, who left the company to recuperate. Although Fedden had created a long line of hugely successful engines for Bristol, he had fought constantly with management over funding priorities. Without Butler's influence it seems Fedden "had enough", and shortly after being knighted, he left Bristol to take up a variety of positions within the Government. For much of the remainder of the war, he travelled in the United States with another Bristol employee, Ian Duncan, to study their production line techniques in order to improve their own.

On his return, Duncan and Fedden set up Roy Fedden Ltd. in 1945. Their first product was a small horizontally-opposed aero engine intended to be installed within the wings of twin-engine aircraft. The Fedden O-325 saw no use. He then turned to a new turboprop design which also found little interest. Finally they decided to design their own car, powered by a three-cylinder air-cooled radial, but they found it had serious handling problems and tended to flip over when being cornered hard. Work started on a replacement chassis, but the rest of the company's engineers lost interest and left, and soon the company had to be dissolved.

After this, Fedden worked for a time consulting with George Dowty, but soon retired and spent his time teaching at the College of Aeronautics at Cranfield University.

Fedden was childless. He has sometimes been mistakenly described as the father of a prominent British artist called Mary Fedden. He was in fact her uncle.

References

* [http://100.rolls-royce.com/people/view.jsp?id=113 Roy Fedden]