The Armstrong Siddeley Jaguar was an aero engine developed by Armstrong Siddeley.
 The Jaguar was a petrol-fuelled air-cooled 14-cylinder two-row radial engine design.
 The Jaguar III was first used in 1923, followed in 1925 by the Jaguar IV and in 1927 by the Jaguar VI.
The Nakajima Ha-5 is a twin row, 14 cylinder air-cooled radial aircraft engine built by the Japanese Nakajima Aircraft Company.
 The engine was a development of earlier single-row Japanese engines, the Kotobuki and Hikari, which had combined features of the Bristol Jupiter and Pratt & Whitney R-1340 Wasp designs.
 First introduced in a 1,000 PS prototype in 1933, about 7,000 civilian and 5,500 military Ha-5's were built during World War II.
 The Ha-5 had separate cam-discs for the front and rear rows of cylinders like American designs, rather than using a single, front-mounted cam-disc with long and short pushrods to operate both rows of cylinder valves.
 The Ha-5 was a twin-row development of the Nakajima Hikari, which was itself a development of the Nakajima Kotobuki.
 It spawned several improved variants, namely the Ha-41, with a single stage supercharger, and the Ha-109, which featured a two-speed, single stage supercharger.
 The later Ha-219 was based on the same cylinder design, but was increased in size to 18 cylinders.
The Aquila was a nine-cylinder single-row radial aircraft engine designed by the Bristol Engine Company starting in 1934.
 A sleeve valve engine, its basic design was developed from the Bristol Perseus.
 The Aquila was never used in production, but further developments led to the Bristol Hercules, Bristol Taurus, and Bristol Centaurus.
The Pratt & Whitney R-1830 Twin Wasp was an American aircraft engine widely used in the 1930s and 1940s.
 Produced by Pratt & Whitney, it was a two-row, 14-cylinder, air-cooled radial design.
 It displaced 1830 cuin and its bore and stroke were both 5.5 in (140 mm).
 A total of 173,618 R-1830 engines were built, and from their use in two of the most-produced aircraft ever built, the four-engined B-24 heavy bomber and twin-engined DC-3 transport, more Twin Wasps may have been built than any other aviation piston engine in history.
 A "bored-out" version (to a 5.75 inch/146 mm cylinder bore) with a slightly higher power rating and other slight changes in detail design was produced as the R-2000.
The Gnome-Rhône 14N was a 14-cylinder two-row air-cooled radial engine designed and manufactured by Gnome-Rhône.
 A development of the pre-war Gnome-Rhône 14K, the 14N was used on several French and German aircraft of World War II.
The Bristol Hercules was a 14-cylinder two-row radial aircraft engine designed by Sir Roy Fedden and produced by the Bristol Engine Company starting in 1939.
 It was the first of their single sleeve valve (Burt-McCollum, or Argyll, type) designs to see widespread use, powering many aircraft in the mid-World War II timeframe.
The Mitsubishi Zuisei (瑞星 , Holy Star ) was a 14-cylinder, supercharged, air-cooled, two-row radial engine used in a variety of early World War II Japanese aircraft.
 It was one of the smallest 14-cyl.
 engines in the world and the smallest diameter Japanese engine.
 The Mitsubishi model designation for this engine was A14 while it was an experimental project, in service it was known as the MK2, followed by the revision code letter, and known as the Ha26 & Ha102 by the Army and "Zuisei" by the Navy.
 Unified designation code was [Ha-31].
The Taurus was a British 14-cylinder two-row radial aircraft engine, produced by the Bristol Engine Company starting in 1936.
 The Taurus was developed by adding cylinders to the existing Aquila design, creating a powerplant that produced just over 1,000 horsepower (750 kW) with very low weight.
The SNECMA 14R was a 14-cylinder two-row air-cooled radial engine developed in France just prior to the start of World War II from the Gnome-Rhône 14N.
 The 14N radial engine was itself an improved version of the popular pre-war Gnome-Rhône 14K "Mistral Major" series; designed and manufactured by Gnome et Rhône, a major French aircraft engine manufacturer whose origins pre-date the First World War.
The Shvetsov ASh-82 (M-82) is a Soviet 14-cylinder, two-row, air-cooled radial aircraft engine developed from the Shvetsov M-62.
 The M-62 was the result of development of the M-25, which was a licensed version of the Wright R-1820 Cyclone.

Question: Who was the desiner for the further developments of Aquila which became 14-cylinder two-row radial aircraft engine?
Answer: Sir Roy Fedden