Editing Bristol Jupiter (section)

==Design and development==
The Jupiter was designed during [[World War I]] by [[Roy Fedden]] of [[Straker-Squire|Brazil Straker]] and later [[Cosmos Engineering]]. The first Jupiter was completed by Brazil Straker in 1918 and featured three carburettors, each one feeding three of the engine's nine cylinders via a spiral deflector housed inside the induction chamber.<ref>''Flight'' 9 March 1939, pp.236-237</ref> During the rapid downscaling of military spending after the war, Cosmos Engineering became [[bankrupt]] in 1920, and was eventually purchased by the [[Bristol Aeroplane Company]] on the strengths of the Jupiter design and the encouragement of the [[Air Ministry]].<ref>Gunston 1989, p.44.</ref> The engine matured into one of the most reliable on the market. It was the first air-cooled engine to pass the Air Ministry full-throttle test, the first to be equipped with automatic boost control, and the first to be fitted to airliners.<ref>Gunston 1989, p.31.</ref>

The Jupiter was fairly standard in design, but featured four valves per cylinder, which was uncommon at the time. The [[Cylinder (engine)|cylinders]] were machined from steel forgings, and the cast [[cylinder head]]s were later replaced with aluminium alloy following studies by the [[Royal Aircraft Establishment]]. In 1927, a change was made to move to a forged head design due to the rejection rate of the castings. The Jupiter VII introduced a mechanically-driven supercharger to the design, and the Jupiter VIII was the first to be fitted with reduction gears.<ref>Bridgman (Jane's) 1998, p.270.</ref>

In 1925, Fedden started designing a replacement for the Jupiter. Using a shorter stroke to increase the [[revolutions per minute]] (rpm), and including a [[supercharger]] for added power, resulted in the [[Bristol Mercury]] of 1927. Applying the same techniques to the original Jupiter-sized engine in 1927 resulted in the [[Bristol Pegasus]]. Neither engine would fully replace the Jupiter for a few years.

In 1926 a Jupiter-engined [[Bristol Type 84 Bloodhound|Bristol Bloodhound]] with the [[aircraft registration|registration]] G-EBGG completed an endurance flight of {{convert|25,074|mi|km|abbr=off}}, during which the Jupiter ran for a total of 225 hours and 54 minutes without part failure or replacement.<ref>{{cite web |url=http://www.flightglobal.com/pdfarchive/view/1926/1926%20-%200183.html |title=1926 {{!}} 0183 {{!}} Flight Archive |website=www.flightglobal.com |url-status=dead |archive-url=https://web.archive.org/web/20121019142218/http://www.flightglobal.com/pdfarchive/view/1926/1926%20-%200183.html |archive-date=2012-10-19}} </ref>

===Licensed production===
The Jupiter saw widespread use in licensed versions, with fourteen countries eventually producing the engine. In France, [[Gnome-Rhone]] produced a version known as the Gnome-Rhône 9 Jupiter that was used in several local civilian designs, as well as achieving some export success. [[Siemens-Halske]] took out a licence in Germany and produced several versions of increasing power, eventually resulting in the [[Bramo 323]] Fafnir, which saw use in German wartime aircraft.<ref>Gunston 1989, p.29.</ref>

In Japan, the Jupiter was licence-built from 1924 by [[Nakajima Aircraft Company|Nakajima]], forming the basis of its own subsequent radial aero-engine design, the [[Nakajima Kotobuki|Nakajima Ha-1 Kotobuki]].<ref>Gunston 1989, p.104.</ref> It was produced in Poland as the PZL Bristol Jupiter, in Italy as the [[Alfa Romeo 125|Alfa Romeo 126-RC35]],<ref name="aroca-qld.com">{{cite web|url=http://www.aroca-qld.com/library_articles/alfa_romeo_aero_engines.php |title=Alfa Aero Engines |access-date=25 August 2007 |work=aroca-qld.com |archive-url=https://web.archive.org/web/20071008150746/http://www.aroca-qld.com/library_articles/alfa_romeo_aero_engines.php |archive-date=8 October 2007 |url-status=usurped }}</ref> and in [[Czechoslovakia]] by [[Walter Engines]]. The most produced version was in the [[Soviet Union]], where its [[Shvetsov]] M-22 version powered the initial Type 4 version of the [[Polikarpov I-16]] (55 units produced). Type 4 Polikarpovs can be identified by their lack of exhaust stubs, rounded NACA cowling and lack of cowling shutters, features which were introduced on the [[Shvetsov M-25]] powered Type 5 and later variants (total production 4,500+ units).<ref>{{Cite web|url=http://vvs.hobbyvista.com/Modeling/Polikarpov/I-16/Kit_Comparison/description.php|title = Modeling the VVS: I-16 Development}}</ref><ref>Gunston 1989, p.158.</ref> Production started in 1918 and ceased in 1930.