Cirrus Engine was a British aircraft engine manufacturer, known for their line of 4-cylinder air-cooled inline engines for general aviation use. The company was bought by Blackburn Aircraft in 1934, and operated as a separate division until production ended in the post-WWII era. The term aircraft engine, for the purposes of this article, refers to aircraft reciprocating, or rotary, internal combustion engines as opposed to jet engines or turboprops. ... General aviation (abbr. ... Blackburn Beverley photographed in 1964. ... German soldiers at the Battle of Stalingrad World War II was the most extensive and costly armed conflict in the history of the world, involving the great majority of the worlds nations, being fought simultaneously in several major theatres, and costing tens of millions of lives. ...

Cirrus's first product was the 90 hp (67 kW) Cirrus Minor, which passed its 50 hour type rating in 1925. It was the first air-cooled inline engine, a design that proved extremely popular for light aircraft. The basic layout was quickly copied by a number of other manufacturers.

The Minor was known for excellent reliability, and had a major "win" when it was selected to power the RAF's Auster observation aircraft. The RAF's version had several modifications, known as the Series I. Although externally identical, the Series II engine was redesiged to operate on 77 octane fuel, as opposed to the original's 70, increasing power to 100 hp (75 kW). RAF is an three letter acronym for: Royal Air Force -- the Air Force of the United Kingdom (see also Air Ministry) Red Army Faction (Rote Armee Fraktion) -- a German terror organisation Rigas Autobusu Fabrika -- a factory making buses in Riga, Latvia Rapid Action Force in India Računarski Fakultet RAF... Auster Autocrat from 1952 For the Roman god of the south wind, see Notus. ...

In 1934 Cirrus introduced the Cirrus Major, roughly doubling displacement and boosting power to 150 hp (112 kW). The Major was mechanically similar to the Series II Minor's and introduced as the Major Series II, but the new Series III boosted octane ratings to 87 and offered 155 hp (116 kW) at a compression ratio of 6.5:1. The compression ratio is a single number that can be used to predict the performance of any internal-combustion engine. ...

Designs

• Cirrus Minor
• Cirrus Major