Junkers Ju 87 armoured protection of the Ilyushin Il-2 "Sturmovik" - a feature pioneered by the 1916-17 origin Junkers J.I all-metal sesquiplane of World War I Imperial Germany's Luftstreitkräfte - was copied to protect the crew from ground fire now that the Ju 87 would be required to conduct low level attacks. Hans-Ulrich Rudel, a Stuka ace, had suggested using two 37 mm (1.46 in) Flak 18 guns, each one in a self-contained under-wing gun pod, as the "Bordkanone BK 3,7", after achieving success against Soviet tanks with the 20 mm MG 151/20 cannon. These gun pods were fitted to a Ju 87
Bristol Aeroplane Company Bristol Record Office include the papers of Lionel Harris, an engineer at the Bristol Aeroplane Company in the 1940s (Ref. 42794) (online catalogue) The Bristol Engine Company was originally a separate entity, Cosmos Engineering, formed from the pre-First World War automobile company Brazil-Straker. In 1917, Cosmos was asked to investigate air-cooled radial engines and, under Roy Fedden, produced what became the Cosmos Mercury, a 14-cylinder two-row (helical) radial, which they launched in 1918. This engine saw little use but the simpler nine-cylinder version known as the Bristol Jupiter was clearly a winning design. With the post-war rapid contraction of military