Jet Aircraft Travelling At Transonic Speed

The first flight of a jet engined aircraft to come to popular attention was the Italian Caproni Campini N.1 motorjet prototype that flew on August 27, 1940. Test pilot Major Mario De Bernardi of the Regia Aeronautica was at the controls. It was the first jet aircraft recognised by the Fédération Aéronautique Internationale (at the time the German He 178 program was still kept secret). Campini had proposed the motorjet in 1932.
The British experimental Gloster E.28/39 first took to the air on May 15, 1941, powered by Sir Frank Whittle's turbojet, and piloted by Glosters test pilot Flt Lt PG Sayer. After the United States was shown the British work, it produced the Bell XP-59A with a version of the Whittle engine built by General Electric, which flew on October 1st, 1942, piloted by Robert M. Stanley .
The first operational jet fighter was the Messerschmitt Me 262., made by Germany during late World War II. It was the fastest conventional aircraft of World War II – although the rocket-powered Messerschmitt Me 163 Komet was faster. It had first flown in 1941 but mass production started in 1944 with the first squadrons operational that year, too late for a decisive effect on the outcome of the war. About the same time, mid 1944, the United Kingdom's Gloster Meteor was being committed to defence of the UK against the V1 flying bomb – itself a jet powered aircraft – and then ground-attack operations over Europe in the last months of the war. In 1944 Germany introduced into service the Arado Ar 234 jet reconnaisance and bomber, though chiefly used in the former role. USSR tested its own Bereznyak-Isayev BI-1 in 1942, but the project was scrapped by Joseph Stalin in 1945. The Imperial Japanese Navy also developed jet aircraft in 1945, including the Nakajima J9Y Kikka, a crude copy of the Me 262. By the end of 1945, the US had introduced their next jet fighter, the Lockheed P-80 Shooting Star into service and the UK its second fighter design, the de Havilland Vampire
The US introduced the North American B-45 Tornado, their first jet bomber, into service in 1948. Although capable of carrying nuclear weapons it was used for reconnaissance over Korea.