The Me 262 Swallow was the world's first operational jet-powered fighter aircraft. Several years before World War II, the Germans foresaw the great potential for aircraft that used the jet engine, constructed by Hans Joachim Pabst von Ohain in 1936. (Ohain was unaware of Englishman Frank Whittle's jet engine patent in 1928.) After the successful test flights of the first jet of the world, the Heinkel He 178, they adopted the jet engine for an advanced fighter aircraft. As a result, the Me 262 was already under development as Projekt 1065 (P.1065) before the start of World War II. Plans were first drawn up in April 1939, and the original design was very similar to the aircraft that eventually entered service. The progression of the original design was delayed greatly by technical issues involving the new jet engine. Funding for the jet engine programme was also initially lacking as many high-ranking officials thought the war could easily be won with conventional aircraft. Among those were Hermann Göring, head of the Luftwaffe, who cut the engine development programme to just 35 engineers in February 1940; Willy Messerschmitt, who desired to maintain mass production of the piston-powered Bf 109 and the projected Me 209; and Major General Adolf Galland, who supported Messerschmitt through the early development years, flying the Me 262 himself on 22 April 1943. By that time, problems with engine development had slowed production of the aircraft considerably. One particularly acute problem arose with the lack of an alloy with a melting point high enough to endure the high temperatures involved, a problem that by the end of the war had not been adequately resolved.Design work started before World War II began but engine problems prevented the aircraft from attaining operational status with the Luftwaffe until mid-1944. Compared with Allied fighters of its day, including the British jet-powered Gloster Meteor, it was much faster and better armed. One of the most advanced aviation designs in operational use during World War II, the Me 262 was used in a variety of roles, including light bomber, reconnaissance and even experimental night fighter versions. Me 262 pilots claimed a total of 542 Allied kills (although higher claims are sometimes made)The Me 262 was so fast that German pilots needed new tactics to attack American bombers. In the head-on attack, the closing speed, of about 350 yd per second (320 m), was too high for accurate shooting. Even from astern, the closing speed was too great to use the short-ranged 30 mm cannon to maximum effect. Therefore, a roller-coaster attack was devised. The 262s approached from astern and about 6,000 ft higher (1,800 m) than the bombers. From about 3 mi behind (4.8 km), they went into a shallow dive that took them through the escort fighters with little risk of interception. When they were about 1 mi astern (1.6 km) and 1,500 feet (460 m) below the bombers, they pulled up sharply to reduce their excess speed. On levelling off, they were 1,000 yd astern (0.91 km) and overtaking the bombers at about 100 mph (160 km/h), well placed to attack them The Allies countered its potential effectiveness in the air by relentlessly attacking the aircraft on the ground and while they were taking off or landing. Engine reliability problems and relentless attacks by allies on fuel supplies during the deteriorating late-war situation also reduced the effectiveness of the aircraft as a fighting force. In the end, the Me 262 had a negligible impact on the course of the war as a result of its late introduction and the consequently small numbers that were deployed in operational service. The Me 262 influenced the designs of post-war aircraft such as the North American F-86 Sabre and Boeing B-47 Stratojet.