The Messerschmitt Me 262, nicknamed Schwalbe (German: "Swallow") in fighter versions, or Sturmvogel (German: "Storm Bird") in attack versions, was the world's first operational jet-powered fighter aircraft. Design work started before World War II began, but engine problems and top-level interference kept the aircraft from operational status with the Luftwaffe until mid-1944. The Me 262 was faster, and more heavily-armed than any Alliedfighter, including the British jet-powered Gloster Meteor. 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.[Note 1] The Allies countered its potential effectiveness in the air by attacking the aircraft on the ground and during takeoff and landing. Engine reliability problems, from the pioneering nature of its Junkers Jumo 004axial-flow turbojet engines—the first ever placed in mass production—and attacks by Allied forces 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 put in operational service.
While German use of the aircraft ended with the close of the Second World War, a small number were operated by the Czechoslovak Air Force until 1951. Captured Me 262s were studied and flight tested by the major powers, and ultimately influenced the designs of a number of post-war aircraft such as theNorth American F-86 Sabre and Boeing B-47 Stratojet. A number of aircraft have survived on static display in museums, and there have also been several privately built flying reproductions.
Design and development
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. After the successful test flights of the world's first jet aircraft—the Heinkel He 178—within a week of the Invasion of Poland to start the war, 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. The project originated with a request by the Reichsluftfahrtministerium (RLM, Ministry of Aviation) for a jet aircraft capable of one hour's endurance and a speed of at least 850 km/h (530 mph; 460 kn). Dr Waldemar Voigt headed the design team, with Messerschmitt's chief of development, Robert Lusser, overseeing.
Plans were first drawn up in April 1939, and the original design was very different from the aircraft that eventually entered service, with wing root-mounted engines, rather than podded ones, when submitted in June 1939. The progression of the original design was delayed greatly by technical issues involving the new jet engine. Because the engines were slow to arrive, Messerschmitt moved the engines from the wing roots to underwing pods, allowing them to be changed more readily if needed; this would turn out to be important, both for availability and maintenance. Since the BMW 003 jets proved heavier than anticipated, the wing was swept slightly, by 18.5°, to accommodate a change in the center of gravity. Funding for the jet engine program 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 program to just 35 engineers in February 1940 (the month before the first wooden mock-up was completed); Willy Messerschmitt, who desired to maintain mass production of the piston-powered, 1935-origin Bf 109 and the projected Me 209; and Major General Adolf Galland, who had initially 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. The aircraft made its first successful flight entirely on jet power on 18 July 1942, powered by a pair of Jumo 004 engines, after a November 1941 flight (with BMW 003s) ended in a double flameout.
The project aerodynamicist on the design of the Me 262 was Ludwig Bölkow. He initially designed the wing using NACA airfoils modified with an elliptical nose section. Later in the design process, these were changed to AVL derivatives of NACA airfoils, the NACA 00011-0.825-35 being used at the root and the NACA 00009-1.1-40 at the tip. The elliptical nose derivatives of the NACA airfoils were used on the horizontal and vertical tail surfaces. Wings were of single-spar cantilever construction, with stressed skins, varying from 3 mm (0.12 in) thick at the root to 1 mm (0.039 in) at the tip. As a conservation measure, late in the war, wing interiors would not be painted. The wings were fastened to the fuselage at four points, using a pair of 20 mm (0.79 in) and forty-two 8 mm (0.31 in) bolts.
In mid-1943, Adolf Hitler envisioned the Me 262 as a ground-attack/bomber aircraft rather than a defensive interceptor. The configuration of a high-speed, light-payload Schnellbomber ("fast bomber") was intended to penetrate enemy airspace during the expected Allied invasion of France. His edict resulted in the development of (and concentration on) the Sturmvogel variant. It is debatable to what extent Hitler's interference extended the delay in bringing the Schwalbeinto operation; it appears engine vibration issues were at least as costly, if not more so. Albert Speer, then Minister of Armaments and War Production, claimed in his memoirs that Hitler originally had blocked mass production of the Me 262 before agreeing in early 1944. He rejected arguments that the aircraft would be more effective as a fighter against the Allied bombers that were destroying large parts of Germany, and wanted it as a bomber for revenge attacks. According to Speer, Hitler felt its superior speed compared to other fighters of the era meant it could not be attacked, and so preferred it for high altitude straight flying.
Silhouette of the V3 prototype - V1 through V4 similar
Although the Me 262 is often referred to as a "swept wing" design, the production Me 262 had a leading edge sweep of only 18.5°, too slight to achieve any significant advantage in increasing the critical Mach number. Sweep was added after the initial design of the aircraft, when the engines proved heavier than originally expected, primarily to position the center of lift properly relative to the center of mass. (The original 35° sweep, proposed by Adolph Busemann, was not adopted.)On 1 March 1940, instead of moving the wing backward on its mount, the outer wing was repositioned slightly aft; the trailing edge of the midsection of the wing remained unswept. Based on data from the AVA Göttingen and wind tunnel results, the middle section's leading edge was later swept to the same angle as the outer panels, from the "V6" sixth prototype onwards throughout volume production.
The first test flights began on 18 April 1941, with the Me 262 V1 example, bearing its Stammkennzeichen radio code letters of PC+UA, but since its intended BMW 003turbojets were not ready for fitting, a conventional Junkers Jumo 210 engine was mounted in the V1 prototype's nose, driving a propeller, to test the Me 262 V1 airframe. When the BMW 003 engines were installed, the Jumo was retained for safety, which proved wise as both 003s failed during the first flight and the pilot had to land using the nose-mounted engine alone. The V1 through V4 prototype airframes all possessed what would become an uncharacteristic feature for most later jet aircraft designs, a fully retracting conventional gear setup with a retracting tailwheel — indeed, the very first prospective German "jet fighter" airframe design ever flown, the Heinkel He 280, used a retractable tricycle landing gear from its beginnings, and flying on jet power alone as early as the end of March 1941.
This airframe, Wrknr. 111711
, was the first Me 262 to come into Allied hands when its test pilot defected in March 1945. It was subsequently lost in August 1946, the US test pilot parachuting to safety.
The V3 third prototype airframe, with the code PC+UC, became a true jet when it flew on 18 July 1942 in Leipheim near Günzburg, Germany, piloted by Fritz Wendel. This was almost nine months ahead of the British Gloster Meteor's first flight on 5 March 1943. Its retracting conventional gear, a feature shared with the first four Me 262 V-series airframes, caused its jet exhaust to deflect off the runway, with the wing's turbulence negating the effects of the elevators, and the first takeoff attempt was cut short.
On the second attempt, Wendel solved the problem by tapping the aircraft's brakes at takeoff speed, lifting the horizontal tail out of the wing's turbulence. The aforementioned initial four prototypes (V1-V4) were built with the conventional gear configuration. Changing to a tricycle arrangement — a permanently fixed undercarriage on the fifth prototype (V5, code PC+UE), with the definitive fully retractable nosewheel gear on the V6 (with Stammkennzeichen code VI+AA, from a new code block) and subsequent aircraft corrected this problem.[Note 2]
Test flights continued over the next year, but engine problems continued to plague the project, the Jumo 004 being only marginally more reliable than the BMW 003. Airframe modifications were complete by 1942 but, hampered by the lack of engines, serial production did not begin until 1944, and deliveries were low, with 28 Me 262s in June, 59 in July, but only 20 in August. This delay in engine availability was in part due to the shortage of strategic materials, especially metals and alloys able to handle the extreme temperatures produced by the jet engine.
Even when the engines were completed, they had an expected operational lifetime of approximately 50 continuous flight hours; most 004s lasted just 12 hours, even with adequate maintenance. A pilot familiar with the Me 262 and its engines could expect approximately 20–25 hours of life from the 004s. Changing a 004 engine was intended to require three hours, but this typically took eight to nine due to poorly made parts and inadequate training of ground crews. With one engine out, the Me 262 still flew well, with speeds of 450–500 km/h (280–310 mph; 240–270 kn), but pilots were warned never to fly slower than 300 km/h (190 mph; 160 kn) on one engine, as the asymmetrical thrust would cause serious handling problems.
Due to the high speed jet stream, turbojet engines develop much less thrust at low speed than propeller powered aircraft, resulting in poor low-speed acceleration. This was particularly noticeable in the Me 262, since early jet engines had relatively low power and responded slowly to throttle changes. The introduction of a primitive autothrottle late in the war helped only slightly. Conversely, the superior power of jet engines at higher speeds meant the Me 262 enjoyed a much greater rate of climb. Used tactically, this gave the jet fighter an even larger speed advantage in climb than in level flight at top speed.
Operationally, carrying 2,000 l (440 imp gal; 530 US gal) of fuel in two 900 l (200 imp gal; 240 US gal) tanks, one each fore and aft the cockpit, and a 200 l (44 imp gal; 53 US gal) tank beneath,[Note 3] the Me 262 would have a total flight endurance of 60 to 90 minutes. Fuel was usually brown coal-derived J2, with the option of diesel oil or a mixture of oil and high octane B4 aviation petrol. Fuel consumption was double the rate of typical twin-engine fighter aircraft of the era, which led to the installation of a low-fuel warning indicator in the cockpit that notified pilots when remaining fuel fell below 250 l (55 imp gal; 66 US gal).
Unit cost for an Me 262 airframe, less engines, armament, and electronics, was RM87,400.[Note 4] To build one airframe took around 6,400 man-hours.