Saturday, 24 October 2015

Messerschmitt Me-262 Schwalbe / Sturmvogel. The Beginning of Story. Part 1. German Dzib -Compiler-



 W
orld War II saw the introduction of jet aircraft. One of the most prominent jets of the conflict was the "Messerschmitt Me-262", a twin-jet fighter of advanced design. The Me-262 was recognized after the war as generally superior to anything the Allies had, and helped point the way to postwar aircraft development. This document provides a history of the Me-262.

The Messerschmitt Me-262 was an outgrowth of German turbojet-engine development work that had begun in the mid-1930s, with the initial concepts conceived by an engineer named Hans-Joachim Pabst von Ohain, whose efforts paralleled those of Frank Whittle of Britain. In 1933, while von Ohain was working on his doctorate at the University of Goettingen, he began investigate the gas turbine as a basis for an advanced aircraft engine. Although most of the feedback he received suggested that gas turbines would be too heavy for such a role, he pressed on anyway, developing a demonstrator model of a "turbojet" engine in his garage, with the help of a mechanic named Max Hahn.

Von Ohain managed to impress his professor, R.W. Pohl, with a test run of the model. Pohl was both open-minded and well-connected, and in 1936 he sent von Ohain on to aircraft manufacturer Ernst Heinkel with a letter of recommendation. Von Ohain defended his ideas under grilling by Heinkel engineers, and was put in charge of a design team to develop a practical turbojet engine.
Von Ohain's team had a working bench-test prototype in September 1937, six months after Whittle had reached the same benchmark. Von Ohain's prototype burned hydrogen, an impractical fuel, but further work with Max Hahn led to an engine that burned kerosene.
Ernst Heinkel gave the go-ahead to develop a flight-test engine, designated the "HeS-3", which was strapped to an He-118 dive bomber for evaluation. Tests began in May 1939 and continued until the engine burned itself out a few months later. Enough had been learned to build a pure jet-powered experimental aircraft, the "Heinkel He-178", powered by an improved "HeS-3B" engine with 2.94 kN (300 kgp / 835 lbf) thrust. Later in the flight test program, the He-178 would be fitted with a further improved "HeS-6" turbojet with 5.78 kN (590 kgp / 1,300 lbf) thrust.
HEINKEL HE-178:

Spec                     Metric                    English

Wingspan            7.2 meters            26 feet 4 inches
Wing area            9.10 sq meters    97.96 sq_feet
Length                    7.48 meters           24 feet 6 inches
Height                  2.10 meters          6 feet 11 inches
Empty weight     1,560 kilograms     3,439 pounds
Loaded weight   1,995 kilograms     4,400 pounds
Max speed           700 KPH           435 MPH / 378 KT



The He-178 was a simple "flying stovepipe", with straight-through airflow from nose to tail. The aircraft had high-mounted tapered wings and a conventional tail assembly. Although it had fully

The He-178 performed its first test flight on 27 August 1939, a few days before the outbreak of World War II. The flight lasted about five minutes, with the pilot reporting that the aircraft "had no vibration and no torque like a propeller engine. Everything was smooth, and ... felt wonderful." Von Ohain was now well ahead of Whittle, whose efforts were bogged down, first by official indifference and then by national crisis. Whittle would not fly his own experimental jet aircraft, the "Gloster-Whittle G.40", until May 1941.
The Luftwaffe and the German Air Ministry (Reichs LuftfahrtMinisterium/RLM) were preoccupied with war, and the authorities didn't witness a flight demonstration of the He-178 until November 1939. They were generally unimpressed, since the He-178 was not as fast as the best piston fighters. Heinkel was told: "Your turbojet is not needed. We will win the war on piston engines."
That was not as complacent as it sounded, because the Reich was not expecting a long war -- indeed, those in charge knew Germany would be very hard-pressed to win a long war -- and jets wouldn't be in service by the time the shooting was likely to be over anyway. After a total of about a dozen test flights, the He-178 was sent to the national air museum in Berlin, where it

was destroyed in a bombing raid in 1943. A second He-178 was planned but not completed.
Although the RLM seemed indifferent to the He-178, the ministry was still actively pushing German industry to develop turbojets. In hindsight, it seems that the left and right hands of the RLM were not in agreement, which summarizes much of the Third Reich's attempts to develop advanced weapons.
Hans A. Mauch had become head of rocket development at the RLM in April 1938, and quickly expanded his office's charter to include turbojet development, working with an experimental department under Helmut Schelp in the RLM research branch. By mid-1938, the two men had set up a comprehensive program of jet engine development that was soon sponsoring a range of turbojet and turboprop projects.
In response to RLM urging, the Bramo company began work on a pair of "axial flow" engines. Both Whittle's and von Ohain's engines were "centrifugal flow" engines, which feature a compressor like a pump impeller shoving air into combustion chambers ringing the engine. The compressor in an "axial-flow" engine, in contrast, uses rings of blades to drive air directly back into the combustion chambers.
The two Bramo engines included one with a contra rotating compressor assembly to reduce torque, which eventually was designated the "109-002", and a simpler engine without the contra-rotating fan scheme that was eventually designated the "109-003". Incidentally, the "109-" suffix was used by the RLM to specify turbine engine projects.
Bramo's works at Spandau were bought out by the BMW concern in mid-1939. BMW engineers had been working on a centrifugal-flow turbojet, but the company quickly decided to abandon
their own effort and focus on the two Bramo engines obtained in the buyout. The contrarotating 109-002 proved too complicated and never flew, the project being abandoned in 1942. The company focused on the simpler 109-003, with fabrication beginning in 1939 and first test runs in 1940. By that time, the engine was known as the "BMW-003".
The Junkers company had actually been working on turbine propulsion since 1936, and was running a bench prototype of an axial-flow turbojet in 1938. In the summer of 1939, the RLM awarded Junkers a contract to develop a simple, powerful axial-flow engine that could be put into production as quickly as possible. A design team under Dr. Anselm Franz conducted the development work on the engine, which became known as the "109-004" and later the "Jumo-004". A full-scale bench-test engine was operating by November 1940.


ME 262 Origins
  Despite spotty official interest, German companies were working on combat aircraft based on the new turbojet engines. Following the flight tests of the He-178, in the fall of 1939 Heinkel began serious development of an operational fighter, the "He-280", which was to be powered by twin improved Heinkel engines and is discussed below.

Even before this, in the fall of 1938, a Messerschmitt design team under Dr. Waldermar Voight had drawn up concepts for a interceptor fighter with twin turbojet engines. The preliminary designs for "Project 1065", as it was designated, went through a iteration or two and finally resulted in a proposal submitted to the RLM in May 1940.
Messerschmitt's dream fighter had the turbojets mounted in nacelles under the middle of the
wings. The wings were slightly swept to ensure proper center of gravity, and had an unusually thin wing for good high-speed performance. Since the wing's features for high-speed performance compromised low-speed handling, a "slat" was added to the front of the outer wings. The slat was automatically extended to improve handling at low speeds. The fuselage had a triangular cross section and substantial fuel capacity to feed the thirsty engines. The aircraft fully retractable tailwheel landing gear. In July 1940, the RLM ordered three prototypes, under the designation "Messerschmitt 262 (Me-262)", to be powered by BMW-003 engines.
Airframe development far outpaced engine development, and so the first prototype, the "Me-262-V1" ("V" standing for "Versuchs / Experimental"), was fitted with a single Jumo-210G piston engine with 530 kW (710 HP) and a two-bladed propeller for preliminary test flights. First flight was on 18 April 1941. The RLM was becoming more interested in the aircraft, ordering five more prototypes in July 1941, to follow the initial order for three.
The Me-262-V1 was finally fitted with a pair of BMW-003 turbojets, each with 5.40 kN (550 kgp / 1,200 lbf) thrust, in November 1941. The Jumo 210G piston engine was retained, which was fortunate, since the turbojet engines were hopelessly unreliable. On 25 March 1942, Messerschmitt test pilot Fritz Wendel took off, to suffer immediate failures of both turbojets. He managed to make a go-round on the piston engine and land, damaging the aircraft but suffering no injury himself.
Development of the BMW-003 engine was progressing slowly while work on the Junkers Jumo-004 seemed more promising, and so the third prototype, the "Me-262-V3", was fitted with two Jumo-004A pre-production engines with 8.24 kN (840 kgp / 1,850 lbf) thrust each. Wendel took the V3 into the air on 18 July 1942 and found the aircraft extremely impressive. Unfortunately, the V3 prototype was wrecked on its second test flight, three weeks later.

The Me-262V-2 prototype, also powered by Jumo-004As, was not delivered until 2 October 1942. Despite all the delays and problems, the RLM had already ordered 15 preproduction Me-262s in May 1942, and added 30 more to the order that October. The He-280 was inferior in performance and the Me-262 was clearly the better option, but there was still no commitment to put the Me-262 into full production.
The RLM was waffling between production of the Me-262 and the "Me-209", an improved version of the piston-powered Messerschmitt Bf-109 fighter. The head of the RLM, Erhard Milch, was conservative and favored the Me-209 over the much more radical Me-262. However, in the spring of 1943 the tide began to shift towards the jet fighter. The Luftwaffe General of Fighters, Adolf Galland, flew the recently-delivered "V4" prototype on 22 May 1943. He enthusiastically endorsed the type and suggested that the Me-209 be canceled. A few days later, the RLM placed an order for 100 production Me-262s.
Apparently this decision did not clear away all the bureaucratic obstacles. Willi Messerschmitt kept on lobbying to produce both the Me-209 and the Me-262, partly it seems as an exercise in bureaucratic empire-building, and it wasn't until November 1943 that the Me-209 was dropped for good. Even then, the Me-262's political troubles were far from over, and in fact were just
about to take a very nasty turn. Hitler, alarmed by the success of Allied amphibious landings in Africa and Italy, was very concerned about developing a fast fighter-bomber ("Jagdbomber /Jabo") to pin down invasion forces on the beaches until reinforcements could arrive to drive them back into the sea.
On 2 November 1943, Reichsmarshal Hermann Goering, head of the Luftwaffe, and Milch visited the Messerschmitt plant in Augsburg. Goering asked Willi Messerschmitt if the new jet fighter could carry bombs. Messerschmitt answered without hesitation that the Me-262 had been designed from the outset to carry 500 kilograms (1,100 pounds) of bombs, could possibly carry twice as much, and would be easy to adapt to the "Jabo" role.
On 26 November 1943, Hitler inspected the Me-262 at Insterburg, and asked the same question: Can it carry bombs? Messerschmitt gave him the same answer that he had given Goering. Hitler's prayers had been answered. He ordered the Me-262 to be built as a fighter-bomber, and the Me-262 "Jabo" featured prominently in his military plans from then on. There is little record of anyone contesting his decision. The reality was that Messerschmitt completely ignored the will of the Fuehrer and busily worked to put the machine into production as a fighter.
Milch, on reading intelligence reports that the Americans were getting ready to field new bombers such as the Boeing B-29 that would be a handful for existing interceptors, also pressed on with production of the Me-262 as a fighter. Though Milch made agreeable noises about building it as a fighter-bomber, little or nothing was done to that end.



ME-262 into production 
 Whatever the political issues surrounding the Me-262 program, the real difficulty was that the aircraft was still a long way from being a production machine. At the time, there was only one Me-262 flying, the "V4" prototype. The previous three prototypes had been wrecked one way or another, and the "V5" prototype was being rebuilt to use tricycle landing gear, at the suggestion of Adolf Galland. Given the aircraft's long nose, the tailwheel landing gear configuration made forward visibility on the ground extremely poor, and the downward-pointing jets also tore up the runway.

The V5 had fixed nose gear, but was followed by the "V6" in October 1943, which had fully retractable landing gear and was close to production specification, and then the last test prototype, the "V7". By April 1943, 13 preproduction "Me-262A-0s" had been completed, of a total of 23 ultimately built out of the 45 ordered. These aircraft were close to production specification, but some had specialized test fits. For example, the "V12" was modified as a high-speed test article with a smaller canopy and other changes, and was clocked at 1,005 KPH (624 MPH), substantially faster than a standard Me-262.
Some of the preproduction machines were also sent on to the Luftwaffe for operational evaluation by a group organized in April 1944 for the task, designated "Erprobungskommando (Proving Detachment) 262". It seemed like the Me-262 was coming into service at precisely the right of time, since now the US Army Air Forces (USAAF) had adequate numbers of long-range P-51 Mustang fighters to escort bombers on daylight raids over Germany, greatly complicating the air defense of the Reich. The Me-262 might well tilt the balance back to the defenders.
The problem was that building an adequate force of Me-262s was easier said than done. Messerschmitt was straining to keep up with demands for production of existing aircraft types, a difficulty that had been compounded by a devastating Allied air raid on the company's plant at Regensburg on 17 August 1943. Production had to be relocated to Oberammergau, near the Bavarian Alps. Delivering the temperamental Jumo-004 turbojets was even more troublesome.
Work muddled on into 1944, and then the political disconnect between the left and right hand finally led to an uproar. On 23 May 1944, Goering, Milch, Galland, other senior Luftwaffe officials, as well as Armaments Minister Albert Speer and his people, were called to Hitler's residence at Berchtesgaden to discuss the current fighter production program. The meeting was routine up to the point where production of the Me-262 as a fighter was discussed. Hitler was puzzled: "I thought the 262 was coming as a high-speed bomber. How many of the 262s already manufactured can carry bombs?"
Milch replied: "None, mein Fuehrer. The Me-262 is being manufactured exclusively as a fighter aircraft." After a chilly silence, Milch then pointed out that the aircraft could not be adapted to the "Jabo" role without major design changes, and even then it would not be able to carry more than 500 kilograms (1,100 pounds) of bombs.
Hitler was flabbergasted. Back in November, he had asked if the Me-262 could be adapted to the "Jabo" role, and was given an unqualified YES. He had ordered that it should therefore be built as a fighter-bomber, and nobody had protested the decision. He had been including the "Jabo" Me-262 in his plans for the defense of the Reich against an amphibious landing by the Western Allies, which was expected any time soon and in

fact would take place within weeks, on 6 June 1944. Now Hitler was being told that not only were there no "Jabo" Me-262s, but that the assurances he had been given about its feasibility were false, and to make matters worse nobody had told him of any of this. That would have angered far milder men than Hitler, and he was furious: "Who pays the slightest attention to the orders I give?! I gave an unqualified order, and left nobody in any doubt that the aircraft was to be equipped as a fighter-bomber!"
Goering made excuses and passed the blame onto Milch, who was soon stripped of most of his powers. Hitler ordered that work now be focused on delivering the "Jabo" version of the Me-262, though he did consent to continued testing of the fighter version as long as it didn't slow down deliveries of the "Jabo" variant. Messerschmitt engineers now belatedly began to fit the "V10" prototype as a fighter-bomber that could carry two 250 kilogram (550 pound) bombs. The result was clearly an improvisation, but since the Arado company was already working on an optimized jet bomber, the "Ar-234", the "Jabo" variant of the Me-262 could serve as an interim solution.
By late June 1944, a fighter-bomber unit, "Erprobungskommando Schenk", had been formed under Major Wolfgang Schenk. A month later, the unit was relocated to France with nine aircraft, in order to oppose the "real" invasion that was expected in the Pas de Calais, an expectation fostered by elaborate and comprehensive Allied deception programs.
The "Jabo" Me-262s in France accomplished little, and with the Allied breakout from Normandy they were gradually pulled back, to end up in Belgium at the end of August. With the invasion now history, Hitler rescinded the order to focus solely on the "Jabo" Me-262 version, and the focus of production returned to the fighter variant. The Fuehrer still insisted that any fighter variants that were built to be easily converted to the "Jabo" configuration on short notice. (1) (2) (3)