Messerschmitt Me 262.

[Panzerknacker]

continued problems and poor quality of engines,

Well I think you get the point my dear Digger, there is difference between "poorly manufactured" (wich was not) and "poor quality materials" ( wich was sometimes).

Is also worth to note that most of the destroyed Me-262 were attacked in the groud or in the fianl aproach to their airfield, thing that deprived the Schwalbe to his best characteristics.

Also the plane was undermined by several bad tactical desitions and unnecessary delays wich hampered it to display his potential.

Me-262A-1/a, EKdo 262.










There was however a lot of Me-262 aces like Galland, Bär, Steinhoff, etc.

One pilot of the JV 44 destroyed 2 P-51 in 3 minutes in his first sortie.

[Raven]

Wow his first sortie, that's pretty impressive.

I've always thought if Hitler hadn't insisted it be a bomber it may have made a change to the war.


Of course if Germany had invested the time and costs into creating or upgrading their current piston-engine fleet I imgagine the outcome would have been more effective.

[Digger]

Just to let you guys know, this thread was not started by me, it was shifted from another thread. I doubt I would have chosen the title for this thread.

To clear one thing up, I have never said the Me 262 was a bad aircraft, rather it was an aircraft yet to reach it's potential, when the war ended.

Engine development was it's biggest stumbling block, remembering this was cutting edge technology at the time, and it was this developmental problems with the Jumo engines which caused most of the delays. Hitler's decision to convert Me 262s to fighter bombers was not the cause for delay.

And yes, there was evidence of poor manufacturing in the Me 262, but this was the symptom of the times with most manufacturing suffering air attacks, disruption of supplies, shortages of strategic materials and a largely unskilled workforce. Many of the workforce in German war industry, were poorly treated, starving, were beaten(sometimes to death), had minimal skills training and because of these reasons good manufacturing principles lapsed dramatically throughout 1944.

In some cases there was evidence of sabotage, particuarly in engines, but to what degree this effected overall production is hard to say. In spite of these difficulties Messerschmitt did get the Me 262 into service, a remarkable achievment.

Regards digger.

[Panzerknacker]

Yeap I splitted the topic, the Me-262 is interesting enough to made a thread of it.

most manufacturing suffering air attacks, disruption of supplies, shortages of strategic materials

I think those (in despite the others you named ) are the most important causes, the german ended assemblig jet fighters in the woods.

Wow his first sortie, that's pretty impressive.

I've always thought if Hitler hadn't insisted it be a bomber it may have made a change to the war

That was Walter Schuck, he scored 206 victories and was awarded the Knight's Cross with Oak Leaves. In April 1942 he was sent to the bitterly cold Eismeer Front with 7./JG 5 at Petsamo, Finland. In March 1944 he shot down seven Boston bombers in a single day. On 1 August 1944 he was promoted to Staffelkapitän of 10./JG 5. He was transferred to the West to fly the Me 262 and was appointed Staffelkapitän of 3./JG 7 on 24 March 1945. He shot down eight aircraft while flying the Me 262, including four B-17s on 10 April. He was forced to bail out on the same mission.

[Raven]

Amazing. Thanks for the information Panzerknacker.

[Librarian]

As usually, honorable ladies and gentlemen, Mr. Digger has the point in this case:

… it was an aircraft yet to reach it's potential, when the war ended… Engine development was it's biggest stumbling block, remembering this was cutting edge technology at the time, and it was this developmental problems with the Jumo engines which caused most of the delays.

Indeed, engine development was Me 262’s biggest faltering obstruct, but it has to be emphasized that this gas turbine jet power plant actually was a compromise between engineering desires and available materials and production facilities.

Outstanding evidence of technological compromises resulting from lack of strategic materials is situated in the fact that more than 7% of the engine intake-air was bled-off for cooling purposes. Despite this, however, most engines were found to have a service life of about only 10 hr., against a "design life" of 25 – 35 hr. Additional compromises are evident in the design, which shows that the production engineers were undoubtedly hampered by lack of both plant facilities and adequate skilled labor, but the main reason for a delay in Me 262 production was the diversion of critical materials into U-boat production and other projects late in the war, ant that verity forced Junkers to produce the 004 B engines with only 1/3 of the high grade steel that had been used in the very first 004A engines. It was a disastrous concession for the Me 262.

It has to be also emphasized that these failures were actually anticipated to some extent and the Me 262 was designed to permit really rapid engine changes.

Contrary to popular belief, the Jumo 004 was a fairly sound performer when first-rate steel alloys of excellent heat-resistant qualities were used just after the German capitulation, and it was proved by US post-war tests that simple application of different materials made possible to get average endurance of the turbines up to 150 hours service in actual flight tests, and up to 500 hours on the test stand.



Junkers Jumo 004 B - Cross-Section


The Junkers Jumo 004 B was the first large-scale produced axial-flow aircraft gas turbine engine, developed by Dr. Ing. Anselm Franz from Junkers. Even though Dr. Franz was familiar with centrifugal compressors from his previous work on piston-engine superchargers, he opted for an axial compressor design because he was convinced that the low frontal engine area cross-section was of fundamental importance for a high-speed airplane aerodynamics and that aforesaid low-drag gains could be achieved with an axial design only. This also turned out to be a correct choice as the Gloster Meteor was delayed by problematic airframe integration issues caused by its large, centrifugal compressor equipped Derwent engines.



Rolls-Royce Derwent - Cross Section

The axial compressor concept was based on the steam-turbine experience achieved by AEG in Berlin and it didn’t use a vortex design that was characteristically used by British engineers in their own constructions.

In 1936, when the first work on turbojets began, a high-temperature Krupp-made steel alloy known as P-193 was available. This material, which contained nickel, chromium, and titanium, could be given good high-temperature strength by means of solution treating and precipitation hardening. Dr. Anselm Franz initially used an improved version of P-193 known as Tinidur – austinitic 'stainless steel' like steel alloy with 6% titanium, 18% nickel 12% chromium with the balance of steel.

The first turbine blades of the Jumo 004 A version were solid ones. Early tests showed that even supposedly identical blades would have a large scatter life. By 1944, Junkers had solved the problem and obtained uniform quality of the blade by close control of manufacturing, especially of the critical forging process. Attempts to produce hollow blades by folding flat sheets of Tinidur and welding down the trailing edge resulted in failure, as Tinidur could not be welded. Eventually, a deep drawing process was used, in which the stock for the blade was a flat circular blank. Hollow blades could be manufactured faster than solid blades by this process.

However, constant lack of Nickel caused a forced and rapid abandonment of the previously used materials. Chromite ore, from which is derived chromium, an element essential for the manufacture of stainless steel was evaluated as one of the few raw materials that were essential for the German war industry and for which there were no fully adequate sources within German territory, was very scarce.

At the beginning of the war Germany had an estimated stockpile of about 250,000 tons of chromite, which had been accumulated by heavy purchases in Africa, Turkey, and the Balkans in the late 1930s. By 1941 the only European source within the German range available for new deliveries of ore was the Balkans, and the only accessible source outside occupied Europe was Turkey, with another one potentially reachable replacement – a mammoth Nikopol manganese ore district - located in Ukrainian part of the USSR. In mid-1944, however, Germany’s loss of all remaining chromite as well as manganese ore supplies was disastrous: the Soviets recaptured Nikopol and succeeded in denying an important source of manganese to the Germans. Subsequently, total German steel production declined from the 35 million tons in 1943 to 2 millions tons per quarter by the end of 1944, and Germany was forced to abandon the production of high alloy-steels. The output of engineering steels declined by two-thirds, and the special steel available for military ordnance declined from nearly 2.5 million tons to less than 900,000 tons. The manufacture of airplanes, tanks, motor vehicles, tank shells, U-boats, and almost the entire gamut of artillery has suffered, but German engineers were still very devoted and skillful, and they successfully developed some even today very intriguing and highly original, even today applicable Ersatz (substitute) solutions.

Previously mentioned forced abandonment of Tinidur alloy, with 30-percent nickel content, strained Krupp toward development of the alloy called Cromadur, which was actually better than their earlier attempt, as Cromadur proved easy to weld. The process of folding the blade flat and welding it turned out to be superior to deep drawing, so the Cromadur blades proved more reliable than the Tinidur blading despite Cromadur's lower creep strength!

However, intensive air cooling was essential, and it was used throughout the engine. A later version of the 004B engine had hollow, air-cooled stator vanes, because these parts were the most critical ones. Compressor discharge-air was used to cool the blades. With hollow blades made out of Cromadur-alloy sheet metal, the complete 004B engine contained less than 2.3 kg of chromium. Due to these improvements the first production model of the 004B weighed 45.5 kg less than the 004A! Additional modifications were made to the first compressor stages too. A series of 100-hour tests were completed on several engines, and time between overhaul of 50 hours was achieved.



Junkers Jumo 004 – Compressed Air Cooling

Cooling airflow was derived from between the fourth and fifth compressor stages, and led to the double skin around the combustion-chamber assembly. Most air passed down one exhaust cone strut to circulate inside the cone and through small holes to cool the downstream face of the turbine disk. Air was also taken in through three tunnels in two of the casting ribs and into the space between the two plate diaphragms in front of the turbine disk. Most of this air passed through the hollow turbine nozzle guide vanes, emerging through slits in the trailing edges.



Junkers Jumo 004 – Motor Management Schematics

Forced end of the part I… To be continued.

[Librarian]

Part II

The turbine, designed in collaboration with AEG, had a degree of reaction of 20 %, which represented a compromise between AEG, which wanted less, and Junkers, which wanted more (from afterburner considerations). The single-stage turbine had 61 blades fixed to the turbine disk by a formed root and kept in position by rivets. The production version had air-cooled hollow blades. A movable 'bullet' was mounted in the tailpipe and controlled by a servomotor to vary the nozzle area.

On the other side of the hill situation was pretty different. In England the early development of age hardening nickel alloys was influenced by works of on the nickel-chromium heat and oxidation resistant alloys which showed the outstanding characteristics of the 80% nickel, and 20 % chromium composition (Tapsel & Bradley, 1925). Thus when in the early 1940s, at the request of Britain's Air Ministry, different private company scientists worked feverishly to solve the problem of appropriate materials for emerging designs in jet and gas turbine engines, that what became one of the most noted contributions during the war by metallurgists (Pfeil, Allan and Convay from the Henry Wiggin & Co. Ltd.) facilities in Birmingham, was the specific re-invention of an low-ferrite alloy for jet-propelled aircraft engines.



Nimonic 80 Alloy Turbine Blades, De Havilland Goblin II Engine

This new nickel alloy called "Nimonic 80" allowed the jet engine's turbine parts, particularly the blades, to operate for long periods under tremendous stress, under high heat and corrosive exhaust, without deforming or melting. This new non-ferrite alloy was far superior to all German constructive metal alloys used in the aircraft industry. After the war, Nimonic 80 set the stage for a revolution in jet-propelled aviation.

For much of the past century the key location for this essential metal was the legendary Sudbury Basin, with the South Pacific island of New Caledonia coming a distant second.

And finally an additional historiographic remark: After the WW2 Dr. Anselm Franz immigrated to the United States, where he worked for the U.S. Air Force from 1946 until 1950. In 1951, he joined Avco Lycoming and soon moved to Stratford (Connecticut), where he established the gas-turbine department of the aforementioned company, being responsible for several successful engine-development programs, including the T53 (which powers the U.S. military's AH-1S Cobra, Grumman OV-1 Mohawk, and Bell UH-1 Huey helicopters) and T55 series of turbo-shaft engines, as well as the T55 high-bypass turbofan (named the ALF502). In the 1960s Dr. Anselm Franz led a team to design the three-spool, 1,500 shaft-horsepower AGT-1500 V gas turbine, the power plant for the U.S. M1 Abrams main battle tank. He retired as vice president of Avco Lycoming in 1968.



Dr. Ing. Anselm Franz, Chief Engeneer of the Junkers Jumo 004 Development Program

But that is a completely different story…

As always honorable ladies and gentlemen - all the best!

[Twitch1]

Say all you want about the first jet turbines. The fact is that German engineers were aware of the initial shortcomings and had the situation in hand with the 2nd generation of engines that were being developed.

[Panzerknacker]

Nice drawing and comments Librarian, the titanium was also a metal wich was completely unavailable for those times in Germany.

Say all you want about the first jet turbines. The fact is that German engineers were aware of the initial shortcomings and had the situation in hand with the 2nd generation of engines that were being developed.

They were aware but due the war situation they were unable to cure it completely, still some 1400 Me-262s were completed, not all used in combat.

I believe (firmly) that the Me-262 was a powerful combat machines despite his shorcomings.

More devastating than all the material poorness was the 25th May order of A.H who said every Me-262 should be a bomber.

[Chevan]

Thanks for detailed engeen material mst. Labrarian.
You've wondered us as always by your extremaly wide and deep-specific knowleges at the same time.
BTW i have to add that inspite of engeens problems the Me-262 was the much better aircraft then the first British Meteor Mk i.
The Me-262 had a much more speed and a much more firepower 4x30 mm gun !!! This was a uber-wearpon which could really finish the allies strategic aviation if it was done in the 1944 and in enough quantity.
P.S. oh my god it seems i become a one more "german wearponry soccer" in here
what to do?

[Panzerknacker]

P.S. oh my god it seems i become a one more "german wearponry soccer" in here
what to do?

What to do?...I guess that you might enjoy the conversation while eating some knackwurst and bier.

[Chevan]

Originally Posted by Panzerknacker

What to do?...I guess that you might enjoy the conversation while eating some knackwurst and bier.

I would enjoy but where you are when you are needed?
BTW is it an Me-262 HG II perspective modification which were never finished?

[Panzerknacker]

I am always available my dear russian sargeant. ( i did receive your PM)

Indeed that is an Me-262HG "stüfe 1" ( stage 1)... nice isnt ?

Me 262 B-1a des KG 54 in Giebelstadt

[Chevan]

Originally Posted by Panzerknacker

I am always available my dear russian sargeant. ( i did receive your PM)

I've never doubt in it comrade general

Indeed that is an Me-262HG "stüfe 1" ( stage 1)... nice isnt ?

Very nice.
Could you prove for other our comrades ( mostly from the "misty Albion") that this aircraft could fly enough good.
Becouse some our members , who are the specialist on aerodinamic field recently tryed to prove me that the Me 262 HG i/II/III simply was not able to fly.

Cheers.

[pdf27]

Originally Posted by Librarian

Contrary to popular belief, the Jumo 004 was a fairly sound performer when first-rate steel alloys of excellent heat-resistant qualities were used just after the German capitulation, and it was proved by US post-war tests that simple application of different materials made possible to get average endurance of the turbines up to 150 hours service in actual flight tests, and up to 500 hours on the test stand.

True, although it should be pointed out that Allied engines at this point in time were happily managing over 1,000 hours in service with what were IIRC higher TITs and with no cooling air.

Originally Posted by Librarian

The Junkers Jumo 004 B was the first large-scale produced axial-flow aircraft gas turbine engine, developed by Dr. Ing. Anselm Franz from Junkers. Even though Dr. Franz was familiar with centrifugal compressors from his previous work on piston-engine superchargers, he opted for an axial compressor design because he was convinced that the low frontal engine area cross-section was of fundamental importance for a high-speed airplane aerodynamics and that aforesaid low-drag gains could be achieved with an axial design only. This also turned out to be a correct choice as the Gloster Meteor was delayed by problematic airframe integration issues caused by its large, centrifugal compressor equipped Derwent engines.

BS. AA Griffith at the RAE in Farnborough made the same fundamental mistake. For a peacetime programme where they had time to get it right, it may have been true. For a wartime emergency programme where they had to get it right first time with limited resources, it was deeply wrong. The point about the Gloster Meteor is savagely flawed too - despite these supposed "issues", it started development work later and yet entered squadron service before the Me-262 did.
The absolute genius of Frank Whittle - and I make no apologies about using the word - was not in the invention of the Turbojet engine. The concept had been around for quite some time, and he was merely refining it a bit. His genius was in realising that it could be made with simple parts that were already well understood, fettled a bit, and it would beat any engine then in service or on the drawing board by a huge margin. His use of centrifugal compressors is a large part of this - axial flow compressors even today are huge, heavy, a major pain to design right and suffer from stall/surge problems. Centrifugal compressors don't, and the only reason that they are nowadays limited to a few applications like helicopter engines is simply due to ducting problems when stacking compressors, rather than issues of frontal area.
It is worth noting that Whittle-type engines powered all the first generation of postwar jet aircraft, despite the supposedly "superior design" of the Jumo-type engines being freely available. Given that the Soviets had full access to the German plans - including those for the second-generation engines - and yet decided to build a copy of the RR Derwent instead is to me further evidence that your thesis that the Jumo-004 wasn't too bad really does not hold water. It wasn't until engines like the Armstrong-Siddely Sapphire and RR Avon became available in the 1950s that axial flow engines gained widespread acceptance.