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syscom3
Pacific Historian
But it looks like it only effected production by two months or so.
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Yeah, if airframes had to be retrofitted with components or other alterations that would be a solid indication that production started too early. However with new technology there are always certain issues that only surface once the thing is put to use, so it'll be hard to tell if it was rushed. I have never heard of any changes regarding the 262-airframe that are out of the ordinary.A flurry of Engineering Change Orders due to Design changes required to solve problems encountered in prototypes for which new tooling had to be made (or make them as piece parts/cutomized) would be one possible reason.
You could make the decision to not make those changes and use existing tools, then send field mods out to retrofit to a production block number..that might happen if it was not a flight safety issue.
Just a couple of possibilities
That is exactly the opposite of what the books say on this topicOk, so are these true statements:
2) The engine was available for use (although with a short lifetime) throughout the first 1/2 of 1944, and all that was needed were airframes.
What exactly made the airframes coming out of factories "not ready for mass-production"?
Hm, this site points out that Hagenah was transferred to a Me 262 only in March 1945:
That is exactly the opposite of what the books say on this topic![]()
Agreed; in fact, the first tail-dragger 262 airframes used a Jumo Ju 210G recip engine in the nose to test the airframe, because the 004's weren't ready yet. When the BMW 003's were (supposedly) ready, they tested them on the same airframe that already had the Jumo recip installed, just in case the engines failed in-flight, which they did.
I misquoted, sorry. The quote should read
"Yet, if anything, production of the aircraft was initiated too early with the result that Me262 airframes were starting to come off the assembly lines before **the engines to power** them were ready to enter mass production"
This would imply that the Me 262 had had all the major bugs worked out by this point and the necessary tooling was in place, or being geared up for full production. Which means in a technical sense that it was not entering production prematurely.
Couple of more quotes regarding the engines:
" Due to Allied economic blockade, German industry was critically short of nickel and chromium from the summer of 1941. These elements were essential ingredients for effective high temperature-resistant steel alloys, but Junkers engineers were forced to use substitutes whenever possible.
Jumo 004 turbine blades were manufactured from a steel-based alloy containing 30% nickel and 15% chromium, a material sufficiently resilient to withstand the very high temperatures and high tensile stresses encountered. Under these conditions the blades soon developed 'creep', gradually deforming and increasing in length. When blade creep exceeded a laid-down limit the engine had to be changed.
I believe Finnland was the major or possibly sole sourse of Nickel for wartime Germany, which means, prior to the Finnish armistice in Sep 1944 it could still be obtained. In the case of chromium iirc, supply (while scarse) was not as limited as Nickel. The alloy referred to doesn't seem to match quite right either as those used on the 004 should be:
"The production Junkers Jumo 004B-1 and the Jumo 004B-4 turbines and
stator blades used an austinitic 'stainless steel' like steel alloy
called tinadur or an concurrently used alternative called cromadur.
Tinadur was about 6% titanium 18% nickel 12% chromium with the balance
steel while cromadure substituted super scarce nickel with manganese to
achieve an alloy of about 18% chromium, 15% manganese with only traces
of nickel with the balance steel. The BMW engines used a similar
alloy series called sicromal. This alloy was also used on gasoline
engined turbo superchargers and its shortage also explains the minimal
use of turbos on German aircraft.
"
Jumo 004 flame tubes were formed out of mild steel sheet, with an oven baked spray coating of aluminium to prevent oxidation. This inelegant material did not survive long at the extreme temperatures generated in the hottest part of the 004, and during running the flame tubes slowly buckled out of shape.
Limited by turbine blade creep and flame tube buckling, as exacerbated by problems with the fuel regulation system, the running life of pre-production Jumo 004 engines rarely exceeded 10 hours. Then the Me262 had to be grounded for new engines to be fitted.
This is an interesting not and something I haven't heard of before. Assuming the author is using the correct terminology the falme tubes refer to the tube located within the "flame can" or can-type combustor where the fuel is actually injected and burned at stoichiometric proportions before mixing with the additional air. So the internal component would be deforming not the entire chamber or "can."
The Aluminum coating would have no effect on the buckeling problem as it was there to protect against oxidation not for heat resistance.
...
In September 1944, following a series of incremental improvements, the nominal running life of the the Jumo 004 at last reached 25 hours. Although the engines' life was still short, given the desperate war situation that was considered sufficient for the design to be frozen so that mass production could begin.
The alloy referred to doesn't seem to match quite right either as those used on the 004 should be:
"The production Junkers Jumo 004B-1 and the Jumo 004B-4 turbines and
stator blades used an austinitic 'stainless steel' like steel alloy
called tinadur or an concurrently used alternative called cromadur.
Tinadur was about 6% titanium 18% nickel 12% chromium with the balance
steel while cromadure substituted super scarce nickel with manganese to
achieve an alloy of about 18% chromium, 15% manganese with only traces
of nickel with the balance steel."