Talk:Junkers Jumo 004

Assessment
Nice article, if it had inline citations or any references it might be GA class. As it is, it doesn't meet all of the B-class criteria. Pity. --Colputt 00:48, 12 September 2007 (UTC)

WikiProject Military history/Assessment/Tag & Assess 2008
Article reassessed and graded as start class. --dashiellx (talk) 17:46, 13 May 2008 (UTC)

Unit confusion
The article on specific fuel consumption (SFC) states that SFC for jet engines can be statet either in kg/(kN*h) (as the article on the BMW 003 does) and kg/(kN*km) (by dividing by airspeed in km/h). Apparently, this article does neither (it uses kg/km/h), so one has to ask: What is the SFC for the Jumo 004, and in what units? Does anyone have sources? Laschatzer (talk) 13:35, 11 July 2008 (UTC)

Add this link?
I found http://www.enginehistory.org/German/Me-262/Me262_Engine_2.pdf extremely useful, maybe it should be under external links? 85.196.101.178 (talk) 20:22, 31 October 2010 (UTC)

Add this link too?
I found "Design of the Junkers Jumo 004 B explained @ a cut-away version of the turbojet engine of the Me 262" https://www.youtube.com/watch?v=04DrmN9QM0E useful, maybe it should be under external links? — Preceding unsigned comment added by 82.115.104.34 (talk) 08:59, 6 December 2019 (UTC)

Design and Development
"but it also had a smaller cross-section, important for a high-speed aircraft design."

Smaller than what? It is not clear (to me anyway) what the comparison is being made with.Dawright12 (talk) 09:37, 14 May 2011 (UTC)


 * Smaller than an engine with a centrifugal compressor (like the Rolls-Royce Derwent as an example) I think it means. I can't easily clarify it as the whole section is unsourced. Nimbus (Cumulus nimbus floats by)    20:32, 14 May 2011 (UTC)

Design and Development
"Vibration problems with the compressor blades delayed the program at this point, until a new stator design by Max Bentele solved the problem. The original alloy compressor blades were replaced with steel ones and with the new stators in place...."

I will clarify the above statements after reading Max Bentele's autobiography and the detailed design anlysis of the engine in "Jet Propulsion Progress" by Neville and Silsbee, 1948. The statements use the terms blades and stators interchangeably which is confusing since they are more commonly known as rotating compressor blades and stationary stator vanes. The vibration problem was with the stators. Bentele dooesn't say what the fix was but does say the stators were originally cantilevered from the outside which suggests this was changed. Moving to the other book, production engines examined after the war had stator rings consisting of inner and outer shroud rings so presumably the inner ring was the cantilever fix. As far as material goes not all the stator stages were steel. The first 2 (or 3 in early production engines) were aluminium. The 2/3 Al stages is at variance with the later statement in the article "The four front stators were constructed from steel alloy". This apparent contradiction may be explained by the statement in the book "Considerable variation, both in materials and methods of construction, was found in this (compressor) section." Whether steel was also a vibration fix for some stages is not clear.

" and the problem was solved by raising the blades' natural frequency"

Further on, this statement will also be clarified as it refers to turbine blades.Pieter1963 (talk) 23:37, 27 July 2014 (UTC)

Incidentally I've just noticed the "enginehistory" link has the same words as in the above book "JPP".Pieter1963 (talk) 23:45, 27 July 2014 (UTC)

External links modified
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External links modified
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 * Added archive https://web.archive.org/web/20120320004113/http://www.enginehistory.org/German/Me-262/Me262_Engine_2.pdf to http://www.enginehistory.org/German/Me-262/Me262_Engine_2.pdf

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Specifications - specific fuel consumption
I had a look at this. The original version of the article gave the figure as 1.42 kg/(kp h).

Converting in two stages: 1.42 kg/(kp h) → 13.925 kg/(kN h) (multiply by 9.80665 N/kg) → 3.868 g/(kN s) (multiply by 1000 g/kg and divide by 3600 s/h aka divide by 3.6).

So the original article claims a thrust specific fuel consumption of 3.868 g/(kN s); 3.87 si tsfc. That is not realistic. E.g., the similar Westinghouse J30 (same type of engine, same type of age) has a thrust specific fuel consumption of 38 g/(kN⋅s) - which would make the Jumo 004 ten times more efficient.

If Thrust-specific_fuel_consumption is any guide, there's no such thing as a modern gas turbine working at anything near the efficiency claimed for the Juno 004.

I've had a look at past edits and I can't find a properly referenced realistic looking figure for this spec, so I've removed it. But in the article, I've just commented out the data. It occurs to me that the original figure might just be out by a factor of ten: if it were 14.2 kg/(kp-h), that'd be reasonable. Also, I might well have made a really stupid unit conversion mistake.

Michael F 1967 (talk) 22:39, 1 September 2019 (UTC)

Surviving engines section
I cleaned up the section today and deleted unsourced claims, while updating/adding sources. I put them into a quasi-list format, as it looks cleaner, IMO. How does everyone thinks this looks?

Also, please feel free to add additional museums/collections that have 004s!

Cheers :-)

MWFwiki (talk) 03:20, 24 January 2020 (UTC)