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  #11  
Old 16th November 2018, 04:56
Jukka Juutinen Jukka Juutinen is offline
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Re: Bf 109 vs. Spitfire production costs

Based on the samples available on Amazon U. K., most reference notes are to published secondary sources and great many archival references are to documents of non-technical nature. I got the feeling that Isby did not personally peruse German archives in a thorough manner.
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  #12  
Old 16th November 2018, 09:58
Bruce Dennis Bruce Dennis is offline
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Re: Bf 109 vs. Spitfire production costs

Jukka, you attacked first the book and then the writer as untrustworthy and then you praised an article you have not read. I do not expect everyone to agree on every book but, really, if you are going to rubbish someone's work you should at least get your facts straight. Look at the book, and at the cited sources and then please answer the question put to you earlier: what did you find in the book that was not correct? (And I now think you should state YOUR source for any answer).

Bruce
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  #13  
Old 16th November 2018, 11:36
sidney sidney is offline
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Re: Bf 109 vs. Spitfire production costs

Quote:
Originally Posted by Jukka Juutinen View Post
Based on the samples available on Amazon U. K., most reference notes are to published secondary sources and great many archival references are to documents of non-technical nature. I got the feeling that Isby did not personally peruse German archives in a thorough manner.
So... you did not actually read the book, except for a couple of sample pages available on Amazon.co.uk, right?
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  #14  
Old 16th November 2018, 15:13
schwarze-man schwarze-man is offline
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Re: Bf 109 vs. Spitfire production costs

"Cheaper" is an interesting concept. The "Cost" can be measured in many ways and not all comparisons will be valid. I have worked on the actual airframes of both the Spitfire and the Bf109. Although they are both aluminium monocoque structures, I would classify the Bf109 wing structure as easier to build from almost all press-formed parts, but with the added complication of the Slats. The Bf109 fuselage construction is unusual but, when the forming tools/jigs are available, it is simple. So, overall, without knowing the man-hours figures, I would guess that, given the production tooling and material available, the Bf109 Airframe would take less manhours to build. Am I right?

SM
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  #15  
Old 16th November 2018, 16:07
sidney sidney is offline
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Re: Bf 109 vs. Spitfire production costs

I will again quote the aforementioned source, page 131, this time from the early 1940, which perhaps gives more meaningful comparison because at that time there was no forced labour involved: "In January 1940, it took 15,200 man-hours to build a Spitfire, 10,300 to build a Hurricane (compared to about 9,000 for a Bf 109 E)...."

These figures should be broken down to: 1. Airframe, 2. Engine, 3. Armament, 4. Internal components, such as for example radio, or the like, to see where the quoted difference of some 6,200 man-hours came from.
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  #16  
Old 16th November 2018, 16:59
schwarze-man schwarze-man is offline
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Re: Bf 109 vs. Spitfire production costs

Thanks Sidney.
The engines are interesting to compare with regards to production, Merlin III / 601A. Both similar with regards to crank, blocks/heads (one piece), spur reduction gear, cam drives. However, purely from working on them both, I suspect there is a greater amount of man hours in the production of the 601A.
The 601 valve gear looks simpler with interposed roller followers but the Merlin rockers are simple cast sleeves with welded-on arms and follower pad. Hmm...
The 601 roller Big-ends certainly have a greater precision parts count and that leads on to the hydraulic supercharger drive with its controller pump and precision coupling, definitely more precision parts. The Fuel injection system compared to the SU carb? No contest, the SU does the job but, the Bosch injection system has a large parts count and, a great many of them are precision ground for matched fit.
Overall, I would expect that the complete 601A needed more hours than the Merlin III to build. Cheers

SM
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  #17  
Old 16th November 2018, 17:32
sidney sidney is offline
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Re: Bf 109 vs. Spitfire production costs

Hi SM,

Many thanks for your insight, much appreciated.

I really thought that the Merlin III took longer to produce than DB 601 A, and the reason for that was that the Merlin apparently had not been designed for mass-production (one of the versions is said to have 14,000 individual parts). Please refer to the article: https://www.tested.com/art/makers/49...lt-powerhouse/

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Sidney
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  #18  
Old 16th November 2018, 22:14
schwarze-man schwarze-man is offline
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Re: Bf 109 vs. Spitfire production costs

Hi Sidney,
Yes, I am looking at these engines with a calibrated eye that says, "same job-same man hours". I agree, that might not translate to a certain performance at a different manufacturer. The early UK RR Merlin production was very much a finished-by-hand operation. Serious mass production and skills dilution at RR took a lot of effort. The re-drawing and tolerance specification for Packard production was a major task. I guess that this was all part of the workload that led to mass production. The first Packard engines were 28's and incorporated a two-piece block, designed with RR compliance. Out of interest, the DB engines were finely finished until after about 1941 production, then finish quality visibly declined. Unseen, the materials quality also reduced but, overall engine performance did increase, with reservations. Very generally, German engine life reduced while Western allied engines reached higher lives at higher power. The reality was that high quality materials were in real short supply for Germany and Aviation Gasoline never really saw the octane improvement above 87 B4 that was the industry standard due to supply limitations. Cheers

SM
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  #19  
Old 16th November 2018, 23:36
Icare9 Icare9 is offline
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Re: Bf 109 vs. Spitfire production costs

The comment about the Merlin not being designed for mass production rings a faint bell about the Merlin being produced by Ford and that they had much finer tolerances than RR, so much so that RR engineers had to be sent to Ford factories to get the engines into mass production. That's speaking from recollections of my father in law who was a RR engineer who then spent the rest of his career with Ford in Basildon - so may not be factually correct, but that was the impression I got, the Merlin had to be "redesigned" with automobile tolerances....
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  #20  
Old 17th November 2018, 00:30
Graham Boak Graham Boak is offline
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Re: Bf 109 vs. Spitfire production costs

The story about Ford telling Rolls that they were unable to build the Merlin because the tolerances were too loose for mass production has certainly been told in a number of works, usually to point out that this was not the answer that RR were expecting. As I understand it the Merlin XX was intended for Ford mass production and designed to motor industry tolerances that required a considerable investment in tooling but would permit assembly by an unskilled workforce. This did have the implication of a rigidity in production where modifications were anathema because of the cost and loss of production, but large benefits in output. Similar conditions reigned at Castle Bromwich on the Spitfire line.

I don't know whether the changes introduced on the Mk.XX were carried over to later Merlins - I suspect that many were but not all in order to retain a greater degree of flexibility in responding to the service demands.
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