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  #21  
Old 17th November 2018, 00:38
schwarze-man schwarze-man is offline
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Re: Bf 109 vs. Spitfire production costs

Having read a fair amount about the huge increases in production of the Merlin, it seems to me that the often quoted need to work to tighter tolerances for Ford (UK) and Packard (USA) is a bit of a throw-away line. In the late 1930's Rolls-Royce worked to their company standards on many components. Their skilled fitters and machinists produced quality work. The critical clearances on parts like pistons, rings and bearings were well defined in the RR way and things like gear backlash were perhaps judged by very skilled men. However, the true mass production by motor car companies did require more definition of specification. Selective fitting of components to achieve fits was superceeded by better definition of finished size and surface finish so that, parts could be assembled without extra finishing or selective fitting. Also, there was a fair amount of redesign for the American produced Packard version. As RR expanded their own production plants, many of these changes were needed anyway as the skilled workforce was diluted by unskilled workers. I am also certain that RR learned quite a bit from the other car companies practices so that, the whole process was a mutual effort to the benefit of all. Cheers

SM
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  #22  
Old 17th November 2018, 12:04
schwarze-man schwarze-man is offline
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Re: Bf 109 vs. Spitfire production costs

Another factor that would impinge upon aero engine build man hours (and overall cost) that might be important statistically, is the quality control of finished engines that requires endurance testing and subsequent strip/rebuild/examination before final test and issue. Rolls-Royce certainly did this with all new Merlin types and production plants for a certain amount of production. Alec Harvey-Bailey states that even after satisfactory production was established, a certain amount of engines were still given the full test strip-down proceedure. Obviously, the initial production engines would incur a considerable production effort penalty. Details of German production QC of aero engines are even more difficult to quantify. Daimler Benz certainly worked through many test engines in development work. When a new engine type went into production, it was initially produced in a 0 series that had a shorter overhaul life. I have no information about the strip testing of production engines but, I would expect it was done in a similar way to RR until late in the war, for instance, the latest DB605 I have seen with an 0 series designation is an Autumn '44 built DB605DM-0.
Overall, these sort of extra factors would make differences to the production cost that might or might not be included in quoted statistics. Cheers

SM
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  #23  
Old 17th November 2018, 16:16
Jukka Juutinen Jukka Juutinen is offline
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Re: Bf 109 vs. Spitfire production costs

1. Yes, my comments on Isby's book are based on Amazon's samples. The samples were sufficient to establish that the book's style is not to my liking (it is obviously intented for general readers who are not interested in a more technical approach, hence the book has those "human interest" stories). Second is that AFAIK Isby is not a technical expert by training (e.g. an aircraft designer well-versed in WW2 German industry practices).

2.SchwarzeMan: How about the C3 fuel with its PN of over 140? Plus B4 with MW50 gives quite a detonation resistant combination.

3. My original question remains unanswered, i.e. does someone remember Hopp's post and the accompanying document.
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  #24  
Old 17th November 2018, 17:25
schwarze-man schwarze-man is offline
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Re: Bf 109 vs. Spitfire production costs

Hi Jukka,
I don't really want to divert this thread too far but, yes C3 was available and had a range of PN that became somewhat ill defined judging by test reports late in the war. Overall, the engine manufacturers were forced to make many of their engines suitable for B4 because of its availability. However, ultimately many late DB605/603 did/could use combinations of B4 or C3, with or without MW/EW. Cheers

SM
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  #25  
Old 17th November 2018, 22:18
ArtieBob ArtieBob is offline
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Re: Bf 109 vs. Spitfire production costs

The term PN was not in wide use in WWII, having really only been defined at the engineering level (I believe by the Ethyl Corporation) around 1943. PN ratings are normally expressed as a ratio ( i.e. 100/130 or lean/rich ratings for supercharged engines) In most US manuals I have seen from the late WWII era, neither the term Octane or PN was used, but rather the term "rating" followed by the "100/130" ratio format. I do not believe the Luftwaffe had a directly comparable system for rating fuels. Some intelligence documents do discuss the the relative performance and ratings of german to allied fuels in the later stages of WW II. If the war had continued using high performance supercharged piston engines, the US had tested Triptane fuel with PN 100/165
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  #26  
Old 18th November 2018, 11:49
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Re: Bf 109 vs. Spitfire production costs

Terve Jukka
I don't have time to look if I have somewhere Hopp's docu but here is something else, IMHO better than the early 1940 figure because Supermarine Woolston was fairly small aeroplane factory which before Spitfire mostly produced flying boats. Castle Bromwich, which began produce Spit Mk IIs circa September 1940 was a mass production factory which is shown in man-power figures. One point to remember, Supermarine was more flexible plant and it produced e.g. Mk VIIIs and XIVs, which had retactable tailwheels and also smallish fuel tanks in the wings besides the fuselage tanks. So while CB spitted out IIs, Vs , IXs and XVI, Supermarine also produced a bit more complicated versions. So I'm not quite sure on the logic of Hop in that Supermarine could produce Mk VIII less than 13,000 hours in 1944 because it had used 13,000 hours for Mk Vc in 1942, entirely possible but not sure.

http://www.ww2aircraft.net/forum/avi...-20-print.html
Spitfire V ME109. I have found these links on the net.

07-03-2011 11:15 PM Hop
All figures from Sebastian Ritchie:
1942, Supermarine man hours for Spitfire Vc: 13,000
1941, Castle Bromwich man hours for Spitfire (V, presumably): 10,400
1944, Castle Bromwich man hours for a Spitfire: half the hours Supermarine required in 1944.

Given that man hours reduced throughout the war, Supermarine should have required a lot less than 13,000 man hours, and Castle Bromwich would therefore require less than 6,500...
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  #27  
Old 21st November 2018, 12:13
Kurfürst Kurfürst is offline
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Re: Bf 109 vs. Spitfire production costs

1. During preparing the licence production agreementin Győr, Hungary, Generalluftzeugmeister has sent a 18 page letter titled Bf 109 in Lizenz für Ungarischen Waggonwerke Győr, detailing the very intricate details (labour, factory space, raw materials need) for series licence production of 109F, production assumed at a rate of 10 aircraft per month. The figures have been produced by László WINKLER some ten years ago in the automn 1997 Haditechnika magazine.

109F
Proto series: 18 000 hours
From 100. aircraft. 7 200 work hours
From 200. aircraft: 6 000 work hours

2. To quote George's earlier post in this board from the thread 'Compare of Bf 109 and Fw 190 cost of production':

According to an Mtt report of 11.5.44, the manhour cost in hours, "Femi-Kosten in Stunden" is how they state it, for the 109G is as follows: For 50 a/c produced per month - 460,000 hours (9200 hrs/per); for 200 a/c per month - 1,300,000 hours (6500 hrs/per); and for 500 a/c per month - 1,900,000 hours (3800 hrs/per). I did the division to get the time used per a/c, so you might check it. The production was broken down into four assemblies: fuselage, control surfaces, wings, power plant; with times for each assembly.

This report was to breakdown the assembly time for the various components of the Me 262, so gives only the above breakdown for the 109.


3.
From another source showing actual production hours needed for large scale series production in Germany, by 1944 construction time went down from IIRC 9000 hours for the 109E to 6000 hours per airframe on the 109F, and to something like 2300 hours per 109G airframe by 1944. Cannot find the comparison but iirc it compared the learning curves and decreasing man hour costs for the 109, 190, 88 across the war. I will try to find it amongst my files and post it..
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Last edited by Kurfürst; 21st November 2018 at 13:06.
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  #28  
Old 21st November 2018, 16:30
Jukka Juutinen Jukka Juutinen is offline
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Re: Bf 109 vs. Spitfire production costs

Schwarzeman, do you have valve overlap info for the DB 605A/D?
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  #29  
Old 21st November 2018, 16:49
Kutscha Kutscha is offline
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Re: Bf 109 vs. Spitfire production costs

The workmanship, or the lack there of, of late war 109s reflected the decrease in assembly times.

Late war C3 had gumming problems if the fuel sat too long. Did Allied 150 fuel have this problem?
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  #30  
Old 21st November 2018, 17:35
schwarze-man schwarze-man is offline
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Re: Bf 109 vs. Spitfire production costs

Quote:
Originally Posted by Jukka Juutinen View Post
Schwarzeman, do you have valve overlap info for the DB 605A/D?
Hi Jukka,
Well, we have the data for the DB605A but, only some of the DB605DB/DC detail in genuine document. As you will know, the Nockenwelle is different between the DB605A and the D series engines with the forward scavenge pumps. However, here is some of the valve timing for the DB605A: Overlap 106*, Inlet Duration 306*, Cam timing, Exhaust opening 67*BBDC. All timings are taken at roller/cam contact with correct valve clearance set. The DB605DB/DC has the same cam timing setting but, no other details genuinely known. Cheers

SM
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