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Old 08-10-2017, 10:04 PM   #21
dairwin
 
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Actually Henry Ford refused to make the engines in the US (although a Ford plant in the UK did so). Whether it was Packard or RR that initiated the deal I hadn't discovered, but in any case Packard had to redraw all the plans. That took a year.
There are differing reports on this; however RR did set up a US based subsidiary to source components and machine tools before 1939. This subsidiary did have discussions with Packard before the war, and before discussions with Ford-USA.

It seemed to be an evolving story with Packard initially trying to drive a stiff deal, but with war under way and the need for more Merlins, by the spring 1940 the UK government approached the US government directly to source a US manufacturer. Ford-USA was then approached with Henry Ford refusing to comply, so Packard was then approached through the US government and the deal was secured.

Ford-UK was also approached. Both Packard and Ford-UK had to redraw the RR provided drawings into US projection (RR use first-angle projection, and the US use third-angle). The Packard redraw was completed in late November 1940, with the fist prototype Packard engine running in July 1941 and the first production engine in October 1941.

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Old 08-10-2017, 11:19 PM   #22
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What I read is that the drawings were redone for reasons of tolerances. One wouldn't think a redraw was needed for first vs. third angle projection alone.


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Old 08-11-2017, 06:55 AM   #23
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What I read is that the drawings were redone for reasons of tolerances. One wouldn't think a redraw was needed for first vs. third angle projection alone.
In a way, I would agree but not for the reasons given.

Whilst Spitfires were all of 5000 then, they were expendable and so were the little fellows that had come out of University Air Squadrons and supported by a tiny handful of fine US volunteers, the lads from the Commonwealth and Eastern European stalwarts that had seen it all before.
That was 1940 and by 1945, only a handful- and I mean handful would be left and all the Merlins lovingly constructed by RR personnel would have been scrap or perhaps lying in the English Channel. War dictated different standards- both pilots and machines might only last a scant single fill of 100 octane. In my spot of the firmament, it was 1949 and I stood as very young RAF corporal watching the first Avro Shackleton take off on three Griffons and then maintain height on one. Shackleton was designed as a wartime aircraft designed to last 168 hours and by then was expected to have gone- one way or another. In a few scant months, I too, would either be dead or trying to keep whoever it was whilst somebody piled our wounded into an aging Anson 12. Where I would be at the end of things was not important- I would probably get out with the Commandos but who cared?

In war or whatever my little lot would be, I was a 6 week wonder-- and there were more important things to consider.

To win a war, preconceived notions of Rolls Royce quality had to be swept away. Britain and later the US needed men and machines which would work on the day. Tolerances had to be relaxed. Henry Kaiser was making things called Liberty ships that were under engined, had welds which would crack but provided that they could be loaded up in Halifax NS harbour and get to Liverpool without being 'tin fished' , the ends justified the means.

If a Packard Merlin was not quite what one would expect- on the Good Old Days-so what? If it took its share of 12000 lbs of bombs to the target, another Goldstar- Arthur Harris was doing what Churchill expected him to do.

My view, gentlemen, and rather nearer to cold reality.

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Old 08-13-2017, 03:17 PM   #24
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Hi Norm,

I agree with much of what you have said. Your view of the expectations of war at that time strike resonance with the reality learned from two RAF pilots I knew who were on ops from 1942.

Regarding tolerance; it is a fact that Packard (and Ford) defined tolerances in more detail than RR, and machined to tighter tolerance as well. There is a well know anecdote that Packard had questioned machining tolerances with RR, which they assumed meant the RR tolerances were too tight; Packard replied that even their cars were made with smaller tolerance.

By 1939, the Merlin was being manufactured at Derby in relatively small numbers in a pre-war environment, with production rates of 30 per month. They were hand built, machined, assembled and fettled to make good. Within two years, there was no time for the expert machinist; we needed mass production by lesser skilled personnel, on a far larger basis.

Packard's initial frustrations (beyond the drawing details) included their observation that webs, castings and thicknesses varied between engine sections. Subassembly drawings were not RR normal practice, neither were parts lists. Thicknesses of sections varied without documentation as RR engineers had changed these areas based on results of engines on operations.

I understand that sample engines sent to Packard were dismantled and sections cut through castings to determine thickness variations which were then documented.

Tighter tolerances resulted in more inter-compatibility of engine parts swapping during maintenance. Packard parts could be used on RR engines are well, which could not have happened without Packards mass production approach to tolerance control.

However, RR did adopt the practice of defining tolerances and I have several RR manuals for my engines that provide this detail.

Productions rates for Packard were over 1,200 engines per month by late 1943, all with tight tolerances!

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Old 08-17-2017, 06:37 AM   #25
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So the Battle of Britain Memorial Flight's Spits, Hurri's and Lanc have been grounded.

Engine problems but no further details

Nil Illigitimi Carborundum

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Old 08-17-2017, 07:47 AM   #26
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So the Battle of Britain Memorial Flight's Spits, Hurri's and Lanc have been grounded.

Engine problems but no further details

Nil Illigitimi Carborundum

Norm
Ha! I hope grinding is not the problem. Will be interesting to learn what it is though.

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