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I frequently see anecdotes saying that P-51 pilots could tell a Rolls Engine from a Packard, how many P-51s were fitted with Rolls Royce engines?
At the factory they may have been pre matched and sent out in sets, to the assembly area/s.
I do not have the manufacturing tolerances. Like at what point a piston is judged to heavy or too light to try and put into a set.
However you still have the complete rod assembly weight requirement.
The system you are suggesting would suit the narrative of RR having lovingly handcrafted the engines. But I suspect was not the methodology that would have been applied. I am by no means a production specialist but I do know the value of a process to reduce a man-hours to product ratio. Having many workers with many scales sorting hundreds of pistons is a very haphazard way to manage things imo. One or two workers with one scale, sorting the pistons by weight and dimensions as they become available and inventorying, labelling and creating matched sets to be sent downstream would be an appealing approach in a mass production environment.If all pistons were matched for weight by the worker how were they matched. Your going to need hundreds of pistons to choose from and a very accurate set of scales for each worker. To assemble one engine how many pistons do you have to go through to find 12 that match and how lucky would you need to be for the first 12 you picked up to match. Instead of the hundreds of Merlins per day that British factories churned out the RAF would be lucky if they got one a day.
The system you are suggesting would suit the narrative of RR having lovingly handcrafted the engines. But I suspect was not the methodology that would have been applied.
I wasnt suggesting this was how it was or should have been done I was replying to the myth that Rolls Royce workers would hand pick and measure parts before assembly
I have read that article before and agree that it is better than mostHere's a pretty balanced, albeit not especially detailed, study of whether Packard Merlins were any better than RR units (or vice versa). It includes a number of observations already made in this thread, notably that RR in the UK produced more Merlins than anyone else, and that it is inconceivable for such a number to be achieved using only skilled tradesmen. RR had effective production lines that largely used unskilled or semi-skilled workers to churn out engines by the thousand.
Rolls-Royce Vs. Packard: Wh
Here's a pretty balanced, albeit not especially detailed, study of whether Packard Merlins were any better than RR units (or vice versa). It includes a number of observations already made in this thread, notably that RR in the UK produced more Merlins than anyone else, and that it is inconceivable for such a number to be achieved using only skilled tradesmen. RR had effective production lines that largely used unskilled or semi-skilled workers to churn out engines by the thousand.
Rolls-Royce Vs. Packard: Who Built a Better Merlin?
Just to put a final nail in the nationalistic coffin, we owe an incalculable debt to the countless workers, on both sides of the Atlantic and elsewhere, who provided the tools so that Allied military forces could get the job done. Yes, America was the Arsenal of Democracy but it was very much a team effort, with bright ideas emerging on both sides of the Atlantic, to the benefit of the entire world.
o Built a Better Merlin?
Just to put a final nail in the nationalistic coffin, we owe an incalculable debt to the countless workers, on both sides of the Atlantic and elsewhere, who provided the tools so that Allied military forces could get the job done. Yes, America was the Arsenal of Democracy but it was very much a team effort, with bright ideas emerging on both sides of the Atlantic, to the benefit of the entire world.
I have read this article in the past. The author makes some good points, but I have to disagree with his characterization of Packard "operating at a scale that dwarfed Rolls Royce.". As I have noted in the past Packard had far more in common with Rolls Royce than with Ford or Chevrolet. In fact, it was a bit of a mutual admiration society. A Packard ad from 1934 opens with "Only Packard and Rolls Royce" and goes on to describe how both companies manufacture super silent gears.Here's a pretty balanced, albeit not especially detailed, study of whether Packard Merlins were any better than RR units (or vice versa). It includes a number of observations already made in this thread, notably that RR in the UK produced more Merlins than anyone else, and that it is inconceivable for such a number to be achieved using only skilled tradesmen. RR had effective production lines that largely used unskilled or semi-skilled workers to churn out engines by the thousand.
Rolls-Royce Vs. Packard: Who Built a Better Merlin?
Just to put a final nail in the nationalistic coffin, we owe an incalculable debt to the countless workers, on both sides of the Atlantic and elsewhere, who provided the tools so that Allied military forces could get the job done. Yes, America was the Arsenal of Democracy but it was very much a team effort, with bright ideas emerging on both sides of the Atlantic, to the benefit of the entire world.
It sort of illustrates the point. The Whitley started with Tiger engines and was changed pre war with some Merlin engined planes in service. The Halifax had already been changed and the prototype flew in Oct 39, the Manchester/Lancaster would follow. Before the extra RR factories were producing it was obvious that they werent enough.I would add the Whitley to the list of specified engine pre war. The Armstrong Siddeley Tiger engined production was over quite quickly as soon as the Merlin X was available
D Deleted member 68059 - a member on the another forum posted this:
According to Volume 1 of 'the magic of the name' states the following regarding the two-piece block used on Packard engines, 'their early engines, Merlin 28's were similar to the Merlin XX, but had a two-piece block designed in the USA.
(my bold)
I've read in your book that 2-piece blocks were slated for Merlin 60 production at 1st; care to add something that might clear the picture about who designed the 2-piece block for Merlin?
FWIW, the book 'The Merlin in perspective' also notes that there were both American- and British-type of the 2-piece blocks.
.......I believe the Packard initially used a different solution to connecting the water passages in the block and head, but this was later changed to the Rolls-Royce design.
D Deleted member 68059 - a member on the another forum posted this:
According to Volume 1 of 'the magic of the name' states the following regarding the two-piece block used on Packard engines, 'their early engines, Merlin 28's were similar to the Merlin XX, but had a two-piece block designed in the USA.
(my bold)
I've read in your book that 2-piece blocks were slated for Merlin 60 production at 1st; care to add something that might clear the picture about who designed the 2-piece block for Merlin?
FWIW, the book 'The Merlin in perspective' also notes that there were both American- and British-type of the 2-piece blocks.
I just read in a book on the Lancaster that the Ford shadow factory in UK required a special machine made in Switzerland to achieve the tolerances they wanted, it could machine to 1 millionth of an inch. They eventually imported it via USA, it took three attempts, the first two are somewhere at the bottom of the Atlantic.This all gets down to the core assertion that RR tolerances were crap until the US automotive industry fixed the problem. It's absolute nonsense. You can't hand-pick components in a construction line and still maintain throughput.
The criteria for a sub-assembly would be a QC check but you don't check every sub-assembly on a production line, you check a percentage. To achieve a 1oz margin for the entire assembly of crankshaft, pistons and con rods, then it suggests upstream processes would output components such that any 12 pistons and con rods, when connected to the crankshaft, could be expected to fall within limits with a very high degree of repeatability. The alternatives are a slowed production line and either wasted production or go back to highly-skilled individuals to fettle out-of-spec sub-assemblies back into spec. The problem with the latter option is that it doesn't help detect upstream problems that caused the out of tolerance issue in the first place...so you're back to your upstream tolerances.
I'm afraid this whole issue of RR not having robust production line processes for Merlins prior to US automotive companies getting involved is absolute nonsense and the more it gets repeated, the angrier it makes me. It smacks of nationalistic willy-waving rather than actual technical study and reasoned analysis. Not one of the "hand crafted by elves" stories has EVER come up with a document that shows how poor RR specs were compared to the U.S. automotive industry, indeed most are of the "I knew a guy once who worked [insert location here] who always said that...." That's not proof or evidence, it's hearsay or folklore.