JWL115C wrote:
Not an expert on aircraft engines, but know a little about the Packard-build RR Merlin. Many of you probably know all about this, but just in case. The British Production Commission first approached Henry Ford to build the RR Merlin here as they could not satisfy demands. Ford turned down the invitation because it was considered too complicated for them to build in mass production. Packard was then approached and accepted the invitation. Packard had a long history designing and building aircraft engines (e.g., the Liberty engine from WW-I). Packard built a huge production complex at their plant in Detroit, Mich. in record time (something like 6-weeks) to manufacture the Merlins. One of the stipulations the British put on Packard was that the US engines must be able to be changed in the field without any modifications needing to be made. All the mounting and connections had to match the ones built by Rolls Royce. One of the many problems Packard had to deal with was constructing the engines using Whitworth fasteners. They spent considerable effort getting the machines made to make the fasteners. Whitworth fastener tools are sized not by the bolt head dimension, but by the shaft size. A one-half inch Whitworth was for a bolt one-half inch in diameter. A US wrench to fit a one-half inch bolt was usually three-quarters of an inch. Packard made many improvements to the engine in order to do precision mass production. Packard built over 55,000 RR Merlin engines. Later in the war Ford of England, and Continental also made Merlins. A four engine Lancaster bomber could have been powered by engines from four different manufactures (Rolls Royce, Packard, Ford of England, and Continental). I don't know if this ever happened, but it was possible. A good book on this subject is: Allied Aircraft Engines of World War II by Graham White. Great site, thanks for the opportunity to post.
(o{I}o)
I have read that Henry really didn't believe that the British could prevail and that influenced his decision on Merlin production. IIRC he was inclined toward being neutral. World events forced a different response and the Ford organization contributed greatly to the Arsenal of Democracy.
With the resources available to a company like Ford its hard to imagine that any production hurdle couldn't have been overcome.
I believe much or at least some of the production machinery that was used to make the Merlin parts, as well as everything else for their war effort, came from America.
If production of parts and even complete engines needed to be outsourced it would also stand that the production machinery needed to make the parts would have been in short supply.
One example of the machinery is a photo I have seen of mounting holes being drilled in a valve cover. It has maybe 50 - 60 holes or so. The machine had many drill bits precisely positioned so that all the holes would be drilled in unison. So all the drill bits spin and move up and down together and these holes will match up to the studs on the head. All machining was done in this fashion. This equipment wasn't only used in making Merlins but was an adaption of technology used on all engines, transmission and the like.
The difficulty with building parts for the Merlin more had to do with creating the tooling for the threads in the hardware and parts. It was difficult but not that difficult as we were called on to provide tooling and machines for the British production even prior to Pearl Harbor.
Ford also sued after the war to recover costs of the buildings and equipment destroyed in France.
There was an effort to build Merlins in France at the beginning of the war. There was problems with building the parts in part to some believing that any advanced tools and machines would be lost. They did produce some engines but from parts provided from the UK.
I'll have to find the book but it is an autobio on the people involved in Merlin development and production.
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