Packard/R-R Merlin Propshaft Question

[JDK]

So to recapitulate.... IF Packard Merlins were used in RAF ships they were essentially building US and UK application powerplants thus the following statement is untrue?

I think the answer to your question is very simple. Packard built engines under license from Rolls for the US airplanes while Rolls built engine's for the British airplanes.

Yes, that statement's not correct, although it's driving in the right direction. [EDIT] Packard Merlins were built in the US and used primarily in US aircraft, but the superb production achievement meant that Packard engines were also available for non-US aircraft as well. I may be off beam, but: Rolls Royce built Merlins used in British and Commonwealth operated aircraft. Packard built Merlins were used in US aircraft, and certain models of Commonwealth and British built aircraft - such as Canadian Lancasters and Hurricanes (IIRC) some Avro (UK) built Lancasters, and most famously, the Mk.XVI Spitfire, which is a Mk.IX with a Packard Merlin. Correction welcome.

I'd also add to Bill's post that the problems with the early Packard Merlins wasn't Packard's fault, so much as cultural and production differences. Simplistically, Rolls Royce made 'handbuilt' Merlins which were not suitable for American, or arguably, 'full/proper' mass-production. Changes had to be made to allow for that, which Packard did.

To say RR handbuilt the Merlins is obviously simplistic - better to say, perhaps, that RR expected their staff to be skilled in using the machines, while Packard expected production-line operators to just do as instructed. Interestingly, LTC Rolt, one of the great writers on early engineering, walked away from working at RR's wartime factory because he saw Rolls' production line methodology in wartime as soulless; again coming from an innovation in engineering background, he saw the mechanisation as having gone too far, where I'd bet Henry Ford (for instance) would see a cottage industry style set-up.

RR Merlin history is well documented; see the Rolls Royce Heritage Trust's books.

Regards,

Last edited by JDK on Mon Jul 23, 2007 11:20 pm, edited 1 time in total.

[SparrowV12]

I have read and re-read alot of this and I don't really understand what you are after Wheels Up?!?!? As an example, a Merlin 266 (British) is pretty much an identicle engine to a Packard built -7. The 266has differant types of connections for coolant & oil as it uses the Avimo's instead of the push on style fitting used on American (Packard) engines. The Merlin 266 also has the Rotol style of prop shaft. Aside from those minute but noticeable changes the engines are the same. The Lancaster used the 224 or 225 which was built buy Packard, but the Rolls where Mark 24 or 25, however they are still basically the same engine. The basic Merlin engine is built on the same "base" so to speak just about no matter what Mark or Dash number. There are differances in the oiling systems, heads and banks etc., etc., etc. There are numerous, and I do mean numerous, volumes of mods and updates that effect just about every type of Merlin engine ever made. So, is that clear as mud?

[JDK]

As an example, a Merlin 266 (British) is pretty much an identicle engine to a Packard built -7. The 266has differant types of connections for coolant & oil as it uses the Avimo's instead of the push on style fitting used on American (Packard) engines. The Merlin 266 also has the Rotol style of prop shaft. Aside from those minute but noticeable changes the engines are the same. The Lancaster used the 224 or 225 which was built buy Packard, but the Rolls where Mark 24 or 25, however they are still basically the same engine.

Sparrow, I've edited my post above for clarity, HTH. As you rightly point out, many Packard and RR Merlins were exact equivalents; so, for technical purposes, could (I believe) be swapped engine-for-engine in an aircraft. But of course Packard Merlins were Packard built, as RR were RR built, so they are 'different' in origin, paperwork, and designation, even if 'equivalent'.

It's certainly easy to muddy this complex story.

[Wheels up]

I have read and re-read alot of this and I don't really understand what you are after Wheels Up?!?!?

As I stated in my very first post....

This poses a real interesting logistics problem.....

To which ...

In what manner does it pose a logistics problem? Could you explain what you mean?

Logistics according to Webster's:
The military science of the methods of procuring, distributing, maintaining, and replacing materiel and personel

An entirely boring subject to which many simply say "Who cares?". I find it interesting, to look at the effort and organization required to accomplish such feats. Efforts which go unheralded and unlauded. I have a pretty good grasp on manufacturing, in particular machining processes, and for one can appreciate what engineering, tooling, gaging and proceedures are involved with manufacturing a intensely critical item as a propeller spline. Something most observers haven't even a grasp on the dimensional difficulties to produce said item. If they do, then they are tainted by not realizing what '40's manufacturing technology was like. This was all slide rules. The machines to hob out a spline were all mechanical iron to iron....no linear ways, no Turcite, no ball screws, no servo drives, no CNC controls, no indexable carbide tooling, they didn't even have digital read outs.....all gears, leadscrews, dials, indicators, and likely high speed steel cutting tools. So when Packard was faced with the proposition to produce a complicated (I think it is pretty well accepted that Rolls had a way with incorporating alot of parts) item as a Rolls Royce engine after being out of aero engines for some 6 plus years, it must have seemed insurmountable. Producing possibly 2 or 4 "dash" numbers should be do-able. But then run that up to say 20 or 30? Yes, as you stated SparrowV12, the case, crank, bearings, rods, studs, cams, springs, etc were the same. But how do you "batch" these going down the assembly line? They were licensed to build these "en masse"...not one at a time. It would take a manufacturer full concentration to handle this to the quality levels that aerial powerplants demand. Now compound your production line by adding in a different prop spline. I am guessing here but if I were in 1943 asked to produce a "non standard" prop spline, I would knock a hole in the wall, get some masons out there build an entire new room, get to Barber Colman (or whoever makes a spline hobber or miller) to see when I can get a new machine, wire (no internet or faxes, barely a telephone) Greenfield to set us up all the gaging, get ahold of Cleveland Twist Drill and have a meeting to set up the tooling, new stock racks, a duplicate set of handling carts as we wouldn't want to mix these up, etc. All dedicated tooling...it has but one use. Flexible machining was infant in the 40's. It is nearly endless. Nothing that many manufacturers faced which again makes it more challenging....everybody else wants those same exact tools or at least the production slots it takes to make them. All this, and much more, is the manufacturers's logistics. As mentioned earlier, this material makes for boring study and hardly engrossing reading to most audiences which explains why the vast amount of writtten material rarely cover these subjects. You don't make bestsellers and peddle magazines talking about milling machines!
This is what I was "after".... to get an appreciation of the accomplishments and effort that this undertaking required. No more, no less. I shall press the matter no further here.
As a parting thought: license in regard to manufacturing is thought to mean you are allowed to produce and sell the licensed item. Does it not seem strangely ironic then that Packard was building a product licensed to them by the British and they then sold it back to the licenser! That's nothing more than contracting. How did that affect the license agreement? Strange.

Last edited by Wheels up on Tue Jul 24, 2007 11:53 am, edited 1 time in total.

[bdk]

Does it not seem strangely ironic then that Packard was building a product licensed to them by the British and they then sold it back to the licenser! That's nothing more than contracting. How did that affect the license agreement? Strange.

Rolls Royce was a private company, no? They licensed Packard to build Merlins for the US, perhaps Rolls procured the Packards and sold them to the UK to fulfill their own contract? Or maybe that was just written into the license.

I doubt that Rolls made 30 variants of the Merlin at one time. There was a progression as improvements were made. Rolls may have cut the gears for their engines, but I doubt they did the forgings and castings themselves. Those were likely contracted out to their supply chain.

Regarding support of the engines in the field, they either replaced the entire engine or just replaced components like starters, water pumps, generators, etc. Not sure whether they replaced heads and banks in the field or not. If so, the interface would be between the case and the bank and the piston to connecting rod. The remainder of the engine could be made to completely different speciafications as long as those interface locations were the same. The engine overhaul depots would be where all the major parts were spared. Not sure how it worked, but Packard may even have set up and supplied an overhaul depot in the UK for the the Packard built engines. In any case, Packard's output was probably high enough towards the end of the war that it was more an issue of economy than one of supply.

I belive that numeric control was used (at least in US factories) with paper punch tapes. The numeric control speeds things up but you still need good tooling and fixturing regardless.

This is all just speculation on my part. You might want to read Graham White's book on Allied piston engines. I read it about ten years ago but my retention isn't so good any more...