Packard vs. Rolls-Royce

Well done, that man. Settles it then.

The point about thread types on studs and fixings is a good one. There is no mention in the summary of all Rolls Merlin/Griffon engines in their ‘Aero Service Bulletin’ of 1950. Anybody have the definitive answer to this one?

It is hard to imagine the Americans building Merlins for Mustangs with BA, BSF & BSW threads.

Mark

Just found a reference to the threads. All Merlins and V1650s were produced with BA, BSF, BSW threads. Packard could not source its fasteners in the US so it decided to produce its own high quality fasteners. Source Graham White

Detroit Diesels

Mark 12
Those darned Detroits, they remind me of a Perkins.
Mike

I don’t suppose there was much need for Rover to change anything. The factory was handed over to them as a going concern, already in full production AFAIK. Their’s would be more of a management role than anything else..

I would be pretty sure that many parts from the Merlin would interchange with the Meteor engine as fitted to the Centurion tank.

I think the Aviation Jersey core business was the reconditioning of said engines for Centurion export customers around the world.

Using Meteor parts in an airworthy Merlin is a different matter. They might well interchange but are unlikely to have been manufactured to the same stringent processes, fine limits and quality control the the civil and military authorities would require in recent years.

Mark

As far as design authority goes, I can’t believe RR would ever have relinquished it. There was huge reluctance within RR to let any other organisation build their engines, in fact for a long time, point-blank refusal.

best inline rather than radial perhaps. I think, as ever, there is some who’d dispute the Merlin being best ever. Damn good though!

My point was that it was arguably the best ever because of that succesful adaption between air/land/sea. I don’t believe that could be said of many other inline aero engines (Allison maybe?) and certainley not radials, although, obviously, a Continental radial was used to power the Stuart light tank variants as well as many Shermans.

I don’t suppose there was much need for Rover to change anything. The factory was handed over to them as a going concern, already in full production AFAIK. Their’s would be more of a management role than anything else.

As Mark12 said, it does seem difficult to believe Packard would use BA, BSF and BSW threads. In similar vein, the DH Gipsy range of engines used metric threads and they were re-drawn for Australian production.

Greatest piston engine ever? Possibly military but I believe it took a lot of work to get it reliable enough for civil use.

arguably the greatest piston engine ever.

best inline rather than radial perhaps. I think, as ever, there is some who’d dispute the Merlin being best ever. Damn good though!

Design authority always stayed with RR. Packard was a licence producer, and developed a close relationship with RR, hence the success of the venture.

Did RR retain design authority over the other applications of the Merlin for land use in tanks and marine use in the MTB and similar class of boat?

What other companies had the license for Merlin production in these applications (Rover presumably with the Meteor tank engines…?) and how many more ‘Merlins’ for tanks and boats were made in addition to the aircraft ones.
The Merlin’s successful adaptation into these land and marine environments is further evidence of just what a good design it was, arguably the greatest piston engine ever. 🙂

So, when did Merlin engine production finally cease?

It is hard to imagine the Americans building Merlins for Mustangs with BA, BSF & BSW threads.

Mark

Hence the supplied tool kits? Just a thought.

Interchangeability

There is clearly an enormous amount of interchangeability on UK/US, Rolls/Packard, Merlin engines. If not as individual parts, certainly as sub-assemblies. Equally there are many parts that will not interchange on the diverse range of developed UK built Rolls and Ford engines.

For over thirty five years US Warbird engine builders have long sought and sourced parts from Europe, Aviation Jersey being a prime example.

US built Merlins for US aircraft were specified with the US (SAE?) spline on the output shaft whilst US built Merlins for British aircraft were specified with the standard British spline.

The point about thread types on studs and fixings is a good one. There is no mention in the summary of all Rolls Merlin/Griffon engines in their ‘Aero Service Bulletin’ of 1950. Anybody have the definitive answer to this one?

It is hard to imagine the Americans building Merlins for Mustangs with BA, BSF & BSW threads.

Mark

I’ve always understood the Packard Merlins were re-drawn for American threads. This could cause problems with interchangeability on certain parts. However, I can’t find any references to it so it may have just been an assumption on my part.
I used to know an-ex RAF engine fitter who worked on both so he may have told me. He was also the only person I’ve ever known complain about the Packard Merlin – but he liked moaning so I never took much notice of that.

Packard Merlin’s used British threads. Popular misconception has it that Packard completely redesigned the engine. This is not true. They redrew the blueprints, as did Ford in Manchester. Apart from the interim 2 piece head on the 28 and the supercharger drive on the two stage engines they were mechanically similar. Design authority always stayed with RR. Packard was a licence producer, and developed a close relationship with RR, hence the success of the venture.

I’ve always understood the Packard Merlins were re-drawn for American threads. This could cause problems with interchangeability on certain parts. However, I can’t find any references to it so it may have just been an assumption on my part.
I used to know an-ex RAF engine fitter who worked on both so he may have told me. He was also the only person I’ve ever known complain about the Packard Merlin – but he liked moaning so I never took much notice of that.

Guys – I’m finding this a really interesting thread – and also continue to be amazed at the sheer volume of knowledge available on this forum.

I note various comments in posts above that suggest interchangeabilty, but this may only be in one-off non-operational circumstances (eg: post war racing).

So I’m left with a question – to what degree were engines and/or parts exchangable between the different manufacturers at operational level? I’ve heard of Lancs being fitted with mixtures of the two engines (3 of one, 1 of the other, etc.) – can anyone confirm that? But I also wonder whether you could swap parts between the engines, external parts like manifolds etc., and perhaps even internals?

many thanks, Gnome

In theory it was entirely possible to mix parts between Packard and RR engines. In practice A Lanc squadron would be all BI’s or BIII’s and a Spit squadron IX’s or XVI’s so it is difficult to say how much if any interchangability went on.

As I mentioned above the two manufacturers used differently sourced Ignition systems and carburettors. This would have caused some issues in cross fitting the engines in the field. On Packard Merlins for US aircraft such as the P40 (V1650-1) or P51 (V1650-3) the propeller shaft was different and in the case of the Mustang engines the reduction gear ration was different to the Spitfire, not withstanding that the Core of say a V1650 – 3 was the equivalent of a Merlin 61. V1650 engines had different accessory drives to suit the aircraft requirements and it would not have been practical for these engines to interchangeable.

The 100 series V1650 – 9 for the Mustang that is used in the racing Merlins were nearly all Post war engines.

I’m sure the BBMF Lanc has 3 of one Merlin type, and one of another, but I could be wrong…

Guys – I’m finding this a really interesting thread – and also continue to be amazed at the sheer volume of knowledge available on this forum.

I note various comments in posts above that suggest interchangeabilty, but this may only be in one-off non-operational circumstances (eg: post war racing).

Christer in post 7 says
“Roll-Royce maintained parts interchangability between different marks which necessitated the use of adapters. When Packard redesigned the engine, they adapted it for the use of american accessories and completely broke the interchangability.”
TempestNut says in post 11
“If you read any of the authoritative accounts of the RR Merlin it is obvious there were very few differences between a Packard Merlin and a RR Merlin.”
and
“The racing Merlin’s in the US are incredible engines. They use a Packard bottom end based on the 100 series Merlin, with 500 or 600 series Transport blocks and heads. They use Allison connecting rods from the Allison that powered the P82 …”
and again in post 26
“…companies such as Ford and Packard need to ensure that each part was identical, and completely interchangeable. This work benefited RR no end.”

So I’m left with a question – to what degree were engines and/or parts exchangable between the different manufacturers at operational level? I’ve heard of Lancs being fitted with mixtures of the two engines (3 of one, 1 of the other, etc.) – can anyone confirm that? But I also wonder whether you could swap parts between the engines, external parts like manifolds etc., and perhaps even internals?

many thanks, Gnome

When did Packard start manufacturing Merlins? Was it as a result of US aircraft requirements or were they used initially to suppliment UK demands?

Without looking it up I can’t say when but it was originally to supplement UK requirements, after Ford (U.S) had turned us down.

Detroit Diesel

Careful, Detriot Diesel’s are a religion for some over here. 🙂 I myself am the proud owner of 2 DD’s with over 1,000,000+ miles and 80 years between them. 😀

Whiskey Delta

No criticism of the engine, just the European application.

With fuel being three or four times more expensive in Europe compared to the US, the factor of greater fuel consumption of about, from memory, 1-1.5 mpg difference on 40 tonne trucks compared to equivalent European engines was a death blow to haulage operators running on tight margins. This at a time of major world oil crises.

Mark

…and did the General Motors ‘Detroit Diesel’ engine, so beloved of the cheap fuel US haulage industry, sink Bedford Trucks in the UK with its low MPG figure?

I think so. 🙁

Mark

Careful, Detriot Diesel’s are a religion for some over here. 🙂 I myself am the proud owner of 2 DD’s with over 1,000,000+ miles and 80 years between them. 😀

When did Packard start manufacturing Merlins? Was it as a result of US aircraft requirements or were they used initially to suppliment UK demands?

Tempestnut.

Well it was rhetorical question and of course Bedford sunk themselves…but under American management.

A good read is ‘On a clear day you can see General Motors’. Although thinly disguised it was surely by John DeLorean.

Mark
(formerly on the GM project management engineering team of the Bedford Military TM. Still giving sterling service in the Gulf, I presume,… and with a British engine.)

Mark point taken, and I’m not in anyway trying to defend anything here. I have had plenty of experience of “well it works in the mid west and it works in the Rockies so it should work here” However occasionally the company culture allows you to fight your corner and get things right. My father experience a good deal of “well it works in the Alps so it must be your drivers” from a nameless manufacturer not far from the Alps. They had to suffer the ignominy of eventually removing new parts from newly assembled vehicles and replacing them with durable American parts, before anyone would purchase them. Not a situation that sat well with them but very amusing to witness.

Getting back to aviation the story of Wright Aeronautical is one of the most appalling around, and it sometimes beggars belief that the R3350 actually managed to get into the air at all, and that B29’s ever made it to Japan. It makes the woes of the Sabre look like a stroll in the woods. And it was management greed that created the crisis not lack of engineering skill, because eventually they were forced to get it right and we know what a strong engine it became. Same can not be said of Wright.