59 replies to this topic

[Magoo]

You've seen the Detroit Packard plant in ruins. Now see it in its finest hour: Building Merlin aircraft engines to win World War II. This fantastic old newsreel film provides a rare glimpse - don't miss it.  

 

 

Video: The Packard Merlin Story | Mac's Motor City Garage.com

 

 

 

[mariner]

Magoo, your Detroit historical stuff is always brilliant - history come to life.

 

I also looked at teh "Packard drone vdeo" - stunning.

 

It led me to your link to Detroit drone tv and this one

 

 

you really should have posted that one yourself - its just SO cool

Edited by mariner, 15 December 2013 - 09:56.

[Canuck]

Was I the only one that caught the Bosch tooling?

[Magoo]

Magoo, your Detroit historical stuff is always brilliant - history come to life.

 

I also looked at teh "Packard drone vdeo" - stunning.

 

It led me to your link to Detroit drone tv and this one

 

 

you really should have posted that one yourself - its just SO cool

 

 

I've been on the fence on that one. Guess I should reconsider. 

[Lee Nicolle]

That is a very interesting clip. No wonder that factory was so huge. Something only a war could achieve sadly.

The nitriding tank with all those cranks in it. That was a very big squeeze!.

What would be interesting is a productivity report on how long it took at Rolls and Packard to build similar engines. And PLEASE no bias!

One would guess that both manufacturers had good and bad parts in the units.

Possibly biased reports prefer the Packard over the Rolls units.

Also something that was briefly touched on in that clip was threads and plans. Did as I have been told the Packards use NC and NF threads and Rolls use whitworth? Both work ok and both have good and bad points.

As for plans a friend used to redraw imported plans so Holden could build imported cars and parts here. But really why is that so. He never really explained it. Though it seems Europe, the US and the UK all draw plans differently. And probably different Asian countrys are different again. Especially now it is so silly.

And as a repairer and modifier of 50s to current cars you often wonder what they were thinking in the first place. I have had 'engineers' try to explain it but they sure do not convince many people like me with true practical 'engineering' experience. I know that many innovaters have taught the factory to do things better. Or wanted it done properly or better.Here in Oz, the US and greater Europe.

Edited by Lee Nicolle, 17 December 2013 - 09:51.

[Greg Locock]

When I was wet behind the ears and cocky I used to look at other people's designs and wonder what on Earth they were thinking. Now my hair has fallen out and I look at other people's designs and I wonder, what were they actually thinking about?

[GreenMachine]

IIRC, one difference was in gasket material.

 

That is, I remember reading about it ...

[Magoo]

That is a very interesting clip. No wonder that factory was so huge. Something only a war could achieve sadly.

The nitriding tank with all those cranks in it. That was a very big squeeze!.

What would be interesting is a productivity report on how long it took at Rolls and Packard to build similar engines. And PLEASE no bias!

One would guess that both manufacturers had good and bad parts in the units.

Possibly biased reports prefer the Packard over the Rolls units.

Also something that was briefly touched on in that clip was threads and plans. Did as I have been told the Packards use NC and NF threads and Rolls use whitworth? Both work ok and both have good and bad points.

 

 

 

You and me both. There is so much folklore about R-R vs. Packard Merlin it's nearly impossible to sort it out. One additional complication is the tremendous number of model and running production changes in general, so just who was responsible for what is hard to know. I am by no means a Merlin expert, this is just my take from middle distance. 

 

I don't know this but I have been told that Packard duplicated all the British thread forms exactly, at great trouble and expense. From their own experience with aircraft engines they were aware that very minor deviations from specifications could have unintended consequences, which could be disastrous on a short time line. 

[275 GTB-4]

An ex-RAAF Uncle who serviced P-51s informed me that during the Korean War and after that, Aussie CAC-built Mustangs and their Packard Engines were sought by others (Yanks in particular)...reason, they were the most powerful and reliable...my Uncle passed away so would need another RAAF type to confirm the story.

[HectorPascal]

You and me both. There is so much folklore about R-R vs. Packard Merlin it's nearly impossible to sort it out. One additional complication is the tremendous number of model and running production changes in general, so just who was responsible for what is hard to know. I am by no means a Merlin expert, this is just my take from middle distance. 

 

I don't know this but I have been told that Packard duplicated all the British thread forms exactly, at great trouble and expense. From their own experience with aircraft engines they were aware that very minor deviations from specifications could have unintended consequences, which could be disastrous on a short time line.

 

 

Thanks for posting this McGuire. I agree about the folklore aspect. There is no doubt that R-R were responsible for the design work, but that Packard introduced production engineering changes.

 

Packard re-drew the R-R drawings from 1st Angle (UK standard) to 3rd Angle (US standard) projection. I've often seen this interpreted as Packard "re-designing" the Merlin. I've often wondered about thread compatability, never seen anything definitive, but haven't been able to accept that Packard deviated from Whitworth. That would have made parts interchangeability impossible.

 

Wiki credits Packard with 55,000 Merlins built from a total of about 150,000. In the UK, 30,400 were built by Ford.

 

275 GTB-4

 

 

An ex-RAAF Uncle who serviced P-51s informed me that during the Korean War and after that, Aussie CAC-built Mustangs and their Packard Engines were sought by others (Yanks in particular)...reason, they were the most powerful and reliable...my Uncle passed away so would need another RAAF type to confirm the story.

 

 

As opposed to the US built Mustangs with imported UK built Merlins ?

[WPT]

Think Aussie built P-51s were kits (think about 500) delivered by the US. All Merlin engined Mustangs used Packards. It's interesting that Ford of Britain built Merlins. In 1940 the Brits wanted to open another production line for the Merlin in the US. They first asked Edsel Ford (Henry's son) if Ford would do it. Edsel thought this was a no brainer and agreed to do it. When Henry found out about it he nixed the deal (Henry did not like the Brits, it seems). That's when Packard came into the picture. It took Packard about a year for the first engines to come off the production line after the contract signing. Henry did agree to build aircraft engines during the war, but these were P&W R-2800's, also built in Detroit.  WPT

[Wuzak]

Think Aussie built P-51s were kits (think about 500) delivered by the US. All Merlin engined Mustangs used Packards. It's interesting that Ford of Britain built Merlins. In 1940 the Brits wanted to open another production line for the Merlin in the US. They first asked Edsel Ford (Henry's son) if Ford would do it. Edsel thought this was a no brainer and agreed to do it. When Henry found out about it he nixed the deal (Henry did not like the Brits, it seems). That's when Packard came into the picture. It took Packard about a year for the first engines to come off the production line after the contract signing. Henry did agree to build aircraft engines during the war, but these were P&W R-2800's, also built in Detroit.  WPT

When the British were chasing a deal the US was not at war. Henry Ford was willing to build Merlins - but only for US use. Which sort of defeated the whole purpose.

[Wuzak]

Thanks for posting this McGuire. I agree about the folklore aspect. There is no doubt that R-R were responsible for the design work, but that Packard introduced production engineering changes.
 
Packard re-drew the R-R drawings from 1st Angle (UK standard) to 3rd Angle (US standard) projection. I've often seen this interpreted as Packard "re-designing" the Merlin. I've often wondered about thread compatability, never seen anything definitive, but haven't been able to accept that Packard deviated from Whitworth. That would have made parts interchangeability impossible.
 
Wiki credits Packard with 55,000 Merlins built from a total of about 150,000. In the UK, 30,400 were built by Ford.

Packard did not introduce production engineering changes. These had, in fact, been carried out earlier - possibly by Ford UK or by Rolls-Royce themselves (apparently Ford said to RR they couldn't make them to the drawings supplied, RR asked if the tolerances were too tight - Ford replied that they were too loose).

Packard introduced the two piece block (ie separate head) into production. Initially they used a sealing method of their own, but soon went to the RR method. Some see this as meaning that Packard designed the 2 piece block. That is not the case - Rolls-Royce had designed the 2 piece block, but could not change over due to production requirements. They changed over when the 60-series began production.

As opposed to the US built Mustangs with imported UK built Merlins ?

The only ones of those were prototypes or the RR built Merlin X.

[Wuzak]

What would be interesting is a productivity report on how long it took at Rolls and Packard to build similar engines. And PLEASE no bias!

There is a possible excuse for UK factories - that there was a threat of being bombed.

Note that in the clip the narator repeats the myth that RR built engines were "hand built".

Possibly biased reports prefer the Packard over the Rolls units.

Ground crew supposedly prefered the Packard because they were supplied with a tool kit.

Also something that was briefly touched on in that clip was threads and plans. Did as I have been told the Packards use NC and NF threads and Rolls use whitworth? Both work ok and both have good and bad points.

Packards used BSW, BSF and BA threads - at least where interchangeability was required.

There were differences. Packards used US built carbies - I assume these used NC/NF threads. The two stage engines used an epicyclic gear train for the supercharger, rather than the Farman type used by RR. These may have had different threads.

Those built for US use had SAE splines on the prop shaft. Any retaining threads for them must have been US standard too.

[PJGD]

IIRC, one difference was in gasket material.

 

That is, I remember reading about it ...

 

In Setright's "The Power to Fly" [Page 137], he mentions that the UK Air Ministry refused to accept the use of gaskets in British built engines, but not in the US built Merlins.

 

PJGD

[HectorPascal]

Wuzak

Packard introduced the two piece block (ie separate head) into production.

 

 

Wiki:

Merlin C

Development of Merlin B; Crankcase and cylinder blocks became three separate castings with bolt-on cylinder heads.[6] First flight in Hawker Horsley 21 December 1935, 950 horsepower (708 kW) at 11,000-foot (3,400 m)

 

 

Take note of McGuires caution above:

There is so much folklore about R-R vs. Packard Merlin it's nearly impossible to sort it out.

 

[Magoo]

Folks seem to take a patriotic approach in the retelling of the story, so it does indeed take on the nature of folklore.

 

One story I recall (but not where I got it, note) is that in Rolls-Royce's original dealings with Ford, the Dearborn people were very keen on adapting their automotive manufacturing techniques to the Merlin, including stuff like reducing the fastener count and the famed Ford cast crankshaft. The R-R people said no thanks to that and eventually landed with Packard, where their techniques and manufacturing culture were more aligned.

Edited by Magoo, 19 December 2013 - 09:35.

[275 GTB-4]

Quote
An ex-RAAF Uncle who serviced P-51s informed me that during the Korean War and after that, Aussie CAC-built Mustangs and their Packard Engines were sought by others (Yanks in particular)...reason, they were the most powerful and reliable...my Uncle passed away so would need another RAAF type to confirm the story.

As opposed to the US built Mustangs with imported UK built Merlins ?

Yes! Prezactly! the Aussie maintainers tweaked the Packard's to a very high standard of output and reliability....this is a common thing AFAIK in Australia (in the past!)....US companies are often surprised at what a comprehensive, engineering and scientific lead program can produce against a company providing maintenance to their standard's

[Wuzak]

Wuzak
 
 
Wiki:

Merlin C

Development of Merlin B; Crankcase and cylinder blocks became three separate castings with bolt-on cylinder heads.[6] First flight in Hawker Horsley 21 December 1935, 950 horsepower (708 kW) at 11,000-foot (3,400 m)

 
Take note of McGuires caution above:

I do take note, and what I say is correct.

The original Merlin prototype and the Merlin B had a single piece upper crankcase and cylinder blocks with separate cylinder heads. Originally it was fitted with a flat type combustion chamber, like the Kestrel's, which was replaced by the Ramp Head during testing. The Ramp Head had been tested on single cylinder test engines previously and had showed good results. I believe there was also some related devlopment in their car engines.

I can't find a picture or diagram on the web at the moment, but you could picture the Ramp Head as being like a pent roof design, but tilted so that the intake valve is vertical.

Anyway, Rolls-Royce had difficulty with casting the crankcase/cylinder blocks as it was too large, resulting in porousity and coolant leaks. For the Merlin C the engine was redesigned with separate crankcase, blocks and heads.

It may not have been possible to assemble the Ramp Head if it were cast in one piece with the block.

Development proceeded through new versions up to the F, which passed the type test (reduced requirements) and was named the Merlin I. I suppose this is the first "production" Merlin - but only 172 were built.

The Merlin G was extensively redesigned, incorporating Kestrel type flat heads and a one piece cylinder block/head. The G became the Merlin II, the first true production Merlin - wih just shy of 1300 built. The Merlin II, and the related III, powered the Spitfires and Hurricanes in the BoB.

Some sealing issues persisted, however, and so the Merlin was redesigned to have separate cylinder block and heads. But there was a war on, and production took precedence. Packard, however, were just setting up production, and so were able to adopt the 2 piece designe from the start. I believe that differences between the Packard and Rolls-Royce two piece block engines at this stage was the method used for transferring coolant between the cylinder head and block cooling jackets.

http://upload.wikime.../MerlinHead.JPG

[Wuzak]

Note also that the Rolls-Royce Peregrine, and updated Kestrel, and the Rolls-Royce Vulture both used single piece cylinder block/heads with the flat combustion chamber, and both were under development at the same time as the Merlin - ie mid 1930s.

Would also like to point out that the Vulture was not 4 Kestrel/Peregrine cylinder blocks on one crankcase, though it shared its bore and strok with them. The bore spacing on the Vulture is wider than the Kestrel/Peregrine by nearly 0.5" - and is in fact 0.025" wider than the Merlin's.

The Griffon was designed from the start (1938/39), or at least very early on, with two piece cylinder block and heads.

[WPT]

In post 11# above I stated the CAC built 500 Mustangs. That is incorrect, they built 200. North American sent over 100 kits of which CAC assembled 80, using the leftover 20 for spares and training aids. How the other 120 came to be I do not know. Have read that RR used a copper/lead alloy for the Merlin main bearings. Packard used a Pontiac (GM) developed silver/lead combination with indium plating, which proved to be superior. The 357th FG discovered that British spark plugs were superior to American supplied spark plugs and developed a source for same. They changed them for every mission.  WPT

[Lee Nicolle]

I do take note, and what I say is correct.

The original Merlin prototype and the Merlin B had a single piece upper crankcase and cylinder blocks with separate cylinder heads. Originally it was fitted with a flat type combustion chamber, like the Kestrel's, which was replaced by the Ramp Head during testing. The Ramp Head had been tested on single cylinder test engines previously and had showed good results. I believe there was also some related devlopment in their car engines.

I can't find a picture or diagram on the web at the moment, but you could picture the Ramp Head as being like a pent roof design, but tilted so that the intake valve is vertical.

Anyway, Rolls-Royce had difficulty with casting the crankcase/cylinder blocks as it was too large, resulting in porousity and coolant leaks. For the Merlin C the engine was redesigned with separate crankcase, blocks and heads.

It may not have been possible to assemble the Ramp Head if it were cast in one piece with the block.

Development proceeded through new versions up to the F, which passed the type test (reduced requirements) and was named the Merlin I. I suppose this is the first "production" Merlin - but only 172 were built.

The Merlin G was extensively redesigned, incorporating Kestrel type flat heads and a one piece cylinder block/head. The G became the Merlin II, the first true production Merlin - wih just shy of 1300 built. The Merlin II, and the related III, powered the Spitfires and Hurricanes in the BoB.

Some sealing issues persisted, however, and so the Merlin was redesigned to have separate cylinder block and heads. But there was a war on, and production took precedence. Packard, however, were just setting up production, and so were able to adopt the 2 piece designe from the start. I believe that differences between the Packard and Rolls-Royce two piece block engines at this stage was the method used for transferring coolant between the cylinder head and block cooling jackets.

http://upload.wikime.../MerlinHead.JPG

The top end looks simple enough though I don't quite understand the rockers which seem to be half as wide as the cam lobe.
Obviously the Merlin was a collection of very different engines of the same basic mechanical design. Block and head is an entirely different design to bolt on cylinder heads. And it seems combustion chambers were very different too.
I presume the blocks bolted directly on the crankcase unlike some engines that use through bolts to clamp case block and heads together.
In theory a one piece block and head are better though very hard to handle and assemble. In practice though the easier to assemble bolt on heads is better. And easier to maintain too. Though you have to be very sure of your headgaskets though. I presume they would have been 5 or 6 bolts per cylinder to clamp the heads on? Unlike most passenger engines with just 4.
Looking again the cylinder liners are clamped in by the cylinder head. I guess that would make the cylinder pressure less of an issue though sealing the coolant may be a bigger issue as I suspect that design flexed a bit on such a large engine.

Edited by Lee Nicolle, 19 December 2013 - 22:11.

[Wuzak]

Obviously the Merlin was a collection of very different engines of the same basic mechanical design. Block and head is an entirely different design to bolt on cylinder heads. And it seems combustion chambers were very different too.

Apart from the early prototype Merlins and the few Merlin Is all had the same basic head design. The main difference was that some were two piece and some were one piece. But the combustion chamber was the same for them.

Obviously as the Merlin developed there were improved materials and designs, and many components were strengthened.

I presume the blocks bolted directly on the crankcase unlike some engines that use through bolts to clamp case block and heads together.

Yes, the Merlin had separate bolts to hold down the cylinder block and to hold the cylinder head to the block.

Looking again the cylinder liners are clamped in by the cylinder head. I guess that would make the cylinder pressure less of an issue though sealing the coolant may be a bigger issue as I suspect that design flexed a bit on such a large engine.

The solution used in teh Merlin was for a set of ferrules to be inserted between the head and the block. These were basically little pipes to transfer coolant across the head joint.

[Catalina Park]

In post 11# above I stated the CAC built 500 Mustangs. That is incorrect, they built 200. North American sent over 100 kits of which CAC assembled 80, using the leftover 20 for spares and training aids. How the other 120 came to be I do not know. 

The other 120 were the fully Australian manufactured ones. The original order was for 690 aircraft and the by the end of the war order was cut back to 300 and then reduced again to 200. 

108 Merlins were also assembled in Australia and were used in the locally made Avro Lincoln.

[Bloggsworth]

When the British were chasing a deal the US was not at war. Henry Ford was willing to build Merlins - but only for US use. Which sort of defeated the whole purpose.

 

Was Joseph Kennedy a shareholder...

[bigleagueslider]

While it's mostly true that the Packard-built Merlins had better quality than the Merlins built in the UK during the war, we should also consider the fact that the R-R factories in the UK had to deal with bombing raids and had less manpower and financial resources available than the Packard factories in the US. The factories in the US that produced Merlins had no choice in the matter.  Once the US entered the war, the US DoD decided which companies produced which products.

[Magoo]

Another unsubstantiated (at the moment) Merlin story:  If I recall it properly, Maurice Olley played a key role in organizing the production of Merlin engines in the USA. As a former R-R employee living in the States when the war came, he was very keen to get this done and General Motors granted him a leave of absence. I believe his role also included hand-carrying Merlin drawings from Britain to Detroit. 

 

Or at least that's how I recall reading the story in, I believe, Olley's memoirs as published by Bill Milliken. However, at the moment I can't seem to locate my copy between home and the office. Stay tuned. If anyone else has the book please take a peek. 

[mariner]

Tony Rudd was Rolls Royce trained just prior to WW2.His war time RR job was head of reliabilty analysis at Derby. He analysed all the in service failures.

 

it is quite a big bit of his great autobiography " It was Fun".

 

From memory the Merlin was not quite as reliable as the legend would have you beleive.

 

Post WW2 RR lost out on the commercial piston market because of a general civil airline dislike of water coolig according to him.

[GreenMachine]

From my reading, the expression 'triumph of development over design' could have been coined (was coined?) for the eradication of the problems exhibited by the early Merlins.  As I understand it, the production engines of WW2 era were as reliable as the legend suggests.  It's a bit like the 'overnight success', which follows lots of hard work, false starts etc.

 

The crux of the issue is that when they were needed, they were ready.

[Magoo]

Another unsubstantiated (at the moment) Merlin story:  If I recall it properly, Maurice Olley played a key role in organizing the production of Merlin engines in the USA. As a former R-R employee living in the States when the war came, he was very keen to get this done and General Motors granted him a leave of absence. I believe his role also included hand-carrying Merlin drawings from Britain to Detroit. 

 

Or at least that's how I recall reading the story in, I believe, Olley's memoirs as published by Bill Milliken. However, at the moment I can't seem to locate my copy between home and the office. Stay tuned. If anyone else has the book please take a peek. 

 

Found my copy of the book...wow, far more info than I remember... Olley's involvement began in 1939, and was fraught with political complications; had to incorporate himself so he wouldn't be arrested as a foreign agent. Set up supplies of crankshafts, steel alloys, and machine tools to R-R in Britain. Lots of great info here -- one more reason to own the book along with all the chassis design and historical material. 

 

 

 

 

[Magoo]

 

You've seen the Detroit Packard plant in ruins. Now see it in its finest hour: Building Merlin aircraft engines to win World War II. This fantastic old newsreel film provides a rare glimpse - don't miss it.  

 

 

Video: The Packard Merlin Story | Mac's Motor City Garage.com

 

 

 

 

 

 

If you like the Packard Merlin video above, you will also like this very similar old newsreel about the Ford Willow Run plant where the B-24 Liberator was built. 

 

 

http://www.macsmotor...n-bomber-plant/

[bigleagueslider]

Packard started their Merlin production effort in 1940 and began shipping Merlins in late 1941, just prior to the US entering the war. One of the first things Packard engineers did was to make their own engineering drawings for the Merlin.  Packard engineers also made numerous design changes to things like the fuel system, block/head design, crankshaft design, main/rod bearing designs, ignition system, etc.

[Wuzak]

Packard started their Merlin production effort in 1940 and began shipping Merlins in late 1941, just prior to the US entering the war. One of the first things Packard engineers did was to make their own engineering drawings for the Merlin.  Packard engineers also made numerous design changes to things like the fuel system, block/head design, crankshaft design, main/rod bearing designs, ignition system, etc.

They cerainly didn't change that much.

The redrawing they did was to make them to American Standard drawings (ie to 3rd angle from 1st angle).

The block head design was done by Rolls-Royce. Packard initially did their own coolant transfer design, but later went across to the Rolls-Royce method.

[Lee Nicolle]

If you like the Packard Merlin video above, you will also like this very similar old newsreel about the Ford Willow Run plant where the B-24 Liberator was built. 
 
 
http://www.macsmotor...n-bomber-plant/

Again very interesting. Keep them coming.
also sad that the buildings and it seems even the aerodrome are disappearing. But that is progress I guess.

[Magoo]

Packard started their Merlin production effort in 1940 and began shipping Merlins in late 1941, just prior to the US entering the war. One of the first things Packard engineers did was to make their own engineering drawings for the Merlin.  Packard engineers also made numerous design changes to things like the fuel system, block/head design, crankshaft design, main/rod bearing designs, ignition system, etc.

 

I know we've all read and heard those stories. The question is which ones are true. 

[WPT]

RR sent over 2000 drawings to Packard. As stated above these drawings were turned into "American". The Whitworth thread form, however, was retained for the major threads. For early Merlin development: http://enginehistory...e/RHM/RHM.shtml

 

For more on the SR-71 inlets: http://enginehistory...Work8-19-13.pdf        WPT

[bigleagueslider]

I know we've all read and heard those stories. The question is which ones are true. 

 

The major changes Packard incorporated to things like the fuel and ignition systems are well documented. Packard replaced the SU carburetors with the much better Bendix injection carburetors. Packard substituted the more reliable AC Delco magnetos. Packard used their own design for the supercharger drive. And Packard changed to a much better main bearing material. As for the 2-piece head, while it was designed by RR, they also had trouble manufacturing it while Packard did not. So Packard was the first to put the 2-piece Merlin head into production.

[Wuzak]

The major changes Packard incorporated to things like the fuel and ignition systems are well documented. Packard replaced the SU carburetors with the much better Bendix injection carburetors. Packard substituted the more reliable AC Delco magnetos. Packard used their own design for the supercharger drive. And Packard changed to a much better main bearing material. As for the 2-piece head, while it was designed by RR, they also had trouble manufacturing it while Packard did not. So Packard was the first to put the 2-piece Merlin head into production.

Rolls-Royce didn't have trouble making the two piece block. They were busing building the one-piece design for Spitfires, Hurricanes, Lancasters and Mosquitoes. There were many instances during WW2 where improvements were delayed or not implemented because production could not be interrupted. In any case, the first production two piece block built by Rolls-Royce came off the line only a few weeks after the first Packard engine. That engine was a Merlin 61 - the changeover to the two piece block having been held back until they changed over to 60-series production.

Packard adapted US built magnetos to fit the Merlin. Never heard anything about them being more reliable than the British types. They adapted the Bendix-Stromberg carburettor - items that were already in production in the US, rather than having to make the British items.

They introduced an automatic gear change for the 2 speed supercharger drive - it was still the Farman type for the single stage engines. The two stage engines used an epicyclic type gearbox, but it wasn't designed by Packard - rather by Wright. It used the same gear ratios as the British equivalent engines, so there was no great advantage in it.

Packard did improve the coolant pump (though probably not for the first production engines), and also developed an air separator for the oil.

Packard also introduced cadmium plating to the screws and bolts. Obviously wouldn't have changed much in the way of reliability, but maybe prevented them from rusting out.

Not sure on teh main bearing material. I am checking that now.

[Lee Nicolle]

Try unlimitedexcitement.com It is more related to boats but has some specs on the V1650 engine and also some on the Allison also.
Just from a little research via Google it appears the Packard was probably the better engine. Better finish and quality and better ancillaries.
Though one other site I read blew the bags of Ford UK for Merlin production. Would have been a VERY large comedown making sidevalve Ford 8 engines after making 4 valve OHC Merlins.

[Wuzak]

It seems that Packard did indeed change the bearing materials but later changed to the same material that Rolls-Royce were using.

[bigleagueslider]

Rolls-Royce didn't have trouble making the two piece block. They were busing building the one-piece design for Spitfires, Hurricanes, Lancasters and Mosquitoes. There were many instances during WW2 where improvements were delayed or not implemented because production could not be interrupted. In any case, the first production two piece block built by Rolls-Royce came off the line only a few weeks after the first Packard engine. That engine was a Merlin 61 - the changeover to the two piece block having been held back until they changed over to 60-series production.

Packard adapted US built magnetos to fit the Merlin. Never heard anything about them being more reliable than the British types. They adapted the Bendix-Stromberg carburettor - items that were already in production in the US, rather than having to make the British items.

They introduced an automatic gear change for the 2 speed supercharger drive - it was still the Farman type for the single stage engines. The two stage engines used an epicyclic type gearbox, but it wasn't designed by Packard - rather by Wright. It used the same gear ratios as the British equivalent engines, so there was no great advantage in it.

Packard did improve the coolant pump (though probably not for the first production engines), and also developed an air separator for the oil.

Packard also introduced cadmium plating to the screws and bolts. Obviously wouldn't have changed much in the way of reliability, but maybe prevented them from rusting out.

Not sure on teh main bearing material. I am checking that now.

The Bendix injection carbs used by Packard were much better than the SU carbs used by RR, since they were less susceptible to the effects of g-forces.

 

The supercharger drive used by Packard Merlins was indeed an epicyclic design licensed from Wright, but at least Packard engineers were smart enough to appreciate how much better the Wright epicyclic design was versus the Farman design used by RR, regardless of what the gear drive ratio was.

 

Packard used a dual plating overlay on their main bearings and had better quality control of their crankshafts than RR did during this period.

 

In general, during WWII US companies like Pratt and GE had better basic technical capabilities than RR. Pratt did fundamental research into the issue of torsional vibration of recip engines.  GE did lots of basic research into high temp metal alloys for turbocharger turbines and exhaust valves, and the aerodynamics of supercharger compressors. And Allison engineers also seemed to have a better understanding of combustion chamber design than RR at the time, based on the pent-roof chamber used by Allison versus the ramp-head design used by RR.

[Magoo]

The major changes Packard incorporated to things like the fuel and ignition systems are well documented. Packard replaced the SU carburetors with the much better Bendix injection carburetors. Packard substituted the more reliable AC Delco magnetos. Packard used their own design for the supercharger drive. And Packard changed to a much better main bearing material. As for the 2-piece head, while it was designed by RR, they also had trouble manufacturing it while Packard did not. So Packard was the first to put the 2-piece Merlin head into production.

 

 

If the changes are well-documented, then by all means let's document them -- with primary and original source materials where possible. It would be nice to be able to separate the truth from the oft-told tales, the accurate from the embellished.

 

Why should we simply assume, for example, that the Packard magnetos were more reliable than the British magnetos? In the first place, is there a documented shortcoming with the R-R mag to support such a claim? You can see that a lot of this stuff is generated by patriotic sentiments. 

[Wuzak]

The Bendix injection carbs used by Packard were much better than the SU carbs used by RR, since they were less susceptible to the effects of g-forces.

They were used because they were available and in production. Not because they were "better".

 

The supercharger drive used by Packard Merlins was indeed an epicyclic design licensed from Wright, but at least Packard engineers were smart enough to appreciate how much better the Wright epicyclic design was versus the Farman design used by RR, regardless of what the gear drive ratio was.

Better, how? Maybe because they didn't have to pay Farman a licence fee?

 

Packard used a dual plating overlay on their main bearings and had better quality control of their crankshafts than RR did during this period.

I've never seen this quality control issue. Where did you find that?

Packard went to Rolls-Royce bearing practice later - so much for it being better.


 

In general, during WWII US companies like Pratt and GE had better basic technical capabilities than RR. Pratt did fundamental research into the issue of torsional vibration of recip engines.  GE did lots of basic research into high temp metal alloys for turbocharger turbines and exhaust valves, and the aerodynamics of supercharger compressors. And Allison engineers also seemed to have a better understanding of combustion chamber design than RR at the time, based on the pent-roof chamber used by Allison versus the ramp-head design used by RR.

And yet the Merln out-powered the V-1710 pretty much the whole conflict.

Pratt & Whitney did research on torsional vibration because it was a major issue with the R-2800. It wasn't with the Merlin. The Merlin didn't even have a TV damper on the crankshaft.

GE made compressors for Wright, P&W and Allison before the war and in the early war years (ie after 1939). One by one the engine manufacturers dropped GE as a compressor supplier and developed their own. This was because they weren't particularly fantastic, especially compared to Rolls-Royce's superchargers when developed by Hooker.

[Wuzak]

Speaking generally, having spent time in a few aircraft forums over the years, I have seen the claim that Packard engines were better built than Rolls-Royce or Ford UK engines, but this has never been supported by evidence. In fact the view of people more knowledgeable than me on the subject,is that there is nothing to choose between Rolls-Royce, Ford and Packard built Merlins.

[mariner]

Tony Rudd gives some actual data on RR merlin reliability in his autobiography "It was Fun" ISBN 1 85260 413 1. He was a senior reliability  engineer for RR in WW2.

 

In chapter two

 

"The Derby and Crewe factories were at this time ( 1941) building 860 engines per month. More than 240 engines failed every month, and 220 reached their specified overhaul life which was 240 hours in a fighter, 360 in a bomber. Another 180 were damaged in crashes and the rest lost through enemy action"

 

As the Merlin had been in volume production somle time you can't directly correlate the 240 failed engines to the 860 build but reliablity was clealry not outstanding if the monthly failure ratio was probaby over 20%. In fairness poor field maintainance procedures were a significant problem.

 

The RAF challenged RR on this reliablity and there was apparently some validity in their complaints asTony Rudd discovered several Lancaster's which had used up nine  engines in six  months .It was a 10 -12 hour nightly mission  in each Bomber Command  sortie so 360 hours was about 30 missions which I would guess was 2 to 3 months of combat.

 

By 1944 R Merlin reliablity had improved dramatcally. Production was up to 3200 per month ( excluding Packards) and failures down to under 200 per month.

Edited by mariner, 27 December 2013 - 16:28.

[Magoo]

Speaking generally, having spent time in a few aircraft forums over the years, I have seen the claim that Packard engines were better built than Rolls-Royce or Ford UK engines, but this has never been supported by evidence. In fact the view of people more knowledgeable than me on the subject,is that there is nothing to choose between Rolls-Royce, Ford and Packard built Merlins.

 

I am inclined to agree. We've heard all the tales. Where are the facts? 

[275 GTB-4]

I am inclined to agree. We've heard all the tales. Where are the facts?

Whilst I am wary of any "reliability" claims (I worked in a related field for many years), it would be interesting to hear from Tony Rudd's counterpart in Packard.

Didn't want to get into pedanticism, but the definition of what constituted a "failure" would need to be agreed or tailored to allow a valid "apples with apples" comparison.

[Wuzak]

The P-51B prototype's first flight was delayed because an early Packard V-1650-3 failed during testing at Wright Field and had to be returned to Packard for modifications. There were at least 2 failures and the power output was well below the British equivalent. It also delayed production of the V-1650-3.

From David Birch, Rolls-Royce and the Mustang, RRHT.

[bigleagueslider]

 

And yet the Merln out-powered the V-1710 pretty much the whole conflict.

The V-1710 was not given anywhere near the same development priority by the US as the Merlin was given by the UK during the war. The US military made the decision early on to develop big air-cooled radials, since they felt this approach presented less risk.  By the end of the war, the Allison V12 was every bit as good as the RR V12.

 

 

Pratt & Whitney did research on torsional vibration because it was a major issue with the R-2800. It wasn't with the Merlin. The Merlin didn't even have a TV damper on the crankshaft.

 The early Merlins had horrible problems with crank TV causing failure of the prop gear reduction.

 

 

GE made compressors for Wright, P&W and Allison before the war and in the early war years (ie after 1939). One by one the engine manufacturers dropped GE as a compressor supplier and developed their own

GE's greatest contribution during the war was their developement of high-temp metal alloys and turbocharger design. By the end of the war, GE knew far more about these two critical technologies than anyone else.  That's why GE was given the task of building the first turbine engine for the US.

[Wuzak]

The V-1710 was not given anywhere near the same development priority by the US as the Merlin was given by the UK during the war. The US military made the decision early on to develop big air-cooled radials, since they felt this approach presented less risk.  By the end of the war, the Allison V12 was every bit as good as the RR V12.

It is a fallacy to think that the US concentrated on the air-cooled engine.

In fact the opposite is true - the US Army worked on and developed a liquid cooled "hyper" cylinder. The aims for the hyper engine were 1hp/ci and 1hp/lb weight.

Continental was the first company to design an engine based on the hyper concept - hemi combustion chamber, 2 valves per cylinder and 300°F coolant temperatures (to reduce the size of the radiator). They spent more time on single cylinder development than Rolls-Royce did to get the Merlin into production. The Continental project was wholly funded by the Army. Originally a horizontally opposed 1230ci engine it ended up an inverted vee - the IV-1430. After 13-14 years of development it was cancelled, the factories that were built for its production were turned over for Merlin production.

Lycoming developed their own horizontally opposed engine, the O-1230. Unlike Continental, they actually put their own money into the project. Realising that the engine was not going to be powerful enough, Lycoming doubled it up as the H-2470. That also went nowhere after quite some time.

Chrysler were late to the party, but they developed an engine based on the hyper cylinder too - the IV-2220, an inverted V-16. Though of similar power to the Rolls-Royce Griffon from a similar capacity, it was heavier and as much as 50% longer.

Allison were a smaller company than Rolls-Royce, but they also started 2-3 years earlier on the V-1710 than Rolls-Royce did on the Merlin. There was no market for the V-1710 other than the military market, specifically for Army projects. A friend of mine claims that the US government owned the V-1710 design - I don't believe that, but it shows how much funding and influence the government had with the V-1710.

There were a couple of problems with V-1710 development, as far as I can tell. One was that they tried to develop all manner of variations, like extansion shafts for tractors, extension shafts for pushers, fuel injected engines, 4 bank X versions, doubled up twin crank versions, etc. All before they had sorted the basic engine.

Second was a lack of urgency - Rolls-Royce in England had the impending European war, a war that was being expected from 1933/34, pushing them forward. The US in the '30s was neutral and isolationist. Also several thousand miles away from the potential war. Allison's situation was less urgent than Rolls_Royce's.

In contrast to the liquid cooled engines, the air cooled engines had the civilian market to fall back upon. wWithout military orders the R-2600, R-3350 and R-2800 would still have been developed.

btw, when the Army called for a new generation of bombers (XB-15, XB-16) the preferred engine was the V-1710.

The early Merlins had horrible problems with crank TV causing failure of the prop gear reduction.

That may be so (I have no knowledge either way), the fact remains that Rolls-Royce did not have the need to fit a TV damper. Instead they used torsonally flexible shafts to drive the reductiion gear and supercharger gears. The clucthes in the supercharger gears had a small amount of slip built in to allow for TVs.

The V-1710 also used torsionally flexible shafts to drive the reduction gear and supercharger. But they also fitted a TV damper.

As far as I am aware, the Griffon did not have a TV damper either.

GE's greatest contribution during the war was their developement of high-temp metal alloys and turbocharger design. By the end of the war, GE knew far more about these two critical technologies than anyone else.  That's why GE was given the task of building the first turbine engine for the US.

GE was given the task of building the first US jet engine (from plans of the Whittle W.1) because of its experience with turbines - steam turbines and exhaust turbines.

I'm quite sure that Whittle didn't use GE materials or knowledge when he built the WU demonstration engine or the W.1. Nor did Griffiths and Metropolitan Vickers when they built the F.1 (turboprop) and F.2 (jet). Or even the Halford H.1.

Rolls-Royce ran a turbo on a Condor in 1928, quite sure it wasn't a GE. Bristol played with turbos in the 1930s.

BMW built turbos before the war. They didn't quite have the alloys for the high temperatures, so the made the turbine blades air-cooled. This design was carried forward to their turbojets, after some modification son the method of construction.

No, I don't think high temperature alloys was the main contribution of GE. Building turbos was. Without turbos the B-17 and B-24 would not have been able to function in daylight and not be able to carry the loads that they did. Not quite as important was the role of teh turbo with the P-38 and P-47.