Packard built vs RR built Merlin engine differences?

[51fixer]

I have a copy of a Feb, 1953 RR Pamphlet titled-

Mark Numbers Chart for RR Piston Engines

It lists around 130 different model numbers for RR produced Merlins. A few never made it to production or were field modifications but the majority were series of models produced. Sometimes it seems if they changed a bolt length or dia they gave it a new model number. Other changes include Reverse Coolant Flow, Aftercooler Matrix Flow changes, addition or deletion of Cabin Blower Mount, ect

This chart also lists 17 American Produced model numbers. 5 show they didn't get produced including one listed for the Kingcobra. Also included is the reverse rotating P-82 engine.

[The Inspector]

Someone did a post within the last few months regarding the different dash numbers at least for commercial engines, and a different dash # meant 'customer unique' for a particular airline or operator, I found the info to be very illuminating.

[agent86]

and you are right mr.Inspector.there is nothing more disturbing nor frightening than the Free food being on fire.how traumatic

[John Dupre]

I read a brief magazine article several years ago in one of the British magazines. The article stated that when Packard got the license to build the Merlin they got the blue prints first before they got a sample engine. Using the blueprints they had already built tooling and were producing engines. They tore down the sample engine to compare Packard's parts with Rolls Royce and found they often didn't match. They compared both parts to the prints and found Packard's were right on and Rolls Royce' parts didn't match their own blue prints. The explanation was that back at Rolls Royce' overhaul shop as the technicians found failed or stressed parts they would walk the part back to the casting or milling shops directly and decide on strengthening or changing parts as needed without any input from engineering or any written record at all. At heart Rolls Royce was still a hands on hand built carriage shop.

In another book about a Canadian pilot who flew Mosquitos in WW2 and in racing postwar he had nothing good to say about Packard built engines having seen several of the early versions self destruct. Have to wonder if those were built to the print models.

[avenger2504]

I find any discussion about aircraft engines fascinating and lap it up and hopefully learn a thing or two. I read a book about P51 Mustang and of course enjoyed the technical side of it and the stories from the ground crews. One said that with the Merlin Mustangs, when they did an engine change the first thing they did with the new Packard Merlin when it came out of the box was to remove the US Spark plugs and throw them away! He stated that Rolls Royce supplied plugs were generally better. I think he also commented that the Packard Merlin tended to leak less oil than a Rolls built one so he must have been involved with Spits(or similar) at one stage as I don't think any Mustangs had british built Merlins (apart from the test aircraft in the UK)

[JDK]

Beg borrow or... an article published many years ago now in Warbirds Worldwide called 'Reinventing, Not Fixing' IIRC, which was a very worthwhile article on the Packard approach to building the Merlin. One of the most popular articles we ran.

[51fixer]

There is an official publication that lists parts interchangeability between various RR and Packard models.

I guess if you have spark plugs by the 1000s laying around you can afford to throw away good ones. Like everything else spark plugs evolved. The Griffon in the Spit could use the same plugs listed for the Merlin but a later type of plug was developed so we use that. So at any time of the war you had older and newer technology. Whether it is the complete engine, magneto, prop gov or a spark plug.

There were times when RR Merlins had devastating problems. One period of time the nose case reduction gears were failing and several aircraft were lost. Alex Henshaw talked in his book about making landings in fields while testing brand new Spits at the factory. So problems came along and got solved.

As to one airplane they were great but another type was craap stories need to be taken with a grain of salt. With over 100 different models of the engine produced it often wasn't comparing apples to apples.

The production of RR parts and engines were done under wartime conditions. Workers were killed by German bombing while standing at their machines producing parts. Damaged factories started producing parts on whatever equipment was usable after these raids.

RR was able to salvage and rebuild engines so for leaking oil, I wouldn't be surprised. Fits and tolerances of mating surfaces under these conditions with huge demands for the engines wouldn't be the same as non wartime conditions. The engines had repair schemes for bullet holes in the crankcases among others.

Edit Note- Brain wasn't working this am. I fixed Alex Henshaw's name.

[P-38 fan]

Thanks, guys. I appreciate all the input. Keep it coming.

[JDK]

Anyone seriously interested in the RR Merlin should have a look at the RR Heritage Trust's books.

I thought they had a website with the publications listed, but I may be mistaken. As old RR guys they may be handcrafting the website on a lathe and wondering how to power the internet with a high-octane cocktail.

Anyway, details here: http://www.rolls-royce.com/about/herita ... /index.jsp

One of the books: http://www.allbookstores.com/Merlin-Per ... 0951171011

While Rolls Royce Crewe and RR (Ford, Manchester) were bombed in W.W.II, and many other armaments factories also, we must remember that the German bombing on the UK, terrible though it was, was NOT a continuous barrage of all industrial centres, but was (mostly) a single location attacked per night, with varying industrial impact (the human toll was always high for the time*). So the majority of the time the German attack's effects were indirect with the loss of time through 'down tools' during air raid warnings - as you'd expect, reduced as habituation the risk increased, as well as direct damage to factories and tooling.

The attack on Crewe: http://www.crewechronicle.co.uk/crewe-n ... -27968706/

The production locations, and efficacy of the workforce is touched on here (Note it is a Wiki page, with citations per point. Like anything else, that's a clue to better than average data.) Note also that the Ford (Manchester)'s Merlins were high production, low cost and person (inc woman-)hours and high quality. The Ford engines are often unfairly overlooked IMHO in the story.

http://en.wikipedia.org/wiki/Rolls-Royc ... Production

Just some thoughts.

*Of course by 1944, 17 deaths (the number killed in the Crewe attack) was significantly less than the estimate variance in Germany. truly the 'whirlwind'.

[ZRX61]

I seem to remember reading something about early Packards versions being down on power to RR versions. Apparently Packard was omitting some minor machining process on the pistons (?) & that's what caused the lower power.

& yes, it's Whitworth...... Wentworth is a Golf Course

ARP apparently use Whitworth style SAE threads on some of their hardware. Whitworth is a far stronger design than the others so you can really put the hurt on those fasteners

www.tracytools for all things Whit & BS etc..

[JDK]

Whitworth - if it's good enough for a Crimean Gunboat, is good enough for a newfangled flying machine...

http://en.wikipedia.org/wiki/British_Standard_Whitworth

I didn't know this though:

Nearly all current cameras accept a 1/4 in Whitworth tripod thread in their baseplate.

[A slight diversion, but British engine fastening oddities - the de Havilland Cirrus (and I think the Gipsy) engine had Metric (French style) fastenings in a (very) Imperial environment as the Cirrus was a direct lift from half of a Renault V8. However that's well out of my expertise, and I don't have a ref to hand, so over to those who do know.]

[ZRX61]

[A slight diversion, but British engine fastening oddities - the de Havilland Cirrus (and I think the Gipsy) engine had Metric (French style) fastenings in a (very) Imperial environment as the Cirrus was a direct lift from half of a Renault V8. However that's well out of my expertise, and I don't have a ref to hand, so over to those who do know.]

Also:
Enfield used their own thread system in the beginning before getting with the program & I think Napier may have done the same pre-WWII

[greatgonzo]

I belive the biggest Packard share in Merlin developmnet was their supercharger drive and designing the two piece bank-head assembly. The Packard products did introduce British splines for the prop shafts. They were mounted on the engines delivered to Canada and GB. It would be quite strange if the british workers found it impossible to mount Rotol propeller on 266 Packard Merlin .
Continental had almost 1000 Merlins under their belt, by the way.

[51fixer]

I belive the biggest Packard share in Merlin developmnet was their supercharger drive and designing the two piece bank-head assembly. The Packard products did introduce British splines for the prop shafts. They were mounted on the engines delivered to Canada and GB. It would be quite strange if the british workers found it impossible to mount Rotol propeller on 266 Packard Merlin .
Continental had almost 1000 Merlins under their belt, by the way.

The prop shaft was made with a flange to which the drive gear bolted. This meant it was fairly simple to shafts which were made for British or SAE props. The same basic design of bearings and installation worked for both.
Other interesting facets of this is that Hamilton Standard Props used on some Mosquito, Hurricane and Lancaster A/C where made in the USA. They operated using the same design, blades function and operating parts as the US installed props on American engines. However they were designed with the splines and retention methods as used on British engines.
Thus you could have a Packard built Merlin with HAmilton Std made props but both with British Prop Shafts.

[Jim Beasley]

James is absolutely right. This RR Heritage Trust series is amazing. The book about the spark plugs alone is quite interesting, and when you read about, among other designs, the Rolls 2 stroke V12 engine, you see how hard these guys were working and how creative they were. A must-read.

Anyone seriously interested in the RR Merlin should have a look at the RR Heritage Trust's books.

I thought they had a website with the publications listed, but I may be mistaken. As old RR guys they may be handcrafting the website on a lathe and wondering how to power the internet with a high-octane cocktail.

Anyway, details here: http://www.rolls-royce.com/about/herita ... /index.jsp

One of the books: http://www.allbookstores.com/Merlin-Per ... 0951171011

While Rolls Royce Crewe and RR (Ford, Manchester) were bombed in W.W.II, and many other armaments factories also, we must remember that the German bombing on the UK, terrible though it was, was NOT a continuous barrage of all industrial centres, but was (mostly) a single location attacked per night, with varying industrial impact (the human toll was always high for the time*). So the majority of the time the German attack's effects were indirect with the loss of time through 'down tools' during air raid warnings - as you'd expect, reduced as habituation the risk increased, as well as direct damage to factories and tooling.

The attack on Crewe: http://www.crewechronicle.co.uk/crewe-n ... -27968706/

The production locations, and efficacy of the workforce is touched on here (Note it is a Wiki page, with citations per point. Like anything else, that's a clue to better than average data.) Note also that the Ford (Manchester)'s Merlins were high production, low cost and person (inc woman-)hours and high quality. The Ford engines are often unfairly overlooked IMHO in the story.

http://en.wikipedia.org/wiki/Rolls-Royc ... Production

Just some thoughts.

*Of course by 1944, 17 deaths (the number killed in the Crewe attack) was significantly less than the estimate variance in Germany. truly the 'whirlwind'.