Talk:Rolls-Royce Merlin

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Featured articleRolls-Royce Merlin is a featured article; it (or a previous version of it) has been identified as one of the best articles produced by the Wikipedia community. Even so, if you can update or improve it, please do so.
Main Page trophyThis article appeared on Wikipedia's Main Page as Today's featured article on March 27, 2010.
Article milestones
September 10, 2009WikiProject peer reviewReviewed
October 6, 2009Featured article candidatePromoted
Current status: Featured article

Recent adds[edit]

Good stuff folks but I am worried that an unencyclopaedic level of detail is creeping in, particularly in the 'Variants' section. Why not add this information to the dedicated main article; List of Rolls-Royce Merlin variants? It's hardly been edited since it was split off, room for lots of expansion there. Cheers. Nimbus (Cumulus nimbus floats by) 21:23, 29 December 2010 (UTC)

Adjusting 1940 price to 2010 values[edit]

Please don't bother adjusting the 1940 price to 2010 figures: for one thing does the Wiki template calculate according to the retail price index (RPI), or GDP? Such figures are always variable and can be different, according to the formula used to calculate relative values. Without adding a note explaining how the calculated figures are arrived at it is simply an added complication and not worth using in an article meant to be read by the general public. See also this external website which explains some of the variations...Minorhistorian (talk) 20:38, 19 January 2011 (UTC)

I would agree, interesting though the figure might be. I visited the template documentation and there is not much indication on how these figures are derived, scope for original research and wild variation there. I'm glad that you reverted as it was also presented in a very strange way; £80.9 thousand I think it was. Few, if any, would understand this format (should be plain £80,900) and it also conflicted with the format of the existing figure ('000' vice 'thousand' in words), not desirable in an FA level article.
What would be more interesting and relevant is the asking price of an overhauled Merlin today, there is definitely room in the article text for this (not the infobox) or as a footnote. With Spitfires now in the £1,000,000 to £1,500,000 range (I believe), I would hazard a guess that a 'new' Merlin would cost at least £200,000. Just need a reliable source to verify it. Nimbus (Cumulus nimbus floats by) 00:01, 20 January 2011 (UTC)
Agree, a current/recent sales price would be interesting & more relevant. I'm no fan of inflation templating that far back in any case, since it ignores contemporary buying power & changes in exchange rates, & implies a price equivalence where none exists. Compare it to the price of a V1710 or a Model A, or something, if you must give it a relative value. TREKphiler any time you're ready, Uhura 01:41, 20 January 2011 (UTC)
During the war both engines and aircraft were built to government contract in various, sometimes government-owned, 'shadow' factories, so any attempt at giving a meaningful 'market' price is prone to errors. This is why a Lancaster was only reckoned to cost around £55,000, but the actual cost if someone else had wanted to buy one would have been much higher. Also, what exchange rate would one use, today's, or those in effect at the time - in 1940 there were 4 USD to the GBP, today there are around 1.5. After the war in around 1946-47 you could buy a surplus Spitfire IX for around £250 with a spare zero-time engine still in its crate thrown-in. Several people did, intending to use them for racing in the first post-war air races held at Lympne.
BTW, from an earlier post; Someone, somewhere will be the current 'Design Authority' in the UK (similar to Type Certificate holder in the US) for the Merlin. Not tracked this down yet either but I'm working on it. Nimbus (Cumulus nimbus floats by) 20:05, 28 March 2010 (UTC) - at least as recent as the 1980s Rolls-Royce were still supplying technical support for the Merlin and they did-so on the various engines in use by the Battle of Britain Flight as well as others. Reference to this is made in the accident report of the Mosquito RR299. —Preceding unsigned comment added by (talk) 13:30, 22 February 2011 (UTC)
A May 1981 letter to Flight from P.D Sherrard, Manager for Dart/Griffon servicing, stating that although they no longer possess the tooling necessary for manufacturing the parts, Rolls-Royce still supply technical information for Griffons, here: [1]
Almost all such work for the last 20-30 years has been done in the US, as air racing means far more demand over there than over here. There are UK people who work on Merlins and Griffons, but for anything major, the tooling question means that it's the racers who support the restorers. I sold a Griffon for very good money (and my own modest commission) in that direction in the early '90s. Strange thing is, his widow knew that there were two Griffons, crated and inhibited, which had gone into that shed in the '70s, but we never did find the other one! Andy Dingley (talk) 16:19, 27 July 2015 (UTC)

No, not really. The Royal Air Force has the Merlins and Griffons of the Battle of Britain Memorial Flight's aircraft overhauled by Retro Track and Air of Dursley, Glos. (Which is not in the United States.) The firm is CAA authorised, it manufactures new parts for Merlins and Griffons, and it serves Britain's, and Europe's, fairly large body of warbird owners. The firm of Vintage V12s in California is comparable -- it rebuilt the Merlins for the recent Mosquito restorations in New Zealand, and it looks after the Griffon of the Commemorative Air Force's California-based Spitfire XVI, and it can also do Allisons. But racers run non-standard engines with completely different specs, and that US-only game is not the same. A Mustang owner will fly to Reno on the standard Merlin and then spend a day swopping it out for the race engine (delivered to the venue by road), which has a quite different set of custom parts and is designed to run at silly pressures and stresses for only a few minutes at a time. Khamba Tendal (talk) 18:59, 2 November 2016 (UTC)

I suspect that the reason that Rolls-Royce still supplied technical information for the Griffon in 1981 was due to the Shackleton, which was then still in both RAF and SAAF service. — Preceding unsigned comment added by (talk) 11:29, 6 November 2015 (UTC)


I know that the "PV" in PV12 stands for "private venture", but I also remember hearing that the "12" stood for it being a V-12. If this is accurate, maybe it should be noted in the same section. I hesitate to add this myself as I have no sources for this factoid, and I know that Rolls-Royce also produced the R11 (also a V-12) engine prior to the PV12.-- (talk) 20:42, 24 May 2011 (UTC)

"Right-hand tractor" rotation[edit]

At present the article reads

"All but the Merlin 131 and 134 engines were "right-hand tractor", i.e. the propeller rotated clockwise when viewed from the rear."

A sensible amplification would be

"Except for the handed engines on the Hornet and Sea Hornet, all Merlins were "right-hand tractor"-- i.e. the propeller rotated clockwise when viewed from the rear. Kestrels were right-hand as were most American engines, but most British engines of the era were left-hand."

Unfortunately some people imagine there is some doubt about this-- so take a look at Jane's.

The section on British engines in 1938 Jane's list the following manufacturers:

Aero Engines had taken over a Weir 40-hp engine; no mention of any aircraft it powered and no indication of its rotation. No mention of the company in 1941 Jane's.

Aeronco was in liquidation. They had had a license to make Aeronca engines; no mention of any engine of their own. They're not in 1941.

Alvis engines were all left-hand; ditto in postwar Jane's with the Leonides.

Aspin shows an 80-hp engine-- no info on rotation. No mention of any aircraft using it; the 1941 edition says development suspended during the war; 1945-46 still lists Aspin, and 1949-50 does not.

Bristol is all left-hand. No mention of the Centaurus (and later editions don't give its rotation) but plenty of pics of Sea Furys and Beverlys and Ambassadors and Firebrands showing its left-handedness. Also plenty of pics of left-hand Jupiters if I'm too lazy to check the older Jane's for its rotation.

Carden/Chitton-- no info on their 32 hp engine; they're not in the 1941.

Caunter-- no info on their 100 hp engine; they're not in the 1941.

Cirrus doesn't give the Midget's rotation; the Midget isn't in 1941 Jane's. The Minor was LH; postwar editions say the Major and Bombardier were LH.

Coventry Victor-- no info on their 40 hp engine; in 1941 it has been suspended, and the 1945-46 doesn't mention any resumption.

De Havilland all LH.

Luton Anzani-- finally a known right-hand engine, a 35 hp inverted V-2. No mention of any application; they're not in the 1941.

Napier-- no info, but pics of the Short Mercury show the Rapier LH. 1941 Jane's says the Dagger is LH, and 1945-46 says the Sabre is too, if we didn't have enough pics showing them.

Pobjoy Niagara is LH; development ceased during the war, no mention of resumption in 1945-46.

Rolls Royce no info (but plenty of published pics).

Villiers Maya-- another RH engine, 120 hp; the company's not in the 1941.

No additional manufacturers (of their own engines, that is) in the 1941; the 1945-46 adds Coventry Climax but doesn't mention any engine of their own, just license-built.

In 1949-50 add Jameson with a circa-100-hp engine (just for helicopters?) and Monaco, whose production has been discontinued already.

"Kestrels were right-hand as were most American engines"-- the guys will of course object to that, and I'm not going to try to support that part. But pick an American-engined aircraft at random and I'd say odds are better than 90% it will be LH-- "most" is actually quite conservative. Tim Zukas (talk) 22:21, 24 August 2011 (UTC)

You have missed the point entirely, as I explained on your talk page: Simply adding "Jane's AWA 1938, 1941, 1945-46, 1949-50" is meaningless, and it does not comply with several Wikipedia referencing standards: using a "shotgun" approach to referencing, when the references used do not specifically point out that the Merlin was exceptional in using RH rotation is also a waste of time.
The reason your added info with the attached reference was removed is because it is entirely inadequate for a Featured Article, not because anyone imagines there is some doubt.
Find a single-definite-reference which states that the Merlin engine was unusual in that it used R-H as opposed to L-H tractor rotation NOT a whole screed of Jane's AWA with no page numbers. Min✪rhist✪rianMTalk 01:05, 25 August 2011 (UTC)
"You have missed the point entirely"
Your point is unmissable. Your point is, the sentence "Most state names in the United States have more than six letters" must not appear in a Featured Article because we can't find anyone who specifically says that, and just going down the list of states would be a "shotgun approach".
Can anyone find where Wikipedia rules out such a citation, for Featured or Unfeatured articles? Tim Zukas (talk) 23:13, 30 August 2011 (UTC)
WP:SYNTHESIS and WP:CITEHOW are what you are looking for. Nimbus (Cumulus nimbus floats by) 23:20, 30 August 2011 (UTC)
So you think "Most state names in the United States have more than six letters" would be synthesis, and not allowed?
How about this: "On all Platonic solids, the number of faces is a multiple of four and the number of edges is a multiple of six." Probably we can't find anyone who says that in so many words; does that make it synthesis?
Fortunately, somebody at Wikipedia very presciently saw how popular such accusations would be, and clarified what is not synthesis.
Also, it seems "synthesis" always involves advancing a position (a thesis)-- i.e. forming an opinion from more than one source. Just using more than one source isn't automatically synthesis. Tim Zukas (talk) 21:38, 1 September 2011 (UTC)
You have, once again, completely missed the point!! Please read your citation again "Jane's AWA 1938, 1941, 1945-46, 1949-50" This does not provide any useful information whatsoever, except to convey the message that somewhere in this sequence of Jane's AWA references something might just confirm that the R-R Merlin's RH rotation was unusual amongst British aero engines. So what if it seems obvious to you? It might not be obvious to the majority of those who read the article - which is one reason why cites are used. Where on earth do you expect people to look for this information without any page numbers for reference? You added a whole series of Jane's AWA without any reference to the bibliography, nor did you add any of the cited books to the bibliography. This is a careless, "shot-gun" approach to referencing which does not conform to any Wikipedia guideline, and it is not acceptable for a Featured Article: read WP:CITEHOW to see how the system works. Min✪rhist✪rianMTalk 19:53, 2 September 2011 (UTC)
Perhaps we're making progress. Have you abandoned your demand to "Find a single-definite-reference which states that the Merlin engine was unusual in that it used R-H as opposed to L-H tractor rotation"? Once we include page numbers (for people who can't find the engine section in Jane's) you'll be satisfied? Tim Zukas (talk) 23:08, 3 September 2011 (UTC)
You are the one who put an inadequate reference in place, with no page numbers and no indication that the information you insist on adding is actually included in the references you want to use: You also tried to add this statement "Unlike most British engines, Merlins (and Kestrels) were usually "right-hand tractor" without any references whatsoever, so please don't pretend that I and others are somehow at fault for pointing out that there is a problem with your approach.
A single definite reference which actually supplies the relevant information for the definite statement "Unlike most British engines, Merlins (and Kestrels) were usually "right-hand tractor", is infinitely better than a whole screed of references which may or may not say the same thing. I have the Jane's AWA aircraft 1945-1946 - although several British engines listed supply the direction of rotation not all entries do so eg: Armstrong Siddeley Cheetah XV, Bristol Centaurus, Hercules, Pegasus, Mercury. Nor is it obvious where one should look to find the relevant information. How do you expect people to know what to look for even with a whole swag of page numbers? It isn't quite as clear-cut as you like to make out as your list (above) also shows. Min✪rhist✪rianMTalk 06:02, 5 September 2011 (UTC)
The early aero engines were all hand-swung to start and so, as the majority of people are right-handed, the rotation of the engine was chosen as to allow the person swinging the propeller to more easily get out of the way when the engine fires. The opposite rotations were intended for pusher/tractor installations, each one being chosen so as to minimise the risk to the swinger. As engine powers and compression ratios increased, hand starting became impracticable - the RR Falcon took three men with linked hands to swing - and alternatives such as the Hucks starter were introduced. — Preceding unsigned comment added by (talk) 19:48, 23 December 2012 (UTC)
A 1938 official Rolls-Royce handbook/manual for the Merlin II here: [2] — Preceding unsigned comment added by (talk) 18:21, 23 October 2013 (UTC)
IIRC the SBAC standardised on engine rotation direction between the major UK manufacturers of large engines some time pre-war or early in the war, so as to simplify the supply of propellers, accessories, etc, in time of war. The Merlin pre-dated this, and the SBAC standard is also the reason the Griffon rotated in the opposite direction, as it was designed after the new SBAC standard came in to effect. — Preceding unsigned comment added by (talk) 19:58, 5 August 2016 (UTC)

Ford Factory section[edit]

In the second paragraph it is stated that "Ford’s investment in machinery and the redesign..." What redesign? There's nothing else in the text explaining any redesign, apart from mentioning that the drawings had to be re-drafted to Ford's manufacturing tolerences. I let this one pass, but some explanation might be worth adding to add context to this statement. Min✪rhist✪rianMTalk 19:29, 15 November 2011 (UTC)

Probably should read 'new drawings' or something like that. Any chance that you could add a cite for the new footnote on the Luftwaffe bombing please? I'd add it myself but I don't know where that fact came from. Cheers Nimbus (Cumulus nimbus floats by) 20:09, 15 November 2011 (UTC)
If you think that's bad you should take a look at the Packard V-1650 article - anyone reading it would think they (Packard) were instrumental in designing and developing the two-stage engines. Whilst Packard did an excellent job on producing the Merlin in large numbers I don't think they had an awful lot to do with the design of the engine. ISTR, that the Packard 'dash-number' variants were just the corresponding UK RR Mark No.s built in the US.— Preceding unsigned comment added by (talk) 19:20, 23 December 2011 (UTC)
Packard did do a certain amount of work on redesigning and adapting the Merlin to use American manufactured components and change bolt sizes, screw thread gauges, etc to American standards, and it would seem, this needs to be clarified in that article. Min✪rhist✪rianMTalk 20:55, 23 December 2011 (UTC)
Actually, according to the site, they didn't; [3] - all the British bolt and screw sizes were replicated in the Packard Merlin. Otherwise the parts would not have been interchangeable between corresponding equivalent UK/US versions. Not much point the British having engines of their own design built for them overseas if they then need a whole set of different tools and spares to maintain them. — Preceding unsigned comment added by (talk) 12:47, 29 December 2011 (UTC)
Interesting video featuring Stanley Hooker talking about his engine work on YouTube here: [4] — Preceding unsigned comment added by (talk) 10:37, 2 January 2013 (UTC)
The added complications of using differing thread standards between the UK, and Canada and the USA, was the reason for the Unified Thread Standard introduced post-war. This was mainly a result of the manufacturing problems in manufacturing the Merlin in the US, and the Lancaster in Canada. Both used BSW and BSF bolts and other fittings not available in either country. — Preceding unsigned comment added by (talk) 11:56, 5 February 2015 (UTC)
This is one of the reasons that later Packard-Merlins came crated with a comprehensive tool kit. US units didn't have any of the tools needed to work on them. — Preceding unsigned comment added by (talk) 19:54, 5 August 2016 (UTC)

Applications (of the Merlin engine)[edit]

I have to say the inclusion of aircraft like the Hawker Hart* in this section is inconsistent at best (after all, the Merlin isn`t even mentioned in the Wiki article on the Hawker Hart), and downright misleading at worst. Reading this Wikipedia article will mean there are people out there who think the Hawker Hart had a Merlin engine, which, in reality it didn`t. Why would Wikipediens wish to spread disinformation, albeit unwittingly. If aircraft which only used a Merlin engine in some obscure test bed must be included, it should be in a separate list.

* I use the Hart as an example, I`m sure there are many more in that list.--JustinSmith (talk) 21:31, 6 July 2012 (UTC)

It was agreed in the aircraft engine task force discussions to include all applications for all engine types including test beds, the guideline is at Wikipedia:WikiProject Aircraft/Engines/page content. A footnote is invariably included in the applications section of aero engine articles (as it is here) to explain that it may not be the main powerplant for that aircraft type. To link the test bed aircraft in the text but not include them in the application list would be an omission. In the case of British piston engines the lists have been taken directly from Lumsden (who also includes the test aircraft). We should in theory add notes for some of the stranger, unlikely applications but we don't, the Griffon Beaufighter was disputed even though it was cited and it was eventually accepted. Nimbus (Cumulus nimbus floats by) 21:46, 6 July 2012 (UTC)
I should note that the omission of the Merlin from the Hawker Hart article is a fairly large one as it was the first aircraft to fly the engine. The difference is that article is 'B' class and this is a 'Featured Article', it has not yet been written or researched to the same level. Another editor may have addressed concerns with a recent edit but it does untidy what was a simple list and negates the purpose of the standard single covering footnote IMO. Nimbus (Cumulus nimbus floats by) 22:34, 6 July 2012 (UTC)
The addition of cites is unnecessary as the list was completely covered by the single cite No.88 (the specification section is also covered by one cite), it is overkill basically. Nimbus (Cumulus nimbus floats by) 22:38, 6 July 2012 (UTC)
Overkill? One can only kill once - but I take your point, better a .303 than a bazooka. It is, however, worthwhile to at least indicate that both the Hart and Horsley were used to test the Merlin, because some readers who don't follow the notes may be misled into thinking that the Merlin was a primary engine type. I have also added a section on engine test beds in the Hart article under variants. Min✪rhist✪rianMTalk 22:53, 6 July 2012 (UTC)
If readers read articles from the top downwards and understood the context there would be no need for footnotes or cites in some of the lower sections, the Hart and Horsley are clearly noted well before the application section in this article. Copious citing seems to be an untidy answer to the way that articles are being read nowadays (from the bottom upwards). Nimbus (Cumulus nimbus floats by) 23:29, 6 July 2012 (UTC)

How many of our readers read the footnotes ?
Not many.
I`m sorry, I think that list of Merlin engined aircraft is at best misleading, and I would surmise that the vast majority of readers of that page (as opposed to Wikipedia editors) would agree with me.
Let`s try to remember why we`re all here.
Is it for experts in the way Wikipedia works ?
Is it for experts in planes (I suspect most real experts in any sphere would be expanding their knowledege by reading more specialist sites, or, even more likely, from specialist books) ?
Or is it for everyday people trying to add to their knowledge, or checking up something they`ve heard ? And they`ll tell everyone down the pub (or wherever) that the Hawker Hart had a Merlin engine.......--JustinSmith (talk) 21:15, 15 July 2012 (UTC)

I take it you haven't read the revised entry? Min✪rhist✪rianMTalk 00:57, 16 July 2012 (UTC)

I think you`re right.....
I haven`t got time to go through all the models on that list but do I take it all the ones which don`t have "Test bed" after them used the Merlin in a production variant (preferably one produced in significant numbers) ?--JustinSmith (talk) 07:36, 18 July 2012 (UTC)

Ejector Exhausts[edit]

The article implies that the exhaust gasses left the pipes at supersonic speeds (1,300 mph). Is this really the case? I would have thought that would create shockwaves that would have needed to be managed carefully. — Preceding unsigned comment added by RichardRegal (talkcontribs) 16:53, 7 July 2012 (UTC)

I can confirm the figure of 1,300 mph from the cited source. Wouldn't argue that the number is supersonic. I had a trawl through my aero engine theory books and found plenty on exhaust systems but not the speed of the gases, a section in a motorcycle tuning book on expansion chambers didn't give any speeds either. There is quite a lot of information on these systems in the Flightglobal archive but I couldn't immediately see any speeds but they did need to be carefully designed.
I know nothing at all about sound pressure waves but would have thought that supersonic exhaust gases is what causes the considerable noise from these engines, I think the propane cannon bird scarer works on this principle. Perhaps someone will write an article on ejector exhausts for us in time. Nimbus (Cumulus nimbus floats by) 20:18, 7 July 2012 (UTC)
Not much help for your specific question I know, but there's a Flight article on the Hornet's Merlin 130/131 here [5] that states the thrust from the multi-ejector exhausts being equivalent to an extra 450bhp per-engine at full-throttle height.
BTW, there's a useful 1954 Flight article on the history of Rolls-Royce aero engines with some basic information on the various Merlin Marks here: [6] — Preceding unsigned comment added by (talk) 10:02, 16 July 2012 (UTC)
James "Jimmy" Ellor's 1937 patent for ejector exhausts here [7] - note this US patent is dated 1940 but was originally filed by RR in UK in Sept 1937. — Preceding unsigned comment added by (talk) 09:26, 29 September 2014 (UTC)


this was rated 'top-class' for WikiProject Engineering; generally the top class is reserved for the foundational articles within a subject, e.g. mechanical engineering. I've changed this to "high importance". -- phoebe / (talk to me) 02:35, 21 March 2013 (UTC)

Possibly is without the scope of that project, of 1,400 plus aero engine articles this is the only one I can think of that has been tagged. Nimbus (Cumulus nimbus floats by) 01:16, 22 March 2013 (UTC)

Order of number of Merlin engined planes[edit]

I think the order of planes using Merlin engines (assuming it`s in the order of the total number of Merlin engines used, e.g. 4 per Lanc, 1 per Spit) is incorrect. Using info on the various Wiki articles on the relevant planes, the total number of Merlins used would be as follows :
Lancs approx 7000 (= 28,000 Merlins)
Spits (Merlin types) approx 18,000 (=18,000 Merlins)
Mossies approx 7800 (= 15,600 Merlins)
Hurricanes approx 14,500 (= 14,500 Merlins)
Halifaxes approx 500 (?) Merlin variants (= 2000 Merlins)
I`ve adjusted the order of the list to reflect the above. If this is incorrect please indicate why !--JustinSmith (talk) 21:39, 15 June 2013 (UTC)

The list order in the applications section also needs altering to reflect these numbers if we can agree they`re correct. If they`re incorrect then the relevant Wiki articles on Merlin powered Spits needs updating, or at least clarifying ! --JustinSmith (talk) 21:49, 15 June 2013 (UTC)

The note on "In descending order of total number used..." seems to be a waste of time anyway - what's wrong with a simple alphabetical order and let intelligent people figure out that 7,000 odd Lancasters used 28,000 Merlins? Otherwise leave the list order in applications alone - it is much clearer and easier using alphabetical order rather than trying to organise it to a "descending numbers of Merlins used". Min✪rhist✪rianMTalk 23:28, 15 June 2013 (UTC)

Why is the P-51 Mustang not listed at all? I added it today and someone deleted it. More than 15,000 Mustangs were produced, nearly all with Merlin engines. Banjodog (talk) 06:46, 31 August 2015 (UTC)

Because it was powered by the Packard V-1650 variant, where it is covered in detail, and you also tacked in on in the middle of a sentence about the Spitfire, which broke the flow. - BilCat (talk) 07:33, 31 August 2015 (UTC)
I've added the P-51 to the sentence about the Packard Merlin. Also, I placed the applications list in the infobox back in alphabetical order, which is more intuitive. - BilCat (talk) 08:19, 31 August 2015 (UTC)

Engines on display section referencing[edit]

At the time of Featured Article promotion (October 2009) there were five museum entries in this section (uncited!), I count 19 now with only one entry cited (to a non-reliable source). Aircraft project editors have recently been working through long lists of museum aircraft, removing uncited entries, I think that example should be followed here especially as it is a Featured Article. I can confidently cite three or four entries from reliable sources, more entries do have specific museum webpages but as was demonstrated during the FAC process these sites would be deemed 'non-reliable' by WP guidelines.

I suggest that we cite all the entries that can be cited and 'nowiki' the remainder in case sources become available. It would also discourage unsourced entries being added. Nimbus (Cumulus nimbus floats by) 11:46, 21 June 2013 (UTC)

Coolant temperatures[edit]

In the section on "Production engines" it was stated that water/glycol engines ran 70 degrees cooler than those cooled with pure glycol. Nothing in my copies of R-R Merlin service manuals (Merlin II/III, 45-50 series, 60, 70 & 85 series) indicates such a radical difference. On Merlins IIs and IIIs the temperatures were Oil 90-95 degrees; coolant 95 degrees cooling, 120 maximum during climb. For the Merlin 45-50 series the temperatures were 90-105 degrees and 105-135 degrees. Thus it is very unclear what Fozard meant - presumably the pure glycol was less efficient at conducting heat away from gaskets etc and it was these types of components that were supposedly running 70 degrees hotter than with the glycol/water mix. Anyway, 'tis better to steer away from such debatable figures without clarification. Min✪rhist✪rianMTalk 10:50, 30 January 2014 (UTC)

There was something not quite right there. Lumsden discusses the change to 70/30 coolant and gives a reduction in temperature of 30 degrees C (he appears to be talking about cylinder head temp and not the coolant itself). Also notes that this improved coolant leaks and not oil as apparently noted by Fozard. Nimbus (Cumulus nimbus floats by) 13:04, 30 January 2014 (UTC)
Would it be better to use Lumsden as a source, rather than Fozard - or at least find out exactly what Fozard wrote? I think my local library has a copy of Fozard's book so I'll see if I can dig it out. Min✪rhist✪rianMTalk 19:23, 30 January 2014 (UTC)
Well, Lumsden's words are slightly unclear whether he is talking about head temps or coolant temps. I don't think it matters as long as the improvement in cooling is noted (which it is). I thought you had added the Fozard stuff and was going to ask you to check it!! Cheers Nimbus (Cumulus nimbus floats by) 21:07, 30 January 2014 (UTC)
IIRC, pure ethylene glycol was replaced with a 70/30 water/glycol mix because of the fire hazard represented by 100% pure glycol which will burn if the temperature is high enough. — Preceding unsigned comment added by (talk) 19:21, 4 April 2017 (UTC)

New, unreferenced material being added to "engine components"...[edit]

This is a Featured Article, meaning that any unreferenced material will be rejected out of hand...please find good references before adding any such information. Min✪rhist✪rianMTalk 09:50, 15 February 2014 (UTC)
Anyone can check this information, but as it happens you do not only have my word for it.
Is this going to be another "We`re more bothered about protocol than interesting (and correct) facts".......
How sad.
I sometimes wonder why I bother adding to Wikipedia --JustinSmith (talk) 10:18, 15 February 2014 (UTC)

The information was originally added without any source - appearing to claim that it came from Jane's, which it didn't. You haven't given sufficient information on the source of the data for it to be used as a source here - and a photo of an info board at a museum isn't a great source anyway - it may struggle to meet WP:RS.Nigel Ish (talk) 10:50, 15 February 2014 (UTC)
I don`t think having a crankshaft on display is particularly notable to the Merlin but may be if an article on Ambrose Shardlow & Company if it was ever created. The London Times<ref>"Ambrose Shardlow & Company." Times [London, England] 9 July 1945: 10. The Times Digital Archive. Web. 15 Feb. 2014.</ref> says they stamped out 16,402 crankshafts for the Merlin and Meteor so they may not have been the sole supplier as loads more engines than that were built by Rolls-Royce. It appears in the early days they may have been the only supplier but the Times reference doesnt say that. MilborneOne (talk) 11:15, 15 February 2014 (UTC)
I think there's some mileage in noting that the cranks weren't produced at the shadow factories, but were such a complex forging that they had to be left to specialists in Sheffield. Andy Dingley (talk) 12:05, 15 February 2014 (UTC)
Also we probably do have an article (of sorts) on Shardlows. Most of those smaller forges merged in the 1950s and 1960s and we do now have an article on what became their parent company. It's easy enough to add a section there beginning to list their history. Andy Dingley (talk) 12:07, 15 February 2014 (UTC)
"15 ton" steam hammer? That's practically a hobby smith! What size was it really? Andy Dingley (talk) 12:08, 15 February 2014 (UTC)

Well I don`t know about anyone else but I think the info that Merlin cranks were stamped out flat then twisted is very interesting. I also think seeing one of the actual dies which carried out the operation is very interesting and proves the point as well. I`ve heard before that during the Battle of Britain Merlin cranks were only being produced at a factory in Sheffield`s Don Valley before, I also think that`s very interesting, and significant, in fact it should also be on the BofB page (for obvious reasons). It`s very very interesting to speculate what would have happened if the Luftwaffe had gone after the River Don works in a big big way and put it out of action.
To imply that Kelham Island, the major industrial museum for Sheffield, could be an unreliable source is, frankly, laughable. Nothing is 100% (apart from what I`ve actually seen with my own eyes, but, ironically, that`s not allowed because it`s, that nebulous and inconsistent concept, "original research") but if KI is deemed an unreliable source then what, I pray, is a reliable source ? Why not junk everything on Wikipedia then we could be sure there`s no incorrect content on it.....--JustinSmith (talk) 13:53, 15 February 2014 (UTC) I think you misunderstand it is not the Museum that is an unreliable source but using a picture of an info board as source is. If the museum has a published work which mentions all the points then that would be considered reliable. MilborneOne (talk) 14:05, 15 February 2014 (UTC) Bit confusing the infoboard talks about the Vickers River Don Works but the museum example is made by Ambrose Shardlow which were not the same company, this is why we need a reliable source. MilborneOne (talk) 15:10, 15 February 2014 (UTC)

The info board is about the Vickers works, the sample of a Merlin crankshaft was made in 1942 at (what was at the time of the inscription) GKN Shardlows.
I see no reason why a museum reference board should be less reliable than a published book, in fact it is likely to be more so as and errors can be (and normally are) pointed out to the museum, staff then corrected--JustinSmith (talk) 16:09, 15 February 2014 (UTC)

The newly added material should be removed. Unsourced material in a start class article is one thing but it should not appear in a Featured Article, someone might nominate it for a review. Apart from that the section it is appearing in is a summary overview of the engine parts description, not a detailed description of how and where they were made, also seems unfair to single out the crankshaft for special treatment. This level of detail is unencyclopaedic. Pretty sure that a museum placard can not be used as a reliable source in any article, nor can a photo of one next to an exhibit. Plenty around that have errors, who writes them and where did they get the information from? Nimbus (Cumulus nimbus floats by) 20:42, 15 February 2014 (UTC)

Let`s get this right, some people want to remove interesting and relevant and correct information because, in their opinion, it doesn`t conform to every dot and dash of some obscure Wikipedia policy ? They`re more bothered about some arcane classification which no reader is bothered about anyway, than information. Why are we here by the way ?
And how can the information about Merlin cranks being stamped out flat be wrong ? There`s a sample of the original [flat] die there for God`s sake, you can see it (in the photo if you don`t want to vist the museum) with your own eyes. --JustinSmith (talk) 10:25, 17 February 2014 (UTC)

From WP:OWN which is a WP policy:
While Featured articles (identified by a bronze star in the upper-right corner LinkFA-star.png) are open for editing like any other, they have gone through a community review process as Featured article candidates, where they are checked for high-quality sources, a thorough survey of the relevant literature, and compliance with the Featured Article criteria. Editors are asked to take particular care when editing a Featured article; it is considerate to discuss significant changes of text or images on the talk page first. Explaining civilly why sources and policies support a particular version of a featured article does not necessarily constitute ownership. The {{articlehistory}} template on the talk page will contain a link to the Featured article candidacy and any subsequent Featured article reviews.
Whether the classification system is arcane or not could be discussed elsewhere, Wikipedia says that its articles should not be used as a reference source however I do tend to trust the content of any Featured Article because it has gone through a very thorough review process and it is likely that editors have been maintaining the standard since promotion (as this article has). Any article with unsourced and unencyclopaedic information is not good. 'Which no reader is bothered about' is not correct because I at least do care and I'm sure that many other editors and readers do to. Many, many hours of hard work by many editors go into producing and maintaining Featured Articles, to dismiss this great work is quite disheartening. Nimbus (Cumulus nimbus floats by) 11:18, 17 February 2014 (UTC)

I really can`t be bothered with this any more. If people never get to find out (certainly not from Wikipedia) how the Merlin`s crankshafts were manufactured or the fact that for the whole of the BofB there was only one factory capable of producing Merlin crankshafts, that`s not going to be my fault. I think I`ll use this whole farce (because that`s really what it is) on my Talk page as an example of how Wikipedia shouldn`t work.--JustinSmith (talk) 13:25, 17 February 2014 (UTC)

What we can see is that JustinSmith is against many of the Wikipedia guidelines and is now bent on using a Featured Article that other editors have spent hours on just to try and get your way. If you don't like the guidelines by all means discuss your POV on the relevant talk pages and articles; don't screw around with a featured article then accuse other editors of being stupid because they happen to follow the guidelines. In the meantime, thanks for leaving this article alone.Min✪rhist✪rianMTalk 19:11, 17 February 2014 (UTC)
Terms like "sabotage" and "personal crusade" really aren't helping here. Andy Dingley (talk) 21:01, 17 February 2014 (UTC)
No, they're not. There has to be a more polite and respectful way to suggest that JustinSmith is not taking Wikipedia sourcing policies seriously enough, particularly for a featured article. Yaush (talk) 00:06, 18 February 2014 (UTC)
Then please ask JustinSmith to stop making out that other editors are stupid or simple for following the guidelines; since when has that been respectful or polite? Min✪rhist✪rianMTalk 00:26, 18 February 2014 (UTC)

A 1939 Flight advertisement for the English Steel Corporation (ESC) and their making of Kestrel and Merlin crankshafts, here; [8] — Preceding unsigned comment added by (talk) 20:20, 8 March 2014 (UTC)

A post-war Rolls-Royce film about Merlin production on YouTube here: [9] — Preceding unsigned comment added by (talk) 14:38, 22 August 2014 (UTC)

Australian Production[edit]

While added with good intentions, the section on Australian built Merlins has been given a totally inadequate citation. Aeroplane Monthly, November 2008 confirms that CAC did build R-R Merlins (called the Merlin 102) to power CAC built Lincolns but, unfortunately, doesn't mention where they were built or how many. Will look for more information. Min✪rhist✪rianMTalk 10:58, 22 March 2014 (UTC)

The current footnote cite (62) is mis-spelt and not much use to us as it is, is there a web page from that museum that can be used (assuming the museum's web site is a reliable source)? Nimbus (Cumulus nimbus floats by) 20:26, 22 March 2014 (UTC)
A 1955 Flight article on CAC that mentions Merlins being built at the Lidcombe annex of CAC, here: [10]
BTW, photo of a prototype Merlin fitted in a Horsley here: [11] ... and article on cross-over exhaust for Transport Merlin - TML - for Canadair North Star (Argonaut) here: [12] — Preceding unsigned comment added by (talk) 19:55, 21 April 2014 (UTC)

Ford tolerance levels[edit]

< As a consequence over a year was taken up re-drafting 20,000 drawings to Ford tolerance levels >

The reference (Hooker, 1984, p. 58) doesn't mention any number. Where does '20,000' come from? (If it can't be supported, it has to go). (talk) 00:55, 17 February 2015 (UTC)

What does that page say? This snippet was not in the article at Featured Article nomination, it has been added since and taken in good faith as it is cited. Agree that it has to go if it is not true. Nimbus (Cumulus nimbus floats by) 01:13, 17 February 2015 (UTC)
'. . . Ford would have to redraw all of the Merlin drawings to their own standards, and this they did. It took a year or so, but was an enormous success . . . ' (talk) 02:26, 17 February 2015 (UTC)
The 20,000 was added by Trident13 at 01:47 on 22.11.2010 (talk) 02:39, 17 February 2015 (UTC)
That account is currently blocked for copyright violations. Originally the citation (which was added with a fair amount of text and the 20,000 figure) did not give a supporting page number, that was added here by User:Minorhistorian. I have modified the text to closer fit the reference source. Thanks very much for pointing the problem out. Nimbus (Cumulus nimbus floats by) 08:07, 17 February 2015 (UTC)
It gets worse. 'The percentage of engines rejected by the Air Ministry was zero. Not one engine of the 30,400 produced was rejected ...' isn't in Hooker either. Our friend added it inside an existing direct quote.
The nearby sentence about cost reduction ' Ford's investment in machinery and the redesign resulted in the 10,000 man-hours needed to produce a Merlin dropping to 2,727 man-hours three years later, while unit cost fell from £6,540 in June 1941 to £1,180 by the war's end. ' is uncited altogether. ('redesign' is the wrong word, too, IMO) (talk) 11:56, 17 February 2015 (UTC)
Oh dear. I have reverted the Manchester section back to just before Trident 13's unsourced additions, the tolerance matter does not now appear, it can be re-added with the correct citation. The facts and figures must have come from somewhere, shame that their source was not given. Nimbus (Cumulus nimbus floats by) 12:55, 17 February 2015 (UTC)

At no time did either Ford or Packard 'redesign' any part of the Merlin, what they did do was re-draw Rolls-Royce design drawings to their own internal drawing specifications and conventions.

In the case of Packard this was done because there were differences between US and British drawing conventions, e.g., ways of representing things on paper.

As the engine's design authority no-one other than Rolls-Royce had the right to 're-design' any part of the Merlin, as the engine's type certification would have been effected, needing lengthy and costly re-testing of the modified engines, and this would have delayed deliveries and defeated the purpose of having the engine manufactured in different places, which was to increase production.

Besides the Merlins built by outside contractors such as Ford and Packard were being built at the express order of their customer - either Rolls-Royce or the Ministry of Supply. So they built the engines exactly as Rolls-Royce had told (and in Packard's case, paid) them to.

BTW, the two-piece block was designed by Rolls-Royce but was sent to Packard and introduced by them first because of the delay introducing it would have caused due to production lead-ins at RR.

When the US Government obtained Packard-built Merlins for US use they had to pay Rolls-Royce a royalty/licence fee - the 1940 RR/Packard contract preceded Lend-Lease and was signed under Cash and Carry - for every Packard-Merlin obtained for use in any US operated aircraft, as having the engine built in the US had been originally intended for UK use only. The US government had nothing to do with the Packard-Merlin other than having given permission in 1940 for Packard to accept the British contract, which had been necessary due to the US's neutrality laws. Because of the royalty/licensing fee Truman's government in 1945 stopped North American from using the Packard-Merlin and they were forced to re-engine the F-82 with Allison V-1710's instead.

There was only very minor differences between RR and Packard-built Merlins of corresponding Marks, and indeed in the 1970s the Battle of Britain Flight's Lancaster PA474 was at some time flying with three Rolls-Royce and one Packard-Merlin installed. — Preceding unsigned comment added by (talk) 10:18, 30 March 2015 (UTC)

"My favorite story of Rolls-Royce’s faith in Packard comes from Bill Lear Jr’s book, “Fly Fast…Sin Boldly – Flying, Spying & Surviving”. In 1963, Lear was living in Geneva, Switzerland and flying a surplus P-51. After numerous problems with the starter clutch on his Packard-built Merlin, he contacted Rolls-Royce. They instructed Lear to send them the clutch, which was quickly repaired and returned. Lear adds:
“I called my benefactor to thank him and to ask him when to expect an invoice. His reply was: ‘My dear Mr. Lear, Rolls-Royce-designed products do not fail. They may require occasional adjustment, but this is covered by our unlimited warranty. So there is no charge, sir.’
I was blown away. The engine and clutch had been manufactured under license in the U.S.A. by Packard in 1944, yet Rolls still stood behind them in 1963!” [13]
Lear couldn't go to Packard as they had ceased to exist several years prior to 1963, and Rolls-Royce were probably only able to do this because there were still civil Merlins in Avro Yorks being operated by Skyways Limited and Dan-Air.— Preceding unsigned comment added by (talk) 19:01, 10 May 2016 (UTC)
The actual Packard 'redesign' consisted of taking the Rolls-Royce design drawings drawn in the first-angle projection used in the UK and re-drawing them using the third-angle projection that is commonly used in the US. — Preceding unsigned comment added by (talk) 09:35, 31 May 2016 (UTC)
I have a feeling the Merlin licence fees were waived by Rolls-Royce and HMG for the duration of the war, and only came into effect with the war's end, hence the switch over to the Allison V-1710 in the F-82 at that time.

Basic component overview (Merlin 61) - crankcase[edit]

< Two aluminium-alloy castings joined together on the horizontal centreline >

The words 'on the horizontal centreline' do not appear in the cited source (Bridgman 1998). Where did they come from and, in particular, what do they mean? (talk) 17:42, 25 February 2015 (UTC)

I think this is the case for every Merlin since the PV12. "Centreline" is inaccurate – it's simply describing a sump pan (a thin aluminium casting and AFAIK unstressed) attached to the single main crankcase casting below the crankshaft centreline.
It's not an important distinction. The Merlin is famous for the variations of its cylinder blocks and whether the heads were monoblocs or not. At the same time, the crankcase was little changed and retained a forward housing for the propeller reduction gear. In a crash, this was inevitably damaged. The supply of damaged Merlin crankcases was one factor behind the development of first the Meteor| and later metal-stitching techniques for repairing castings.
The Merlin 61 is widely described as the first Merlin with two piece (i.e.non-monobloc) head and block. However these actually appeared slightly earlier, with the Merlin XX. Andy Dingley (talk) 18:36, 25 February 2015 (UTC)
The sump pan is actually referred to by Rolls-Royce as the "crankcase lower portion" and is an aluminium-alloy casting. As with most aero engines of this type the Merlin used a dry sump lubrication system.

Fuel Octane[edit]

Article says "100/150" grade (150 octane) fuel". Perhaps someone could explain that the 100 is a 'dry' rating and the 150 is 'wet' - with water/methanol injection. 2001:56A:F414:D300:4570:B44D:6DC:9CB6 (talk) 23:59, 7 December 2015 (UTC)

First figure is the 'lean' mixture octane rating, second is the 'rich' rating. On engines with automatic mixture control (AMC) such as the Merlin, Griffon, etc., the mixture is governed by throttle/boost setting, the mixture being lean (weak) at low throttle settings, becoming increasingly richer as the throttle is opened. Thus low throttle settings (lean mixture) are used for cruising. Usually the Pilot's Notes will specify a recommended boost figure for cruising, at which the mixture will be relatively lean. On these engines only the second figure ("150") is usually relevant to the operator.
On engines with manual mixture control the mixture can be varied by the pilot, and using high powers and a weak mixture may cause damage to the engine via knocking - hence the first figure ("100") is the anti-knock value for a weak mixture, and is lower than the rich ("150") figure. In other words, the pilot must adjust the mixture to fully 'rich' for the full anti-knock rating of the fuel at high powers. Thus both figures ("100/150") are important for engines with manual mixture control.
BTW, strictly-speaking only octane numbers up to 100 are valid - beyond this the figure becomes a 'Performance Number', although the 'octane' is still usually quoted as before. Post WW II petrol of 100 octane was available in the UK for road use where it was called '5 Star' (*****) fuel, although it later disappeared with the drive towards unleaded.— Preceding unsigned comment added by (talk) 11:29, 13 March 2016 (UTC)

Hives and the production of the Merlin[edit]

Regarding these uncited comments under Production:

Production of the Rolls-Royce Merlin was driven by the forethought and determination of Ernest Hives, who at times was enraged by the apparent complacency and lack of urgency encountered in his frequent correspondence with Air Ministry and local authority officials. Hives was an advocate of shadow factories, and, sensing the imminent outbreak of war, pressed ahead with plans to produce the Merlin in sufficient numbers for the rapidly expanding Royal Air Force.

This is but one of several uncited references to Hives' opinions and/or actions in this section. I don't know how long this material has existed, but IMO it doesn't match the standards set in Wikipedia:Featured article criteria, because, apart from being uncited, it pushes one individual's (Hives') particular point of view, therefore it is not "neutral". On what basis is all of this written, and is there any source material that can be cited to back up the claims about Hives' rage over the AM's apparent complacency/ lack of urgency? (One possible source is Rolls-Royce Hillington: R-R Heritage Trust; does anyone have this book?) Otherwise, unless proper citation is included, I propose either deletion or a comprehensive rewrite, using properly cited material. AFAIK, the Air Ministry started the Shadow factory scheme in 1936, and I have solid material to show this.Min✪rhist✪rianMTalk 23:46, 7 March 2016 (UTC)

I have cited the text, it is from Pugh 2000, 'The magic of a name', chapter 'Preparing for war'. The paragraph is a summary lead in for the production section where particular problems addressed by Hives are noted and cited. To record that an individual had a particular viewpoint or mannerisms is not non-neutral, whole WP articles are based on people with very strong views on certain subjects. Hives had similar views within his own company, not tolerating inefficiency or delays etc. and reformed the organisation as he thought fit. Not a man to get on the wrong side of is the impression most sources give. Nimbus (Cumulus nimbus floats by) 09:23, 8 March 2016 (UTC)
No problem, it wasn't immediately apparent that the paragraph noted belonged to Pugh. Another thing that isn't immediately apparent is that Hives' problems with the Air Ministry notwithstanding, most of the funding for the expansion of the Crewe and Derby factories came via the Air Ministry, as well as the funds for building the Glasgow shadow factory, and roping Ford into building Trafford Park. No doubt many manufacturers were becoming impatient with the Air Ministry, but the Air Ministry had a huge job to do with what money the Government was going to provide - the implication that Hives alone was responsible for all of the expansion of R-R and building the shadow factories during the immediate pre-war years is, historically, a little one-sided. Min✪rhist✪rianMTalk 12:19, 8 March 2016 (UTC)
The paragraph doesn't say that he invented the shadow factory idea nor that he was alone responsible for the expansion of Rolls-Royce. An advocate is a supporter of something. He was probably very grateful for Air Ministry funding but frustrated that it was not enough at times and spoke out. Like the arrangements back then this paragraph is not perfect, this engine article is one of very few that covers production in any detail but it needed to be included for FA status (covers all aspects). More could be added to his own article or the company article Rolls-Royce Limited which IMHO needs a lot of work to get away from being a collection of classic car images.
I am still concerned about the number of entries in the 'Engines on display' section, only two cited (reliable sources?) and could fall foul of WP:NOTGUIDE. Nimbus (Cumulus nimbus floats by) 12:35, 8 March 2016 (UTC)
A 1939 Flight article on the opening of the new Rolls-Royce factory at Crew here: [14] and a 1945 one on Merlin production here: [15] and a 1971 one on the Rolls-Royce flight test facilities at Hucknall here: [16]— Preceding unsigned comment added by (talk) 09:30, 31 May 2016 (UTC)
The large-scale manufacture of the Merlin and further impetus to implement the 'Shadow Factory' scheme may well have been helped by Hawker's decision before the war to lay down a production line for 1,000 Hurricanes at their own (company) expense some time prior to receiving a substantial order for the aircraft from the Air Ministry.
Although the general feeling throughout the country was one in favour of appeasement, there were still some in Britain who were fairly sure war was inevitable, and who did what they could to provide some means of proper defence, despite opposition from those who did not see things the same way, and who did not want to appear to be 'provoking' Germany by re-arming. Chamberlain usually gets the blame for this, but rather surprisingly it was he who after Munich authorised most of the re-arming that was to prove vital to Britain in the first two years of the war. — Preceding unsigned comment added by (talk) 00:21, 30 November 2016 (UTC)

Engines on Display section[edit]

Nimbus is right, this section has become an un-cited list, without direct confirmation that all of these museums exhibit Rolls-Royce Merlin engines. Museums that only exhibit Merlin powered aircraft and Packard Merlin V-1650s should also be excluded, for obvious reasons. Please, don't list museums that might exhibit Merlins (or have Merlins in storage, away from the public) but cannot be verified, either through their official website or brochures or other publications. Thanks Min✪rhist✪rianMTalk 22:39, 11 March 2016 (UTC)

I would like to understand why the latest edit adding Solent Sky as an exhibitor of Merlin engines has been deleted. I am a guide at the museum. The wiki site for the museum lists two Merlin engines on display.pfkilty Oct 30 2016. Pfkilty (talk) 21:33, 30 October 2016 (UTC)

To include the information you need to provide a Reliable Source to verify the fact. You cannot use the museum's Wikipedia page as a source, or personal knowledge. The museum website does not appear to be detailed enough to confirm weather or not it has Merlins on display.Nigel Ish (talk) 21:41, 30 October 2016 (UTC)
This section became understandably long because of the large number of museums that display Merlins, most entries were not sourced and there had to be a cleanup which happened last winter. Since then all entries have had to be sourced which is actually policy for all Wikipedia articles but especially so for Featured Articles. I probably have photos of the Solent engines. Possibly room for a separate article on Merlin exhibits but that would bust WP:NOTGUIDE and a few more rules and regs. Nimbus (Cumulus nimbus floats by) 22:24, 30 October 2016 (UTC)


Archive 3 has some inconclusive discussion of this. It may be of interest that Gunston, on page 84 of 'Rolls-Royce Aero Engines', has:

'Most of the British production [of the Merlin] was priced at approximately £1 per horsepower or per pound weight.' (talk) 00:08, 6 May 2016 (UTC)

Marine use[edit]

There is a 1939 Flight article here on Scott-Paine's use of Merlins in one of his MTBs: [17] — Preceding unsigned comment added by (talk) 20:23, 10 May 2016 (UTC)

R-R Kestrel[edit]

I read somewhere that the Merlin was a development of the "R", which makes it a development of the Kestrel, right? - ZLEA (talk) 18:54, 26 January 2017 (UTC)

Everything you ever hear or read (including this article) is wrong. This article isn't too bad for inaccuracy, but it misses out so much. If you must read something, try reading the Rolls-Royce Heritage Trust monographs, which are at least accurate.
Then there are several aspects to engine history: the knowledge it embodies, the ancillaries, the broad construction, the overall dimensions and the claimed version history (not everything called a 'Merlin' had all that much in common).
Also the Merlin simply has a complex history: there are several false starts, a few very different starting points (Are the cylinders cast to the crankcase? The head? What shape is the head?) and also a very long service history. In wartime, 5 years is a long time. A late-war Merlin is a lot more sophisticated than a Battle of Britain engine, let alone a pre-war or Fall of France engine.
The Kestrel was highly developed engine in which R-R developed a lot of small detail design features. The R was a beast! A completely useless engine for anything other than racing, it made itself survivable against detonation (on 1920s petrol) at the cost of over-rich mixtures and a fuel consumption that would make it unworkable for any distance flying. Look also at the Supermarine S.6B and how fuel chemistry (and pretty much fuel chemistry alone) allowed the increases from 1929 to 1931. A better comparison in most ways is the Buzzard: same dimensions (the 5:6 scaled-up "H engine" from the Kestrel) as the R, but using the production engine technology of the day, for real aircraft to fly real journeys on real fuel.
There's a story (which I grew up on as a kid) that the Schneider Trophy was won by "a Spitfire on floats", Merlin engine and all. This is just wrong (OK, the wing spar and planform are).
So the PV12 really begins as a clean sheet drawing, but with many Kestrel detail parts. The Merlin does develop from the PV12, but goes through several stages and dead ends on the way. And yes, it's the Kestrel broad dimensions, rather than the enlarged Buzzard-R-Griffon size (which causes trouble later on, by pushing the demands for specific power on wartime petrol). It uses the knowledge gained from the 1931 R, and particularly the chemistry of leaded fuels. In some ways it's the hot bits of an R on the cold bits of a Kestrel. The moving parts are from the K details (but sometimes using the bearing shell metallurgy of the R) whilst the combustion chamber and metallurgy is that of the R. The spark plugs are lead-fouling resistant, as are the piston rings. The oil scraper rings from the R keep the fragile oils of the day out of the upper rings and blocking them with carbon, but needed the gudgeon pin from the Kestrel to keep the engine reliable. Pistons of new alloys, proven on the R, are fed by valves edged with the latest refractories.
Was the Merlin the ultimate development of the Kestrel? No - that of course was the Peregrine. An excellent engine, which really was the simple evolution of the Kestrel, but curtailed by lack of need, the need to standardise engine production and also the mid-war shift from fighters to bombers favouring larger engines.
The Merlin was never a really good engine though. Like the Sherman, a highly useful engine, but mostly because it was what there was and there were many of them available. R-R (apart from the Meteor) never learned to make a "wartime engine", as the American copyists did. They insisted on making pre-war R-R cars, hand-fitted by time-served apprentices. Which of course weren't available. The R-R Merlin remained dependent on hand-fitting, making it expensive to produce, difficult to exchange spare parts, hard to rebuild outside the main factory and also (compared to the US engines) less resistant to abuse, such as shock-cooling in a dive. R-R never learned to fix this, but eventually the reliability and precision of gas turbines made it a more appropriate approach and we now forget their foibles. Andy Dingley (talk) 21:49, 26 January 2017 (UTC)
The R was a specialised racing engine required to be run flat-out for no more than an hour. As such it achieved its design and performance targets completely as an engine of four times the power of any other aero engine in the world with the exception of the 1,000 hp Napier Cub, which was only half the power of the R. In order to beat the R Fiat was forced to resort to using two-engines in tandem for their subsequent design, the Fiat AS.6. The fuel used by the R was a specialised blend devised by F. R. Banks who was one of the originators of higher-octane fuels. He also later advised Fiat on fuel for the AS.6.
"which causes trouble later on, by pushing the demands for specific power on wartime petrol)" - what wartime petrol. British aviation spirit (Avgas) was in plentiful supply in any of the normal octane ratings, right up to the 150 octane fuel late in the war. It was only civil petrol that was limited to IIRC an 80 octane rating, the so-called 'pool petrol' because the various octane ratings were all mixed-up and pooled for military vehicle and limited civilian use.
"The R-R Merlin remained dependent on hand-fitting, making it expensive to produce, difficult to exchange spare parts, hard to rebuild outside the main factory and also (compared to the US engines) less resistant to abuse" - this claim is often made however it fails to take into account the differing roles of the two companies, Packard had merely to produce the engines to the drawings supplied by Derby, RR however had the responsibility for the design and development of the engines, and so all modified test components had to be made by hand simply because the production tooling did not yet exist - you cannot build a machine tool until you know what the component to be made on it looks like. In addition Rolls-Royce supplied spares in various over-sizes to allow for wear on engines already in service, e.g., bearing shells, gudgeon pins, etc., BTW, Rolls-Royce is I believe still in business today. Packard isn't. I nearly forgot, many of the 'skilled' factory workers at Crewe, Glasgow, and Derby, were in fact women who had never operated a machine tool before, so that rather negates the 'hand built by skilled workers' myth, highly-competent though these good ladies no-doubt were.
"The Merlin was never a really good engine though" - thousands of pilots and aircrew would beg to differ. Each production engine was run at full power for two hours before delivery, then the engine was stripped and inspected, before re-assembly and then re-running for another two hours at varying powers, before being crated-up for the customer. By 1942-43 a Merlin could be run flat-out for several hours in an emergency without problems. Useful if you only have two engines and one is knocked out due to enemy action. The Merlin also accumulated millions of hours in airline service, (including numerous repeated two-way wartime flights across the North Atlantic) something that one would suspect the airlines would not have contemplated doing with something that " ... was never a really good engine ...". Civil Merlins BTW were still in service up until IIRC Skyways and Dan-Air retired their last Avro Yorks in the 1960s.
The Pregrine was abandoned because it was of too low power and the aircraft designers had stopped specifying it for their designs. At most it could have been developed to 1,200 hp - a figure Rolls-Royce could see soon being approached and surpassed by the Merlin. The lack of development potential to higher powers was why Bristol also abandoned the Taurus. 800-1,000 hp was by then too little. The potential of the Merlin was also the reason that fixing the Vulture's problems was halted and the engine cancelled - by 1938 a test 'Racing' Merlin along the lines of the R had already achieved 2,160 hp. That was before Stanley Hooker had ever even seen a supercharger.
" ... less resistant to abuse, such as shock-cooling in a dive. R-R never learned to fix this ... " - the Merlin engine cooling and oil system each has a thermostat incorporated similar in function to that on a car. The thermostat by-passes the cooling systems when the engine temperature makes cooling unnecessary, such as when starting. When the engine temperature is low enough to make cooling unnecessary the cooling systems are by-passed completely. So no "shock-cooling in a dive".
I nearly forgot, the early US-built engines suffered a spate of crankshaft failures in service necessitating Rolls-Royce sending someone from Derby over to sort it out. This he did, after some rather clever detective work. — Preceding unsigned comment added by (talk) 14:39, 12 February 2017 (UTC)
You know more than I do on this subject, you should consider re-righting the article. - ZLEA (Talk,Contribs) 23:16, 9 May 2017 (UTC)
Thank you for the compliment, but the article itself is actually pretty good. — Preceding unsigned comment added by (talk) 18:50, 26 May 2017 (UTC)
BTW, for anyone interested in that sort of thing, a Merlin-powered multi-engine aircraft, possibly an Argonaut, Lancastrian, or York, can clearly be heard overhead in one of the Viennese night scenes of Carol Reed's The Third Man. — Preceding unsigned comment added by (talk) 09:21, 2 August 2017 (UTC)

Whilst on the subject of Merlin's heard in films, during the golf scene of the 1964 James Bond film Goldfinger, what sounds very much like a multi-Merlin powered aircraft can be heard thundering overhead. — Preceding unsigned comment added by Harry Johnson (talk) 14:20, 15 July 2018 (UTC)

Thanks. I must look out for that next time I see Goldfinger, IIRC there were still Argonauts and Yorks flying in 1963-4. BTW, one of the reasons the Merlin was selected by Canadair/TCA for what became the C-4 North Star/Argonaut was because of TCA's excellent experience using the Lancastrian on numerous two-way Trans-Atlantic flights during the war. Most other aircraft only made the trip one way and were not required to make the same journey again in the other direction with minimal attention between flights, TCA and BOAC's aircraft OTOH operated a regular service both ways. TCA and BOAC made direct flights Prestwick-Gander, whereas most other flights were made in stages via Greenland and Iceland.
Most of Rolls-Royce's post war work on the civil Merlin was aimed at increasing TBO which prior to this had not been of such importance in what had previously been an exclusively military engine. — Preceding unsigned comment added by (talk) 08:41, 9 September 2018 (UTC)
The RAF was puzzled by a spate of crankshaft (it may actually have been camshafts, I can't remember which) failures on early Packard Merlins and in the absence of any identifiable evidence, an engineer from Rolls-Royce was dispatched to Packard in the US. At first it was thought that Packard had deviated in some way from the specified manufacturing process, but upon inspection it was found that Packard had been following the directions scrupulously. Upon closer examination of failed cranks, microscopic etching of the bearing surfaces was discovered, and it was surmised to be the result of some sort of acid. Further investigation was narrowed down to the foundry where the crankshafts were forged, and it was discovered that the foundry workers had been slaking their thirsts with Coca-Cola. Upon satisfying their thirsts, they had been emptying the remains of the bottles into the tank containing water used for quenching the red-hot crankshaft forgings. This accumulated concentration of the drink had been slowly raising the acidity of the water, which had subsequently affected the bearing surfaces, leading to weak spots and cracks, and then failure in use. Once the practice of emptying the bottles into the tank was stopped, there were no more crankshaft failures.
Similarly, Rolls-Royce built engines for a short time around 1941-42 suffered from a failure whereby the engine would suddenly stop running for no apparent reason, leading the pilot to have to resort to either baling-out or a forced landing. This was traced to failure of the skew gear that drove the magnetos, engines that had had the failure were discovered to have had a skew gear with incorrect backlash that had allowed shock loads to shear the drive to the gear. Once the importance of this seemingly trivial adjustment was discovered, it's backlash was carefully specified and the failures then ceased. — Preceding unsigned comment added by (talk) 08:25, 18 October 2017 (UTC)

External links modified[edit]

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Derby Factory[edit]

According to Stanley Hooker ( all the Merlin engined aircraft taking part in the Battle of Britain had their engines assembled in the Derby factory. Also that the men at Derby at the beginning of the war worked 18 hour days 7 days a week. These two facts are worth recording. I hope that the moderator of this allows update editing of this WIKIPEDIA article with interesting and important historical facts about the unsung heros of WWII. — Preceding unsigned comment added by (talk) 18:05, 22 August 2017 (UTC)

It was for the above reason that the Air Ministry sought to have the Merlin produced in the US, initially by Ford, but as things turned out, in actuality by Packard.
IIRC, during the Battle of the Beams the German location beams were detected crossing over the Rolls-Royce factory at Derby.
BTW, Hillington was still making Merlins in 1956 for the Spanish Air Force, Flight news item here: [18]

External links modified[edit]

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Power ratings[edit]

The power ratings from the Jane's source seems quite different from the one cited at the Rolls-Royce Merlin maintenance manual (found at lib-gen). Rdclzn (talk) 19:35, 3 December 2017 (UTC)

Greater Romania Campaign over Stalingrad 1941-1943 Rolls-Royce,1200Hp[edit]

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Greater Romania Campaign over Stalingrad 1941-1943 .......................


Source, Ministerul Fortelor Aerului R56 02478 BIBLOTECA 11.834/4, hence ,public domain,Library of Air Ministry of Romania, books?Aristiderazu (talk) 10:52, 9 February 2018 (UTC)Aristiderazu Romanian Aeronautic in 1935-1941

Chief of Romanian Air Ministry of Air Secretaey was named Engineer Nicolae Caranfil.These proposes a daring program of reorganising of the Aeronautics which would suite the needs and real financial possibilities of Greater Romania.Before him Radu Irimescu .The new plan was to have a total of 83 Squadrons,aviation and 41 companies of aero-stations letter of Engineer Caranfil to the Prime Minister at the time .. MR.Prime Minister Following the discussions we had with Mr.General Paul Angelescu , Minister of National Defence , at yor Mr.home , in the day of 24th of December 1936, seeing once more that the connectionwhich must therefore exist between leaders of departments of National Defence and of Air thus, and Navy cannot take place , due to the permanent animozity which Gral Paul Angelescu had always towards me , and of which cause I have never seen and do not see a way of acomplishing my urgent program of organising the Aeronautics and Navy,our underlyning , I have the honor to present to zou Sir my resignation from Government .

With this occassion I thank you ,Mr.Prime Minister , for the conqur which zou Sir have always given to me , in all circumstances and please have my deepest gratitude..signed .Eng.N.Caramfil ............... 40 Bristol Blenheim and 12 Hawker Hurricanes(for dog fighting role), have been aquired by Romanian Air Ministry from Great Brittain , of which 37 have landed safely in Bucharest .In 1941 in Romania Campaign to Stalingrad ,these were used for long ricconaisance purpose ,equiped with two Bristol Mercury engine, each, of 825 Hp, speed 418Km/h, ceilling 8130mAristiderazu (talk) 16:20, 8 February 2018 (UTC)Aristiderazu .The Huricannes have all landed safely in Bucharest.

In those political circumstances ,initially , the British have refused to aacept the order by Romanian State , oficially .Has though interveened unoficially ,Commandor.Av.Nicolau Constantin , Aero -attache to London then,1939, .Through connections with certain pollitical factours , he succeeds tochange the decission of the British Government.The matter have been discussed in the Room of Communes , too.Finally has been approved the delivery towards Romania of a number of 40 Bristol Blenheim which have arrived in the country in three batches .The romanian pilots have left for England in two groups .,the first group at 17th of August 1939, made up of ten flying pilots crews under the command of Cpt.Cdor.av.Georgescu Laurentiu .The second group under the command of Cpt.Cdor.av.Alecu Demetrescu leaves at 6th of September 1939. At 14th of September 1939 , a formation of fourteen planes , having as head of formation Lt.Cdor.av.Cristescu P.Ioan have left towards the country on the intinerary ..Oxford -Bristol-Caen-Nantes Bordeaux.At 15th of September they have flown from Bordeaux to Marseille ,and at 16th of September they have arrived at Milano.At 17th of September with an escale at Belgrad, have arrived at Bukarest only 13 planes .Number 4.plane with the crew made out of Lt.av.Nicolae Mirescu and maister/master Petre Todica , due to a torrential rain and to a visibility almost nulle , enter in lossing of speed when landing .They crush to the edge of Bordeaux Aerodrome.The plane goes on fire , and the crew sadly perish in flames.

The other formation ,led by Cpt.Cdor .av.Alecu Demetrescu , have left England at 27th of September with direction Bordeaux , from where on the same intinerary , on which have flown the precedent batch , have arrived in Bucharest/Bukarest/Bucuresti at 10th of October 1939, with an escale at Milano of nine days.

The last formations of planes leaves England at 15th of October 1939, under the command of Capt .Cdor.avLaurentiu Georgescu and arrives into the country at 18th of November 1939, in extremly difficult atmospheric conditions .

At take off on Bordeaux erodrome , the plane piloted by Cpt.av.Dumitru Popescu -Pufi is accidented .Luckily the pilot escapes unharmed.

In the last stage of flight of the said formation , the number 14 plane , piloted bz Adj.Chief av.Vasile Mezin , having colleague of flight Maestru/Master Enache, due to the very dense fogg, engages and crushes at Orsova .The crew perish in Danube River waters. Have arrived in the country 37 Bristol-Blenheim , instead of 40.

At take off on Bordeaux erodrome , the plane piloted by Cpt.av.Dumitru Popescu -Pufi is accidented .Luckily the pilot escapes unharmed.

In the last stage of flight of the said formation , the number 14 plane , piloted bz Adj.Chief av.Vasile Mezin , having colleague of flight Maestru/Master Enache, due to the very dense fogg, engages and crushes at Orsova .The crew perish in Danube River waters. Have arrived in the country 37 Bristol-Blenheim , instead of 40. From Germany have beenaquired *Romanian petrol being the exchange coin* starting with 1940 , 30 Heinkel 112*dog-fighting* planes , 32 twin engined Heinkel 111 planes *bombers* , 20 planes Ju 87 ,,Stukas,, *dive bombing role* , 50 Messerschmitt 109 E3 and E7*dog-fighting role* As to the plan, from France have been aquired , special autovehicles for airfields and equipment, from Germany heavy tonaje transport trucks Henschel , from Switzerland 20mm Oerrlikon cannons,the necessary of ammunition for airplanes and wirst watches ,necessary for the navigant personel .From United States autotrucks Ford Marmon with double tracktion , destined to the units of anty air defence .From Italy ,silk for parashutes , Beretta hand pistols for the navigant personell , tractors and buldozers for the Aero Pioneers Regiment and shit /foil for the campaign tents. Obtaining of these materials was beginning to come more and more difficult after 1st of September 1939 ,once the second part of the Mondial War started, the situation became critical. England,Belgium,Holland ,France have definitivelly stoped the shipments towards the Greater Romania,Germany and Italy have drastically reduced them.The Romanian Aeronautical Industry was in great difficulty of primery matters and semifabricated ones, hence raw materials .The situation had become thus critical. With the order nr.11349 from23rd of March 1940, the General Staff of Romanian Army ,asks to the Romanian Ministry of Air and Navy to pass at the latest 1st of April 1941 , to the integral execution of hzpotesis 32.Thus 84 different Squadrons with a total of 834 planes mono and twin engined within the operative units , to which were added 338 reserve airplanes and 350 airplanes for interior for school and training of the navigant personell.Thus , a total of 1517 aiplanes. The value of 32nd Hzpotesis rose up to 32 milliards Lei , at 1938 value,.

Material Staff 1941 For long range reconaisance and light bombardment,,Bristol Blenheim,Bristol-Mercury twin engined ,825Hp,418km/h,ceilling 8310m, Potez 63, equiped with Gnome-Rhone 14M of 670Hp,425km/h,ceilling 8500m. For observation , IAR 38 , BMW,132-700Hp,220Km/h and IAR 39, equiped with IAR K/14 engine of 870Hp,280km/h,ceilling 7000m.Also in this category were included SET 7K ,with an IAR K7-120 of 420Hp,250km/h. , For bombing role Savoia Marchetti S79b.which were aso produced under license in Romaniawhich (),twin engined Gnome Rhone K14 and 1000 A and starting with July 1941 also Savoia Marchetti 79 B manufactured at IAR Brasov after the Italian license ,modified at IAR Power Plant , equiped with 2 Junkers 211 E and 211F of 1200Hp engine each and 1350 Hp , 3350Km/h,ceilling 8000m,PZL planes P-37B Los,manufactured in Poland , equiped with two engines Bristol Pegasus XII and Bristol Pegasus XX of 918Hp,440km/h,ceilling 6000m. The planes IAR 81 ,equiped with IAR K 14-1000A , of 1000Hp,500km/h,used for divebombing role ,, Junkers Ju 87 Stukas ,Junkers Jumo 211 D.a. of 1200Hp for dive bombing role ,385Km/h,ceilling 8000m,,planes Heinkel He 111 ,Karas and Bloch. For dog-fight IAR 80 ,IAR K 14 engine ,510km/h,,Messerschmitt Bf 109E,Daimler-Benz,1250Hp,520Km/h,ceilling 10500m,, planes PZL P 11 ,engine IAR K 9,600Hp,380Km/h,9000m,,PZL P24 planes ,engine IAR K 14 ,870Hp,430km/h,9500m,,planes Hawker Hurricane , Rolls -Royce ,1200Hp,500Km/h,11900m,planes Heinkel 112 ,400Km/h,10500m. For Hydroaviation Savoia Marchetti S 62 bis, with one engine I.F.Asso 800Hp,225Km/h and Kant Z 501 , engine Asso I.F.833 Hp,265Km/h planes. For transport planes Junkers 34, the three engined Junkers 52 ,Potez 56, Lockheed 14 and Lockheed 10. For connection and school planes Fleet F-10G.ICAR,Nardi-PWS,ST,Klemm K1 35D and Me 108 Taifun.

Hence in 1941 ,there were 50 squadrons/Escadrile  to 80 ...The 32 Plan

..................for missing text Aristiderazu (talk) 17:58, 11 February 2018 (UTC)Aristiderazu

No sure why you are dumping similar text on different talk pages? Do you have anything specific to improve the Merlin page ? MilborneOne (talk) 18:16, 11 February 2018 (UTC)