# Merlins > Packard vs RR



## KraziKanuK (Aug 16, 2005)

Picked this up on another forum:

Ho-Hun
"A small point was made to me by an ex-Lancaster X pilot some years ago, that will advance this thread not one tiny bit. He mentioned that the Packard Merlins, which powered the Lanc X, gave only about 82% of the power of the equivalent Rolls Royce Merlins, and that crews would practically kill to get the RR Merlin Lancs because they took off more quickly, and had a higher ceiling. To aircrews ceiling meant life."


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## evangilder (Aug 16, 2005)

I have not heard that, but there were different versions of the Merlin, so maybe that could explain the difference.


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## FLYBOYJ (Aug 16, 2005)

I seen this on another post. I have a hard time believing this for several reasons.

1. If Packard was to build the Merlin under license, their products would have to comply with the same requirements as a RR built one unless Packard convinced the USAAF for engineering and performance waivers - I doubt that happened.

2. When each engine was finished, it was run in a teat cell, again if RR set the original parameters, I can't see Packard or the USAAF procurement office allowing sub-performing engines to be delivered.

3. I never heard of this problem in the fighter community?!?

Comments anyone else?

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## KraziKanuK (Aug 16, 2005)

RR Merlins were completely re-engineered by Packard to American manufacturing standards, starting with the drawings.

You have never heard of all the problems the Packard Mustangs had when introuduced?


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## evangilder (Aug 16, 2005)

They didn't really re-engineer the Merlins. The drawings that were provided were not the usual customary drawings that American engineers are used to, so they had to tear it down and do the drawings that they expected to build the motors.



> Probably the best liquid cooled engine ever developed was the Rolls Royce Merlin. Since 1935 the British had the engine under continuious development. designed to be hand made, however, the enginedid not lend itself to mass-production techniques. On June 24, 1940 Packard was asked by the British goverment to redefine the engine and make it practical for American mass-production. The process required a complete set of new drawings which Packard prepared under the direction of Jesse Vincent. The Rolls Royce drawings from which Packard worked lacked details and specifications and were not in the third angle projection as is the American practice. The Rolls Royce drawings also omitted tolerances which Packard had to develop from an actual engine. It became a matter of taking an actual engine apart and going backwards to develop the needed drawings and specifications. Packard, under the direction of William H. Graves, chief metallurgist for the company, also had to develop the foundry specifications for the Packard-made engine.

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## DaveB.inVa (Aug 16, 2005)

Sounds to me like a case of national pride.

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## wmaxt (Aug 16, 2005)

I've read in several places that the Packard Merlin had some changes like more bolts holding valve covers and crank pan on, to eliminate some leakage due to uneven tension on those parts. 
There were also several Blower styles and prop speed reduction setups that affect engine operation, climb, speeds and service ceilings.
It's also possibly that curing/annealing processes had to be adjusted for the rapid pace of manufacturing. Normaly complicated castings require from 6mo. to 2 years to cure before machining and use to avoid stress cracks. 
Lastly on the introduction of the P-51s/Packard Merlins in the UK, there were some failures, I've wondered if they suffered, in part, from hand measured/mixed octain adjustments like the first P-38s did.

wmaxt

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## FLYBOYJ (Aug 17, 2005)

KraziKanuK said:


> You have never heard of all the problems the Packard Mustangs had when introuduced?



I heard there were some, but they were quickly fixed. I remember reading much of the problems involved operating the engine with the right mixture and overboosting. I heard that most of the RR drawings gave measurements in fractions and these had to be converted to 3 place decimal measurements. This coupled with lack of tolerances as previously posted shouldn't of given great problems.....


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## the lancaster kicks ass (Aug 18, 2005)

in service RR ones were found to be more powerful yet packard were found to have slightly better fuel economy.........

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## FLYBOYJ (Aug 18, 2005)

wmaxt said:


> . Normaly complicated castings require from 6mo. to 2 years to cure before machining and use to avoid stress cracks.



Explain that one to me wmaxt? I've worked with aircraft castings and there wasn't no "cure" time on the ones I worked on (both sand and investment castings). After they were poured and cooled they were heat treated and then machined. Maybe the process was different 60 years ago.

The long lead times were uaully due to making moulds on the more complicated parts.

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## wmaxt (Aug 18, 2005)

FLYBOYJ said:


> wmaxt said:
> 
> 
> > . Normaly complicated castings require from 6mo. to 2 years to cure before machining and use to avoid stress cracks.
> ...



The heat treating is the key, Flyboy, as in a forging a part, it is anealed (heated) to relive stress in the part. Engine blocks (automotive) are often not heat treated in manufacturing and left to cure naturaly. I learned about it studying manufacturing, in the 60s when Ford came out with its high performance 427/428 engines they would pick the earliest castings they could because the natural heating/cooling relived enough stress to allow the extream machining required (all FE blocks started as 331cid castings), and still not break in use.

This may/may not have anything to do with the Packard Merlin but is more of an "I wonder" on my part.

wmaxt


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## FLYBOYJ (Aug 18, 2005)

wmaxt said:


> FLYBOYJ said:
> 
> 
> > wmaxt said:
> ...



OK- I remember seeing a company I used to vist do that for landing gear forgings. "Menasco" had a division in Burbank, Ca., they made lots of civilian and military landing gear. On some of the Boeing stuff they would let some of their forgings sit for awhile before they started machinig them, but they always got heat treated first. I thought they did this for schedueling.


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## wmaxt (Aug 21, 2005)

FLYBOYJ said:


> OK- I remember seeing a company I used to vist do that for landing gear forgings. "Menasco" had a division in Burbank, Ca., they made lots of civilian and military landing gear. On some of the Boeing stuff they would let some of their forgings sit for awhile before they started machinig them, but they always got heat treated first. I thought they did this for schedueling.



For lower output/stress castings heat treating is not always criticle. In more important castings heat treating is a must and I would think landing gear fits that catagory. 

You are also right in that with heat treating a part may be worked anytime. It's also true that the plant you saw the castings in the yard, were probably just setting up a slight backlog for scheduling purposes.

My original thought was maybe the first Packard Merlin engines weren't heat treated and that changed when the cracks were found.

wmaxt


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## FLYBOYJ (Aug 21, 2005)

wmaxt said:


> FLYBOYJ said:
> 
> 
> > OK- I remember seeing a company I used to vist do that for landing gear forgings. "Menasco" had a division in Burbank, Ca., they made lots of civilian and military landing gear. On some of the Boeing stuff they would let some of their forgings sit for awhile before they started machinig them, but they always got heat treated first. I thought they did this for schedueling.
> ...



Agree wmaxt - I don't know, until someone could produce test cell data showing that RR built Merlins put out more power than Packard Merlins, I think it was "all in the pilot's head."

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## wmaxt (Aug 22, 2005)

FLYBOYJ said:


> Agree wmaxt - I don't know, until someone could produce test cell data showing that RR built Merlins put out more power than Packard Merlins, I think it was "all in the pilot's head."



Your most likly right, there were so many prop reductions and supercharger combinations that comparisons must be taken with a grain of salt.

There is a test of two Spitfire IXs and a P-38F. The P-38F was right in the middle performance wise between the Spits. The only difference in the Spitfires was the prop reduction ratios.

wmaxt


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## FLYBOYJ (Aug 22, 2005)

wmaxt said:


> FLYBOYJ said:
> 
> 
> > Agree wmaxt - I don't know, until someone could produce test cell data showing that RR built Merlins put out more power than Packard Merlins, I think it was "all in the pilot's head."
> ...



I think this is where part of the mystery lies, aside from a pilot's over-active imagination.

CASE IN POINT: Years ago I worked on this guys airplane. After about a month he claimed he wasn't getting the right "fuel burn." I cleaned his carb., removed and re-timed his mags, inspected all the fuel filters and there was nothing wrong. Finally I flew with him and he was going by the position of the fuel needle on the gage based on time in the air. When we actually did a fuel tank 'top off' and computed the fuel used based on the time in the air, the fuel burn was right where it should be. When he argued about the gage, I told him the FAA only required the fuel gage to be accurate reading empty in a level-flight attitude! 

The moral of the story?!? Pilots will believe 'things' based on inaccurate sources and here-say, those 'things' will sometimes find their way into assumed law and operating procedures that no one could remember where it was written! 8)

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## schwarzpanzer (Aug 23, 2005)

I guess that the RR's were stress-relieved, the Packards weren't?

Annealed means softened IIRC?

For the Packard the carb was changed and I think the supercharger.

The carb was draw-through in the RR, one of the keys to it's power! But may have been blow-through with the Packard, like the DB605's FI?

The simplest possible explanation is just that the RR's carbs were set up for a richer fuel/air mixture than with the RR's?

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## FLYBOYJ (Aug 23, 2005)

schwarzpanzer said:


> I guess that the RR's were stress-relieved, the Packards weren't?



That shouldn't have anything to do with engine performance. 



schwarzpanzer said:


> Annealed means softened IIRC?



Yes - it is used to relieve stresses, and to soften metal for additional processing (machining)



schwarzpanzer said:


> For the Packard the carb was changed and I think the supercharger.



Later models had a pressure carb in lieu of a float carb. if anything this should of enhanced perfromance



schwarzpanzer said:


> The carb was draw-through in the RR, one of the keys to it's power! But may have been blow-through with the Packard, like the DB605's FI?



This still should not make a difference



schwarzpanzer said:


> The simplest possible explanation is just that the RR's carbs were set up for a richer fuel/air mixture than with the RR's?


 ????

I think until someone produces flight test or test cell evidence, i think this is a myth!

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## plan_D (Aug 23, 2005)

I don't know the exact facts but I would imagine it would all come down to what the engineers did with the hand-built ones. We must remember that there are people out there that can just tweak a piston-engine off his own back. Surely, in the RR factory they could have had some of these people that played with these engines to increase their power. It could even have been possible in the Packard built engines but they were mass-produced and wouldn't really be tinkered with.

But then, the engineers on the line could have done it when it was in the aircraft.


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## FLYBOYJ (Aug 23, 2005)

Good point D!


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## schwarzpanzer (Aug 23, 2005)

I know the tricks that drag racers use to achieve silly hp figures, stress relieving is done after machining.

The only time I've seen annealing used is to soften a copper head gasket.

I think I've seen Merlins with 2 and 4 valves per cylinder, with obvious performance differences, but could be mistaken.

Draw-through carbs reduce the inlet temp and thus density, increasing power, believe me this works with a Garret T3/SU HIF44.

A richer mixture would increase performance/reliability at the expense of fuel economy and is a possibility.

The bolts weren't Whitworth-thread and maybe slight variations did make performance suffer.

At the end of the day, if any engine is blueprinted, it will produce more power than a mass-produced one.

As PlanD said though, 

But then, the engineers on the line could have done it when it was in the aircraft.

This would make a Packard be in the RR's performance league.

Personally, I reckon it's the carb/mixture, this would explain the Merlins supposed higher performance/lower economy.

Adding tetra-ethyl to the fuel would also improve performance if the octanes used were below aprox 90 RON, dunno if anyone knew that then though?

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## FLYBOYJ (Aug 23, 2005)

schwarzpanzer said:


> Draw-through carbs reduce the inlet temp and thus density, increasing power, believe me this works with a Garret T3/SU HIF44.
> 
> A richer mixture would increase performance/reliability at the expense of fuel economy and is a possibility.



This would only be the case when "flying by the numbers." Remember all of these engines had mixture controls operated by the pilot. If one pilot felt he was operating with a high cylinder head temp., he would simply richen the mixture short of fouling plugs.


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## wmaxt (Aug 23, 2005)

Schwarz, While your correct in your answer there is more to annealing, stress relief and heat treating. Based on how and what the desired effect is you can relive stress, harden or soften a part depending on how you heat/cool it. There are some machining procedures that also relive stress. A large complicated casting like an engine block needs some ammount of stress relief to stabilize it. 

Just richening the mixture or adding octain will not add power by themselves. Coupling mixture and octain to prevent detonation, with more boost, more mechanical compression, more ignition advance will. 

The type of carb is not as important as its compatability and efficency in the context of its use.

Blueprinting has to start with a bare block and goes from there. It's the optimizing of balance and clearences to their exact design perameters. Its normaly recognized that a good blueprinted engine will provide 10/12 hp per 500 cu/in or 40/60hp in a Merlin.

Bolt sizes will not affect the relative performance of an engine.

wmaxt


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## FLYBOYJ (Aug 23, 2005)

wmaxt said:


> Just richening the mixture or adding octain will not add power, coupling that with more boost, more compression, more ignition advance will.
> 
> wmaxt



Yep!

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## Parmigiano (Aug 23, 2005)

There is also another general consideration : those engines were about the top that technology could achieve at the time, more extreme than today's racing engines. It makes sense that different batches of the engines were a bit different, that even in the same batch an unit was better or worse than the others and that some RR batch was working better than Packard's and vice-versa.
Also there were almost infinite variants, a comparison could make sense only between units belonging to the same development level.
The Pilot impression might be right, but is not enough to state that in general 'RR were more powerful than Packards'


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## FLYBOYJ (Aug 23, 2005)

KraziKanuK said:


> Picked this up on another forum:
> 
> Ho-Hun
> "A small point was made to me by an ex-Lancaster X pilot some years ago, that will advance this thread not one tiny bit. He mentioned that the Packard Merlins, which powered the Lanc X, gave only about 82% of the power of the equivalent Rolls Royce Merlins, and that crews would practically kill to get the RR Merlin Lancs because they took off more quickly, and had a higher ceiling. To aircrews ceiling meant life."



To go back to the original statement, some other things to consider...

To say the Packard Merlins gave 82% of the RR ones without the benefit of a test cell would say that at least 2 aircraft was flown at a certain altitude, at a certain power setting, and at that point airspeed, rate of climb and service ceiling was probably compared. To accurately achieve a good comparison the airframes would have to be perfect. I doubt any "perfect" Lancaster airframes were available where the asymmetry was right on the money, either from inherent quality lapse from the factory (not taking anything away from the overall quality of the aircraft) or from not being repaired, subject to field abuse (hard landings) or other operational hazards that would of changed they dynamics of the airframe. Without the benefit of test-cell data or comparisons from factory fresh airframes, I would have a hard time believing this if it came from pilots flying operational missions.

At the same time, I doubt the Air Ministry would of accepted Packard Merlins (even at the height of the bombing campaign) that were 17% deficient in performance when compared to their British cousins!!!!

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## evangilder (Aug 24, 2005)

Good points, FBJ!


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## FLYBOYJ (Aug 24, 2005)

Thanks!

Some other things to consider. I believe the RR Merlin put out 1,280 HP. A 17% reduction in my calculator comes out to 1,062 HP. That's a big reduction! Aircrews would of really noticed the differance during take off and climb and would of screemed bloody murder over this performance lapse.


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## FLYBOYJ (Aug 24, 2005)

One more point.....

As some of you know major components of an aircraft come with logbooks (airframe, engine and propeller) The format of aircraft logbooks were basically the same. On engines, the usual first entry is the data gathered at the test cell when the engine is completed and at that time the engine is checked on a dyno and results annotated. These log book entries would of showed any variances in the engines......

Additionally if a crew complained to a maintenance officer about engine performance problems (especially after an engine change utilizing brand new Packards) the first place one would look is in the engine log books to see what the factory annotated about that particular engine.

Either the dyno results were wrong or falsified (I really doubt either) 

or the engines put out as advertised and the deficiencies in performance were inherent in the airframe

or another variable was present that gave the RR Merlins better performance (someone tweaking them in the field, factory mods not shared with Packard, etc....)

In either case I doubt any of these gave a 17% variance between RR and Packard Merlins!


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## schwarzpanzer (Aug 24, 2005)

> Remember all of these engines had mixture controls operated by the pilot.



Didn't know that!  Kinda throws the mixture point, damn!  



> There are some machining procedures that also relive stress.



Seriously??  

On the stress-relief thing, if blocks were used but not stress-relieved from the factory. The 'use' would stress relieve them anyway. 



> Just richening the mixture or adding octain will not add power by themselves.



It depends I suppose, adding octane reduces inlet temps usually if it's under a bonnet, dunno about in a fuselage?

I know 12.6:1 air/fuel is optimal, though that's after twiddling for me (usual is 13-14:1), do planes usually run that?

Any higher would cool the exhaust, reducing scavenge? and that thingy that uses the exhaust heat to increase speed (what is it called? It slips me!)



> Its normaly recognized that a good blueprinted engine will provide 10/12 hp per 500 cu/in or 40/60hp in a Merlin.



Bloody Yanks, why don't you use cubic centimetres like everyone else? - only kidding!  



> Bolt sizes will not affect the relative performance of an engine.



Actually, they can! ARP are great as are the now deceased(?) Whitworth thread.

Also:



> Finally, note that Peugeot changed the bolt that holds the cam pulley on from a 12mm diameter bolt on early engines to a 10mm bolt on later ones. As with the crank bearings, why on earth they messed around with something which was fine to start with I have no idea. Maybe the smaller bolt saved 0.1 of a penny per engine and they were going through hard times. All Kent and Piper cams use blanks with the original 12mm thread in them so if you have an engine with a 10mm bolt you'll need to go and buy the 12mm one from a Peugeot dealer to be able to fit the new cam.



(Taken from Pumaracing.co.uk)

Also variations is true, look at the Sierra Cosworth, it's '205' blocks were specially selected standard '205' Pinto blocks allowing more power, whilst being 'the same'.



> At the same time, I doubt the Air Ministry would of accepted Packard Merlins (even at the height of the bombing campaign) that were 17% deficient in performance when compared to their British cousins!!!!



To see were they were going wrong maybe? 
More likely on a dyno than in combat that though? 

Or to see if the drop in hp would be noticeable in combat?



> Aircrews would of really noticed the differance during take off and climb and would of screemed bloody murder over this performance lapse.



Did take off times really matter to Lancs' crews?



> Either the dyno results were wrong or falsified (I really doubt either)



Well, I know dyno readings, rolling road-readings and actual real-world readings can (and do) differ in cars, maybe it's the same with aircraft?

Maybe the piston tops/combustion chambers were polished in the Rolls etc?

The ports gasflowed etc.

If they were hand built it's likely, I know DeHavilland components were surface-ground etc, maybe RR's were too, but Packards weren't?

Is there any way to find this out?

Hope someone here understtands me, I know I'm having a hard time communicating, sorry.


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## FLYBOYJ (Aug 24, 2005)

schwarzpanzer said:


> > At the same time, I doubt the Air Ministry would of accepted Packard Merlins (even at the height of the bombing campaign) that were 17% deficient in performance when compared to their British cousins!!!!
> 
> 
> 
> ...



I doubt many RAF Maintenance Officer would allow this - it's like allowing your squadron or group to be a "guinea pig."



schwarzpanzer said:


> > Aircrews would of really noticed the difference during take off and climb and would of screamed bloody murder over this performance lapse.
> 
> 
> 
> Did take off times really matter to Lancs' crews?



Not so much the time, it's the rate. With a certain load the aircraft is expected to climb so many feet per minute. This is usually a "barometer" of aircraft performance....



schwarzpanzer said:


> > Either the dyno results were wrong or falsified (I really doubt either)
> 
> 
> 
> Well, I know dyno readings, rolling road-readings and actual real-world readings can (and do) differ in cars, maybe it's the same with aircraft?



No - the hp readings and torque are taken right off the crank shaft.


schwarzpanzer said:


> Maybe the piston tops/combustion chambers were polished in the Rolls etc?
> 
> The ports gasflowed etc.
> 
> ...



That I don't know??? Maybe someone else could shed some light



schwarzpanzer said:


> Hope someone here understtands me, I know I'm having a hard time communicating, sorry.



No problem!


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## schwarzpanzer (Aug 24, 2005)

> I doubt many RAF Maintenance Officer would allow this - it's like allowing your squadron or group to be a "guinea pig."



Yes, those were my thoughts.

I suppose testing over England would be done?

Maybe this is where the reports came from?

I expect the 1st Packard Merlins would have slight teething trouble?

Also, I heard of a Spitfire fitted with a DB605 engine and an attempt by the Germans to copy the Merlin that went wrong and was scrapped, anymore info on this?



> Not so much the time, it's the rate. With a certain load the aircraft is expected to climb so many feet per minute. This is usually a "barometer" of aircraft performance....



Ah, so it's cumulative is it?



> No - the hp readings and torque are taken right off the crank shaft.



Well, ram-air effects from NACA cowls and road/air drag etc all cause hp differences.

There's other factors too, but I'm rusty  , you sure nothing like this happens with aircraft engines?



> That I don't know??? Maybe someone else could shed some light



I can find out about DeHavilland, dunno the rest, I wonder if DeHavilland ever built Merlins for the Mossie, if so I might be able to check that out.

Glad you understand my banter!


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## FLYBOYJ (Aug 24, 2005)

schwarzpanzer said:


> > I doubt many RAF Maintenance Officer would allow this - it's like allowing your squadron or group to be a "guinea pig."





schwarzpanzer said:


> Yes, those were my thoughts.



Yep!


schwarzpanzer said:


> I suppose testing over England would be done?



I would think so. Perhaps the curiosity was raised during missions or after a functional check flight after the engines were installed



schwarzpanzer said:


> Maybe this is where the reports came from?



That would be my guess


schwarzpanzer said:


> I expect the 1st Packard Merlins would have slight teething trouble?


 and that they did!


schwarzpanzer said:


> Also, I heard of a Spitfire fitted with a DB605 engine and an attempt by the Germans to copy the Merlin that went wrong and was scrapped, anymore info on this?



Never heard that one!


schwarzpanzer said:


> > Not so much the time, it's the rate. With a certain load the aircraft is expected to climb so many feet per minute. This is usually a "barometer" of aircraft performance....
> 
> 
> 
> Ah, so it's cumulative is it?



To a point. You would expect a certain time to get to an altitude, or best climb rate vs time, this is referred as 'Vx.' Best climb over a given distance is 'Vy.' These values are usually shown in the pilot's manual and will vary with air temp, altitude, and air density. 



schwarzpanzer said:


> > No - the hp readings and torque are taken right off the crank shaft.
> 
> 
> 
> Well, ram-air effects from NACA cowls and road/air drag etc all cause hp differences.



Yes, on the airframe, but performance values are taken static in the test cell without the benefit of ram air.



schwarzpanzer said:


> There's other factors too, but I'm rusty  , you sure nothing like this happens with aircraft engines?



Not normally - I've worked on a lot of GA recip aircraft. When "bug-smasher" engines come from the factory, they usually are pretty consistent on their performance when compared to other engines built at the same time.




schwarzpanzer said:


> > That I don't know??? Maybe someone else could shed some light
> 
> 
> 
> I can find out about DeHavilland, dunno the rest, I wonder if DeHavilland ever built Merlins for the Mossie, if so I might be able to check that out.



I don't think so - most airframe manufacturers stay away from making their own engines


schwarzpanzer said:


> Glad you understand my banter!



So sweat!


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## plan_D (Aug 25, 2005)

There was a Spitfire with a DB605, some people have pictures of it on here.


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## cheddar cheese (Aug 25, 2005)

Yep!


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## evangilder (Aug 25, 2005)

Another point with horsepower/take off. Rate of climb is part of the barometer, but if you have a fully loaded bomber and are coming to the end of the runway fast, the more horsepower, the better. That's not the place to find out you are deficient. 

Like our maintenance officer says "There's no replacement for displacement". I know there is a difference, but you get the idea.


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## FLYBOYJ (Aug 25, 2005)

evangilder said:


> Another point with horsepower/take off. Rate of climb is part of the barometer, but if you have a fully loaded bomber and are coming to the end of the runway fast, the more horsepower, the better. That's not the place to find out you are deficient.



There is no worse feeling in the world when you have 500' of runway left and you have not lifted off yet!

I could imagine the pucker factor when you're carrying 10,000 pounds of bombs to boot!


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## evangilder (Aug 25, 2005)

Exactly. That will make your sphincter tingle!


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## wmaxt (Aug 25, 2005)

If a casting is not sufficently stress relived before machining it will (if its going to) crack when power (stress) is put to it.

12.6:1 is the ideal for a Lean Burn engine, giving low emisions and fuel economy. 13.7:1 is normaly used/ideal for max power, at least in older engines (pre computer controls and advanced designs). This is why performance carbs have an enrichment circut or "Power Valve". Newer engines use an oxygen sensor and with the computer to adjust the fuel mixture until a minimum oxygen content is reached giving the engine just as much as it can use/needs. Much less than 12.6:1 burns engine components and more than 13.7/14:1 starts fouling plugs, rings, oil, and valves with unused fuel/deposits. Excesively rich mixtures can also damage turbos. 

Another thing to consider is that bombers are loaded differently for each mission the differences in weight will also change the relative performance for those loadouts. This is true even within a formation to some extent.

New Reciprocating engines also produce less horsepower when new than after being fully broken in. This added power can be a significant percentage, as much as 10%. Could the RR engines have been broken in better in the test cells, if there really was a difference?

wmaxt

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## FLYBOYJ (Aug 25, 2005)

wmaxt said:


> Could the RR engines have been broken in better in the test cells, if there really was a difference?
> 
> wmaxt



I doubt it. Recips are usually started, run for 5 mins and shut down, provided no defects are observed. Break in times could be between 10 - 20 hours. At that time variable RPMs are avoided.


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## wmaxt (Aug 25, 2005)

One thing about the Merlin in the US durring the war. It took an average of 320hrs to overhaul and 198 average to overhaul an Allison. I don't know for sure but this might illistrate the complexity/precision required for the Merlin engines. That would make the Merlin more dependant of careful assembly and would result in a wider variation in power output possible between engines. 

wmaxt


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## FLYBOYJ (Aug 25, 2005)

Good point!


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## wmaxt (Aug 25, 2005)

FLYBOYJ said:


> I doubt it. Recips are usually started, run for 5 mins and shut down, provided no defects are observed. Break in times could be between 10 - 20 hours. At that time variable RPMs are avoided.



That's interesting, in smaller recips, cars, bikes the key is to graduly vary thr rpms to avoid "setting" an engine in a particular rpm range. I had a guy bring me an old Honda bike for a tune-up, I found it would not rev beyond 4,500rpm because the owner never reved it beyond that, compression and tune were right on the numbers. The owner confirmed it was never reved higher and was very happy with the job said "It never ran better". 

Break in time varies with the pistion ring type but I'll bow to your expertise - I'm ASE certified not A&P. Your much more familiar with aircraft.

wmaxt


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## wmaxt (Aug 25, 2005)

FLYBOYJ said:


> Good point!



Thanks!

wmaxt


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## FLYBOYJ (Aug 25, 2005)

On smaller GA recips it's usually about 10 hours break-in. I think some lycomings want you to avoid certain RPM ranges. Also during break in mineral oil is used in lieu of the regular motor oil....


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## wmaxt (Aug 25, 2005)

FLYBOYJ said:


> On smaller GA recips it's usually about 10 hours break-in. I think some lycomings want you to avoid certain RPM ranges. Also during break in mineral oil is used in lieu of the regular motor oil....



Ya, cars and bikes also have rpm restrictions the first 10 hours, some like Suzuki requires running the engine in top gear (for a load) at ~2,000 and wide open to about 2/3ds red line and then blip the throttle (to cool the pistons) as you coast down. You do that about 10 times to force the rings against the bores. Engine oil is normaly just good oil but is changed at 100 to 600mi the first time.

Interestingly one shop I worked at set up a show in another location, to transport the bikes we rode them. As we were trying to stock the second location, across 15 miles of desert and we were young we ran those bikes hard, much harder than we were supposed to. I watched those bikes for several years (until I went back to school) and the bikes we ran the hardest were the best bikes we ever sold. They got measurably better power, economy and required the least maintenance. Valve adjustments in particular required Half the shim changes (overhead cam shim/bucket adjustment) of any other bikes I ever did!  

Sorry I strayed from the topic.

wmaxt


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## FLYBOYJ (Aug 25, 2005)

wmaxt said:


> FLYBOYJ said:
> 
> 
> > On smaller GA recips it's usually about 10 hours break-in. I think some lycomings want you to avoid certain RPM ranges. Also during break in mineral oil is used in lieu of the regular motor oil....
> ...



You know, very similar with aircraft engines. i knew a gut who had a Grumman Tiger - Ran it close to red line but maintained it accordingly. The engine has a 2000 hr TBO. His went to 3500 hours, still had good compression and hardly burnt any oil.

Maybe this RR/ Packard mystery is in the "break in?"


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## wmaxt (Aug 25, 2005)

FLYBOYJ said:


> You know, very similar with aircraft engines. i knew a gut who had a Grumman Tiger - Ran it close to red line but maintained it accordingly. The engine has a 2000 hr TBO. His went to 3500 hours, still had good compression and hardly burnt any oil.
> 
> Maybe this RR/ Packard mystery is in the "break in?"



Maybe, or maybe a combination of detailing and break in OR it isn't really there in the first place.  

wmaxt


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## FLYBOYJ (Aug 25, 2005)

wmaxt said:


> FLYBOYJ said:
> 
> 
> > You know, very similar with aircraft engines. i knew a gut who had a Grumman Tiger - Ran it close to red line but maintained it accordingly. The engine has a 2000 hr TBO. His went to 3500 hours, still had good compression and hardly burnt any oil.
> ...



Yep! I'll state again; "Pilots will believe 'things' based on inaccurate sources and here-say, those 'things' will sometimes find their way into assumed law and operating procedures that no one could remember where it was written!"


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## KraziKanuK (Aug 28, 2005)

posted by Buzzsaw on the UBI Il-2 forum

_"Couple comments on the Packard Merlin:

I am currently doing a documentary on a Canadian Ace James Edwards, who got most of his kills in the Desert as a Sergeant pilot in Kittyhawks in '42.

However, he was later promoted to Wing Commander, and commanded a Canadian wing of 4 Squadrons of Packard engined Spitfire XVI's in 2nd TAF in the spring of '45.

He says that they ran the Packards at 81 inches MAP, (+25 boost) for most of 1945, but found there were issues with reliability which they could not deal with in the temporary airfields they were operating out of at the end of the war, so he made a decision to downrate the operating boost at the very end of the war, (last few weeks) back to 72 inches MAP, +18 boost. At that level of boost, they had no reliability problems at all.

He said the British manufactured Merlins in Spit IX's had a better reliability record at +25 boost than the Packards in the Spit XVI's, perhaps because of Rolls Royce's more stringent manufacturing standards. He also mentioned that the RAF Mustang Squadrons based out of Britain continued to use +25 boost, since they could deal with the relibility issues more successfully in their better equipped permanent facilities. These Squadrons also often used Merlin engines as replacements in their Mustangs when the original Packards went over their max. operating hours."_


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## FLYBOYJ (Aug 28, 2005)

That's good but one thing was left out - at 81" what was the RPM? I find a lot of folks talk about MP and boost but always exclude engine RPM in the discussion. By keeping the throttle at a certain setting, the MP can be varied by using prop control. When operating an aircraft with a controllable pitch propeller, the two are related in their operation and many charts in the POH show the relationship in climb and cruise performance. 

That tells me that when they were operating out of these temp airfields, they were probably doing "short field takeoffs" because of field length, or the field might of been at a higher elevation above sea level requiring more power for take off.

Again, while I believe your source, they only way to prove that RR Merlins were "tighter" built is to actually examine drawings and compare the two.

I would also like to know what components were failing. Valves? Piston Rings? Bearings? Cylinder heads? Knowing that will also provide more information of how the engines were being operated and what components were inferior. Many times pilots won't concern themselves with the root cause of the problem.....

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## wmaxt (Aug 28, 2005)

While there were some reliability issues on the early production Packards, that the RR Merlins were significantly more precise isn't likely. Plus, were talking short field, max power, poor maintenance and lots of dust as contributing factors.

Recently a DB crank from a Bf-109 was taken to RR. After anyalizing the crank, RR gave it back with the warning: "Take care of it WE can't duplicate it"  . With an additional 50/60 years advancement in experiance and technical know how it's unlikely they were much better in the '40s, not to mention in a war.

Like Flyboy has mentioned these differences are pretty subjective. Do we have any comments from US pilots that might have had both engines, as a counter point?

wmaxt


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## FLYBOYJ (Aug 28, 2005)

wmaxt said:


> Recently a DB crank from a Bf-109 was taken to RR. After anyalizing the crank, RR gave it back with the warning: "Take care of it WE can't duplicate it"  . With an additional 50/60 years advancement in experiance and technical know how it's unlikely they were much better in the '40s, not to mention in a war.
> 
> wmaxt



I heard about that! I guess the DB tolerances were amazingly tight and the crank, when measured fell right at nominal!


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## Gemhorse (Aug 30, 2005)

Alex Henshaw commented in his book, ''Sigh for a Merlin'';
''The new Merlin engines came from Packards and although they were beautifully finished, they had cut out one of the machining processes on the piston skirt, the result of which was that on many of the machines one would get one or two distinct thuds as if the engines were about to seize up. Mostly, however, they settled down...''

Quite an interesting read on the RR thoroughbreds....

Gemhorse


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## FLYBOYJ (Aug 30, 2005)

Gemhorse said:


> Alex Henshaw commented in his book, ''Sigh for a Merlin'';
> ''The new Merlin engines came from Packards and although they were beautifully finished, they had cut out one of the machining processes on the piston skirt, the result of which was that on many of the machines one would get one or two distinct thuds as if the engines were about to seize up. Mostly, however, they settled down...''
> 
> Quite an interesting read on the RR thoroughbreds....
> ...



Ah-ha! Now here getting somewhere!


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## helmitsmit (Apr 28, 2006)

I heard a report from an ex Mk1X and XV1 pilot that Packard used it metric measurements which might make a difference. There was also a dead spot on the Packards when at a certain RPM, I think 2400rpm. He also said the is fellow pilots couldn't keep up with his older Mk1X when they had XV1s.


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## Twitch (Apr 28, 2006)

Christ, Packard brought the Merlin into the modern world of production line assembly that RR never had at that point. Packard was able to improve reliability due to standardizing manufacture and assembly proceedures instead of assembling engines in a one off atmosphere of the quaint little shop. This standardization learned in automobile assembly line operation ensured that parts were actually interchangable in the field to a far higher degree than they were before. The ability to produce LARGE NUMBERS of engines of equal quality was the key that Packard brought to the mix.

The Merlin was a great engine and Packard's production of it by no means diminished it.

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## helmitsmit (Apr 28, 2006)

Well, there are so many things I've heard all pointing the same way.


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## chris mcmillin (Apr 28, 2006)

I read a book by Don McVicar that had an experience with his Mosquito MK25 with Packard Merlins. He was going to race in the 1948 Bendix from Long Beach, CA to Cleveland, OH. He was based in Montreal and was ferrying the airplane to LB, when they had an exhaust stack go bad. They stopped in Wichita KS and had the stack repaired. On climb out after a harrowing overweight take off, one of the Merlins threw a rod out of the crankcase. He didn't mention the power setting, but I assume it was high. The mechanic he had with him explained that this Merlin was one that didn't incorporate "blended rods", like RR. There was some stress riser in the shape of the connecting rod that Rolls blended out, Packard hadn't yet done it. The mech said that airplanes with Packards had a reputation for this and some CO's sometimes pulled the engines and had them replaced with RR. 

I assume that sometime down the line the problem was rectified. At that same Cleveland race, a National Airlines pilot named Anson Johnson won the Thompson Trophy in his Mustang that had been modified to accept the Packard Merlin 225 low altitude engine used in the Mosquito MK 25! He used water injection to keep the induction temps low and turned the prop governor up to allow an overspeed of 3200 rpm, getting about 90 in hg at 650 feet msl.

Those speaking of mixture controls on these big recips. They aren't like a small light airplane. The are ACM. Automatic Mixture Controls. They set the mixture for the barometric and manifold pressure needs sensed by the carbs myriad of diaphrams. The only mixture control selections on any Mustang I have ever seen is Run and Idle cut-off, and Rich, Auto Lean, and Idle Cut Off. The B-25 had Auto Rich, Auto Lean, and Idle Cut Off. Same with the DC-3. 

The 81 inches on take off was I'm sure perilously close to detonation inducing induction temperatures without the aid of water injection. I am not suprised that there were reliability problems. Only the low altitude engines could make this MP because of the way the blower was set-up, a high altitude engine will only make about 67 at 3000rpm with the auto regulator blocked off. And by the way, the rpm was set by the propeller governor and it is 3000 rpm on a Merlin, also the only way to spin the blower fast enough to get 81 inches is to turn that rpm. (Any attempt to get high manifold pressure by using high blower down at low altitude will only increase induction temps and reduce hp to the prop because of the power used to turn the too dense air through the too coarse gearing for the conditions.)
Great thread guys.
Chris...

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## helmitsmit (Apr 29, 2006)

I think RR used similar techniques in 1940 with the speed Spitfire and a modified merlin III that also ran at 3200rpm and gave 2130hp.


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## Bullockracing (Apr 29, 2006)

Just like to point out that changing fuel settings, along with other things will not neccessarily affect the output of a motor, unless you change valve timing events, boost/compression, and flow characteristics. Given an engine tested in Canada at one elevation, and the installed in a Lancaster in Britian, unless your mechanics tuned it to achieve the stoichometric burn rate for the exact fuel it will use on a mission, it will be out of tune, and not produce the correct power.

Annealing or heat-treating requires a hypereutectic temperature to be achieved over time (specific to each metal/alloy), and does not require a cure time, however, cooling of various metals varies just as well.

Stress-relieving of engine parts is either done by use (preferrably not in the plane I would have to fly into combat in) or by attaching it to a shaker platform. 

I would have to bet on the RR Merlins anyway. Just compare workmanship associated with both companies...

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## Twitch (Apr 30, 2006)

American auto manufacturers mass produced every aero engine in addition to the parent companies, ie., Allison, Curtis Wright, P&W during the war. In contrast RR was a quaint buggy shop in comparison to massive assembly lines that existed in the US and their industrial tools. This is by no means meant to be negative to the RR Merlin developers and engineers. 

To fight a war you simply can't have hand manufactured and assembled engines with the inconsistent quality control that existed in RR at the onset of hostilities. American auto tooling and productions lines were able to consistently manufacture and assemble a quality product (any product) that was reliable to the point that RR could never achieve until they took lessons and improved quality control and manufacture techniques from their American cousins.

Allisons were manufactured by Cadillac. Were they lesser quality? We live in a world, in an age when automobiles (world cars) are easily produced to conform to specifications under reliable quality control networks from parts ans sub-assemblies from several countries or origin. That concept was born in WW 2.

American auto companies mass produced a myriad of machines, vehicles, equipment and weapons of war that met quality standards and were reliable. When Detroit went to war they did so with victory in mind and drew upon their vast world-leading experiance of quality mass production.

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## Bullockracing (Apr 30, 2006)

Roger that, Twitch!


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## FLYBOYJ (May 2, 2006)

During the war years the basic Quality Assurance systems universally adopted by all military manufacturing companies were adopted. Mil-I-45208 and Mil-Q-9858 provided the basic elements in a manufacturing system where if you were making bullets, bombs or B-17s each company had the same system in place to ensure quality. These standards remained in place for many years until replaced by ISO 9000 and ISO 9001/2000...


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## syscom3 (May 2, 2006)

The reason the allies won............ American production was unstoppable. 

I bet the Brits and Axis powers would have loved to be in a situation where damaged planes and eqmt were sometimes just discarded because it was easier to get a brand new one from the factory than to repair it!

I like this quote "quantity has a quality all by its own"


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## Hop (May 4, 2006)

> American auto manufacturers mass produced every aero engine in addition to the parent companies, ie., Allison, Curtis Wright, P&W during the war. In contrast RR was a quaint buggy shop in comparison to massive assembly lines that existed in the US and their industrial tools. This is by no means meant to be negative to the RR Merlin developers and engineers.



Rolls Royce pre war made small numbers of engines, as the RAF was rather small. For example, in 1930 they produced just 132 aero engines. Their best selling model by far was the Kestrel, which sold a grand total of 4778 in 10 years, spread over 27 different marks for different aircraft types (and customers). That sort of volume and model complexity isn't really suited to mass production.

However, with the increase in orders with British rearmament in the late 30s, Ernest Hives oversaw a radical restructuring of Rolls Royce manufacturing, including expanding the Derby plant and setting up two new factories at Crewe and Glasgow. They did rather well, too, RR Glasgow produced 23,647 Merlins, RR Crewe 26,065, RR Derby 32,377. Ford in Manchester produced 30,428. Packard produced 55,523 in the US.

RR production: 82,809
UK production: 112,517
Packard, US production: 55,523



> American auto tooling and productions lines were able to consistently manufacture and assemble a quality product (any product) that was reliable to the point that RR could never achieve until they took lessons and improved quality control and manufacture techniques from their American cousins.



There's a tendency in America to compare early British weapons to later US models. For example, the Mustang I is frequently compared to the Spitfire V (despite being a contemporary of the Spitfire IX), the P-47 the same. In this case, Packard's late production Merlins are compared to British early production Merlins.

For example, Packard had built a grand total of 45 Merlin engines by the end of 1941. Britain had been producing about 500 Hurricanes and Spitfires a month (with Merlin engines) since the summer of 1940, long before production had started at Packard. Never seen any compalints about the quality of these Merlins. Comparing Packard's 1942 production to Rolls Royce pre war problems gearing up for Merlin production is not a valid comparison.

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## Twitch (May 5, 2006)

I'm talking about mass production quality control which American auto manufacturers led the world in. Nowhere else in the world did any vehicle industry produce the number of units with the attendantly stable quality as in the US.

RR was a superstar in aero engines for the times before and at the commencement of WW 2 . Packard built the Liberty V-12s during 1917 in WW I and were well versed on aero engines too. They developed a diesel-fueled aero engine in 1928 in the 1st aircraft to fly on diesel. Their autos began using V-12 in 1932Along the way during Merlin production Packard introduced 23 upgrades or design evolutions each more powerful than the last. 

Known in the indusrty as "The Master Motor Builder," Packard's VP of Engineering Jesse Vincent held 206 patents for innovations from spiral bevel drive gears to the worlds 1st auto air conditioning. He took a clean sheet of paper and designed the 1,500HP aluminum V-12s that powered the US Navy's PT boats.

The Merlin used the less-than-reliable evaporative cooling system. Ethylene glycol-based antifreeze from the US became available and this proved them to finally be reliably cool running. The simple widespread availability of 100 octane aviation fuel from the US gave the Merlin increased power. This fuel permitted higher boost pressures and temperatures without detonation, and allowed the use of +12 lbs. boost rather than the previous limit of +6 lbs.

RR quality control was primitive by American standards. Merlin engineers randomly selected an engine and ran it on a test stand until something broke. The engine was torn down and the broken part was redesigned. This a painfully slow process to improve quality and reliability for a nation under siege.

Vincent set up specialized assembly line tooling and their draftsmen re-drew the Merlin blueprints with far greater precision that RR's. Packard developed a light measuring tool that allowed Merlin component tolerances to be checked to 1 millionth of an inch! Packard employed the practice of freezing critical parts to set tolerances with no ambient heat to make the part expand and throw off calculations. They performed 70,000 inspections on each of the Merlin's 14,000 parts including magnafluxing- X-raying -parts for consistantcy and to see any stress-related micro-cracking. 

They used 80,000 gallons of av gas daily just to test engines. Each engine was test run then fully disassembled after and rebuilt for shipment. These were some of the ways Packard built a better Merlin. They did this in 1941 as soon as they were chosen to build the Merlins. To say that late-war Packards were on par to the Merlin of 1940 is uninformed at best. Packard didn't just fall off the turnip truck and get chosen to built V-12s.

In a similar quest for more power and quality Cadillac improved the Allisons it built, Nash improved the Wright Cyclones they produced and Studebaker made improvements to the P W Wasp. American auto plants mass produced everything from artillery fuses to the artillery that fired them. They improved quality control over previous original manufacturers in every instance.

Like the BASF commercial "Packard didn't make the Merlin, it made it better."

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## Bullockracing (May 5, 2006)

Excellent information, Twitch. Where can I find more information on the actual production information from these manufacturers?


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## Twitch (May 8, 2006)

That is the correct Merlin production output listed by Hop. As far as all the other items, equipment, vehicles and weapons manufactured by American auto companies, I don't think there is a single source that lists it all. When I was researching info for an article a long while ago I found duece and a half truck production at "over 800,000 with GMC assembling 562,750. Federal, International, and Studebaker built the remainder with Studebaker constructing the Lend-Lease vehicles." 

But things like how many Oerlikon 20 mm cannon did Hudson build, how many artillery shells and cannon did Oldsmobile make? Chrysler did make litterly billions of bullets. There was just so much it is very difficult to find all the production figures one may want on certain areas of items.


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## helmitsmit (May 11, 2006)

Twitch said:


> RR quality control was primitive by American standards. Merlin engineers randomly selected an engine and ran it on a test stand until something broke. The engine was torn down and the broken part was redesigned. This a painfully slow process to improve quality and reliability for a nation under siege."



Arr but it worked didn't it? Rolls Royce then got a reputation for being very reliable.


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## R988 (May 12, 2006)

This is one of the most interesting threads I've read in a while, good stuff guys


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## Twitch (May 12, 2006)

Waiting for a part to break in R D is fine in peacetime but the number of steps to quality and reliability take too long when the Germans are are at the door. RR learned effective quaility control from Packard and took it home to work at the RR facilities.


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## Hop (May 13, 2006)

Twitch, what is your contention? That the Merlin wasn't mass produced until Packard came onboard? Or that the Merlin wasn't reliable until Packard came on board?

Neither is true, of course. The Merlin was designed in the mid 30s, when production was expected to be a few hundred engines in total. But from 1937 Rolls Royce changed both the company and the engine in the light of expected increases in demand. They set up a shadow factory at Crewe, then 2 new factories at Galsgow and Manchester which were designed from the start to mass produce engines with unskilled labour. All this before they first talked to Packard.

As to reliability, the Merlin was considered unreliable in it's very early days in the Hurricane in the late 30s. By the advent of war it was considered a very reliable engine. The same cannot be said of early Packard production. The first 6,000 engines delivered by Packard to Britain required remedial work by Rolls Royce.



> The Merlin used the less-than-reliable evaporative cooling system.



Only in the first two prototypes in 1934 and 1935. Pure glycol cooling was chosen, but abandoned just before the war for a high pressure water/glycol system.



> Ethylene glycol-based antifreeze from the US became available and this proved them to finally be reliably cool running.



Ethylene glycol was synthesised in the 19th century by a French chemist. It was used experimentally in WW1 as a coolant.



> The simple widespread availability of 100 octane aviation fuel from the US gave the Merlin increased power.



100 octane fuel was developed by a Shell subsidiary in the US by blending iso-octane and paraffin. Iso-octane was developed by the Anglo Iranian oil company in the UK in 1935.

However, Anglo Iranian had been working since 1936 on an alternative, which they made by blending Venezualen oil with iso-octane. The iso-octane was produced in A-I refineries in Abadan (Iran), it was blended at 3 Esso refineries in the US and Caribbean, by A-I in Abadan and by Anglo-Dutch Shell in Borneo. Just under half the British supply came from the US, the rest from Anglo Iranian and Shell.



> This fuel permitted higher boost pressures and temperatures without detonation, and allowed the use of +12 lbs. boost rather than the previous limit of +6 lbs.
> 
> RR quality control was primitive by American standards. Merlin engineers randomly selected an engine and ran it on a test stand until something broke.



The fact that in 1940 RAF fighter command switched over to 100 octane, upped the boost level on Merlins that were designed to run at 6.25 lbs to 12 lbs, and increased the power output by about 30%, without suffering any major problems, points to just how reliable RR had made the Merlin.

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## helmitsmit (May 16, 2006)

good stuff I totally agree.


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## Twitch (May 16, 2006)

My point is simply that Packard improved the Merlin at a time when it was technically beyond RR and introduced mass production and quality control concsistancy that was beyond RR as well. High octane and glycol weren't new, of course, but when the US shipped MASSIVE amounts of Lend-Lease fuel to GB it made a huge difference. There was never a question whether Merlins could run on 100-115 octane fuel. Getting all you want for free was pretty damned good deal when compared to the relative trickle GB imported before the war.

The American auto industry more than excelled in war material production. That is primary fact whether anyone wishes to believe it or not. Auto companies were set up for large production and were well aquainted with what quality control and product longevity was for complicated mechanisms. They didn't need to get up to speed in producing heavy industry output. They were already there. Outside the US auto manufacture quantity was miniscule in comparison plagued with inconsistant quality and though they were less sophisticated in technology by and large. Of course premuim producers of basically hand built vehicles like Mercedes, Bugatti, Hispano- Suiza and such were another story. Though innovative, none had the ability to produce quantities like the US manufacturers did. Only Mercedes emerged to some extent with quality war products.

US auto companies like Ford and GM were quite accustomed to producing hundreds of thousands of autos and engines that were reliable, dependable and consistant in quality that no one offshore could duplicte. RR never built 250,000 V-type engines in a year when Ford did that and more annually for a decade before the war as did many other manufacturers! 

Simply installing machine tools to give capacity for numbers does not guarantee consistancy or quality for your new-found quantity output ability. That was the problem RR had. They never manufactured 50,000+ annual units of anything ever before! They had absolutely no experience in large quantity production of complex engines and the attendant quality control consistancy needed to ensure that the 1st engine off the line was as reliable as the last in a given annual prodution run.

There was no way RR could go from a couple hundred engines a year to 200,000 as they did without immense changes to their philosophy of quality control. Simply building factories that could put out quantity didn't mean that modern quality control was automatically apparent. The Merlin's success was partly due to the influence of Packard's modern techniques of quality, mass production consistancy an innovation. RR adopted many of the successful modern production techniques pioneered at Packard and duplicated by most american auto manufacturers. 

Ford and Chevrolet alone each produced over 1 million cars in 1941 before our entry into the war. No one on the planet produced vehicles or engines of those numbers with consistantly reliable reputations, no one.

So did Rolls Royce benefit from Packard's industrial quality techniques? Of course. There is no denying it.

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## Hop (May 17, 2006)

> My point is simply that Packard improved the Merlin at a time when it was technically beyond RR and introduced mass production and quality control concsistancy that was beyond RR as well.



So which are you claiming, that the Merlin wasn't reliable in 1941, or that is wasn't being mass produced?

The answer is that it was relaible and in mass production, so the argument that it was Packards input that made that possible falls down.



> Getting all you want for free was pretty damned good deal when compared to the relative trickle GB imported before the war.



Certainly the extra fuel came in handy, especially with the enormous size of the strategic bomber offensive in 1944 and 1945, but pre war supplies were hardly a "trickle". As of mid 1941, imports from non-US sources of 100 octane were 500,000 tons a year. In November 1940, just after the BoB, stocks of 100 octane in the UK amounted to 500,000 tons, and the air ministry was justifying the large amount of fuel purchased by saying it would have commercial use after the war, and was a "capital asset that will not depreciate".

To put those figures in perspective, Fighter Command consumed about 25,000 tons of 100 octane during the BoB, and the 500,000 tons in Nov 1940 was, according to the report, enough for 80 weeks consumption.

These figures were dwarfed by the expansion later in the war, of course, but hardly represent a trickle, especially by the standards of the much smaller forces in the early war years.



> The American auto industry more than excelled in war material production.



There's no doubt of that. But it's a huge stretch to go from that to claiming that Packard was required to productionise the Merlin, and to improve it's reliability, when both had been done long before Packard became involved. The myth of Rolls Royce craftsmen hand building, and hand fitting, Merlins until Packard came along is just that, a myth.

It's also true that the British motor industry carried out the same functions. For example, it was largely the car inductry that mass produced the Bristol Hercules, turning out close to 60,000 of them before the end of the war. Morris cars created the Castle Bromwich Spitfire plant, that produced more than 15,000 Spitfires during the war.

Don't forget, Britain, with just over half the population of Germany, produced more aircraft, and far more in terms of weight, and far more aero engines, whilst employing less workers in the aircraft industry than Germany.



> Simply installing machine tools to give capacity for numbers does not guarantee consistancy or quality for your new-found quantity output ability. That was the problem RR had.



So you are claiming quality problems for Merlins before Packard became involved? Could you provide some evidence of that (apart from the early models in 1937 and 1938, when the design was still being developed)

Because the RAF seemed very happy with the quality and reliability of the Merlin once it was properly in service during the war. 



> They had absolutely no experience in large quantity production of complex engines and the attendant quality control consistancy needed to ensure that the 1st engine off the line was as reliable as the last in a given annual prodution run.



Which is probably why they also drew experience from the motor industry.



> There was no way RR could go from a couple hundred engines a year to 200,000 as they did without immense changes to their philosophy of quality control.



I don't think they ever went to 200,000 units a year. 



> Simply building factories that could put out quantity didn't mean that modern quality control was automatically apparent. The Merlin's success was partly due to the influence of Packard's modern techniques of quality, mass production consistancy an innovation.



So you are saying that until 1941 the Merlin wasn't reliable? Again, this isn't borne out by the facts. The fact is, long before Packard became involved, the Merlin was being mass produced with excellent quality. Now certainly Packard mass produced a lot of Merlins, and their contribution made sure even more Merlins could be produced, but the Merlin was already in mass production, and already reliable, before Packard became involed. And again, it was the Packard engines that had more of a reputation for problems than the British built engines.



> Ford and Chevrolet alone each produced over 1 million cars in 1941 before our entry into the war. No one on the planet produced vehicles or engines of those numbers with consistantly reliable reputations, no one.



Of course not, America was a much larger country, with far more people, and far more cars. But it's a huge, and unwarranted, jump to go from saying America produced more cars than anyone else to saying only America could mass produce with quality. The historical record is that in the late 30s Rolls Royce developed the Merlin for mass production and sorted out the quality.

If you want to claim Packard was responsible for this, you have to show that the Merlin was either unreliable before Packard became involved (ie in 1940 and 1941) or not being mass produced. Neither is true.

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## Twitch (May 17, 2006)

Dude, whatever you say man. Most people who have delved into the subject of mass production and quality control know that American industry won the war. The Merlin was a great powerplant. Packard helped make it better. Think what you want. I don't care.


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## Bullockracing (May 20, 2006)

Twithch, do you have a source for where I can find more info on how the Packard engines were made and tested, etc.? I have books that mention the production figures and outputs and the normal statistics, but not anything about how the motors were assembled/tested. Actually, does anyone have information on other engines as well, i.e. Jumo, Allison, BMW, etc?


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## helmitsmit (May 22, 2006)

Bullockracing said:


> Twithch, do you have a source for where I can find more info on how the Packard engines were made and tested, etc.? I have books that mention the production figures and outputs and the normal statistics, but not anything about how the motors were assembled/tested. Actually, does anyone have information on other engines as well, i.e. Jumo, Allison, BMW, etc?



I think it is true that Packard helped RR a lot in the later years in terms of producing the merlins in huge quantities. However, it is more likely that, due to the more engines produced, the less reliable the merlin became. This because it is impossible to check every engine you produce you've just got to try and get the measurement consitant. 

Is there any info about a certain rpm which made the Parcard merlins run rough? I heard this from a Spitfire mk XVI pilot.


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## pasoleati (Aug 5, 2007)

This Twitch fellow is unfortunately a typical American, i.e. a brainwashed idiot. First, by comparing American war production to the pre-war production, it was no better than that of the UK or Germany. That is according to a recent study published by University Press of Kansas. Second, Packard intruduced NO improvements on the Merlin, not a single one. Third, Packard had to change the blueprints for their workforce was composed of typical Amis as described above whereas RR had SKILLED workforce who could think with their own brains.


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## trackend (Aug 5, 2007)

pasoleati said:


> This Twitch fellow is unfortunately a typical American, i.e. a brainwashed idiot.



That was a stupid statement to make Paso you cannot just make sweeping remarks like that without it being you that looks the idiot I suggest you delete that very silly line and think before pressing the keys next time.

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## DerAdlerIstGelandet (Aug 5, 2007)

pasoleati said:


> This Twitch fellow is unfortunately a typical American, i.e. a brainwashed idiot.



You just made yourself look like more of an idiot by making that comment.

Dont even start with the anti american bashing here. We do not tolerate it. There are plenty of websites out there where you can post your anti american brainwashed bullshit.

For your insult to him, you get your first official warning. You only get one from me....




pasoleati said:


> Third, Packard had to change the blueprints for their workforce was composed of typical Amis as described above whereas RR had SKILLED workforce who could think with their own brains.



What are you implying? I am an American, are you saying that I can not think with my own brain?

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## pasoleati (Aug 5, 2007)

You are not Twitch...


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## drgondog (Aug 5, 2007)

helmitsmit said:


> I think it is true that Packard helped RR a lot in the later years in terms of producing the merlins in huge quantities. However, it is more likely that, due to the more engines produced, the less reliable the merlin became. This because it is impossible to check every engine you produce you've just got to try and get the measurement consitant.
> 
> Is there any info about a certain rpm which made the Parcard merlins run rough? I heard this from a Spitfire mk XVI pilot.



I never noticed 'roughness' at high rpm bid did on warm up at low revs in the only 51 I ever flew.

I don't know where one could find the statistics to compare RR Merlin reliability in spring 1944 vs Packard - but all of the early 51 groups' records will show many aborts and suspected losses to engine failures. I have my own data base for the 355th FG and it alone lost 6 pilots POW/KIA solely and tracable to engine failure (not the dreaded coolant loss) in March and April 44.

I just quickly glanced at the 358FS ops reports and noted 2 losses plus 20 aborts to 'enine troubles' plus another 6 to oil pressure issues alone... in aprill 1944 alone - it was the same in March but fewer Mustang missions as the first one was March 8.

If someone here with depth of resources for a typical 'spitty' squadron, maybe they can look theirs up. However, in all fairness, mission durations between 51s and Spits would be a severe complication from a statistical POV and conclusions


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## FLYBOYJ (Aug 5, 2007)

pasoleati said:


> You are not Twitch...


No he's not but he is a moderator here and one more ignorant statement or response and you're out of here pal - understand?!?!?


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## trackend (Aug 5, 2007)

Its all gone a bit adrift on a couple of threads recently Joe why cant guys have a discussion without it degenerating into the Yanks this or the Brits that spoils it for the rest of us, all rather daft.

Anyway sorry I digress swinging it back to what this thread is about I am not up on the technicalities but I have seen on a couple programs including the history channel that stated the quality of raw materials available in the US enabled manufactures to produce a higher quality engine even though the spec was the same.


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## FLYBOYJ (Aug 5, 2007)

trackend said:


> Its all gone a bit adrift on a couple of threads recently Joe why cant guys have a discussion without it degenerating into the Yanks this or the Brits that spoils it for the rest of us, all rather daft.


Agree Track - especially when this crap comes from a new-bee.


trackend said:


> Anyway sorry I digress swinging it back to what this thread is about I am not up on the technicalities but I have seen on a couple programs including the history channel that stated the quality of raw materials available in the US enabled manufactures to produce a higher quality engine even though the spec was the same.


Probably true - I know out of necessity that the UK was recycling as much as possible (seen photos of pots and pans being collected for the war effort). Although the alloying of materials cane be controlled, the quality of such raw materials is always a bit degraded when recycled components are used. I know Reynolds Aluminum had a problem with this in the early-mid 80s.


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## trackend (Aug 5, 2007)

Thats interesting Joe. I can well imagine the effect of re smelting, we have had a deterioration in believe it or not Rails of all things when machining it or when its ultrasonically tested we come across all sorts of impurities which degrades its life expectancy a hell of a lot.
I would have thought using re smelted alloys in the aero industry was something that needs very close monitoring.
lee


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## DerAdlerIstGelandet (Aug 5, 2007)

pasoleati said:


> You are not Twitch...



Does that matter? One more smart ass comment and your history...


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## Hop (Aug 5, 2007)

There wasn't really a shortage of materials in the UK. To take aluminium as an example, Britain produced or imported just over 1,520,000 tons, and recycled just under 450,000 tons.

It's not hard to keep the good stuff for airframes when it comprises 75% of the aluminium, and use the low grade stuff for seats and handles and mess tins etc.



> If someone here with depth of resources for a typical 'spitty' squadron, maybe they can look theirs up. However, in all fairness, mission durations between 51s and Spits would be a severe complication from a statistical POV and conclusions



I don't think you can draw accurate comparisons when aircraft are flying different missions, using different engine settings, and subject to different maintenance regimes, The best comparsion would be to look at the difference between Spitfire IX and XVI squadrons in 2nd TAF in 1945, as they were essentially the same aircraft, flying the same missions, for the same air force. The only difference between them was the Spitfire IX used British built engines, the XVI Packard Merlins.

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## FLYBOYJ (Aug 5, 2007)

Hop said:


> It's not hard to keep the good stuff for airframes when it comprises 75% of the aluminium, and use the low grade stuff for seats and handles and mess tins etc.


Yes and no...
When you have aluminum ingot that is on the "low end" of the tolerance, it still meets specs but may have a higher level of impurities. Those impurities may come back and haunt you later on as when the "part" is subjected to environmental conditions, things like intergranular corrosion will develop more easily than if the material was at the upper end of the spec to begin with. As stated, I was involved with this in the early 80s. Several manufacturers refused to used Reynolds in their aircraft because of this...


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## glennasher (Aug 5, 2007)

I don't know anything about technical stuff, but I did overhear a Mustang pilot at an airshow, talking about the Merlin in his Mustang, and he swore the RR he now had, ran smoother than the previous Packard. That is, of course, just hearsay, but he firmly believed it. I don't know any reason to disbelieve him. He does (did) a lot of aerobatics in his bird, and had a pretty good feel for his plane.


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## k9kiwi (Aug 5, 2007)

A collection of notes from varying sources.

Wiki



> The initial Packard modification on the Merlins were done on this engine by changing the main bearings from a copper lead alloy to a silver lead combination and featured indium plating. Indium plating had been developed by the General Motors (Pontiac Division) to prevent corrosion which was possible with lubricating oils that were used at that time. The bearing coating also improved break-in and load carrying ability of the surface. British engineering staff assigned to Packard were astonished at the suggestion but after tear down inspections on rigidly tested engines they were convinced the new design offered a decided improvement.





> The real improvement Packard incorporated into the Merlin was adopting the Wright supercharger drive quill. This modification was designated the V-1650-3 and became known as the "high altitude" Merlin destined for the P-51. The ((two speed, two stage supercharger)) section of the V-1650-3 featured two separate impellers on the same shaft which were normally driven through a gear train at a speed of 6.391:1. A hydraulic gear change arrangement of oil operated clutches could be engaged by an electric solenoid to increase this ratio to 8.095:1 in high speed blower position. The high speed gear ratio of the impellers was not as great as the ratio used in the Allison but speed of the impeller alone was not the factor that increased the engine performance at altitude. The double staging of the compressed fuel/air mixture provided the boost pressure through a diffuser to the intake manifolds which increased the critical altitude of the power plant.





> When the first of the Packard-built Merlins arrived in Britain, the engineers at Rolls-Royce stripped it down and were amazed to find that the production-line built Packard engine, far from being as bad as they expected it to be for component tolerances, was actually better. Up until then, R-R Merlins were hand built, every face being finished off by hand, and this time-consuming process placed great strain on the production capability of the skilled workforce involved in the manufacture of these engines. The Packard engine changed many minds, although there were still some at R-R who remained unconvinced of the quality of the American engine, produced as it was by a largely unskilled and semi-skilled female workforce. In the end, the engine's performance removed any doubts about its quality and workmanship.



Next, by reading the flamin manual (Air Publication 2062 A C) for the Lancaster it shows clearly that the RR Merlin XX, 22 or 24 engines were fitted with SU carbs while the Packard Merlin 28 or 38 had Bendix Stromberg pressure injected carbs.

Also the 28 and 32 engines achieved a significant saving in fuel compsumption.

Boost at +7 lbs./sq.in, RPM 2,650 Medium boost at 5,000 feet altitude usage per hour

Packard 240 gallons
Rolls Royce 260 gallons

It should also be noted that at no point in the AP for the Lancaster is any warning given about a reduction in performance between the two engine types.

That only one type of engine would be used on a particular airframe is of course obvious, as later marks, even batches ordered used immersion pumps and different fuel / oil systems altogether to the early models.

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## mkloby (Aug 5, 2007)

FLYBOYJ said:


> Yes and no...
> When you have aluminum ingot that is on the "low end" of the tolerance, it still meets specs but may have a higher level of impurities. Those impurities may come back and haunt you later on as when the "part" is subjected to environmental conditions, things like intergranular corrosion will develop more easily than if the material was at the upper end of the spec to begin with. As stated, I was involved with this in the early 80s. Several manufacturers refused to used Reynolds in their aircraft because of this...



Especially the havoc that a salt water environment can have on aircraft...


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## trackend (Aug 6, 2007)

k9kiwi said:


> Next, by reading the flamin manual (Air Publication 2062 A C) for the Lancaster it shows clearly that the RR Merlin XX, 22 or 24 engines were fitted with SU carbs while the Packard Merlin 28 or 38 had Bendix Stromberg pressure injected carbs.



That don't surprise me the SU's have always been really beautifully made carbs but noted to be more juicy than strombergs


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## kool kitty89 (Jul 30, 2008)

In the case of the RR Merlin 20 series the boost limitations were continually increased from +10.34 psi, to +12 psi (first in low gear, then later high), to +14 psi (in low), and eventually +16 psi (in high gear) for WEP.

This resulted in power going from 1,300 hp to 1,390 hp, 1,480 hp, and finally ~1,510 hp.

From: Hurricane Mk II Performance
http://www.wwiiaircraftperformance.org/hurricane/merlin-xx-limits-10june40.jpg
http://www.wwiiaircraftperformance.org/hurricane/merlin-xx-15nov40.jpg
http://www.wwiiaircraftperformance.org/hurricane/merlin-xx-18nov42.jpg
http://www.wwiiaircraftperformance.org/hurricane/merlin-xx-21nov42.jpg
http://www.wwiiaircraftperformance.org/hurricane/merlin-xx-curve-c1.jpg



The V-1650-I (based on the Merlin 20 series) was rated for 51.1" Hg MAP (+10.34 psi) for take-off and emergency power and I haven't seen doccuments for increased boost limits for the engine.


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## mhuxt (Jul 30, 2008)

FWIW, Merlin 25s used +18 in the Mosquito FB.VI. Not sure what the Packard Merlins had in the 225, though I imagine if I keep reading, I'll find out eventually.

Then there's the whole 150 octane thing....


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## kool kitty89 (Jul 30, 2008)

Yes, but increases up to the +16 psi were all on the same fuel (100/130 octane iirc) the restricting factor had been structural concerns (not detonation issues), and as testing on the engine progressed higher and higher power settings were allowed.

I just don'r know if this was done on the V-1650-1. (the answer would also introduce some more data to the Allison Vs Merlin P-40 comparison thread)


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## mhuxt (Jul 30, 2008)

Yes, +18 was on the "normal" fuel.


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## kool kitty89 (Aug 3, 2008)

Ok both the Merlin 24 and 25 were rated for max +18 psi resulting in ~1640 hp at ~2,250 ft. With ~1510 hp in high gear at ~9,300 ft.


As shown in the link for graph I posted earlier: 
http://www.wwiiaircraftperformance.org/hurricane/merlin-xx-curve-c1.jpg

And shown for high high gear as well here:
http://www.wwiiaircraftperformance.org/hurricane/merlin-xx-curve-c2.jpg


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## P-Popsie (Oct 27, 2008)

evangilder said:


> They didn't really re-engineer the Merlins. The drawings that were provided were not the usual customary drawings that American engineers are used to, so they had to tear it down and do the drawings that they expected to build the motors.



if by chance you had an online copy of these american conversion blueprints or a location for them i would be most grateful to you for them.


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## P-Popsie (Oct 27, 2008)

Well i've read a bit more of this rather heated thread i could of sworn the original idea was best engine to which my two cents worth goes to the merlin Packard or RR for two reasons one no other engine to my knowledge was used so universially Fighter, Night Fighter, Light Bomber, Heavy Bomber, All classes of A/C in the U.K arsenal were powered by the merlin. Moreover this is the only A/C engine i know of to be used in armoured vehicles if versitility = best then there's my vote


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## kool kitty89 (Oct 27, 2008)

See my post #96 which brings up an important point -pertinant to the original question- not mentioned previously. (despite the long thread )


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## Skip M (Nov 2, 2008)

P-Popsie said:


> Moreover this is the only A/C engine i know of to be used in armoured vehicles if versitility = best then there's my vote



What about all of those funny round things in M3 light, M3 medium, and M4 and M4A1 medium tanks?


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## Skip M (Nov 2, 2008)

In reading this thread that the contributers to this forum have their own thoughts and do not repeat the same old lines. That is why I joined this forum.

Not all that much has been brought up on the very different labor forces that each country had to work with. I do not believe that England could have built a Packard Merlin and I know the US could not build a RR Merlin in the numbers needed. England had the highest percentage of machinists in their population in the world. This goes back to the beginning of the industrial age. This type of skilled worker can do a large number of jobs and hand fitting is the norm and the mark of a craftsman. You do not need to give tolerances for this type of worker. As long as you can move them to the industries that you need at the time and you have enough you will get a RR Merlin engine. Germany and Japan allowed many of their craftsmen to be drafted and their quality suffered. The US had a higher percentage of unskilled and agricultural workers then England in spite of our industrial output. Moreover most of our industries were fairly young and when they started they had train a fresh work force. No other country had the success at that time of creating industries with this type of work force. Instead of taking years to make a craftsman you take days or weeks to teach one small job to a person. The skills of the craftsman is broken down into many jobs. This works very well with mass production. This allows you to go into farm country and in a year build a factory and be producing tanks. aircraft, engines, radar, and build thousands of ships. Craftsmen do not like this type of work as it is below them. I do not remember the book but in the 1960's I was reading that the RR Merlin was a little more powerful and smoother. The Packard easer to fix and keep flying. You did not have to hand fit the replacement parts. Both countries built the correct engines for their work forces.

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## kool kitty89 (Nov 3, 2008)

I seem to remember that after Packard started building Merlins, they colaborated with Rolls Royce to an extent after modifying the engine for US manufacturing techniques, and made some other improvements and modifications that could be transfered over to Rolls Royce. Some allowing Rolls Royce to standardize many of their components as well, though their overally manufacturing system and design remained distinct to the Packard version. (I believe the Superchargers chosen for the 2-stage version was particularly different from the British version, using components from Wright designed superchargers, while RR added the larger Vulture's supercharger)

Testing by Packard also further helped develop and inmprove the engine in a much shorter time than Rolls Royce would have alone. 

The smoother qualities and higher performance of the Rolls Royce versions is certainly often mentioned in anecdotes, as well as some accounts from maintainers and from racing.


I think the comparison of the Merlin 20 series and the V-1650-1 (based on the Merlin 28 ) isn't quite the same though, as the perormance diifference between the two at similar settings should be less significant as the designs were quite similar in performance generally.
However, as I've mentioned the increases in boost limits on the RR Merlin do seem to have been applied to the Packard engine, in fact (according to the P-40F engine refrence sheet I listed above) the Packard engine hadn't even been listed with the normal +12 lbs boost (~54.4" Hg MAP) initially applied to the RR merlin XX. The take-off and WEP are both rated at 1,300 hp at 3,000 rpm with only +10.3 lbs boost (51.1" MAP).


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## pbfoot (Nov 3, 2008)

P-Popsie said:


> All classes of A/C in the U.K arsenal were powered by the merlin. Moreover this is the only A/C engine i know of to be used in armoured vehicles if versitility = best then there's my vote


don't remember any flying boats hqaving the merlin


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## kool kitty89 (Nov 3, 2008)

And in addition to the M3 and M4 tanks already mentioned (using the R-975), the M4A6 used the D-200 (a version of the R-1820, using Diesel) as well as the M6 heavy tank powered by the G-200. (a version of the R-1820, running on gasoline)


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## antoni (Nov 6, 2008)

Interesting as the six page discussion on stresses in engine blocks is, the answer to the question that started this thread is simple and straightforward and explained in the second post, a case of not comparing like with like. 

Three types of Merlin, all from the XX series, were used by the Lancaster Mk I. Merlin XX, 22 and 24. Aircraft fitted with Packard built Merlins were always given a different Mk number.(1) In the case of the Lancaster, when fitted with Packard Merlins it was called a Mk III. Aircraft built under licence outside of the UK were also given their own Mk number and a Lancaster Mk X is essentially the Mk I built in Canada. As you might expect the Mk X also used Packard Merlins. The Mk IIIs and Mk Xs used Merlin 28, 38, and 224, Packard built versions of the XX, 22 and 24 respectively.(2) Engine performance differs according to the source used but generally the Packard Merlin is said to have been slightly more powerful compared to the RR equivalent (see the attachment). Also they were well liked by ground crews because they came with an extensive tool kit. So the difference in performance is due to different variants of the Merlin and not to where, how or by whom they were made. There is a touch or irony here as most Lancaster Mk Is had Merlins built by Ford not RR. However, unlike Packard Merlins, it was difficult to tell if a Merlin was built by RR or Ford. The RAF did not own a single Merlin. They were all owned by RR and leased to the RAF. They had a shelf life of five years or 500 hours after which they were returned to RR and rebuilt as new. Ford did not sell any of the +30,000 Merlins it manufactured at Manchester to anyone other than RR. When RR leased them to the RAF it ensured that no ‘Ford’ markings appeared on the engine. If it had been different I am sure that, like the Packard Merlins, there would be comments that the ones with the blue ovals weren’t quite as good as the genuine RR. As nobody could tell the origin nobody noticed a difference. 

The notion that while Packard could only mass produce some sort of inferior clone of the Merlin engineering masterpieces coming out of the RR factories is risible. RR factories at Derby, Crewe, and Glasgow as well as Ford’s factory at Manchester were all mass production, using similar naïve work forces as Packard. It was in fact Ford that showed RR how to mass produce the Merlin, and they were built to Ford standards, with much of the machinery to do it designed, built, and supplied by Ford. 

When the Ford Motor Company Ltd opened its new factory at Dagenham in 1932, the Chairman, Sir Percival Perry, and his successor Rowland Smith, made sure the Air ministry were aware of their production facilities and expertise. Sir Wilfrid Freeman, Commandant of the RAF staff college at Andover became a friend and encouraged students from the college to visit Ford as part of their management training. Not long after the outbreak of war, Freeman, then the Assistant Chief of Air Staff, suggested that Ford should be asked to build, equip and manage a factory for their own style of production line to produce Merlin engines. The factory would be owned by the government and a licence arranged for the Merlin XX series. 

Perry received Freeman’s letter on 22nd October 1939. He immediately contacted Rowland Smith and the two of them met Freeman in Whitehall. A team was assembled and on 2nd November they went to Derby to meet Lord Hives the chairman of RR and his production manager H.J.Smith. The two sides already held each other in high esteem and worked well together from the start. RR offered Ford everything other than any actual manufacturing assistance. By mid-November, Smith told Freeman the cost for building and equipping the shadow factory would be in the region of £7,000,000. It was immediately accepted. The actual cost was £6.6 million. An 84 acre site at Eccles in Manchester was selected. Building began in March 1940. Smith was appointed as Controller and part of the former Ford factory at Trafford Park was used for preparatory work by draughtsmen and tool-makers. It was during this period that RR received a shock. The events were described by Sir Stanley Hooker. (3) 

“A number of Ford engineers arrived at Derby and spent some months examining the drawings and manufacturing methods. One day, their chief engineer said ‘You know, we can’t build the Merlin to these measurements’.
“I replied loftily ‘I suppose that is because the drawing tolerances are too difficult for you, and you can’t achieve the accuracy’.

“On the contrary, the tolerances are far too wide for us. We make motor cars far more accurately than this. Every part on our car engines has to be interchangeable with the same part on any other engine, and hence, all parts have to be made with extreme accuracy, far closer than you use. That is the only way we can achieve mass production’.”

In the following silence, one of Hooker’s colleagues asked what Ford proposed. He was told complete new drawings were required, to Ford standards. It took about a year to produce the 20,000 drawings. Hooker went on to say that this led to an enormous success with Merlins coming out “like shelling peas, and very good engines they were too”.

In the meantime machine tools that were a vital part of Ford’s construction methods had to be designed and built and a new workforce created and trained in a new philosophy of work. Tools to make the tools that made the components had to be designed and procured from specialists. Every one of the companies capable of such work in the UK was working at full capacity. Much was not even available here at that time. A crankshaft machining tool was sourced in the USA. A U-boat put it on the bottom of the Atlantic and the same fate befell its replacement. The third finally got through. Boring equipment clearly labelled ‘Ford Motor Company, Trafford Park, Manchester, England’ .was shipped from Switzerland through occupied France and hostile Spain to Gibraltar and on to England. The Swiss firm warned the Germans that as a neutral country they were entitled under international law to trade with anyone, and any interference with this right would bring a halt to the supply of any similar equipment to Germany. 

The first Ford designed machine tools were made as early as August 1940 and sent to the RR factory at Crewe. While the factory at Eccles was being constructed a shadow factory at Derby was set up alongside the main Derby works. 190 Dagenham employees were sent there and started proving the various machine tools and manufacturing processes. They also spent time working alongside Rolls workers in the main factory to become thoroughly conversant with all the parts of the Merlin. By September 1940 the first building for the new factory were complete. 2,300 w0rker were employed there that winter, including those that had trained at Derby. The whole factory was finished in May 1941 and the first five engines delivered in June. By 1943 Ford was making 200 a week. Ford’s investment in machinery and management paid off handsomely. The 10,000 man-hours needed to produce a Merlin dropped to 2,727 in three years. The unit cost fell from £6,540 in June 1941 to £1,180 by the war’s end. The percentage of engines rejected by the Air Ministry was zero. Not one engine of the 30,400 produced was rejected. 

--------------------------------------------------------------------------

(1) It is often said that this was because Packard Merlins were built to metric standards and required a completely different set of spares. However, those that restore and repair Merlins say that parts are interchangeable.
(2) Ford in the USA was given the opportunity of building Merlins there. Henry Ford passed up the chance, expressing the opinion that Britain was unlikely to win the war. Packard seized the opportunity and their Merlins were produced on a similar basis to the Ford versions built in Britain, but with Stromberg carburettors and one or two other differences such as silver-lead-indium bearings and a different supercharger drive. 
(3) Not Much of an Engineer, Crowood Press.


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## Glider (Nov 6, 2008)

The idea of the Germans watching such a critical piece of equipment go past their noses is almost to good to be true. I am a little suprised that it didn't have a road traffic accident along the way.

The only thing I can add is a number of years ago the BBF Lanc had three RR built engines and one Packard. They mentioned that the only difference was that the Packard engine ran a little warmer than the RR engines. It wasn't much and wasn't a problem, just a point of interest


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## kool kitty89 (Nov 16, 2008)

Good info, I han't known much about Ford's involvement.

Coinsidentally (US) Ford Motors was developing a 1,650 in^2 diplacement V-12 aircraft engine as one of the USAAC's "hyper engine" concept. (I don't know much else except it used an integeral lower rear mounted turbocharger with an electric motor to reduce turbo-lag)


This still doesn't explain why the Packard V-1650-1 was only rated for 1,300 hp at take-off/WEP and 51.1" Hg MAP (+10.3 psi boost). At least that's what a USAAF engine data chart for the P-40F/L says.

http://www.raafwarbirds.org.au/targetvraaf/p40_archive/pdfs/1650-1.pdf


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## MiTasol (May 8, 2013)

I saw a document many years ago by the Brits (War Ministry or similar) on which Merlins were most reliable and the answer was the ones made by the Austin Motor Car company. The main thing as previously discussed was that not all Merlins were same horsepower, or had the same blower output, gear ratio etc.

That said it is probable that Packard did have to redraw the Merlin's because the English use first angle projetion and Americans use third angle projection. I know that when the US started producing Hispano 20 mm cannons from the Brit drawings many parts were not interchangeable for just this reason so it stands to reason that all drawings would have been converted to keep Murphy at bay.


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## nuuumannn (May 9, 2013)

This thread goes back a bit. I remember talking to a chap from the Rolls Royce Heritage Trust about Packard engined Spitfires as a place I worked at had a Spit XVI; I said that I'd heard that Packard sent a little tool kit with each engine sent over (can't remember where I heard that?) and the RRHT guy said that Rolls didn't supply such a thing with RR built Merlins because they didn't need them!


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## Jabberwocky (May 9, 2013)

nuuumannn said:


> This thread goes back a bit. I remember talking to a chap from the Rolls Royce Heritage Trust about Packard engined Spitfires as a place I worked at had a Spit XVI; I said that I'd heard that Packard sent a little tool kit with each engine sent over (can't remember where I heard that?) and the RRHT guy said that Rolls didn't supply such a thing with RR built Merlins because they didn't need them!


 
The reason that Roll-Royce manufactured Merlins didn't need them wasn't that they were more reliable, its that the Packard Merlins used slightly different dimensions for things like bolt heads and nuts. As a result, you needed tools operating on American measurements to work on them. When Packard redesigned the engine, they changed most of the measurements to US standards and adapted the engine to use US tooling.

A British workshop would have plenty of tools using British standard measurements, but I'd doubt that they'd have many that would fit standard US dimensions.

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## glennasher (May 9, 2013)

Hearsay only, I've been re-reading William Dunn's autobiography (he flew in the RAF and USAF, flying Hurricanes, Spitfires, P-47s and P-51s in combat, and he swore, several times, that the Rolls-Royce Merlins ran smoother and better than the Packards. That was his impression, anyway, and I'm just repeating what he wrote.

Then again, from other sources I can't recall offhand, that the Packards were better and easier to work on. This was something regarding Lancasters, so it would be different than the Merlins powering fighter aircraft.

Since those opinions are contradictory, I don't know who to believe. Dunn comes off very credibly, though, even if he might be a bit prejudiced. He really, REALLY loved the Spitfires..............


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## buffnut453 (May 9, 2013)

glennasher said:


> He really, REALLY loved the Spitfires..............



What a sensible chap!


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## drgondog (May 9, 2013)

glennasher said:


> Hearsay only, I've been re-reading William Dunn's autobiography (he flew in the RAF and USAF, flying Hurricanes, Spitfires, P-47s and P-51s in combat, and he swore, several times, that the Rolls-Royce Merlins ran smoother and better than the Packards. That was his impression, anyway, and I'm just repeating what he wrote.
> 
> Then again, from other sources I can't recall offhand, that the Packards were better and easier to work on. This was something regarding Lancasters, so it would be different than the Merlins powering fighter aircraft.
> 
> Since those opinions are contradictory, I don't know who to believe. Dunn comes off very credibly, though, even if he might be a bit prejudiced. He really, REALLY loved the Spitfires..............



Bill Dunn never flew a P-51 in combat. Interestingly all his kills save two were in Hurricanes - with one in a Spit IIa with 71 Squadron and one in a P-47D - 406FG-9th AF


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## nuuumannn (May 9, 2013)

> A British workshop would have plenty of tools using British standard measurements, but I'd doubt that they'd have many that would fit standard US dimensions.


Yeah, I knew that. I guess you missed the gist of what I was writing; the anecdote was a joke cracked by the RRHT guys.


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## fastmongrel (May 9, 2013)

nuuumannn said:


> This thread goes back a bit. I remember talking to a chap from the Rolls Royce Heritage Trust about Packard engined Spitfires as a place I worked at had a Spit XVI; I said that I'd heard that Packard sent a little tool kit with each engine sent over (can't remember where I heard that?) and the RRHT guy said that Rolls didn't supply such a thing with RR built Merlins because they didn't need them!



My late father was an RAF instrument fitter and he said that they loved Packards because every engine came with the tool kit. He accidentally forgot to hand back some of the Packard supplied tools when he finished his service and I still have some of them. A set of AF taps and dies, a micrometer, a Crescent adjustable wrench, 2 x sets of Armstrong AF sockets and a set of Waukesha T handle nut spinners, all in war service chromeless finish. 

The Coastal Command Lancs he worked on postwar had a mix of Merlins from either UK or US and the engines were identical as far as controls and service life. Pilots were never bothered even when they might have had any combination of UK or US built engines on the same kite

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## nuuumannn (May 10, 2013)

Thanks for that little anecdote there Mongrel; I knew it was true, I just couldn't for the life of me remember where I'd heard about the tool kits.



> A set of AF taps and dies, a micrometer



Still useful today; you can keep the other stuff unless you work on warbirds or old British bikes! You don't use adjustable wrenches on aeroplanes today, they don't call them nut fXckers for nothing!


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## fastmongrel (May 10, 2013)

They come out of the toolbox occasionally but they are mostly for sentimental purposes.


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## nincomp (May 10, 2013)

antoni said:


> (1) It is often said that this was because Packard Merlins were built to metric standards and required a completely different set of spares. However, those that restore and repair Merlins say that parts are interchangeable.



This is what I have heard, but it has always been second or third-hand information. If that is the case, the tool kit would be needed for the American, who would not have the correct tools. Another possibility would be that engine is a hybrid of sorts. Most of the parts would use the British standard, but some of the parts unique to the Packard (superchargers and carburetor maybe?) would use the American standard. In this last case, a tool kit containing a mixture of British Standard and American standard would be needed since few mechanics would both types handy. Fastmongrel, if your set of Packard-Merlin tools is complete, would you tell me which of my silly-assed scenarios are correct?* 

Does anyone know for certain about the Packard engines? If Packard needed to retool in order to make British-spec engines, it makes sense that the initial production could be delayed.

In addition, what kind of threads did RR use? Would they be Whitworth threads, 60-degree threads, or some combination. This is not as stupid as it sounds since my Lee-Enfield No.4 Mk2 is such a hybrid according to some sources.** 

* Is the crescent adjustable wrench a left-handed model and does it only work on British bolts? 

** I do know that the barrel attaches to the receiver with Whitworth threads. I am too much of a weenie to disassemble the rifle to find out. The rifle is fairly rare as it is one of the last produced (1955), was never issued, and is unfired (except for its original proof-firing). If I damaged a screw or rounded the head of a bolt, I fear that I would a scream like a little girl.  ***

*** If any of you need to have this rifle in order to live a fulfilled and happy life, contact me.


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## wuzak (May 11, 2013)

I believe Packards used all British fasteners.

They would have been Whitworth, BSF (British Standard Fine) and BA (British Association).

There were differences between Packard and Rolls-Royce engines. The supercharger was the same design, but the supercharger drive on (some) 2 stage Packards was a Wright epicyclic unit, rather than the Farman system used by Rolls-Royce.

The main difference between those delivered to the US and those to the RAF was the propellor shaft. The US bound Packards had SAE splined shafts.


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## Milosh (May 11, 2013)

Packards also used AC Delco magnetos. The carbs were different > Packard - Bendix, R-R - SU.

The prop spline was the SAE No.50


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## GregP (May 12, 2013)

Interesting you should mention the splines. Joe Yancey made a prop adapter for engine break-in and it is 50 spine on the inside and 60-spline on the outside. Thus he can run either prop on an Allsion for break-in. Naturally, being a round, hollow cylinder shape, it is perfectly balanced as made, and very easy to use.

He has a WWII-era 6-blade Hamilton-Standard club prop, and it loads the engine just fine for break-in. When we first tried it, we set the pitch at 45° to start with and could not get it over 1,300 rpm. By the time we were done, the club was at 22.5° and we can get 2,500 rpm at 40 inches for break-in. When we called Hamilton for some data on the prop, they said that the prop was the property of the US Army Air Corps and since we weren't the USAAC, they would not give us any info!

Joe just used standard torque values for the grade 8 bolt sizes and it runs just fine. His break-in stand is a 2.5-ton Ford truck and he can pull the truck backwards, sliding on the tires, if he exceeds 50 inches!

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## Frankenerd (Dec 5, 2016)

the lancaster kicks ass said:


> in service RR ones were found to be more powerful yet packard were found to have slightly better fuel economy.........


I would dispute this. It depends on which variation of each engine you talk about. No R-R Merlin placed in service in any mass produced aircraft made more than 2080 HP and that figure had to be backed down to 2030 HP for longevity reasons. The Packard V-1650-9 in the P-51H on the other hand made 2,218, or 2,220 HP, ( Depending on the info source!) with a TBO more than twice that demonstrated in the Hornet.
On the other hand, R-R Merlins made 1,710 or 1,720 HP when the equivalent Packard -7 only made 1,595 HP. While this looks to be significant, it was in fact just differences in the amount of throttle opening and Boost permitted in order to pass different longevity requirements. The Reduction gear also had something to do with these numbers.
As an aside, the Allison V-1710 made 1800 and 2300 horse power with slightly less blower boost and slightly better fuel economy than either version of the Merlin above, due to the splayed valves and pent-roof combustion chambers. What it lacked was backfire screens in the intakes because of political choices in Washington DC.

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## tomo pauk (Dec 5, 2016)

<gets popcorn>

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## Frankenerd (Dec 5, 2016)

wmaxt said:


> That's interesting, in smaller recips, cars, bikes the key is to graduly vary thr rpms to avoid "setting" an engine in a particular rpm range. I had a guy bring me an old Honda bike for a tune-up, I found it would not rev beyond 4,500rpm because the owner never reved it beyond that, compression and tune were right on the numbers. The owner confirmed it was never reved higher and was very happy with the job said "It never ran better".
> 
> Break in time varies with the pistion ring type but I'll bow to your expertise - I'm ASE certified not A&P. Your much more familiar with aircraft.
> 
> wmaxt


Porsche claimed that >90% of all wear on the engine happened in the first 10 seconds after starting. At the Frankfurt Auto Show in 1972, they showed a car they claimed would last for 1,000,000 miles ( Km?) it had an electric oil pump that filled the galleries with oil before starting.
They also recommended that the break-in use varied throttle levels that included full blast sprints followed by longer periods of slow driving to let the engine cool. It was the hard use that broke it in and heat that damaged it. They claimed that a good break in only required about 100 miles.

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## Frankenerd (Dec 5, 2016)

Hop said:


> So which are you claiming, that the Merlin wasn't reliable in 1941, or that is wasn't being mass produced?
> 
> The answer is that it was relaible and in mass production, so the argument that it was Packards input that made that possible falls down.
> No, the simple statement above misses the point. During the entire war, R-R only built about 32,000 engines in their original plant. In about half that time, Packard built ~56,000. So no R-R did not learn how to build the Merlin at the same rate Packard did.
> ...


I guess it's all a mater of scale and how you define reliability. Durability?


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## Frankenerd (Dec 5, 2016)

Bullockracing said:


> Twithch, do you have a source for where I can find more info on how the Packard engines were made and tested, etc.? I have books that mention the production figures and outputs and the normal statistics, but not anything about how the motors were assembled/tested. Actually, does anyone have information on other engines as well, i.e. Jumo, Allison, BMW, etc?


My Grandfather's next door neighbor was a Government QC Inspector for Piston engines. He would routinely pick one and run it flat out for the entire 150 hours it was supposed go at varied throttle openings. They hated him at the engine plants, but he did not care. he said our boys are going to fight in those planes and they better be the best we can make them.

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## Frankenerd (Dec 5, 2016)

pasoleati said:


> This Twitch fellow is unfortunately a typical American, i.e. a brainwashed idiot. First, by comparing American war production to the pre-war production, it was no better than that of the UK or Germany. That is according to a recent study published by University Press of Kansas. Second, Packard intruduced NO improvements on the Merlin, not a single one. Third, Packard had to change the blueprints for their workforce was composed of typical Amis as described above whereas RR had SKILLED workforce who could think with their own brains.


Not true. We introduced MW-50 ADI!


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## pbehn (Dec 5, 2016)

Frankenerd said:


> I guess it's all a mater of scale and how you define reliability. Durability?


Your edit seems to confuse planes in the fw190 "shock" era 1941 with diver (anti V1) patrols 1944.


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## tomo pauk (Dec 5, 2016)

Yay!
Shooter is back.

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## Shortround6 (Dec 5, 2016)

tomo pauk said:


> Yay!
> Shooter is back.


Yep, the red color is near sure tell tale.

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## fastmongrel (Dec 5, 2016)

I see our very own village idiot is back.


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## fastmongrel (Dec 5, 2016)

Shortround6 said:


> Yep, the red color is near sure tell tale.



Dont forget the poor spelling and crazy grammar


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## DerAdlerIstGelandet (Dec 5, 2016)

Is that you shooter?


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## FLYBOYJ (Dec 6, 2016)

*Frankenerd* - you realize that you're replying to threads that are over 10 years old and that some of those members aren't even around anymore?!?!?

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## bobbysocks (Dec 6, 2016)

the thread has been ageing like a fine wine...just waiting for the a particular stroke of brilliance to weigh in.

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## KiwiBiggles (Dec 6, 2016)

I checked in to this page to see if anything else amusing had come in. The first entry on this page, made three years ago, is prescient:

"They come out of the toolbox occasionally but they are mostly for sentimental purposes"

Admit it, you miss Shooter when he's not around.

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## Sid327 (Sep 11, 2019)

(I hope it's okay to reactivate an old thread)

The Packard Merlin: How Detroit Mass-Produced Britain’s Hand-Built Powerhouse - Tested.com

A quote, word for word from the book ''The Merlin In Perspective'' by Alec Harvey-Bailey (RR Heritage Trust)



> "Packard built engines to very high standards of quality. Technical problems were not dissimilar from those experienced on British engines and when comparing like with like modification standards there was nothing to choose between engine sources.
> At squadron level there were times when there were fortuitous variations in reliability either way but when dealing with large numbers at Group or Command level there was good consistency in results between British and Packard engines.
> The 60,000 engines produced by Packard for the RAF and USAAF were of inestimable value.''..



As an added note: The RM17SM was fully cleared and type-tested @ 2,200hp but was never used. These modifications were included in the V1650-9 
RM17SM additional info from this book:
Max Type Tested HP (3000rpm +30lbs boost) = 2,200hp
Max Flight Clearance Tested Power = 2,340hp
Max Endurance Tested Power (3000rpm +36lbs boost Water Injection) = 2,640hp
Longest High Power Development Test. 100hours @ 3000rpm +18lbs boost) Two successful tests. 
Source: The Merlin In Perspective, Page 84.


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## fastmongrel (Sep 11, 2019)

Sid327 said:


> (I hope it's okay to reactivate an old thread)
> 
> The Packard Merlin: How Detroit Mass-Produced Britain’s Hand-Built Powerhouse - Tested.com
> 
> ...



Merlin's were not hand produced in any factory in Britain. At RRs Derby factory the engines were assembled by teams of workers who built an engine from the crankshaft up but they were built from production line produced parts. The reason for this Derby produced all the special and prototype engines two engines built side by side could be different marks of engine.

RRs factory at Crewe produced thousands of engines on production lines.

Ford's factory in Manchester produced thousands of engines on production lines.

The government factory in Glasgow produced thousands of engines on production lines.

Britain produced almost 100,000 Merlin's the USA produced almost 60,000 V1650s and Merlin's none of them apart from a few hundred prewar engines were hand made.

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## Reluctant Poster (Sep 12, 2019)

fastmongrel said:


> Merlin's were not hand produced in any factory in Britain. At RRs Derby factory the engines were assembled by teams of workers who built an engine from the crankshaft up but they were built from production line produced parts. The reason for this Derby produced all the special and prototype engines two engines built side by side could be different marks of engine.
> 
> RRs factory at Crewe produced thousands of engines on production lines.
> 
> ...


At the end of 1941 Packard had produced a grand total of 45 Merlin’s while Rolls Royce had produced approximately 23,000 mostly in Derby and Crewe. This is more than that marvel of mass production the Liberty. At that point only the Hispano V8 exceeded that number. Rolls Royce went from producing maybe a 1000 kestrels in a good year to over 18,000 Merlins a year in a 5 year period. It must have been an incredible apprentice program to train enough craftsmen to do that.
Here’s a couple of videos on Merlin production:


Here’s one on Wright production

Here’s how Chevrolet made car engines in the 30s

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## pbehn (Sep 12, 2019)

wmaxt said:


> The heat treating is the key, Flyboy, as in a forging a part, it is anealed (heated) to relive stress in the part. Engine blocks (automotive) are often not heat treated in manufacturing and left to cure naturaly. I learned about it studying manufacturing, in the 60s when Ford came out with its high performance 427/428 engines they would pick the earliest castings they could because the natural heating/cooling relived enough stress to allow the extream machining required (all FE blocks started as 331cid castings), and still not break in use.
> 
> This may/may not have anything to do with the Packard Merlin but is more of an "I wonder" on my part.
> 
> wmaxt


A long time since this was posted but this is barrack room metallurgy. Annealing as a process depends on the metal being heat treated and the results you require. The metal is heated above the re crystalisation temperature and allowed to cool, the temperature it is heated to, the time it is held there and rate of cooling depend on the metal itself, the shape and size of the object and the result required. Solution annealing of stainless steel is almost identical to quenching of carbon steel just at a higher temperature, annealing of carbon steel is rare because it usually involves heating to 900C plus then allowing to cool in the furnace itself. Normalising and stress relieving of steel is usually done using still air as a coolant and sometimes at lower temperatures.


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## wuzak (Sep 12, 2019)

Sid327 said:


> As an added note: The RM17SM was fully cleared and type-tested @ 2,200hp but was never used. These modifications were included in the V1650-9
> RM17SM additional info from this book:
> Max Type Tested HP (3000rpm +30lbs boost) = 2,200hp
> Max Flight Clearance Tested Power = 2,340hp
> ...



The V-1650-9 was a 100-series Merlin, not the RM.17SM. So similar to the Merlin 130/131 in the Hornet.

The RM.17SM had a larger supercharger - 12.7/10.7 vs 12.0/10.1 inch in the normal 2 stage engines.

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## Sid327 (Sep 12, 2019)

wuzak said:


> The V-1650-9 was a 100-series Merlin, not the RM.17SM. So similar to the Merlin 130/131 in the Hornet.
> The RM.17SM had a larger supercharger - 12.7/10.7 vs 12.0/10.1 inch in the normal 2 stage engines.



But without the Corliss throttle body? (I can't find much about this type of TB in the book mentioned, though I notice the Griffon 57/58's had this type of throttle body too).

Talking about TB's have you seen the throttle body the Soviets invented during WW2 which apparently was worth 100hp?


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## tomo pauk (Sep 12, 2019)

Sid327 said:


> ...
> Talking about TB's have you seen the throttle body the Soviets invented during WW2 which apparently was worth 100hp?



Polikovskiy's device?
Calum (member here) made one via 3D printing.
In real world, it worked best well under the rated height, though.

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## Sid327 (Sep 12, 2019)

Yes, that's it))
I saw this video about it a while back:-


Have you any info in regards to the Corliss (not sure if the spelling is correct, maybe two "l's").
The Brits had it on the Merlin 130/131 (I saw an actual engine with this type of TB at the FAAM Museum a long while ago) and I see the same type on the Griffon 57/58's too.


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## Reluctant Poster (Sep 13, 2019)

Sid327 said:


> Yes, that's it))
> I saw this video about it a while back:-
> 
> 
> ...



The 


Sid327 said:


> Yes, that's it))
> I saw this video about it a while back:-
> 
> 
> ...




The Corliss is very old device actually invented for steam engines. When it is fully open the passage is completely unobstructed unlike the butterfly valves typically used in aircraft engines. Modern high performance engines often use slide valves for the same reason. Rolls Royce also liked the Corliss as it had less friction making it easier to operate in remote installations like the Hornet.

Corliss Valves

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## fastmongrel (Sep 13, 2019)

The Corliss throttle valve was recently re-invented for 4 stroke Moto Cross engines. It was hailed as a brilliant new invention till someone pointed out it was patented in the mid 19thC and is probably a lot older

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## fastmongrel (Sep 13, 2019)

Half throttle

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## Sid327 (Sep 13, 2019)

Thank you for the info
''Reluctant Poster'' & ''fastmongrel'' 


I had seen the steam engine info after searching but was looking more specifically for a piston engine diagram or drawing.

Since having a gander at the Merlin 130 in the Navy Fleet Air Arm Museum (Yeovilton, U.K.) it interested and intrigued me.
Yes, understand about the slide throttles, SU carbs were a great example if a little slow responding to blipping the throttle (though using a much thinner oil helped).

Here are some decent pictures of the throttle housing on a Sea Griffon.

*pics found on the internet.*

Edit: fastmongrel, re your photo, what is this TB fitted to? I can see it's a Japanese make.


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## Reluctant Poster (Sep 13, 2019)

Sid327 said:


> Thank you for the info
> ''Reluctant Poster'' & ''fastmongrel''
> 
> 
> ...


One of my many Rolls Royce books has a cutaway I’m sure. When I return to the US I’ll find it

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## fastmongrel (Sep 13, 2019)

Don't know what engine it is
https://motocrossactionmag.com/amp/inside-secrets-of-the-innovative-rd-genius-throttle-body/

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## pbehn (Oct 19, 2019)

Ivan1GFP said:


> Hello PBehn,
> 
> Do you believe that this influenced the idea of the Rolls Royce Merlin requiring parts to be chosen and fit to a particular engine without a great concern for parts interchangeability? This is not intended as an argument but REALLY is a question. Redrawing for proper tolerances for parts interchange obviously took a fair amount of time for Packard and I wonder if that was an unnecessary cost for a short production run.
> Many prototypes need to be modified in some way for actual mass production.
> ...



Here is an old thread with the issue discussed at length. There seems to be a school of thought that Packard had a factory that mass produced Merlins while Rolls Royce made a few engines in a garden shed. Most Merlins were actually made in UK.


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## fastmongrel (Oct 19, 2019)

pbehn said:


> Most Merlins were actually made in UK.



Going on RR Trust figures 112,545 Merlin engines built in the UK
Going on wiki figures 55,523 Merlin and V1650 engines built by Packard and 6 by Continental


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## buffnut453 (Oct 19, 2019)

fastmongrel said:


> Going on RR Trust figures 112,545 Merlin engines built in the UK



Imagine the number of parts bins they must have had to hand-pick each component to ensure it matched the weights of the other similar components. Oh...and the number of precision scales involved to do that work. Those RR chappies were sheer geniuses. They must have invented a TARDIS to fit all of those people, machines and storage bins into their factories. 

I'll get my coat!


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## Ivan1GFP (Oct 19, 2019)

pbehn said:


> Here is an old thread with the issue discussed at length. There seems to be a school of thought that Packard had a factory that mass produced Merlins while Rolls Royce made a few engines in a garden shed. Most Merlins were actually made in UK.



Hello PBehn,

I followed this thread for a while much much earlier.
You answered a question that I wasn't asking. It wasn't about quantity of production and where the production was.
Ford in UK also produced quite a few Merlins though I don't recall the number, but again, that was not really the question.
It was more about the design of the engine that required a team to fit the pieces as I understand was the process used by Rolls Royce (and one which required skilled labor) as opposed to much less skilled labor required in a production line arrangement more typical of automobiles and whether that was a conscious choice for an expectation of very limited production.

When it became obvious that production numbers would be much higher, did tolerances change to guarantee parts interchangeability which apparently was not a feature of the earlier engines?

- Ivan.


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## pbehn (Oct 19, 2019)

Ivan1GFP said:


> Hello PBehn,
> 
> I followed this thread for a while much much earlier.
> You answered a question that I wasn't asking. It wasn't about quantity of production and where the production was.
> ...


I pointed you in the direction of this thread, it contains exactly all the numbers produced by each factory, that is why I pointed you here. You are now wilfully ignoring information (you said you read it) because it doesn't suit your Uncle Sam flag waving exercise. This nonsense appears every once in a while and is debunked, it has been debunked on this thread, do not ask me to go over it all again and debunk it again. You obviously believe what you want to believe regardless of any facts, so go to bed believing that Rolls Royce built their engines on a kitchen table until Packard arrived in 1942 to win the Battles of Britain and Malta. I am done here on this topic.


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## Ivan1GFP (Oct 19, 2019)

pbehn said:


> I pointed you in the direction of this thread, it contains exactly all the numbers produced by each factory, that is why I pointed you here. You are now wilfully ignoring information (you said you read it) because it doesn't suit your Uncle Sam flag waving exercise. This nonsense appears every once in a while and is debunked, it has been debunked on this thread, do not ask me to go over it all again and debunk it again. You obviously believe what you want to believe regardless of any facts, so go to bed believing that Rolls Royce built their engines on a kitchen table until Packard arrived in 1942 to win the Battles of Britain and Malta. I am done here on this topic.



Hello PBehn,

I was actually hoping to get a more thoughtful response from you of all people.
I really wasn't discussing the quantities of production by each company but more a matter of design choices with an expectation of production quantities. If you look at even modern low production engines, there were a bunch that were NOT built on production lines but by small teams. The product is higher quality but the product is much more expensive and production numbers are low.
The accounts that I have read state that tolerances were looser with Rolls Royce because parts were expected to be fit to each engine and that Packard did not work in that way and needed tighter tolerances to guarantee parts interchangeability.
Are you telling me this is NOT true?
If not, then what is the truth? I don't know more than what I have read and heard in interviews.
The problem with reading what has already been posted here is that quite a lot contradicts with other sources.
Which sources are to be trusted?


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## pbehn (Oct 19, 2019)

Ivan1GFP said:


> Hello PBehn,
> 
> I was actually hoping to get a more thoughtful response from you of all people.
> I really wasn't discussing the quantities of production by each company but more a matter of design choices with an expectation of production quantities. If you look at even modern low production engines, there were a bunch that were NOT built on production lines but by small teams. The product is higher quality but the product is much more expensive and production numbers are low.
> ...


Read this thread, then when you have read all of this thread state that you have read all of this thread and absorbed the detail within it. You are trusting sources that claim the British in their mud huts machined thousands of pistons and cylinders then started to measure them to see which could be used to fit one another. It is an insult to anyones intelligence but it suits your PACKARD flag waving exercise. The truth is Packard were the main contractor, to sub contract they needed drawings, in the USA all drawings were in third angle projection and so to avoid any errors all drawings were produced by Rolls Royce in third angle projection so that any problems resulting would be down to Packard not Rolls Royce. That is just international engineering business not a statement of different quality standards. Before the Lancaster was produced in Canada all drawings had to be copied and supplied to Canada for the Canadians to work with, that is how you build things in an engineering project, with drawings. Yes I am telling you it is not true, first you produce your accounts of what you believe to be true, it is a myth. The Rolls Royce Merlin engine was an engineering product, there weren't Packard and Rolls Royce versions except in minor detail because it was a Rolls Royce engine built under license by Packard.

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## Shortround6 (Oct 20, 2019)

The truth may be somewhere in between. 
However it may have been the men at Ford of England who production engineered the Merlin and not Packard. Ford of England in this case having very little to do with Ford of America. 
Ford of England had changed the tolerances (tighter) and gone to more fully interchangeable parts in the shadow factory they ran. This work started almost a year before Packard got involved. Ford of England built over 30,000 engines by VE day and over 32,000 engines total by 1946. They built more engines than the RR Derby factory. This changes a bit depending on author or article.
RR themselves had the Derby factory, the Crewe factory and the Glasgow factory. Nobody has ever claimed that the british built engines, despite being built in 4 different factories didn't have interchangeable parts, ar least not anymore than R-1830s built by Chevrolet, Buick and P&W didn't have interchangeable parts. 

The British factories did specialize a bit with one factory making single speed engines and another 2 speed engines but the US did the same thing with some US companies making single speed or single stage R-2800s and another company making only two stage engines.
Development work was centered at Derby due to the higher skilled work force but both Crewe and Glasgow were planned around using lower level or lower skilled employees to assemble the engines. 

The idea that Packard Stepped in and saved the day by showing RR how to mass produce the Merlin is a persistent myth with little basis in fact.

The Merlin may have been designed with many more parts than an allison but the vast majority of extra parts were fasteners. This may have been due to differences in American and British gaskets, surface finish/flatness and design practice. This is a guess. Ability to build in large quantity large parts with the required flatness and stiffness to use a minimal number of fasteners may have changed or been different in the two countries.
The US stayed with cast cylinder heads on radials for a number of years after Britian changed to forged heads because the US companies could get better castings from their suppliers than Bristol in England could get from British foundries for example. It doesn't matter what you can design or specify if you can't actually produce it in numbers given your sources of supply/subcontractors.

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## fastmongrel (Oct 20, 2019)

Shortround6 said:


> The Merlin may have been designed with many more parts than an allison but the vast majority of extra parts were fasteners. This may have been due to differences in American and British gaskets, surface finish/flatness and design practice.



I think it came from Rolls Royces automotive background of a RR never breaks down it just occasionally fails to proceed. Early cars often just fell to bits on the road and Henry Royce designed vehicles were noted for finishing journeys with the same number of parts as it started. We know a bolt can fail but when you have 31 of them the other 30 will get you home


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## fastmongrel (Oct 20, 2019)

In 1943 production of Meteor tank engines was falling behind the Armys needs because of lack of factory space and machine tools and no drop in the production of Merlins could be allowed. Time expired or damaged Merlins were stripped and thoroughly checked and the parts used to build Meteors. For example a crank for a Spitfire engine was not allowed to exceed more than 250 hours but the same crank could be used in a Meteor for another 600 hours. Merlin crankcases often cracked when the plane crashed but the cases could be welded and reinforced and reused in a Meteor.

The Merlin engines that were reused came from all factories and when a crank was reused it was no longer a Ford or a Packard or a Derby built crank it was simply a Meteor crank with no discrimination or mention of origin on the service sheet.

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## tomo pauk (Oct 20, 2019)

Cranks of the Meteor were making 2600 rpm vs. 3000 rpm on the Merlin, while the engines itself never have had boost of any type. Thus less power than Merlin, but also much less of stress on engine parts.


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## Sid327 (Oct 21, 2019)

tomo pauk said:


> Cranks of the Meteor were making 2600 rpm vs. 3000 rpm on the Merlin, while the engines itself never have had boost of any type. Thus less power than Merlin, but also much less of stress on engine parts.



Exactly....

2,550 rpm for the Mark IVB in fact (ex-Centurion tank driver in the distant past) 

.....and I don't remember any instances of failure or even leaks.
They were good for 4,000 track miles or seven years (TBO of AFV "A" vehicles with Brit Mil).

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## Admiral Beez (Oct 22, 2019)

KraziKanuK said:


> Packard Merlins, which powered the Lanc X, gave only about 82% of the power of the equivalent Rolls Royce Merlins, and that crews would practically kill to get the RR Merlin


A peacetime story, but this reminded me of an event in 2014 when Canada’s Packard-powered Lancaster suffered catastrophic engine failure whilst on a tour of the UK, and had to borrow a RR Merlin from the RAF heritage flight. The RAF mechanics were able to fix the Packard engine before the Canadian flew home, but it cost CAD $180K.

Engine failure strands Lancaster bomber in Britain

https://www.cbc.ca/news/canada/hami...r-ends-with-180k-engine-repair-bill-1.2774375


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## pbehn (Oct 22, 2019)

Admiral Beez said:


> A peacetime story, but this reminded me of an event in 2014 when Canada’s Packard-powered Lancaster suffered catastrophic engine failure whilst on a tour of the UK, and had to borrow a RR Merlin from the RAF heritage flight. The RAF mechanics were able to fix the Packard engine before the Canadian flew home, but it cost CAD $180K.
> 
> Engine failure strands Lancaster bomber in Britain
> 
> ...


It was "Stranded" at my local airport Teesside. This was Middleton St George airfield during WW2 and the home airport with nearby Croft of Mynarski who the Mynarski Lancaster is named after. It did a few shake down flights before leaving and flew over my mothers house as we set off to attend her brothers funeral, He was an RAF veteran invalided out of BC air ops early in the war. Lancaster leaves after engine repair

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## GregP (Oct 22, 2019)

You can find several ratings for a Packard V-1650-3 and V-1650-7. I have seen the V-1650-3 rated at 1,280 @ 3,000 rated power and 1,600 Hp @ 3,000 max ... and I have also seen the V-1650-3 rated at 1490/1670/1700 ... depends on where you find the ratings. Similar for the V-1650-7, different ratings.

But there was NO Rolls-Royce equivalent to the V-1650-3 or V1650-7. They were Packard engines with different parts than any Rolls Royce engine. Some could be interchangeable, but that was mounting, not internals.

On the other hand, a Merlin 224 is just a Merlin 24 built by Packard (the 200 part), and it has the exact same ratings for either manufacturer, regardless of the carburetor or other parts fitted. I have been around warbirds for a good number of years and have never heard of U.S. Merlins being called "weak" in any way, shape, or form. Neither have I heard of Rolls Royce Merlins being called same.

I HAVE heard that U.S. engines have much better parts interchangeability. Heard that for 20 years, and then someone in here said Rolls Royce fixed that issue rapidly and, by the end of the war, their parts were also interchangeable. I have never been able to confirm that in action because the active warbirds I know about usually have Packard-built Merlins in various states of parts mixes, usually with transport heads, sometimes new-production pistons and rings, and sometimes modern ignition systems. Basically, they are hybrids.

But, back in the 1960s and 1970s, the warbirds community in the U.S.A. generally wanted Packard Merlins. No doubt the warbird community in the UK wanted British Merlins. Also no doubt, this was very likely due to there being more parts of the home-grown variety being generally available than parts from the other country. I have never heard anyone with either a Packard or a Rolls Royce being particularly dissatisfied with their Merlin, provided it was properly overhauled last time around.

When it comes to racing, EVERYBODY complains when they blow an engine that was manufactured 50 - 70 years ago at 1,600 Hp but has been modified to produce 3,000 + HP. They usually complained about the hit to the wallet, not about why it blew.

About the post above, $180K is NOT a bad price for a "fixed" Merlin, depending on what was wrong. I have seen a complete overhaul of an old Merlin go for $250k. Depends on what needs to be reworked and replaced. Parts ain't exactly "cheap."

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## Admiral Beez (Oct 22, 2019)

When Britain moved to Griffon production did the US show any interest in a Packard version? 

Imagine a P-38 Lightning with Griffons. Mind you, the postwar Hornet used Merlins instead of Griffons.

Griffon powered P-38?


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## pbehn (Oct 22, 2019)

Admiral Beez said:


> When Britain moved to Griffon production did the US show any interest in a Packard version?
> 
> Imagine a P-38 Lightning with Griffons. Mind you, the postwar Hornet used Merlins instead of Griffons.


Britain never really did move to the Griffon, there were 8,000 produced but in 50 variants mainly for the late model Spitfires and the Shackleton.


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## GregP (Oct 22, 2019)

Britain probably WOULD have moved to the Griffon had piston engines not been being supplanted by jet engines. I think the Griffons came at EXACTLY the wrong time in history to have made a mark in the aviation world similar to the Merlin simply due to the timing of jet development.

Personally, I'd have wanted a Griffon that turns the other way ... but that's me.

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## pbehn (Oct 22, 2019)

GregP said:


> Britain probably WOULD have moved to the Griffon had piston engines not been being supplanted by jet engines. I think the Griffons came at EXACTLY the wrong time in history to have made a mark in the aviation world similar to the Merlin simply due to the timing of jet development.
> 
> Personally, I'd have wanted a Griffon that turns the other way ... but that's me.


In terms of its most famous uses the P-51, Mosquito and Lancaster probably wouldn't have been greatly improved with a Griffon without making them new planes.


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## Admiral Beez (Oct 22, 2019)

pbehn said:


> In terms of its most famous uses the P-51, Mosquito and Lancaster probably wouldn't have been greatly improved with a Griffon without making them new planes.


But the Fairey Barracuda suffered, reminding us that the Griffon was intended for the FAA. The postwar Griffon-powered Barracuda was significantly improved over the Merlin model.


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## Reluctant Poster (Oct 22, 2019)

Does anyone seriously believe that Rolls Royce manufactured nearly 84,000 Merlins by hand? That by the way matches the number that Ford and Packard produced together.

For the first half of WWII Roll Royce manufactured more large aircraft engines than any other manufacturer in the world. They had produced over 23,000 Merlins by the end of 1941. By aircraft engine standards this is mass production. At this point it one of the most widely produced engines of all time, exceeded only by the Hispano V-8 of WWI. In fact, this is a greater number than that marvel of mass production, the Liberty. By the of 1941 Packard had manged to produce 45. Rolls Royce reached it peak capacity the next year and produce ~ 18,000 in each of 1942,1943 and 1944. The idea that Packard taught Roll Royce how to build Merlins is obviously nonsense. As a point of reference Merlin production exceeded the combined production of Pratt & Whitney’s R-1830 and Wright’s R-1820 up until the end of 1941.
The Rolls Royce Merlin annual production totals had increased by a factor of ten within 4 years. There is no way that such a massive increase could be accomplished by so called” file and fit” methods. In addition, the new factories at Crew and Glasgow were located in areas that were not populated with a supply of skilled craftsman.
The following is from the book Rolls Royce Hillington Portrait of a Shadow Factory
Personnel Employed at Rolls Royce Aero Engine Factories
1935 7,835
1939 12,500
1941 38,600
1943 55,640
1944 57,067
Obviously, they could not possibly be training enough skilled workers to meet those numbers
Its interesting to note that almost ½ of them worked at Hillington. Hillington produced virtually every component (98%) in house and provided components to the other factories including Ford.
“Of the 25,000 Rolls Royce employees, 37% were female, and only 7% were manually skilled tradesmen, and including supervision and management the total skilled constituent never exceeded 12%.”

It should also be noted Packard was not a mass producer of automobiles akin to Chevrolet or Ford. In fact, they were more comparable to Rolls Royce. Both started out as manufacturers of the world’s finest automobiles. Like Rolls Royce, Packard expanded into aircraft engines, unfortunately, they failed in this endeavor. When sales of luxury cars declined after WWI, Rolls Royce introduced a lower priced car to boost production, but more importantly began to concentrate on aircraft engines such that by the time of the great depression they had become an aircraft engine manufacturer with a side line in luxury automobiles.
Packard did not have that option so in 1935 they introduced a downmarket 8-cylinder car. They had a fair bit of success with that and decided to go further downmarket in 1937 with a 6-cylinder car. They were going into the upper middle-class segment dominated by Buick. 1937 was the peak of Packard production with 123,000 units produced that year. I have always wondered about that number because it is double that of the preceding year as well as the succeeding year. Suffice to say that 123,000 units a year is no where near the 942,000 Fords, the 815,000 Chevrolets and 566,000 Plymouths produced in 1937. 
Packard continued to make small numbers of hand built automobiles. Supposedly they employed as many workers in the luxury section as they did in the lower price lines. Packard still had a very large force of skilled workers.

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## Admiral Beez (Oct 22, 2019)

Canadian Car and Foundry manufactured 1,451 Hurricanes between 1938 and 1943. I wonder if those nearly 1,500 Merlins were all sourced from Britain or if CC&F switched over to Packard Merlins by the end. 

As a side note, until I saw this pic below I had no idea we also produced Sea Hurricanes.






With CC&F being located on the US border, the logistics of getting Merlins from Packard would have to be easier. Though I suppose the convoys from Britain come back mostly empty. By 1942 Victory Aircraft near Toronto, Canada was already producing Packard-powered Lancasters.


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## wuzak (Oct 22, 2019)

GregP said:


> You can find several ratings for a Packard V-1650-3 and V-1650-7. I have seen the V-1650-3 rated at 1,280 @ 3,000 rated power and 1,600 Hp @ 3,000 max ... and I have also seen the V-1650-3 rated at 1490/1670/1700 ... depends on where you find the ratings. Similar for the V-1650-7, different ratings.
> 
> But there was NO Rolls-Royce equivalent to the V-1650-3 or V1650-7. They were Packard engines with different parts than any Rolls Royce engine. Some could be interchangeable, but that was mounting, not internals.



The V-1650-3 was equivalent to the Rolls-Royce Merlin 63.

The V-1650-7 was equivalent to the Rolls-Royce Merlin 65/66. It was also manufactured as the Merlin 266 for British use (eg in the Spitfire XVI).

The main differences between the V-1650-3 and -7 and the British equivalents was the prop shaft (SAE spline vs SBAC spline), supercharger drive (epicyclic on Packards vs Framan type on Rolls-Royces) and a US supplied injection carburettor. 

Some other small changes were made, including different bearing materials.

The internals were completely interchangeable. As evidenced by Rolls-Royce engines being broken down to be used for P-40F spares in North Africa.




GregP said:


> On the other hand, a Merlin 224 is just a Merlin 24 built by Packard (the 200 part), and it has the exact same ratings for either manufacturer, regardless of the carburetor or other parts fitted. I have been around warbirds for a good number of years and have never heard of U.S. Merlins being called "weak" in any way, shape, or form. Neither have I heard of Rolls Royce Merlins being called same.



Almost all Packard Merlins used the same ratings as their British equivalent.

The two stage versions varied a little, as the gear ratios were very slightly different, but were still rated the same.

Packard Merlins fitted to Lancasters required a slightly different control system, due to the injection carburettor. Even so, some Lancasters were fitted with Merlins from different factories, including Packard.




GregP said:


> I HAVE heard that U.S. engines have much better parts interchangeability. Heard that for 20 years, and then someone in here said Rolls Royce fixed that issue rapidly and, by the end of the war, their parts were also interchangeable. I have never been able to confirm that in action because the active warbirds I know about usually have Packard-built Merlins in various states of parts mixes, usually with transport heads, sometimes new-production pistons and rings, and sometimes modern ignition systems. Basically, they are hybrids.



Since the transport heads were British designed and built, doesn't that point to interchageability?

Prior to Packard starting production the British had already productionised the Merlin, with Ford UK being involved in that process.


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## Crimea_River (Oct 23, 2019)

Admiral Beez said:


> Canadian Car and Foundry manufactured 1,451 Hurricanes between 1938 and 1943. I wonder if those nearly 1,500 Merlins were all sourced from Britain or if CC&F switched over to Packard Merlins by the end.



Both. Generally early CCF Hurricanes used RR imports and later ones used Packards.

Canadian built Hurricanes with Merlin engines - Luftwaffe and Allied Air Forces Discussion Forum

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## Sid327 (Oct 24, 2019)

wuzak said:


> ................Since the transport heads were British designed and built, doesn't that point to interchageability?.....................



What was different about these, Wuzak?


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## wuzak (Oct 24, 2019)

Sid327 said:


> What was different about these, Wuzak?



I am not sure what was different about them. They were based on the 100-series engines, so would have kept any improvements there.

Other than that, I can only assume that changes were made to improve reliability and longevity.


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## Reluctant Poster (Oct 27, 2019)

Crimea_River said:


> Both. Generally early CCF Hurricanes used RR imports and later ones used Packards.
> 
> Canadian built Hurricanes with Merlin engines - Luftwaffe and Allied Air Forces Discussion Forum


The majority of CCF Hurricanes were built with the Packard Merlin Mark 28 or later 29. The only difference between those marks was the propeller shaft. The 28 used the std British shaft while the 29 used the std American shaft. CCF Hurricanes with Hamilton Standard props can be recognized by the lack of a spinner due to the bulk of the Ham Stan. The HS prop was also much heavier than the equivalent Rotol.


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## GregP (Oct 28, 2019)

Hi Wayne,

The British did not USE a U.S.-supplied injection carburetor nor the SAE shaft splines nor SAE fasteners and other hardware, so there isn't really any British equivalent for a V-1650-3 or -5. The internals may have matched similarly to the Rolls design (as I would expect since we made "Merlins"), but the engines are NOT interchangeable unless you also interchange props, tool sets, and engine mounts. It's not that TOUGH to change one over, but it also isn't a "swap one for one" deal, either. Heck, we have an interesting time even trying to GET Whitworth bolts here in the U.S.A. , much less Whitworth wrenches and sockets. You can find them, but not at the local hardware store.

Some parts of a Merlin WERE interchangeable, and the head castings were the same for British and U.S. Merlins, at least center-to-center of the head bolts. Probably slightly different diameter holes, but I'm not sure since I have only worked on Packard-Merlins and never measured the head bolt holes for ANY Merlin, or Allison either, for that matter. Never needed to do so. But, you wouldn't try to install a British "machine to fit" part on a Packard Merlin unless you were out of interchangeable parts. Then it makes sense to "fit" a part if that's the only practical way to return the engine to service. Later British mass production parts may BE interchangeable with each other, but are they interchangeable with Packard parts? My contacts say "No," but I'm also not working much with warbird engines like I used to.

I'm playing more with my Ford Coyote V8 than airplane engines at present, and am having more fun doing it, too.


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## Milosh (Oct 28, 2019)

Didn't Lancasters have a mix of engines on the same a/c? No R/R engine available, a Packard would be fitted.


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## pbehn (Oct 28, 2019)

GregP said:


> Hi Wayne,
> 
> The British did not USE a U.S.-supplied injection carburetor nor the SAE shaft splines nor SAE fasteners and other hardware, so there isn't really any British equivalent for a V-1650-3 or -5. The internals may have matched similarly to the Rolls design (as I would expect since we made "Merlins"), but the engines are NOT interchangeable unless you also interchange props, tool sets, and engine mounts. It's not that TOUGH to change one over, but it also isn't a "swap one for one" deal, either. Heck, we have an interesting time even trying to GET Whitworth bolts here in the U.S.A. , much less Whitworth wrenches and sockets. You can find them, but not at the local hardware store.
> 
> ...


I think this is a situation that would only happen in post war warbird set ups though wouldn't it? When engines were taken out in WW2 they were sent for re build, not rebuilt there in the hanger with parts laying about.


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## pbehn (Oct 28, 2019)

Milosh said:


> Didn't Lancasters have a mix of engines on the same a/c? No R/R engine available, a Packard would be fitted.


I found this, my bold, but did they use the same or both types at the same field at the same time?

Demand for the Rolls Royce Merlin engine constantly threatened to outstrip supply. One solution was the manufacture of Merlin engines by the Packard motor company in America. These Packard Merlins were used in a variety of aircraft, but perhaps the biggest consumer was the Lancaster III, of which 3,039 were built (requiring over 12,000 engines). The use of the Packard Merlin 28, capable of delivering 1,420 hp at take-off was the only difference between the Mk I and the Mk III.



Avro Lancaster III of No.619 Squadron
As would be expected, the performance of the Packard Merlin powered Lancaster was very close to that of Rolls Royce powered aircraft. *Many RAF Squadrons used both types*. The only exception was that the Packard Merlin was slightly more likely to overheat during take off and landing, making it less suitable for use in training units.


The Lancaster Mk III was constructed on the same Avro construction lines as the Mk I, with the choice of engines dependent on availability. The Mk III entered production towards the end of 1942, and entered service during 1943. Production continued throughout the war. A number of Mk IIIs were amongst the aircraft modified to carry the famous “bouncing bomb” used on the Dambusters raid.


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## wuzak (Oct 28, 2019)

Hi Greg,



GregP said:


> The British did not USE a U.S.-supplied injection carburetor nor the SAE shaft splines nor SAE fasteners and other hardware, so there isn't really any British equivalent for a V-1650-3 or -5.



No, the British built Merlins did not use the US injection carburettor. No, they did not use the SAE output shaft.

Packard Merlins did not use SAE fasteners. Except, maybe, the supercharger drive system. They even used all the little BA screws to join the supercharger housings together and hold down the rocker covers.

The V-1650-7 was supplied to the British as Merlin 266s. They differed from the Merlin 66 in the supercharger drive (epicyclic, designed by Wright) and the injection carburettor. 

The Merlin 266 only differed from the V-1650-7 in the output shaft.

The Packard V-1650-3 was, absolutely, the equivalent of the Merlin 63. Because that is what it was based on.

The Packard V-1650-7 was the equivalent of the Merlin 65/66. Because that is what it was based on.

The Packard V-1650-9 was a Merlin 100 series. I can't recall which model it was equivalent to, maybe the 113/114. Maybe the 130/131.

The difference between the V-1650-1 and British Merlin XX variants was the injection carburettor and prop shaft. They were supplied with SBAC prop shafts, but otherwise identical, to the British as the Merlin 28.




GregP said:


> The internals may have matched similarly to the Rolls design (as I would expect since we made "Merlins"), but the engines are NOT interchangeable unless you also interchange props, tool sets, and engine mounts. It's not that TOUGH to change one over, but it also isn't a "swap one for one" deal, either.



As mentioned by others above, if a Rolls-Royce Merlin needed maintenance it could be, and was, swapped for a Packard Merlin in aircraft such as the Lancaster.

Don't know why you think the engine mount would change. The output shaft could be easily changed.




GregP said:


> Some parts of a Merlin WERE interchangeable, and the head castings were the same for British and U.S. Merlins, at least center-to-center of the head bolts. Probably slightly different diameter holes, but I'm not sure since I have only worked on Packard-Merlins and never measured the head bolt holes for ANY Merlin, or Allison either, for that matter.



MOST of the parts were interchangeable.

The heads were the same. They were built to Rolls-Royce designs and specs.




GregP said:


> But, you wouldn't try to install a British "machine to fit" part on a Packard Merlin unless you were out of interchangeable parts. Then it makes sense to "fit" a part if that's the only practical way to return the engine to service. Later British mass production parts may BE interchangeable with each other, but are they interchangeable with Packard parts? My contacts say "No," but I'm also not working much with warbird engines like I used to.



"Machine to fit"? I suppose that is an improvement from "file to fit" which is often the term used in this MYTH.

The only engines that were individually fitted were the prototype versions used by Rolls-Royce to test new parts and power ratings. These were built in the tens. 

The "later British mass production" Merlins appeared before any production Packard Merlins.

Why do you, logically, think that a part built in Britain to a set of specs and tolerances not fit in place of a part built in the US to the exact same specs and tolerances?


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## GregP (Oct 28, 2019)

Well Wayne,

I have a LOT more time on Allisons than on Merlins. So, my Merlin knowledge is not what my Allison knowledge is. Say, 100 times as much Allison time as Merlin time. But the guys who own these things that are friends do not feel they are interchangeable. Me, I'll go along with the guys who own one rather than the guys who don't, and they don't think the parts are all that interchangeable. Seems to me as if the guys who are DOING it think that, I can't disagree with them since I don't own one and have no incentive to prove them wrong just to do it.

In another world, where I win a lottery, I'd know these things since I'd be flying a Merlin-powered private aircraft and would have great incentive to figure it out.

The only times I have seen cylinders changed on a Merlin, it seemed like as much, if not more, of a job as it is on an Allison. The only reason it MAY seem like more of a job is because I am less familiar with Merlin work than Allison work. I have actually participated in changing out cyinder liners on an Allison. Since the steps aren't the same for the Merlin, maybe I SAW it as more complex when, in fact, it wasn't if you are familiar with it.

I KNOW the V-1650-3 was based on the Merlin 63, but have never heard anyone but you say they were interchangeable. I KNOW the V-1650-7 was based on the Merlin 66 but, again, have never heard anyone else say they were interchangeable. Most of the P-51s I am familar with are not really a V-1650-3 or -7 these days. They are sort of hybrids, and run the best parts they can find. Some guys are running transport heads on a V-1650-3/7. Some run a different cabruretor. If the aircraft is registered as Limited, they can't. But, if it is in the Experimental or Experimental Exhibition category, they can pretty much run whatever they want to run.

I do not believe the Packard Engines starting with the V-1650-9 were based on any British engine dash number. They were Packard developments. Certainly the -21, -23, and -25 were not Rolls-Royce dash number based. They also were not manufactured in any numbers, being experimental. I think they made 40 of the -23 and 40 of the -25 engines, but I don't know how many -21's were built.


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## Greyman (Oct 28, 2019)

Sorry if this was covered but what is the power of a Lancaster X Packard Merlin at +14 boost compared to a Merlin 24 running +18 boost?

Would this be where the '82%' figure comes from?

A&AEE compared a Lancaster X (KB.721) to a normal Lancaster III (JA.918) and concluded that there was 'very little difference' in climb and 'no significant difference in performance' with regard to level speeds.


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## wuzak (Oct 29, 2019)

GregP said:


> I KNOW the V-1650-3 was based on the Merlin 63, but have never heard anyone but you say they were interchangeable. I KNOW the V-1650-7 was based on the Merlin 66 but, again, have never heard anyone else say they were interchangeable. Most of the P-51s I am familar with are not really a V-1650-3 or -7 these days. They are sort of hybrids, and run the best parts they can find. Some guys are running transport heads on a V-1650-3/7. Some run a different cabruretor. If the aircraft is registered as Limited, they can't. But, if it is in the Experimental or Experimental Exhibition category, they can pretty much run whatever they want to run.



Apart from the output shaft, a V-1650-7 is interchangeable with a Merlin 66. And the -3 with the Merlin 63. To fit it to a British aircraft you would either change the output shaft or change the prop.




GregP said:


> I do not believe the Packard Engines starting with the V-1650-9 were based on any British engine dash number. They were Packard developments. Certainly the -21, -23, and -25 were not Rolls-Royce dash number based. They also were not manufactured in any numbers, being experimental. I think they made 40 of the -23 and 40 of the -25 engines, but I don't know how many -21's were built.



The V-1650-9 was a Merlin 100 series. It was rated either RM.14SM or RM.16SM, I can't recall which. Either way, there were several Rolls-Royce Merlin marks with the same ratings.

Apart from the output shaft, supercharger drive and carburettor, the -9 differed from British marks in having ADI.

I don't know about the -21, -23 and -25, except that the -23 and -25 were used on the P-82 (the -23 being LH rotation version of -25) according to wiki.

I believe the -11 was an experimental version with a variable speed supercharger drive.


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## wuzak (Oct 29, 2019)

According to Lumsden, the -21 was a left-hand version of the -9, the -23 was a right hand version of the -21 and the -25 was similar to the -21.

The -9 had the same rating as the Merlin 110, Merlin 113 and Merlin 114, RM.16SM.

Note that Rolls-Royce mark numbers varied for small changes, such as reduction gear ratio. So -9, -2, -23 and -25 may have been similar except for some detail changes.

Lumsden also says the -11 was similar to the -9 but with a modified fuel system.


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## pbehn (Oct 29, 2019)

If there was a substantial difference between the power output of Rolls Royce and Packard engines at the same setting then there would be an immediate investigation because it denies the laws of physics. Pending a solution of that Rolls Royce engines would be put in those aeroplanes that needed it most that would be P-51s and Lancasters carrying Tall Boys and Grand Slams which were instructed to return with the bomb if not used. In fact the opposite was the case. The difference in performance of RR Merlin engined aircraft like the Spitfire Mk IX and a P-51B/C D are because of aerodynamics not power output.


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## fastmongrel (Oct 29, 2019)

Milosh said:


> Didn't Lancasters have a mix of engines on the same a/c? No R/R engine available, a Packard would be fitted.



I dont think this happened in Britain or at least very rarely but it certainly happened in other theatres. My late Father was a Cpl instrument fitter on a Coastal Command Sqdn in the eastern Med around 1947/48 that flew Lancasters in the Anti Sub and Air Sea Rescue roles. He mentioned that RR and Packard engines were mixed it wasnt a regular thing but when all that was available was a Packard the swap could be done in roughly the same time as fitting an RR. 

Relatively few changes were needed to the aircraft, different pitot head, different ignition switches and a change to the throttle wires which I believe were related to the Bendix pressure carb.

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## wuzak (Oct 29, 2019)

pbehn said:


> If there was a substantial difference between the power output of Rolls Royce and Packard engines at the same setting then there would be an immediate investigation because it denies the laws of physics. Pending a solution of that Rolls Royce engines would be put in those aeroplanes that needed it most that would be P-51s and Lancasters carrying Tall Boys and Grand Slams which were instructed to return with the bomb if not used. In fact the opposite was the case. The difference in performance of RR Merlin engined aircraft like the Spitfire Mk IX and a P-51B/C D are because of aerodynamics not power output.



And the Spitfire XVI did not have a performance advantage or deficit compared to the Spitfire IX, despite being the same aircraft but fitted with a Packard Merlin.

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## wuzak (Oct 29, 2019)

fastmongrel said:


> Relatively few changes were needed to the aircraft, different pitot head, different ignition switches and a change to the throttle wires which I believe were related to the Bendix pressure carb.



Yes, there were changes required to suit the injection carb. One of the main differences, other than the engines themselves, between the Lancaster I and III.


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## pbehn (Oct 29, 2019)

wuzak said:


> And the Spitfire XVI did not have a performance advantage or deficit compared to the Spitfire IX, despite being the same aircraft but fitted with a Packard Merlin.


If there was a substantial difference because of manufacture in any way there would be an immediate investigation to bring the lower powered engine up to the performance of the other no matter which it was. The differences quoted are along the lines of the difference between Merlin and Griffon or single and two stage supercharger at some altitudes. There wouldn't need to be some explanation where the power difference was coming from or going to.


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## MiTasol (Oct 29, 2019)

fastmongrel said:


> Relatively few changes were needed to the aircraft, different pitot head, different ignition switches and a change to the throttle wires which I believe were related to the Bendix pressure carb.



Lancaster 10 KB926 had Packards when I worked on it in Calgary and it had the standard British ignition switches. From memory the parts list showed that applied to all Lanc 10s.

The pitot is not in any way related to the engine installation - it is purely for airspeed calculation - so there is no reason to play with that.

After 50 years I cannot remember if KB976 had a separate idle cutoff control but certainly many British aircraft (Spitfire and Hurricane for example) did. I am fairly confident KB976 used the standard American set up of idle cutoff built into the mixture lever. That would have required changes when changing between RR and Packard engines.


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## chris mcmillin (Oct 31, 2019)

wmaxt said:


> One thing about the Merlin in the US durring the war. It took an average of 320hrs to overhaul and 198 average to overhaul an Allison. I don't know for sure but this might illistrate the complexity/precision required for the Merlin engines. That would make the Merlin more dependant of careful assembly and would result in a wider variation in power output possible between engines.
> 
> wmaxt


Because the cam, followers, fingers of the Merlin head were so complicated. More time in assembly and set-up than the simpler Allison head.
Supercharger on the -3,-7,-9 Packard V-1650 is essentially two blowers, equals more time yet.


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## fastmongrel (Nov 1, 2019)

MiTasol said:


> The pitot is not in any way related to the engine installation - it is purely for airspeed calculation - so there is no reason to play with that.



I am only going by what my dad told me 30 or 40 years ago so that's 2 lots of fallible memory the information is filtered through. 

I should do some research and not rely on memory. It's why I am always a bit wary of the "I spoke to a veteran and he said" anecdotes.


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## MiTasol (Nov 1, 2019)

fastmongrel said:


> I am only going by what my dad told me 30 or 40 years ago so that's 2 lots of fallible memory the information is filtered through.
> 
> I should do some research and not rely on memory. It's why I am always a bit wary of the "I spoke to a veteran and he said" anecdotes.



In his recent autobiography the Australian historian Geoffrey Blainey said something like_ memory is not a reliable source. _ I totally agree, and am equally guilty of the results.


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## Reluctant Poster (Nov 24, 2019)

Although many sources claim that the V-1650-3 was the equivalent of the Merlin 63 that in fact is not true. There was a significant difference in the supercharger design resulting in better performance for the V-1650-3. When the V-1650-3 was being scheduled for production Rolls Royce asked Packard to adopt the much-improved supercharger they had developed for the Merlin 66. Here is the memo from Hives to Lapin on this subject.
“It seems these modifications might be standardized from the start in American and full details are therefore attached for your information. Briefly the modifications consist of the adoption of thin vane diffusers in place of the existing wedge vane type, modified circular arc rotating guide vanes on both stages, and an increase in the first stage rotor diameter from 11.5 ins. to 12 ins……….You will note an increase of 2,500 ft in full throttle height for F.S. gear.”
The reason people compare the V-1650-3 to the Merlin 63 is that it Packard used the higher supercharger gear ratios of the 63’s supercharger drive. Rolls Royce however recommended the lower gear ratio for the same reason they lowered the gear ratio for the Merlin 66, to improve performance at low altitudes. The FW 190 was close to the Merlin 63 Spitfire IX in performance at low altitudes but was way behind over 20,000 feet, therefore Rolls adopted gear ratios that improved low altitude performance while retaining the excellent high level performance. It is a common misconception that the Spitfire LF IX was a dedicated low-level fighter, like the LF V. In fact, the high-altitude performance of an LF IX was superior to the vast majority of WWII piston engine fighters. As an example, the Russian used the LF IX as their standard high-altitude interceptor well past the end of WWII. Eventually Packard followed Rolls Royce’s advice and used the lower gearing on the V-1650-7. Rolls Royce later developed a high-altitude version of the Merlin 66 known as the Merlin 70 which was installed in the Spitfire HF IX.
When comparing the performance of the V-1650-3 the appropriate model should be the Merlin 70 not the 63.

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## Reluctant Poster (Nov 25, 2019)

wuzak said:


> Hi Greg,
> 
> 
> The V-1650-7 was supplied to the British as Merlin 266s. They differed from the Merlin 66 in the supercharger drive (epicyclic, designed by Wright) and the injection carburetor Vt



A minor point. The Merlin 66 did use the Bendix injection carb. Also Packard used a different intercooler which necessitated modifications to the Spitfire IX cowling. The following website tells more about Spitfire cowlings than you may want to know:
Spitfire Mk. IX, XI and XVI – Variants Much Varied — Variants & Technology | Reference | Spitfire Mk. IX | Spitfire Mk. XI | Spitfire Mk. XVI

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## Reluctant Poster (Nov 26, 2019)

pbehn said:


> I found this, my bold, but did they use the same or both types at the same field at the same time?
> 
> Demand for the Rolls Royce Merlin engine constantly threatened to outstrip supply. One solution was the manufacture of Merlin engines by the Packard motor company in America. These Packard Merlins were used in a variety of aircraft, but perhaps the biggest consumer was the Lancaster III, of which 3,039 were built (requiring over 12,000 engines). The use of the Packard Merlin 28, capable of delivering 1,420 hp at take-off was the only difference between the Mk I and the Mk III.
> 
> ...


All of the dambuster Lancasters were built as Mark IIIs or reengined with Merlin 28s. This was because the two piece block of the 28 allowed higher boost pressure for take off.


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## wuzak (Nov 26, 2019)

Reluctant Poster said:


> A minor point. The Merlin 66 did use the Bendix injection carb. Also Packard used a different intercooler which necessitated modifications to the Spitfire IX cowling. The following website tells more about Spitfire cowlings than you may want to know:
> Spitfire Mk. IX, XI and XVI – Variants Much Varied — Variants & Technology | Reference | Spitfire Mk. IX | Spitfire Mk. XI | Spitfire Mk. XVI



Was the intercooler different, or was it positioned differently due top the different supercharger drive?


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## pbehn (Nov 27, 2019)

Reluctant Poster said:


> All of the dambuster Lancasters were built as Mark IIIs or reengined with Merlin 28s. This was because the two piece block of the 28 allowed higher boost pressure for take off.


My point was they are essentially the same engine. The first "Mustang" was a two stage Merlin put in a Mustang MkI frame to replace the Allison engine. It was approx. 30 MPH faster than the same engined Spitfire. The P-51B/C and D were approximately the same difference 30 MPH while the Spitfire Mk IX and XVI were identical to all intents and purposes. The improbable power differences between the two which are often quoted would have caused rapid trips across the Atlantic if there was any truth, either massive mistakes had been made or new laws of thermodynamics discovered.


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## wuzak (Nov 27, 2019)

Reluctant Poster said:


> All of the dambuster Lancasters were built as Mark IIIs or reengined with Merlin 28s. This was because the two piece block of the 28 allowed higher boost pressure for take off.



And the Tallboy/Grand Slam carrying Lancasters were B.I (Special).

Rolls-Royce delayed changing to the 2 piece construction due to production requirements, so Packard got the 2 piece blocks first. But Rolls-Royce production did change to the 2 piece design soon after.

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## pbehn (Nov 27, 2019)

wuzak said:


> And the Tallboy/Grand Slam carrying Lancasters were B.I (Special).
> 
> Rolls-Royce delayed changing to the 2 piece construction due to production requirements, so Packard got the 2 piece blocks first. But Rolls-Royce production did change to the 2 piece design soon after.


There was a long detailed post about this years ago that I just cant find, to do with all the rationalisation of production. The changes were planned by Rolls and agreed with Packard but since the engines were different they still had to produce a lot of other engines to avoid modifications to airframes already produced.


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## Reluctant Poster (Nov 28, 2019)

wuzak said:


> Was the intercooler different, or was it positioned differently due top the different supercharger drive?


The intercooler used by Packard had an integrated header tank while the one used by Rolls Royce had a separate header. The following website shows a Merlin 266 intercooler vs. Merlin 76. Note that it is a Merlin 76 which seems to have a combined intercooler/header. The Mosquito that had a different cooling system than other Merlin applications, which may explain this.

Rolls-Royce Merlins and Packard Merlins

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## Reluctant Poster (Nov 28, 2019)

pbehn said:


> There was a long detailed post about this years ago that I just cant find, to do with all the rationalisation of production. The changes were planned by Rolls and agreed with Packard but since the engines were different they still had to produce a lot of other engines to avoid modifications to airframes already produced.[/QUOTE
> 
> Simply put in 1941 the Merlin was the only viable engine the British had in production. It was not possible to lose any production whatsoever. Since Packard was starting from scratch no production was lost.


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## pbehn (Nov 28, 2019)

Reluctant Poster said:


> Simply put in 1941 the Merlin was the only viable engine the British had in production. It was not possible to lose any production whatsoever. Since Packard was starting from scratch no production was lost.


 It is simple to put it simply but things were anything but simple. The decision was made in 1940, but RR still had to produce Vulture and Peregrine engines while scaling the production down. The Merlin itself was not one engine, they had to improve the single stage engines, develop and put into production the two stage engines and then there were the Griffon series. Engines on Mosquitos had one side with the coolant flow reversed because of the wing mounted radiators.


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## wuzak (Nov 28, 2019)

pbehn said:


> It is simple to put it simply but things were anything but simple. The decision was made in 1940, but RR still had to produce Vulture and Peregrine engines while scaling the production down. The Merlin itself was not one engine, they had to improve the single stage engines, develop and put into production the two stage engines and then there were the Griffon series. Engines on Mosquitos had one side with the coolant flow reversed because of the wing mounted radiators.



I believe the Mosquito had the same engine model for both sides, at least until the 2 stage engines, especially those with cabin pressurisation.

The coolant flow was reversed from front-to-back to back-to-front (IIRC) because of the radiator position.

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## Reluctant Poster (Dec 1, 2019)

pbehn said:


> It is simple to put it simply but things were anything but simple. The decision was made in 1940, but RR still had to produce Vulture and Peregrine engines while scaling the production down. The Merlin itself was not one engine, they had to improve the single stage engines, develop and put into production the two stage engines and then there were the Griffon series. Engines on Mosquitos had one side with the coolant flow reversed because of the wing mounted radiators.


All very true. Also getting the 2 piece block into production. The original Packard version had external coolant piping between the head and block whereas the Rolls Royce version had internal connection. I have not found any information on why there was a difference.


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## wuzak (Dec 1, 2019)

Reluctant Poster said:


> All very true. Also getting the 2 piece block into production. The original Packard version had external coolant piping between the head and block whereas the Rolls Royce version had internal connection. I have not found any information on why there was a difference.



Packard developed their own system.

But I believe they later adopted the Rolls-Royce system.


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## emu27 (Jan 27, 2022)

Pilot who doesn't know what he's flying I'd say, power could be anything between 1,280 and 1,640 HP depending in which version of Merlin installed.


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