Merlins > Packard vs RR

[Reluctant Poster]

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

 

[Reluctant Poster]

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.
View attachment 558647
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.

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.

 

[wuzak]

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?

 

[pbehn]

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.

 

[wuzak]

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.

 

[pbehn]

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.

 

[Reluctant Poster]

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

 

[Reluctant Poster]

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.

 

[pbehn]

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.

 

[wuzak]

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.

 

[Reluctant Poster]

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.

 

[wuzak]

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.

 

[emu27]

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.

 

[Frank Stewart]

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?

Actually, the Packard WAS re-engineered from R-R plans twice in fact! First by Ford of England who told the MoD that we cannot make them on the Assembly line with tolerances this slack, or with "File to fit" notations, and the second time when Packard did the same thing only better. Packard's had longer TBOs and made more power than anything made by R-R during or after the war. Their, R-R that is, version of the superpower Merlin made 2,080 HP when it was first released in the Hornet. Then it was dialed back to 2,050, 2,030, 2,000 and finally just 1,900 HP in order to make it last long enough to last a single voyage on an aircraft carrier! This about 1=1/2 years after the same basic engine made by Packard had been making 2,218 HP and lasting about three times as long as the Hornet's derated Merlin in the P-51H! Then there is the Allison V-1710. Read the history of that engine, the last of which passed it's type tests at 2.920 HP!!!

 

[Frank Stewart]

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

At what altitude did they test the three planes? The P-38 was faster than the Mk-IX at any altitude over 20K'.

 

[Frank Stewart]

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.....

Well, it did give great problems!

 

[wuzak]

Actually, the Packard WAS re-engineered from R-R plans twice in fact! First by Ford of England who told the MoD that we cannot make them on the Assembly line with tolerances this slack, or with "File to fit" notations, and the second time when Packard did the same thing only better. Packard's had longer TBOs and made more power than anything made by R-R during or after the war. Their, R-R that is, version of the superpower Merlin made 2,080 HP when it was first released in the Hornet. Then it was dialed back to 2,050, 2,030, 2,000 and finally just 1,900 HP in order to make it last long enough to last a single voyage on an aircraft carrier! This about 1=1/2 years after the same basic engine made by Packard had been making 2,218 HP and lasting about three times as long as the Hornet's derated Merlin in the P-51H! Then there is the Allison V-1710. Read the history of that engine, the last of which passed it's type tests at 2.920 HP!!!

Doubtful that Rolls-Royce Merlin production drawings called "file to fit".

Ford UK was said to have tightened the tolerances.

Packard didn't do "the same thing only better". They changed the drawings to US standard (3rd angle projection) instead of UK standards (1st angle), changed some components to local supply items, and devised solutions for the 2 piece blocks that Rolls-Royce had yet to finalise (Packard later changed to the Rolls-Royce solution).

Packard Merlins were rated the same as the Rolls-Royce equivalents, and were interchangeable.

The Merlin 130/131 did not had ADI. No Rolls-Royce engine did in WW2.

The V-1650-9 did have ADI. This allowed extra boost and the extra power.

The V-1650-9 also had higher supercharger gearing than the Merlin 130/131. So they weren't directly comparable.

Post war the fuels changed and there was less need for high boost.

There may have been some variation in TBO, but I would not think it that significant.

The V-1710 was never type tested at 2,920hp.

V-1710s that made that sort of power were the turbo-compound engines. The extra power was due to the exhaust turbine which recovered as much as 1,000hp from the exhaust gasses. The engine could not have run at that power for long, however, because the exhaust gasses were hotter than the turbine material could cop with. A production version would have required a new, air-cooled, turbine. But that never happened.

 

[buffnut453]

Well, it did give great problems!

Frank, just to make you aware that FLYBOYJ passed away a few years back. As a relatively new member, you wouldn't know that. Just making you aware.

 

[Reluctant Poster]

Actually, the Packard WAS re-engineered from R-R plans twice in fact! First by Ford of England who told the MoD that we cannot make them on the Assembly line with tolerances this slack, or with "File to fit" notations, and the second time when Packard did the same thing only better. Packard's had longer TBOs and made more power than anything made by R-R during or after the war. Their, R-R that is, version of the superpower Merlin made 2,080 HP when it was first released in the Hornet. Then it was dialed back to 2,050, 2,030, 2,000 and finally just 1,900 HP in order to make it last long enough to last a single voyage on an aircraft carrier! This about 1=1/2 years after the same basic engine made by Packard had been making 2,218 HP and lasting about three times as long as the Hornet's derated Merlin in the P-51H! Then there is the Allison V-1710. Read the history of that engine, the last of which passed it's type tests at 2.920 HP!!!

Actually Royce prohibited files. Any workman caught with one was subject to dismissal. There have been plenty of posts on the website disproving the Ford of England and Packard myths. You also have the Ford myth wrong. It wasn't the MoD it was Hooker who claimed this (with no corroboration from other sources).
The "superpower" Merlin did not first appear in the Hornet but rather in September 1944 in the Mosquito PR 32.

 

[pbehn]

Actually Royce prohibited files. Any workman caught with one was subject to dismissal. There have been plenty of posts on the website disproving the Ford of England and Packard myths. You also have the Ford myth wrong. It wasn't the MoD it was Hooker who claimed this (with no corroboration from other sources).
The "superpower" Merlin did not first appear in the Hornet but rather in September 1944 in the Mosquito PR 32.

The quote is from when RR and Ford of France were involved inn setting up a service facility and factory in France. Lovesey was put in as a coordinator to learn about mass production, it all came to nothing, but it was how Ford had a set of drawings.