Merlins > Packard vs RR

[trackend]

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.

 

[DerAdlerIstGelandet]

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....

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?

 

[pasoleati]

You are not Twitch...

 

[drgondog]

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

 

[FLYBOYJ]

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?!?!?

 

[trackend]

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.

 

[FLYBOYJ]

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.

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.

 

[trackend]

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

 

[DerAdlerIstGelandet]

You are not Twitch...

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

 

[Hop]

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.

 

[FLYBOYJ]

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...

 

[glennasher]

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.

 

[k9kiwi]

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.

 

[mkloby]

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...

 

[trackend]

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

 

[kool kitty89]

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.

 

[mhuxt]

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....

 

[kool kitty89]

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)

 

[mhuxt]

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

 

[kool kitty89]

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