Packard vs Rolls-Royce Merlins

[GregP]

Someone said there was a Merlin with a continuously-variable supercharger drive ... and someone said there wasn't.

Actually there was.

It was a Packard V-1650-19 of which 2 were built. They had a SUndstrand vartiable speed supercharger drive with automatic speed controller. It was 1,170 lbs net dry weight, and made 2,200 HP @ 3,000 rpm WER at sea level, and 1,875 HPP @ 3,000 rpm at 17,000 feet. Takeoff power was 1,700 HP and cruise was 2,700 rpm at 8 lbs boost.

Yes it was an experimental engine but they DID, in fact, built two of these beasts as the big pistons were just about to go extinct. Had pistons hung around a bit, they might have built it for production ... in an alternate reality.

 

[wuzak]

Someone said there was a Merlin with a continuously-variable supercharger drive ... and someone said there wasn't.

Actually there was.

It was a Packard V-1650-19 of which 2 were built. They had a SUndstrand vartiable speed supercharger drive with automatic speed controller. It was 1,170 lbs net dry weight, and made 2,200 HP @ 3,000 rpm WER at sea level, and 1,875 HPP @ 3,000 rpm at 17,000 feet. Takeoff power was 1,700 HP and cruise was 2,700 rpm at 8 lbs boost.

Yes it was an experimental engine but they DID, inf act, built two of tehse beasts as the big pistons were just about to go extinct. Had piston hung around a bit, they might have built it for production ... in an alternate reality.

I had never heard of that until someone mentioned it in another thread.

I think, perhaps, you have mistyped the weight of the engine, since single speed, single stage early Merlins were about 1350-1400lb.

 

[Shortround6]

1770lbs?

http://www.enginehistory.org/ModDesig/I2 5.tif

These charts are not 100% reliable but the weight fits.

 

[GregP]

No, I have not mistyped the weight.

Packard V-S Drive

 

[wuzak]

No, I have not mistyped the weight.

Packard V-S Drive

1,770lbs it is.

(You did have 1,170lbs.)

 

[wuzak]

Thanks for the link Greg.

It seems that the variable speed drive worked on teh same principle as the V-1710's 2 stage drive - ie, the auxiliary stage was driven by the VSD, while the main/engine stage was driven by the normal gearing. The difference being that there was the two speed drive for the main/engine stage impeller.

 

[GregP]

Well hell, I DID mistype ... didn't I? Jeez, that's never happened before!

Next time you visit, slap me, please.

 

[wuzak]

I certainly will!

btw, good to hear that you have found a new job. Hope it is interesting and pays decently well.

And doesn't cut into your time down at the museum.

 

[GregP]

I have Saturdays off ... but woirking on airplanes 6 days a week may prove less than fun. The good thing about Saturdays at the Museum is I don't really HAVE to get anything done on a schedule. We DO make progress, but now I am doing every other weekend on the B-17 and the O-47 projects.

We'll see ... at SOME point.

 

[Shortround6]

Well hell, I DID mistype ... didn't I? Jeez, that's never happened before!

I personally have only done it one or two......................................hundred times


after spell check and edit

 

[GregP]

Me too, Shortround.

I am probably the worst offender in here for mistyping. You're WAY up on the list ahead of me in typing accuracy.

 

[pbehn]

Much of the discussion here is about production engineering. When the merlin was first designed the projected orders would be in the order of thousands I doubt if anyone ever thought that production would run to 150,000. Companies employ different designs and methods when they produce 1000 units per year as opposed to 30,000. Long before the war started the replacements for the merlin were on the drawing board but development of the merlin meant they never really made it.

 

[The Bigfella]

My understanding, based on what my uncle wrote in his autobiography (which I loaned out and haven't got back yet)... he was a Beaufighter / Mosquito pilot - and he did a course at RR as he was being proposed for test flying duties prior to being invalided out with TB.... was that the Rolls engines were built in batches, with a set number of critical spares, eg crankshafts, specific to that batch of engines. The next batch wasn't interchangeable. Packard made everything interchangeable.... need a spare crank... here, have one.

 

[fastmongrel]

My understanding, based on what my uncle wrote in his autobiography (which I loaned out and haven't got back yet)... he was a Beaufighter / Mosquito pilot - and he did a course at RR as he was being proposed for test flying duties prior to being invalided out with TB.... was that the Rolls engines were built in batches, with a set number of critical spares, eg crankshafts, specific to that batch of engines. The next batch wasn't interchangeable. Packard made everything interchangeable.... need a spare crank... here, have one.

Thats not true RR and Packard Merlins were practically interchangeable apart from some specials and the early hand built alphabet series. A lot of time expired Merlins were broken up to provide parts for Meteor Tank engines particulary crankshafts, camshaft drives and conrods. RR and Packard engines were broken indiscriminately and all the parts had the same Rover part number no matter whether they came from the 4 RR factories at Derby, Glasgow, Crewe or the Ford factory at Manchester or Packards in Detroit.

 

[Shortround6]

They also broke up hundreds of RR built Merlins to provide spare parts for the Packard built Merlins in P-40s in North Africa.

These stories may well have been what was being told to troops (pilots and ground crew) in the field who were not doing the over-hauls. Goodness knows there were enough other rumors, legends and tall tales floating around in the absence (or even in the presence) of "official" documents.

ALL Japanese troops wore glasses right?

 

[GregP]

From the Merlin owners I know, which number about 15, the Packard and Rolls engines are not interchangeable in a meaningful way. Some things interchange but aren't normal wear and tear items. You can interchange valve covers, but they don't often fail on their own, so it doesn't help that they interchange. Ditto for parts that bolt on like intake manifolds, oil pans, etc. Packard's tolerances on crankshafts were very tight, so a Rolls crank might or might not fit. Conversely, if a batch of Rolls engine blocks had shorter crank journals than Packard's specs, the Packard crank would not fit in the Rolls.

I understand that neither was particularly "better" than the other, but I know too many people that own one who tell me that the important parts are not all that often interchangeable for me not to believe it. If a guy's P-51 is down and he wants to fly, and has (or can get) a Rolls part, I think he'd use it if he could ... and vice versa if he has a Spitfire, Hurricane, etc. or anything with a Rolls Merlin and he has (or can get) a Packard part.

 

[wuzak]

Packard's tolerances on crankshafts were very tight, so a Rolls crank might or might not fit.

Packard used the same tolerances as Rolls-Royce and Ford UK.

 

[pbehn]

I don't know what a tight tolerance is with a RR engine. The Merlin consumed prodigious amounts of oil, even their car engines burned oil from new.

 

[fastmongrel]

Not surprising 70 year old parts dont fit, it would be amazing if they did fit perfectly. Whats important is that they were interchangeable and the 5 different production units all worked to the same standards something thats not always a given even nowadays.

 

[Shortround6]

The Merlin consumed prodigious amounts of oil, even their car engines burned oil from new.

ALL aviation engines of the time used oil, burned, leaked or out through the breathers. That is why most or all planes fitted with long range fuel tanks had bigger oil tanks or oil tanks had two fill marks, one for normal use and one for long range.
Most specification for aircraft engines not only gave fuel consumption figures in pounds of fuel per hp hour ( or equivalent) but gave oil consumption figures too.