Late model Rolls-Royce Merlin/Packard V-1650 Merlin details

[BarnOwlLover]

This is and inquiry about late versions of the Rolls-Royce Merlin and Packard Merlins of the same vintage. This is about the late 100 series Merlins and the Packard V-1650-9 and later engines and how they differed from the more "mainstream" variants common during World War II.

In particluar, I'm interested in the later Merlin RM series engines (such as the RM 16SM and RM 17SM) and the Packard V-1650-11 and subsequent engines that weren't built in quantity.

Any info floating around about these late engines?

 

[MIflyer]

Well, here is an interesting article, but I'm not sure it covers much of what you want.

 

[BarnOwlLover]

So no further info is known? Especially about the V-1650-11 onwards.

 

[Piper106]

This is and inquiry about late versions of the Rolls-Royce Merlin and Packard Merlins of the same vintage. This is about the late 100 series Merlins and the Packard V-1650-9 and later engines and how they differed from the more "mainstream" variants common during World War II.

In particluar, I'm interested in the later Merlin RM series engines (such as the RM 16SM and RM 17SM) and the Packard V-1650-11 and subsequent engines that weren't built in quantity.

Any info floating around about these late engines?

The Packard V-1650-19 was to be similar to the -11 engines, but with a continuously variable fluid coupling supercharger drive that allowed any ratio between 8.3:1 (max) and 5.0:1 (minimum), in place of the two gear ratios for the supercharger drives in previous engines. The dash 19 was to be rated 2200 HP at sea level and 1875HP @ 17000 feet.

The Packard V-1650-17 was to be similar to the -7 engines (dash 7 was used in large numbers in the P-51D) except for a Simmonds boost control unit.

The RM16SM series was produced as the Merlin 113 and Merlin 114 used in late war / post-war Mosquitos.

 

[BarnOwlLover]

Any details on how this continuously variable drive worked and what it was intended to do (what advantage it was supposed to have)?

 

[MIflyer]

Any details on how this continuously variable drive worked and what it was intended to do (what advantage it was supposed to have)?

It worked like a hydromatic drive transmission. It used fluid coupling to join the drive to the compressor. The BF-109 also used the same basic approach. That approach got rid of the switch point from low to high speed and gave a continuously variable result more like a turbosupercharger. The first stage supercharger was separate from the engine and was driven by the starter coupling, since the starter was not needed after the engine was running. This approach allowed Allison to build one basic accessory section for all models of the V-1710 and thus cut costs, but was a poor decision in my opinion.

Attached is a NACA report on it.

 

[BarnOwlLover]

So it wouldn't have worked on the Merlin (or as well as it did on the two-stage Allisons)? Was there any other way (or at least a better way) to get rid of or get around the whole two speed switch deal?

 

[Piper106]

The Packard V-1650-19 was to be similar to the -11 engines, but with a continuously variable fluid coupling supercharger drive that allowed any ratio between 8.3:1 (max) and 5.0:1 (minimum), in place of the two gear ratios for the supercharger drives in previous engines. The dash 19 was to be rated 2200 HP at sea level and 1875HP @ 17000 feet.

The Packard V-1650-17 was to be similar to the -7 engines (dash 7 was used in large numbers in the P-51D) except for a Simmonds boost control unit.

The RM16SM series was produced as the Merlin 113 and Merlin 114 used in late war / post-war Mosquitos.

Most of the info below comes from "Mustang" by Robert Gruenhagen, which I had to dig out late last night.

The Packard V-1650-9 was built for the P-51H. and was equipped with ADI (water injection). This engine was similar to the British RM16SM except for the carburetor.

The V-1650-9A was same as the dash 9 except the water injection equipment was deleted.

The V-1650-11 was similar to the dash 9 except the Stromberg PD-18 pressure carb on the -9 was to be replaced by a Stromberg speed density fuel injection system with ADI.
The proposed P-51L would have combined the airframe of the P-51H with the V-1650-11.

The V-1650-13 was similar to the V-1650-3 (produced for the P-51B and P-51C) except for addition of a Simmonds boost control unit.

The V-1650-17 and V-1650-19 were as per my previous post.

The V-1650-21 was to be same as the -11 except left hand prop rotation for the P-82.

The V-1650-23 was to be "similar to the V-1650-11" except reverting to a pressure carb. Intended for the P-82B/C/D.

V-1650-25 same as the -23 except left hand prop rotation, again for the P-82.

 

[BarnOwlLover]

I'm going to have to get that book eventually.

 

[Piper106]

Note that the speed density fuel injection systems used by the Merlin 113/114, Merlin 130/131 and V-1650-11 were nothing like the fuel injection systems used by the German aviation engines. The systems on the above Merlin / Packard Merlin engines sprayed a continuous stream of gas into the eye of the supercharger impeller. The German systems injected discreet 'shots' of gasoline into the individual cylinders at a specific time during the intake stroke.

Oh, yes, the V-1650-15. That was to be a updated version of the V-1650-5 with (again) a Simmons boost control unit. The V-1650-5 was a version of the (two stage?) Merlin with a remote propeller reduction gearbox intended for a proposed P-63B, in place of the two stage supercharged Allison V-1710s used in all other versions of the P-63.

 

[Deleted member 68059]

There is a family tree showing the relationship between the major Merlin variants and the Packard versions on page 407 of my book.
It shows the differences between the models, and includes the -11, 21, 23, 25

 

[tomo pauk]

So it wouldn't have worked on the Merlin (or as well as it did on the two-stage Allisons)? Was there any other way (or at least a better way) to get rid of or get around the whole two speed switch deal?

The 2-speed switch worked just fine on the Merlins that were outfitted with it, as well as other engines with 2-speed switch. Or even better than on those, since Merlins were handling over-boosting better than other engines, thus negating any or most of problems at altitudes just under the rated altitudes.
A 3-speed drive would've been nice-to-have.
The Polikovskiy's device (swirl throttle) as used on Milukin engines and on Jumo 213s would've come in handy. Ditto the water-alcohol injection, without waiting for 1945.
The variable speed drive would've also worked good with some development invested on it, like it worked on DB engines. Here is about the Packard Merlin with variable-speed drive: link

 

[MIflyer]

While not providing the detail of the Snowygrouch book, Graham White's book on WW2 aircraft engines does have a summary of Merlin models.

 

[wuzak]

In particluar, I'm interested in the later Merlin RM series engines (such as the RM 16SM and RM 17SM) and the Packard V-1650-11 and subsequent engines that weren't built in quantity.

The RM.17SM used a bigger supercharger impeller than regular 2 stage Merlins.

The RM.17SM had a 12.7/10.7 inch supercharger, compared to the normal 12/10.1 inch supercharger of the regular model.

The RM.17SM never went into production, but would have been rated 2,200hpp in low gear and 2,100 in high gear.

I can't recall the altitudes for those ratings, but it was considered a "low" altitude engine, like the Merlin 66 and V-1650-7.

 

[MIflyer]

A 3-speed drive would've been nice-to-have.

The only one of those I've ever heard of was used on the Mitsubishi J2M Raiden "Jack" fighter. Of course it was a single stage supercharged engine.

 

[MIflyer]

Here is something from the P-51H pilot's manual, 1945 edition. By the way, I've read that postwar the overhaul facilities were not terribly careful about which type V-1650 they put in which type airframe. So H engines might have ended up in D airplanes and vice versa.

 

[tomo pauk]

The only one of those I've ever heard of was used on the Mitsubishi J2M Raiden "Jack" fighter. Of course it was a single stage supercharged engine.

Juno 213E and 213F were with 3-speed, 2-stage superchargers, amounting to perhaps several dozens delivered before VE day?
RR was planning to introduce 3-speed drives for the Merlins and Griffons, at the end only Griffon 100 series for post-war Spitefuls and Seafangs ended up with 3-speed (and 2-stage S/Cs).

 

[Geoffrey Sinclair]

The table from Graham White, I thought there were only 480 Merlin 29, all for the RCAF, only used in their Hurricanes, in two batches of 240, February to April 1942 and July to December 1942, Merlin 28 but taking a US propeller.

The one hundred and forty one Merlin 27 began production in November 1943 and effectively ended in January 1944. Meant for Hurricane V, Francis Mason in his book the Hawker Hurricane notes one of the mark IV converted to a mark V prototype was tested using a prototype Merlin 27 in July 1943. Rolls Royce reports all Merlin 27 were converted to Merlin 25 for use in Mosquitoes, the Ministry of Aircraft Production agrees.

 

[Piper106]

There is a family tree showing the relationship between the major Merlin variants and the Packard versions on page 407 of my book.
It shows the differences between the models, and includes the -11, 21, 23, 25

One bit of data not yet mentioned are the production quantities for the Packard Merlin engines dash 11 and higher. I assume that each variant dash 11 and higher, the production was limited to a single digit number of engines for testing / prototype airplanes (and for some dash numbers, no hardware at all). But again, that is just an assumption... and we are all grown up enough to know what that means.

 

[Deleted member 68059]

One bit of data not yet mentioned are the production quantities for the Packard Merlin engines dash 11 and higher. I assume that each variant dash 11 and higher, the production was limited to a single digit number of engines for testing / prototype airplanes (and for some dash numbers, no hardware at all). But again, that is just an assumption... and we are all grown up enough to know what that means.

Hmmm I`m not actually sure I have any data on that.