V-12 Supercharger Boost Problems

[MiloMorai]

As I continue to research this issue, one thing I have learned is that one has to be careful about WHICH Merlin engine is under consideration. Rolls-Royce unfortunately applied the Merlin nameplate to at least 2 and possibly 3 different engine lineages during the WW2 era.

What would be these engine lineages?

[icepac]

If you want information on high horsepower Allison engines, ask the unlimited hydroplane guys.

This one beat the turbines and I feel a better set up engine could still do that.



Here's a video of it in action.

https://www.youtube.com/watch?v=4FMP9crlA7w

A friend builds merlins for tractor pulling but his engines are way beyond even the engines you see at reno.

If you're familiar with a merlin, then the picture below might not look very familiar but it's been taken further than anybody else has taken one and makes huge hp at far less boost than the merlin guys at reno.



And here's his cam drive setup........again....way beyond what anybody else has done whether Mr. Nixon or Mr. Barrow.

[mobydick94927]

As far as I can tell, the 3 lineages of the Merlin engine were:
Merlin Mark I - an all-new design featuring the Ramp Head concept. It was unsuccessful.
Merlin Mark II - an old design, the Kestrel, scaled up from 22 to 27 liters displacement.
This was the Battle of Britain design.
Merlin Mark LXI (61) - an all-new design, neither Ramp Head nor Kestrel. Introduced in England in 1942 and in the U.S. (Packard) in 1941. This became the Mustang engine, as well as late-model Spits, etc.

[Karnak]

Understand that in the 1920's and 1930's that nobody, absolutely nobody, could anticipate the extreme demands of supercharger boost that were available in the 1940's. It was simply terra incognita.

What boost level do you think the Rolls-Royce R engine used in the Supermarine S6.B was at in 1931 in order to produce almost three times the power of the Merlin II in a Spitfire Mk I in 1940?

I've also never read that the Merlin II was simply a scaled up Kestrel.  Nor that the Merlin 60 series was a completely new design rather than a change to the supercharger built into the engine.  You'll need to support those claims.

[MiloMorai]

The first American version of the Merlin was the Packard Merlin 28 (Mark XX (first production Merlin XX, 4 July 1940)), designated the V-1650-1. The first Packard Merlin ran in Aug 1941. The first Merlin 60 engine ran in March 1941.

The V-1650-1 was had a single stage, 2 speed supercharger.

Karnak, the heads of the Merlin II were scaled up from the Kestrel. Only 172 Merlin Is were made.

[mobydick94927]

One of my main sources was enginehistory . org , in the article:

The Rolls-Royce Merlin Aero Engine
by J. SJ. Wells

Regarding the change from Merlin Mk I to Mk II, Quote:
"At Rolls-Royce, instead of taking off their jackets and sorting the Merlin problems out, they chose to simply dust off the old Kestrel, enlarge the capacity to 27 litres and put it back into production using the spurious title, Merlin II."

This article gives an interesting history of the Merlin(s) beginning in 1932, including a discussion of the early, unsuccessful Ramp Head (Mark I) engine, of which only about 175 were produced.

Regarding the tremendous power of the "R" racing engines:
The "R" engines were enormous at 37 liters displacement - around 600 cubic inches larger than the Merlin (which itself was about 300 cubic inches larger than the Kestrel). The R engines were flat-out racing engines - they only had to last for one race, thus they could be tweaked beyond all reason. The "R" engines were run on custom-made blends of fuel while the Merlin was limited to whatever was available in quantity in wartime. According to one source, the "R" engine could have 18 psi boost. The "R" engines were essentially "hand-made" and 19 were produced.

[GScholz]

Yes, the Rolls Royce R engine led indirectly to the Griffon (Spit14); also a 37-litre engine.

[Karnak]

Regarding the tremendous power of the "R" racing engines:
The "R" engines were enormous at 37 liters displacement - around 600 cubic inches larger than the Merlin (which itself was about 300 cubic inches larger than the Kestrel). The R engines were flat-out racing engines - they only had to last for one race, thus they could be tweaked beyond all reason. The "R" engines were run on custom-made blends of fuel while the Merlin was limited to whatever was available in quantity in wartime. According to one source, the "R" engine could have 18 psi boost. The "R" engines were essentially "hand-made" and 19 were produced.

Absolutely, but that they had been built (and I assume other engines from other companies/nations in the same vein) indicates that the need for ever more power was foreseeable and the boost pressures needed were understood.

[mobydick94927]

The insider details of Merlin supercharger history are fortunately preserved in a filmclip available on youtube:

https://www.youtube.com/watch?v=by4lH2whhjk

(Sir) Stanley Hooker was hired by Rolls Royce with no particular assignment in mind.
He eventually took over management of the Merlin supercharger program.

Check it out.