RR/Packard V-1650 Merlin Dash # Differences

[AHancock51]

Hello WIXer's! I've been trying to do research on the differences/improvements of the V-1650. For example, what's different between and V-1650-1 and a -7? Thanks all!

[51fixer]

Hello WIXer's! I've been trying to do research on the differences/improvements of the V-1650. For example, what's different between and V-1650-1 and a -7? Thanks all!

-1 was an early Packard which IIRC was single stage blower, no Intercooler and used in the P-40.

-3 Was early 2 stage blower with the Intercooler and was used in the early P-51B/C.

-7 was an improved version for AAF A/C.

-9 was much different, thinner and lighter castings in some spots. The heads and banks were improved. Oil system different. Water injection.

Each improved version was an improvement in technology and engineering which upped the horsepower and reliability.

There were also Packard built engines built for the British and Canadian A/C.

And dozens of RR built V-1650 models as well.

[AHancock51]

Oh this is great stuff Rich! Thank you very much for the info. Very interesting to see the "tweaks" made here and there to the 1650. I also found in kinda interesting that the Brits had some birds w/ Packard builts and vice-versa w/ the US.

[Saville]

There may also be carburetor differences between the RR and the Packard but I don't have the details handy.

[AHancock51]

On a side note, what if someone wanted to build a full-scale P-51 around a V-1650-1 series? Would it work as is (without 2 stage blower/intercooler)? Could it or the P-51 be modified so it would work?

[The Inspector]

Partds interchangeability is an isue too as PACKARD made parts to blend with their manufacturing processes and to correct some 'issues' with the original parts design/assemblies as they were used to cranking out a lot of engines daily just like they used to crank out cars, and anything that saved a step or a few seconds was to the good and a few extra cents profit per unit.

[51fixer]

On a side note, what if someone wanted to build a full-scale P-51 around a V-1650-1 series? Would it work as is (without 2 stage blower/intercooler)? Could it or the P-51 be modified so it would work?

The propshaft and engine mounting locations are all in the same as well as the exhaust mounting so externally it would look the same.
Reduced power would have some effect in performance. Real High altitude ops isn't an issue today but would be noticable as you go higher.

[51fixer]

Partds interchangeability is an isue too as PACKARD made parts to blend with their manufacturing processes and to correct some 'issues' with the original parts design/assemblies as they were used to cranking out a lot of engines daily just like they used to crank out cars, and anything that saved a step or a few seconds was to the good and a few extra cents profit per unit.

Rolls has a compatibility list for different models.

[Saville]

Ok here is what I have on Packard vs RR Merlins with regard to the carburetor differences:

This is from the formerly restricted Technical Order T. O. No. 02-55AC-2

Section IX, Chapter 1 -0 The Carburetor

"The Stromberg PD - 18A1 Injection Carburetor,....used on the Packard V-1650-3 engines and PD-18B1 Injection Carburetor used on the Merlin 68 and 69 engines are double barrel twin boost venturi updraft units having "Fuel Head" Enrichment Valves, Automatic Mixture Control, and Idle Cut-off."

......

"For British-manufactured engines, carburetion consisted of a two-barrel SU Carburetor with automatic boost control."

Now here's the juicy part......regarding the tendency for the carbed Merlin to cut out over -G as opposed to the DB-601 fuel injection units:

"An idiosyncracy of the original SU carburetor was a condition known as "rich cutout" caused by negative g. In fact, the negative g cutout was a two-stage event. At the onset of negative g, fuel was forced to the top of the float chamber, which exposed the main jets to air. This caused the first, momentary lean cutout (Fig. 4.31). If a negative g condition continued, the floats reacted to the reverse of normal conditions and floated the wrong way, that is, they floated to the bottom of the float chamber. The needle valve opened wide, allowing full fuel pressure from the engine-driven pump to flood the carburetor. And excessively rich mixture was then admitted to the supercharger, causing the more serious rich cutout (ref. 414).

.................The solution turned out to be disarmingly simple. Miss Beatrice "Tilly" Shilling, a young physicist working at the Royal Aircraft Establishment, was assigned to work out a solution, which turned out to be a simple flow restrictor somewhat similar to a flat washer......"

I find it fascinating that the effect which is typically referred to as fuel starvation was actually a flooding.

[JDK]

Points for managing to avoid mentioning the usual rather ~hem hem~ name of Miss Shilling's famous fix.

As well as the proper documentation for Merlin users, which can be obtained by those interested, there are a number of publications for the technically interested of greater than general-readership interest.

'Merlin Power' by Victor Bingham (Airlife) is a good general introduction to the aircraft that used the Merlin (a list we ran in Warbirds Worldwide counted to about 50 distinct aircraft types that were Merlin equipped at one time or another).

The Rolls Royce Heritage Trust booklets on various aspects of the Merlin are technically sound and in depth and are normally highly recommended. Unfortunately there's no obvious website listing them for the interested that I've found - anyone?

The Merlin has to be one of the best documented aero-engines, given its UK and US development and use, as well as its long, wide use throughout the whole of W.W.II and far beyond. You can spend a lifetime discovering all the factoids about it; but one up front and centre is to beware of any publication claiming that Britain or the US (or anyone else) offered 'the best' Merlin. It was much more complex than that, fundamentally about fitting production to local practice and developing a remarkable design to multiple best fits for specific tasks - right down to today where warbirds may well fly with a different model Merlin than originally required as warbird ops benefit from other (such as 'transport') versions of the engine, or major units of the engine.

In other words, it's a big question!

Regards,

[Saville]

Points for managing to avoid mentioning the usual rather ~hem hem~ name of Miss Shilling's famous fix.

I am nothing if not well mannered

[Avnut]

The book "Allied Aircraft Piston Engines of World War II" by Graham White has a break down of the different Merlin dashes and marks by Packard and Rolls. A very good reference book. Check your library, or have them request it through interlibrary loan if they don't own it, or Amazon. The link below is Amazon's info on the title.

http://www.amazon.com/Allied-Aircraft-P ... 087&sr=1-1

[AHancock51]

The book "Allied Aircraft Piston Engines of World War II" by Graham White has a break down of the different Merlin dashes and marks by Packard and Rolls. A very good reference book. Check your library, or have them request it through interlibrary loan if they don't own it, or Amazon. The link below is Amazon's info on the title.

http://www.amazon.com/Allied-Aircraft-P ... 087&sr=1-1

Thanks for the referral Avnut! I'll be looking for it...