Spitfire V Versus P-40E

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The Spitfire V never had a Bendix carb
 
Merlin 50 & 55 did I believe
They did not.
Merlin 50 Diaphram type carburetor. Rolls Royce developed.
Merlin 55 R.A.E. Anti g type carburetor
Both of these were modified SU carburetors. The diaphragm feed was abandoned in favour of the R.A.E. modification. To quote Lumsden: "These trials resulted in a retrospective modification on all Merlins fitted with S.U. carburettors."
Rolls Royce Piston Aero Engines - a designer remembers figures 90 and 91 illustrate the SU carburetor and the SU carburetor with anti g modification developed in conjunction with RAE Farnborough respectively.
 
We also know that Hurricanes shot down most of the German bombers.
Well, there were a lot more Hurricanes in service so that did tend to affect the scoreboard.

The Merlin 45 engine though more powerful than the Merlin II or III on the Spit Mk I, was not up to it's full potential.
In part due to the Fuel and in part due to the fact that the MK V and it's engines were in production for along time, Mk Vs first show up in the Spring of 1941 and the last are built in the summer of 1943(?). The P-40 didn't stand still either. The first P-40D being delivered May 7th 1941 and by the summer of 1943 Curtiss was building P-40N-5s.

The early Kittyhawk had a 1,050 hp engine
Typo? 1150hp?

But the Spit V improved even more. They got the 130 octane fuel and increased the allowed boost, and put in engines with more horsepower - it went from ~ 1,200 hp to routinely up to 1,585 at high boost.
The 1585hp engines were the ones with the cropped impellers. the 1585hp was at 2750ft (no ram) at 18lbs boost. The standard Merlin 45s were eventually approved for 16lbs boost and either 1515hp at 11,000ft or 1470hp at 9250 depending on exact model and carburetor. The 1200hp figure was at a bit above 18,000ft.
Question on the Spit MK V is when the units in the field went from 9lbs boost to 12lbs and then when they changed from 12 to 15/16lbs boost.
I don't know if the cropped impeller was an interim solution. As in if it was allowed higher boost first and then the full size impeller engines were allowed to use the high boost later?

The cropped impeller engines made 45hp more for take-off at 3000rpm and 12lbs boost than the full size impeller engines.
 

Ok I'm going by Wikipedia which is always a little risky. It says:

Merlin 50 - Merlin 50 series was first to use the Bendix Stromberg "negative-g" carburettor.[10][18][19]

Their first source is this which says: "Merlin 50 series / Similar to Merlin 45. Majority of production engines fitted with anti-G carburettor."
Their second source is this book - but I can't read what it says because it's behind a paywall.
Their third source is this which says "The only difference between a Merlin 45 and 50 is the fitting of a "negative g" carburettor and a fuel de-aerator on the latter engine, and these are unlikely to have a marked effect on performance. "
 

You are right, I transposed the number from the Tomahawk which was 1040 for takeoff. The V-1710-39 on the P-40D / E was initially rated for 1,150 hp at 42" Hg, then this was changed (I think in April 1942) to 1,240 hp for takeoff at 45.5" Hg (5 minute rating) and then later around June or July 1942 (probably with the newer engines with the strengthened cam shaft etc.) bumped up to 1,470 hp at 56" Hg (5 minute rating).

The V-1710-73 on the P-40K was 1,325 hp at 51" Hg for takeoff and 1,550 hp at 60" Hg WEP (5 minutes at Sea Level) with military power back down to the 1,150 hp rating at 42"


There are a couple of references to the LF types in MAW, with kind of a hint that they were 'hot', but they usually don't specify that much detail, typically they just say Spit Vb or Vc or sometimes they only say Spit V

Do you know the answer about the pressurized carb?
 
The Book "The Merlin in Perspective" by Alec Harvey-Bailey lists the different carbs used on Merlin engines but gives model number. No way of knowing if one of the later ones is a Bendix type under a different name or licence

However.
Merlin 45................A.V.T. 40/193 or 214 carburetter.
Merlin 45M............same with stronger boost control spring. Mod 615
Merlin 46................same with larger chokes.
Merlin 47...............same as Merlin 46
Merlin 50...............A.V.T. 40/ 214 carburetter
Merlin 50M..........same with stronger boost control spring. Mod 615
Merlin 55..............A.V.T. 40/ 216 carburetter
Merlin 55M..........as Merlin 55.
 
Anyway do you agree or disagree with my contention that the 1943 Spit V was far more formidable than a 1941 Spit V?

Whether or not it was an LF variant is a secondary factor, it could be good if fighting low as was often the case in N/A, and the LF had that dynamite roll rate, but it may be giving up the altitude advantage to the Luftwaffe. Presumably you could use both types though.
 
Anyway do you agree or disagree with my contention that the 1943 Spit V was far more formidable than a 1941 Spit V?

Against the FW190 the '41 version was outclassed, by '43 the Anton pilot needed to have is brain in gear, what made his job even worse was the Mk IX looked the same except for being 9'' longer, and both had reliable belt fed Hispano's loaded with SAPI rounds.
 
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I couldn't find anything under "A.V.T. 40/ 214 carburetter" or carburetor
Once again I point to Figure 91 of Rolls Royce Piston Aero Engine by A A Rubbra. it is a "TYPE AVT 40 ANTI-g". It is an "SU carburettor with anti-G modification developed in conjunction with R.A.E. Farnborough."
From the same book: "To deal with this problem a negative "G" carburettor was designed which provided a diaphragm controlled fuel supply to the carburettor as a replacement for the normal float and needle. This proved unsuccessful in service trials and an anti "G" version of the S.U. carburettor (91) was developed, with modified valving in the float chamber. This worked satisfactorily and was in use to the end of the war on both single and two stage engines."
In references you provided the only mention of Bendix is the Wiki article. Ant -g does NOT automatically mean Bendix.
 
The negative G problem with the Merlin featured a "Lean Cutout" and a "Rich Cutout."

When the nose was shoved over the fuel in the carb float chamber rose to the top, and therefore could not be sucked into the engine. This was fixed by putting a standpipe in the float chamber giving a path for the engine to inhale the fuel from the top of the float chamber.

After positive G was regained the float chamber had become full of fuel during the negative G period, resulting in an excessively rich mixture and another loss of power, typically evidenced by a burst of black smoke coming out of the exhaust. This was fixed by putting an orifice in the fuel line that limited the amount of fuel that could get into the float chamber.

In contrast, the Bendix Pressure Carb commonly used on US high power engines was completely different and injected fuel into the center of the mechanical supercharger inlet so it was a form of "Throttle Body Injection" and was immune to the G load situation. The British eventually adopted the Bendix carb, seen below on a V-3420.

 

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