Japanese Zero vs Spitfire vs FW 190

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Hey GregP,

The turbulator venturis in the V-1710 air intake manifolds were to help create a more even mix of the fuel/air charge. This reduced the chance of a richer mixture entering some cylinders and weaker mixture entering other cylinders - causing detonation(knock) in the cylinders.

The later Merlin did not use them since the fuel was introduced at the intake end of the supercharger, with the supercharger effectively taking the place of a turbulator venturi.

I do not know why the V-1710 needed turbulator venturis while the Merlin did not, but the "British" fuel did not separate any more than the "US" fuel did.

Please see my post "P-38 or Mosquito?".

edited: changed turbulator to venturi due to info introduced by Reluctant Poster in his post#1,500 below
 
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Did any Merlin use turbulators?

The Merlins also had a simpler intake manifold design. So maybe it was related to the V-1710 design?
 
In the Pacific end June 1943, (using Wiki for the escort carriers)
Saratoga was operational in the South Pacific, along with HMS Victorious. Essex arrived at Pearl Harbor end May 1943. Enterprise was under repair/refit. Independence arrived San Francisco in early July 1943.

CVE Long Island, Copahee, Nassau, Sangamon, Altamaha, Chenango, Suwannee, Barnes, Prince William, Breton. Agreed the escort carriers were mostly on support and supply runs around mid 1943, that changed after the Central Pacific drive began, to provide anti submarine and ground support.
 

I double checked these and came up with the following:

Ranger, Saratoga, Enterprise, Essex, Lexington, Yorktown II, Bunker Hill
Atlantic --- SP ------ (SP*) ----May 43- -Aug 43 -July 43- -Oct 43

*Enterprise at naval battle of Guadalcanal through Nov 42, Solomons through Jan 43,
(Wiki notes that her fighters were able to destroy "most of" the Japanese bombers at the (Jan 43) Battle of Rennell Island. Wiki for that battle says 12 bombers out of 43.

Battle of Rennell Island - Wikipedia

en.wikipedia.org

Then they went to Espiritu Santo. It looks like Enterprise went into refit in July of 43, and was out until November. So it was there for the key period and key battles.

HMS Victorious was in action in the Pacific in May 17 after a partial refit, and then was in action until July.

So it looks like two CVs for most of 1942 (after Midway) and then two more from Spring to Summer 43 (then one of the two- Victorious- went home while the Essex stayed), one more (Yorktown II) in July which is also when CVL Independence shows up. The rest came late in summer / fall 43 (so more concurrent with Hellcats).

The CVLs seem to have also arrived in summer and fall of 43 (3 in each season).

Independence, Princeton, Belleau Wood, Cowpens, Monterey
-July 43--- --- 9 Aug 43 --- July 43 ----- Nov 43 -- Nov 43

I didn't go through all the CVEs but presumably a few of them were in action.

Does anyone know the combat history of 832 Sqn FAA? What were they flying? I couldn't find anything. Avengers? Apparently Victorious had trouble handling Avengers. Were there any FAA fighter units on board?

So two in late 42, then four by Spring 43 to carry Wildcat pilots to the enemy, then five by mid-summer (adding Yorktown II, Independence and Belleau Wood, but losing Enterprise and Victorious), and then two more in August for seven (Lexington and Princeton) and then three more in the fall (Bunker Hill, Cowpens and Montery) for ten.

(Later 1942)---- 2 ----- Saratoga, Enterprise
May 43 ---------4 ----- Saratoga, Enterprise, Essex, HMS Victorious
July 43 --------- 5 ----- Saratoga, Essex, Yorktown II, Belleau Wood (CVL), Independence (CVL)
Aug 43 ---------7 ------Saratoga, Essex, Lexington, Yorktown II, Belleau Wood (CLV), Independence (CVL), Princeton (CVL)
Nov 43 --------10 ----- Saratoga, Essex, Lexington, Yorktown II, Belleau Wood (CLV), Independence (CVL), Princeton (CVL), Bunker Hill (CVL), Cowpens (CVL), Montery (CVL)

So based on that, I'd say there was a deficit in fast aircraft carriers in the South Pacific from late summer 1942 through May of 43, when carrier strength suddenly doubled. From May through August 43 (still Wildcat time) Carrier strength looks pretty good, especially since there were plenty of CVE's available to do the more mundane tasks of escorting logistics and ASW etc.

However when the Hellcats arrived in Nov of 43 the force strength was again almost double what it was in the early Summer, so that no doubt correlates to a more aggressive Navy!
 
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This "Battle of Rennell Island" in January of 43 is pretty interesting. I know we have discussed it before on here (I think in a thread about the Betty) but it's interesting to look at it from the perspective of the air power battle.

In the battle the Japanese made a concerted effort to drive off a US fleet carrying supplies and reinforcements, so that they could evacuate their troops from Guadalcanal. They managed to drive off the US carriers, albeit at some cost, but the transports made it to Guadalcanal and carried out their reinforcement mission anyway. However with the US carriers out of range, the Japanese were able to evacuate 11,000 of their men from Guadalcanal.

The US fleet Task Force 18 consisted of three CAs, three CL, two CVLs (Chenango and Suwanee) and eight destroyers. One CV Enterprise came behind with some more ships.

According to Wikipedia on 29 January they were attacked by 31 G4M and G3M bombers (16 each, with one turning back with engine trouble) from the Japanese 705 and 701 Air Groups. During the initial (dusk) attack CAP was not up. The first attack missed but the second hit Chicago with two torpedos and Destroyer Wichita was hit but the warhead didn't detonate.

On 30 January another wave of attacks came in. Chicago was crippled and was being closely escorted by destroyers. CAP drove some bomber away and specifically drove away an attack on the Enterprise, but arrived too late (in spite of flying into friendly flak) to save Chicago which was hit again. Chicago was hit four more times and sunk, a Destroyer La Vallette was hit and heavily damaged. They claimed 8-10 bombers shot down. The bombers were at long range and appear to have been unescorted.



Shows you how deadly those long range torpedo bombers were, even if they were pretty vulnerable. It was still tricky managing the fighter direction etc. so that enough CAP could intercept them in time. They managed to shoot down a lot of them, apparently (anyone know the actual losses?) but not before they had dropped their lethal torpedoes.

Even if they lost 12 x G4M and / or G3M, that seems like a decent trade for 1 enemy heavy cruiser sunk, a couple of destroyers crippled, and 11,000 friendly troops saved.
 
Schweik said:
However when the Hellcats arrived in Nov of 43 the force strength was again almost double what it was in the early Summer, so that no doubt correlates to a more aggressive Navy!
Click to expand...

There seems to be a lot of confusion lately as to the earliest date the F6F could be found aboard Pacific Fleet carriers. VF-9 holds the distinction of the very first unit to deploy with a full compliment of 36 Hellcats aboard the Essex in May 1943. By early August the F6F was the sole fighter found aboard the Essex, Lexington, Princeton, Belleau Wood, Yorktown, and Independence. Lastly, the Enterprise, Cowpens, Monterey, and Saratoga were all equipped with Hellcat fighters by the end of September 1943.

Many of these units were active during the early Tarawa-Makin raids and Wake Island campaign, which occurred during mid September and early October 1943, respectively.

Source: Location of U.S. Naval Aircraft, Department of U.S Navy (1943)
 
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Well it seems like yet another case where the 'conventional wisdom' about WW2 aviation (including mine in this case) is off!

Where would you put the transition then, June, July? August?

Would you agree that April 1943 is the major turning point for Corsair operations in the Pacific?

I'm trying to build a timeline of how long the F4F was doing the brunt of the work for the Navy and Marines.
 
I would say August 1943 for the Hellcat because by then a predominant number of carrier fighting squadrons were fully equipped with it. Anytime before that the F4F was seeing much greater use.

Because of the carrier shortage there were many fighter units that were not assigned ship duty for roughly the first seven months of 1943 and they largely flew F4Fs from land bases stateside and overseas. VF-12 and VF-17 are two units that flew the F4U at various stages as well.

I'll have to look at the F4U a bit closer, being it saw extensive use by the US Marines, but I feel your estimate of April looks pretty close. Maybe someone who has studied the Corsair in greater detail than I could chime in and confirm this.
 
I found the web link to the archive of aircraft locations. They have reports from 1942-45. There's a section for Marine Air Wings included in each report. Maybe this will help you determine your timeline:

Location of U.S. Naval Aircraft, World War II

Click on the day, month and year (e.g., 2 Feb 1942) to view the Location of U.S. Naval Aircraft report for that particular timeframe. NOTE: All of these records are unclassified or have been declassified. Due to the age of the records, type of typewriter font, and capability of current OCR...
www.history.navy.mil
 

Wow that is an amazing resource! Archiving that baby...
 
So per the other thread where we were discussing this...

Most Overrated aircraft of WWII.....?

Italy.
ww2aircraft.net

... it seems like the Wildcat was on it's own for Navy aircraft from Pearl Harbor (Dec 7 1942) essentially until September 1943 which is when the Hellcats drew first blood.

Exceptions being some F2A (I think only used by Marines, did the USN ever fly them in combat?) and some units of F4U in the Solomons, also by the Marines. I notice there was a Navy F4U unit (VF-12) on the Enterprise at Pearl Harbor (or based out of) in 6 July 1943 but apparently not in combat and soon removed. One of the early workups that didn't work out I guess?
 
Both VF-12 and VF-17 were heavily involved in Corsair carrier qualifications but when the US Navy finally decided on the Hellcat as their standard shipboard fighter the F4U was relegated to the US Marines. Only VF-17 retained the Corsair and operated from land bases in the Solomons.
As a side note the latter unit 'unofficially' flew combat ops from carriers during strikes on Rabaul, when Corsairs from the unit rearmed and refueled aboard ship in order to quickly rejoin the battle.
 
wuzak said:
Did any Merlin use turbulators?

The Merlins also had a simpler intake manifold design. So maybe it was related to the V-1710 design?
Click to expand...
The device added to the intake manifold of the V-1710 was not a turbulator . It was a venturi which, like all venturies, created an area of low pressure . A tube from the venturi was used to suck up the fuel that had dropped out of the airstream and by doing so revaporized it so that it could actually reach the cylinders rather than sloshing around the bottom of the intake manifold. It was in effect a second carburetor. To quote Daniel Whitney's article from the Spring 2002 Torque Meter "The Allison Time Bomb": "...the first was to fit the "Madame Queen " air intake pipe, which incorporated a 'boost venturi " to revaporize any condensed fuel."
The Merlin did not have the problem of fuel collection in the intake manifold because of its much cleaner design. The V-1710 intake manifold it a fluid dynamics nightmare of sharp 90 degree bends, back to back elbows and splits in flow that caused fuel distribution problems. The middle of the manifold divides into 2 streams and immediately does a very sharp 90 degree turn upwards followed by yet another split and another sharp 90. Its a wonder anything get trough at all.
The following image is from the bible of hydraulics, "Handbook of Hydraulic Resistance" by Idel'chik, show the flow through back to back 90s. As you can see there is plenty of turbulence created by the poor design.




Look at all the changes in direction, splits in flow and changes in area . These all contribute to large pressure drop that the Merlin manifold did not have. Note the direct airflow path to the outer cylinders contrasting with the 180 degree bend the air fuel mixture for the center cylinders has to negotiate. The result of this was that the fuel tended to drop out before the reaching the inner cylinders. The outer cylinders ran rich while the inner ones ran lean. Quoting Whitney again: "Lockheed found that piston failures were usually in the #3 or #4 cylinder the cylinders most likely to be running lean under any condition...".
 
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