Maneuverability vs Speed

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Because by the end of September 1945 they would have Seafires and, well, Seafires. The rest of the FAA air fleet would have been tossed overboard. Oh, and the last merchant carrier Swordfish. The last Albacores were with the RAF in Aden. Just as,had the British army standardised only on the Sherman tank, by the same date they would have to meet any Soviet threat with armoured cars, Archer SPGs and a steely jaw and a small revolver.
 
Greg, as you know, the reason for the 'gate' was to identify potential WEP issues as better fuel enabled higher MP. For the P-51B/D more specifically, for example, 67" on 130 octane - and then 75" when 150 octane fuel was rough on both the engine and spark plugs As you have pointed out, the Merlin was a little more 'tender' than the Allison when over-boosted.

You raise an interesting question for me, however. Were factory delivered fighters with V-1710s even capable of higher boost with a longer slot than permitted per 'the book' - but field modified later.

The SOP for a broken gate ,was a.) to identify when the engine was strained to (or beyond) the design limit, and b.) give the crew chief and Squadron Engineering a head's up to set aside that airframe/engine for an inspection and possible replacement. It was a 'future safety' issue for the pilot to avoid losing the airplane (and pilot) during combat ops from a preventable maintenance issue. IIRC, for the 51s using 150 octane, the less than 5 minute rule applied and deemed "OK' with caveats (i.e was the Crew Chief comfortabe in the estimate, was this the first time?, if not how many times before). It was logged in on the Form 1 and sent to Engineering. Usually the absolute threshold was 20 or 25 minutes cumulative WEP in less than 5 minute increments - then mandatory engine change and inspection. If there was a serious question that 5 minutes had been exceeded, usually the airframe was puled from ops minimally to inspect the engine. Replacement of plugs was the minimum post action step for that engine if WEP used at all.

Nobody in command levels during combat ops spent any time worrying about a budget.
 
I believe some units were 'rewiring' their throttles, i.e. where the gate would be set to, already by later 1942. Probably by the summer.

This was not AVG by the way, or if it was, I don't know of any data on it. Shortround6 and I have discussed that a few times. It is not clear if the V-1710-33 was overboosted, though it probably was. We also don't know what kind of fuel they had.

What we do have evidence for however is American and RAAF units in the South Pacific, and RAAF units in the Middle East - would probably means 3 RAAF and / or maybe 450 RAAF, before Dec of 1942.

The manual was increased for V-1710-39 up to 56 or 57" by early 1943, and to 60" for V-1710-73 (P-40K) by second quarter of 1943.

RAF (Allison) Mustang units flying over the English channel were boosting to 70" Hg routinely, so I guess they rewired the throttles too.
 
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The first Allison engines to have automatic boost control were in the P-40M. The later P-38's got that feature and had problems with the automatic boost control fighting the turbosupercharger boost control. This was a real problem with recon Lightnings where jerky engine performance interfered with smooth photography and on some of the F-5 recon aircraft the engine auto boost control was removed.
 

I believe the P-40K had them


I think some of the later run of E too
 
According to this website VF-3 was partially equipped with F2A-1s for a brief period aboard the Saratoga during 1940.
 
Wild_Bill_Kelso said:
I believe the P-40K had them
Click to expand...
Yep, the Big Allison Book says the P-40K had Automatic Manifold Pressure Regulator with its V1-1710-73 (F4R) engine. The P-40M had the V-1710-81(F20R) engine which 9.60:1 supercharger gears instead of the 8.80:1 of the -73. The -81 was also used in the early P-40N models and the -99 engine was the same hardware with an Auto Engine Regulator added, and was introduced on the P-40N-40. They re-engined the P-40F and P-40L with V-1710-81's because the Merlins were requiring more spare parts than had been procured, even with the RAF providing 600 of its own Merlins to provide spare parts for the V-1650's in P-40's.
 
They re-engined a small number of P-40F and L wnich were called P-40R, and were used in the states for training. That was a total of 123 planes (53 P-40L and 70 P-40F) out of a little over 3,000 Packard-Merlin V-1650 engined P-40s.

Aside from that 1,281 P-40F were made for US units, (ultimately 5 fighter groups: 325, 324, 57, 33 and 79- in the MTO at the height, plus the 99th FS -Tuskegegee, and the 18th FG in the Pacific) + 150 export as Kittyhawk Mk II for the British Desert Air Force.

1,327 P-40L made for US units, plus 100 export as Kitty Mk IIa, and (confusingly) another 160 as Kittyhawk mk III, which was also used to designate both P-40K and M for the DAF.

The export F/L planes went to two squadrons- 260 RAF and 3 RAAF exclusively, although some worn out British and US ones were later given to the Free French GC II/5. A few pilots of the latter, perhaps not that pleased with their rides, defected to the Germans so the Germans got a couple. But they were better off than the Italians who got the P-39s!
 
I think the early "long nose" Allisons were not good candidates for overboost. It wasn't the power section, it was the nosecase and the associated gears that were the weak link there. Once the Allison went into the "E" and "F" series engines, then the nosecase was not the weak link and overboost was much less fraught with bad consequences.

As for the Merlins, I never thought they had very many weaknesses when operated within limits, but they DID tend to foul spark plugs faster than Allisons while simultaneously suffering fewer intake-related issues and they DO need the heads retorqued every 25 hours. The main weakness I know of is the Merlin rods. They are fine at stock power levels but fail much sooner than Allison rods when higher-than-stock horsepower levels are employed.

That should not have been a factor in WWII, but now that much higher boost level are being discussed, it might come into play ... but I doubt it. You'd have to get to 2,300- 2,500 hp or more to develop a Merlin rod problem and I doubt they did that too often.

When I said "control the budget," Bill, I didn't mean literally. In the military, you control the budget by controlling the supply function. I'm supposing they put wires on the throttle gates to help control the issue of crate engines from supply. Nobody said you couldn't get one, but having to fill out a form explaining why you used excessive boost givers command someone to pin the expense on.

I was in two military branches and it works that way. They always needed someone to pin the blame on, and it was usually the guy who signed it out and broke it. Commanders are rated on performance of their unit and they have a hard enough time surviving bad times without taking blame for abusing equipment they weren't operating to start with. At least, that's the way it worked in the Army and Air Force. Not saying it's right or wrong, it just seemed to work that way.
 
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Just re-reading this thread and the inevitable subject creep.... and it struck me that we all seem to have missed an elephant in the room moment, given its title.

Fairey Fulmar. Large, docile and pleasant handling aircraft. Reasonable manoeuvrability for its class and size but not a stunt plane. Low top speed for a monoplane, heavy, low rate of climb.

Whilst being dissed, its let slip that its success air to air is purportedly down to it being put up against low performing Italian aircraft. One of which citeed as inferior is the CR 42. A CR42 Falco with a top speed (depending on altitude) as little as 10 to 15mph less than the Fulmar's. For context, itt was being pondered earlier whether even 30mph was a significant speed advantage. But the CR42 ^did^ have superlative and vastly superiour manoeuvrability in just about every plane and a superior initial climb.

And yet it was pretty comprehensively beaten by the Fulmar. Yes, the Fulmar had fighter direction. Yes, the Fulmar had better armament. But clearly the CR42 could run rings round it in a dogfight and Italian fighter pilots were NOT cowards by any stretch.

As with so many examples in WW2, speed may not have been the only, but was clearly the most critical determinant, as evidenced by this shining example.

I think on that note, personally I think the answer to this thread has been addressed and answered.
 
Yes, understood and appreciated. I was in the service too, albeit briefly (not multiple branches!). It appears though that under the extreme circumstances in the more remote field postings, they adjusted as they saw fit, which is what the Allison memo was complaining about. The British use of the P-51 Allisons seems to be more studied and careful, but it works out to the same thing. You are balancing the wearing out of engines with the need to out-run very fast enemy aircraft. The potential loss of both aircraft and pilot can result from flying too slowly, but both aircraft and pilot can also be lost to an engine failure.

I believe there was something of a shortage of engines in both the Middle East and the South Pacific, and later (post AVG) in China as well. Spare parts as well. So a really extreme kind of challenge for the mechanics and supply officers and so on. One benefit they had is that the filtering for dust seemed to work better with the P-40 than with some other aircraft, for reasons I don't fully understand, and the Allison seems to have endured high boost (not in the 2,000 horsepower range, but maybe in the 1500-1600 hp) fairly well. The British seemed to have a very good repair system which also amounted to collection of spare parts and consumables etc., much of which was done in a rear area depot. They repaired an incredible number of planes and overhauled a lot of engines.

That said, as I mentioned in another post in one of these threads, engine trouble, engine failures and even fires didn't seem that uncommon. I've seen estimates on engine life from as low as 50 hours to as high as 200 hours, but neither one is very high.

The attrition rate was extreme, which is part of what makes all this balance out. 75 RAAF was 'reduced' in a few weeks during the time of Milne Bay, and were down to 2 or 3 flyable aircraft and most pilots lost. Many RAF, SAAF and RAAF units in the Western Desert were losing 2-3 pilots a week, sometimes more, for months at a time. The first few months of 1942 were particularly brutal. So obviously anything that could be done to improve the combat odds was probably worth it.
 

Yeah, ok, but how big of a sample are we discussing here? I got grief for pointing out Fulmar suffered badly against A6Ms, but having been through the numbers on some of the Convoy fights, I am struggling to remember more than maybe a handful of Italian fighters lost to Fulmars. Not that many were lost period.. I think most of the victories by the Fulmar were against flying boats and slower bombers, though IIRC they did get some fighters. Do you have any numbers on CR 42s shot down by Fulmars? Or specific examples? I think there were maybe a few at Pedestal or one of the other convoy fights, but not more than you could count on one hand IIRC.

CR 42s were downgraded as fighters by early 1942, but the Italians were still using them as dive bombers for at least another year. In fairly large numbers. They were routinely encountered by Hurricanes, Kittyhawks and Tomahawks, and Spitfires. The Italians did not lose that many of them. This was attributed by the Allied pilots to the frustrating agility of the CR 42. I think the CR 42 was retired because it was too slow to catch bombers like the Martin Maryland, Martin Baltimore, and Boston. Not necessarily because it was so bad as a fighter.

My big counter example to yours here on speed would be Ki-43 vs Hurricane. Hurricane had a 20-30 mph speed advantage over Ki-43s until fairly late (whenever the Ki-43-II started showing up, like later 1943?) and yet the Ki-43 seemed to eat them alive. Ki-43 also held it's own against Wildcats and P-40s.

Wildcats, in turn, seemed to hold up pretty well to Bf 109s, though it is again a small sample of encounters.

I think which matters more, speed or "maneuverabilty", is actually a tricky question. It boils down to the ability to disengage, to catch a fleeing opponent, to roll, to turn, to climb and dive. At high or low altitude. The match ups seem to vary, almost in a paper-scissors-rock kind of way, and are sometimes counter-intuitive.
 
The Maritime battles maybe a bit different than the NA land battles, maybe they are not.

The convoy battles mean the Axis forces have to come to the ships and pretty much bomb from a few thousand feet if they want to get hits.
They also took place over a number of years. The Axis had zero torpedo bombers in the Med in 1940 and only a few in 1941 and a lot in 1942.
Likewise the Axis fighters changed over the years. First MC 202s don't show up until late 1941.Until then it was the G 50 the CR 42 and MC 200,
The G 50 was good for about 290-293 mph at 16,400ft and was probably good for about around 270mph at 6,000ft. The MC 200 was about 20mph faster.
Both could certainly outclimb the Fulmar.
The Fulmar shows up Aug 1940 in the Med and they have 3 squadrons by the end of 1940,
The Italians had less than 160 MC 200s in June of 1940 and only one fighter group with G 50s.
The Italians are getting stronger but they also have forces scattered around a large area.
Now you have the classic do the convoy escorts attack the bombers or do they dogfighter axis escort fighters? And at the low altitudes it is harder for the Italian fighter planes do multiple firing passes at the Fulmars.

in 1940-41 the Italian fighters are little danger to the ships. Things change.
 
Good points. I think the Fulmars did shoot down some MC 200s during Pedestal, if I recall right

The SM.79 were around since the Spanish Civil War though I'm not sure when they first started putting torpedoes on them. The Italian torpedoes seem to have been quite good and the S.79s were sinking a fair number of ships per sortie, enough that some of the pilots became heroes in Italy, akin to famous fighter aces. But they also took heavy losses (I think some to Fulmars as well as Sea Hurricanes and maybe Martlets) so they were mostly soon posthumous heroes.
 
Against single-seat fighters, I show the Fulmar with 5 victories against 3 losses. Of the 40 fulmars lost in combat, only 16 were lost in air-to-air combat. I don;t show the Fulmar being waxed by Zeros at any point.

One place claiming that is here: Armoured Aircraft Carriers.

In point of fact, the Fulmar seems to have taken pretty good care of itself versus about any enemy, up until it was deemed a bit obsolete and was retired.

Possibly that has more to do with how, when, and where it was employed rather than any virtues or vices of the Fulmar, but it still seems to have done pretty well for itself in real-life combat.
 
From my reading there were a number of things going on in 1940-41.
1. was the weakness of the long nose reduction gear set up.
2, was the weakness of the whole engine in the summer of 1940. Which was solved in several stages.

The early engines had plain steel crankshafts.
In the middle of 1940 they had the whole engine failing to meet the 150hr type test and the engine de-rated to 950hp/2770rpm for take-off and 950hp/2770rpm at 8,000ft thing going on. Allison rebuilt the US engines (and US only?) with new crankcases and new crankshafts (shot peened?) and introduced the new crankcases and crankshafts on new production engines.
Part of the problem was a poor set up of the test stand that didn't provide the vibration absorption of the real aircraft airframe/engine mount.
I have seen nothing that says when the British engines (or flying Tiger engines) got the new crankshafts so it is a big unknown.

It took a while for the weakness in the reduction gears to show up as a common failure because the failure was in the not in the forward bearing next to the reduction gears but the next one back. Recognizing that was a gear box problem and not a crankcase/crankshaft problem took a while.

Allison started making the shot peened. nitrided crankshafts in early 1942. in middle of the P-40E production? I believe there was also another change in crankcase production some time in 1941?

The -39 engines used in production P-40D/Es used different crankcases and different connecting rods than the older C series engines. The -39 didn't pass a type test until Feb 17th 1941.

The engineers were working on raising the sea level power to 1500hp at 61in in the summer of 1941. But that was related to the strength of the engine, the 1150hp at 12,000ft was a supercharger problem.


The USAAC wanted WEP to be tested at 7 1/2 hours on a test stand. 5 minutes at a time. 5 minutes at WEP and 5 minutes at Military and switching back and forth. This was on test engine with idea that the worst production engine out of 100s if not thousands, would run at WEP levels without failing for a much period in service.
Just because engine serial # 201 runs at 66in for 20 minutes doesn't mean that engine serial #202 will do the same thing without blowing up. Not until you get hundreds of hours of experience over many engines.
Also note that there were a variety of sparkplugs that could be used in these engines and as time went on only certain ones were approved for WEP use.
 
Wild_Bill_Kelso said:
The SM.79 were around since the Spanish Civil War though I'm not sure when they first started putting torpedoes on them. The Italian torpedoes seem to have been quite good
Click to expand...
Again SM.79s went through a bunch of changes.
The SM.79 I's used 750-780hp Alfa Romeo 126 9 cylinder engines.
267mph at 13,120ft.
224mph at sea level.

This is without a torpedo.

The SM.79 II used 1000hp Piaggio 14 cylinder engines and entered production in Oct 1939. By June 10th 1940 the Italians had 594 SM.79s and as of Oct 1939 they had had 385 of the SP.79 Is in service. This is out of 612 built by that time?
They had been fooling around with torpedoes on the SP.79 since March of 1937, but they didn't form a service squadron until the summer of 1940 with a total of 5 aircraft.
The Crews performed well and achieved a number of successes but I don't think they formed a 2nd unit until 1941. Most 1940 attacks were by 1 or two aircraft.
 


"Waxed by zeros" would be at the well documented Japanese raid into the Indian Ocean.

The first part was the Easter Sunday Raid of 5 April 1942

First engagement - 6 x Fulmars and 21 x Hurricanes intercepted 52 D3A dive bombers escorted by 9 x A6M fighters.

Losses were 8 x Hurricanes and 3 x Fulmars for 5 x D3A and 1 x A6M. My understanding is that the Hurricanes shot down the D3As and the A6M here.

Second Engagement - 19 Vals, escorted by A6M fighters attacked the HMS Hector and the Lucia, intercepted by 14 Hurricanes from 258 Sqn.

Losses were 9 x Hurricanes and 1 x D3A

A third wave of 53 x B5N torpedo / level bombers attacked and sunk HMS Tenedos and the port, but were not intercepted.

Total losses for the April 5 are listed as 16 hurricanes from 30 RAF and 258 RAF, 4 Fulmars from 803 and 806 Sqn, (not sure when the fourth was bagged) for a Japanese loss of 6 x D3A and 1 x A6M. The British also lost 6 x Swordfish bombers and 1 PBY.

There was a second round of fighting on 8 April near Trincommalee

First engagement (IJN Raid)
17 x Hurricanes and 6 x Fulmars intercepted three A6M on the fringe of a much larger strike group and shot down two. The strike group went on to sink the SS Saigaing and bombed the British radar station there were further air engagements. Total losses were 2 x A6M, 2 x D3A, 8 x Hurricane and 1 Fulmar. Plus 1 x Catalina.

Second engagement (British Raid)
Then 9 Blenheim bombers from 11 RAF, unescorted, attacked the Japanese fleet. Japanese CAP missed them initially, but they scored no hits. CAP then shot down 4 x Blenheims, 2 x A6Ms were shot down.

Third engagement (IJN raid)
80 x D3A escorted by 9 x A6Ms attacked and sunk HMS Hermes and Vampire, and the corvette HMS Hollyhock. 12 x Fulmars intercepted (6 of them arrived after Hermes was already sunk). 2 x Fulmars and 4 x D3A were shot down. Not sure if any of those D3A losses were to flak, though I gather HMS Hermes was not well defended.

So the total ratio for the Fulmars appears to be 8 lost for 4 victories against D3A dive bombers. It's also possible the Fulmars got one or both of the A6Ms in the first engagement on April 8, though the odds are the Hurricanes got them.
 
April 5 and 8 1942 are the only two engagements by the Fulmar against Japanese forces that I know of. If there are others, I'd love to read about it.
 
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