Spitfire mk VB/Seafire vs Zero

[slaterat]

Hohun

Yes I found that quite interesting too. It makes sense with the limited room on a carrier but it didn't seem to be a concern for the the FAA.

I also think that the merlin 32 powered Seafire that you mentioned in another post, would have sufficient performance to dominate a zero.

These seem contradictory to me Joe.

10:1 you cite is a claim. I don't see how one claim can measure or validate the accuracy of another claim.

Besides Aug 15 '45, Seafires claimed a few other Japanese fighter types without loss (I think the claimed ratio was actually a little higher than 10:1, August 15 was IIRC their only air combat loss), but it's not clear if any of those other a/c were acting as fighters, rather than kamikazes: the Seafires were on defensive CAP missions. For comparison, the FM-2, which was mostly also used for carrier (CVE) defense in late war claimed 18[3] fighter type a/c for 7 air combat losses, 26:1, Sept '44-Aug '45 (Naval Aviation Combat Statistics).
So even if we had enough of a sample to say much about Seafire v Zero (we don't) we'd have to put it in the context of the particular mission (with kamikaze/fighter confusion in some cases) and of 1945 Pac War air combat overall, very different, in many more ways than just tactics, from air combat v a still pretty first string Zero unit like the 202nd AG in 1943.



Slaterat

 

[kool kitty89]

Sorry, but I can't seem to find the sourse for that. (it was from another discussion on navy a/c)

And now that I think about it more I'm not sure the fresh water issue was specifically for the USN. (I haven't seen it much mentioned, though it should logically be important, though maybe just a disadvantage than condemning atribute)

The issue of carrying glycol coolant is menyioned several places (including wikipedia) as the Navy supposedly disliked storing the flamable substance. But thins doesn't seem to make sense as 1. it's not really any more dangerous than gasoline which also has to be carried for the a/c, and in much larger quantities than coolant. and 2. the coolant could be stored as non-flamable (except in extreme conditions) pre-mixed 70/30 water/glycol mix. (which was the coolant for the V-1710 from the begining of operational use, unlike the far more dangerous, and less cooling efficient 100% glycol used in the early Merlins)

Of course pure water cooling could also be used (as all German engines did iirc) and most of the glycol using engines could probably have been modified to use such without excessive difficulty.


Thare's more reason to the Navy's prefrence though. I'm not sure of the whole history behind it, but in addition to what Renrich said about a better chance of getting back with engine damage, there are also some specific events that effected this as well I think. (I can't remember specifically, but in the '20's iirc there were some navy a/c designs which were adapted from water cooled engines to radial engines, and performance, reliability, and servicability markedly increased)

 

[John Davies]

"I would like to see the statistics showing that Seafires had a 10 to one kill ration against A6Ms."

As I said, I got my figures from the records of every Seafire combat, listed in Appendix Three of David Brown's "The Seafire". (Ian Allan, 1973). He lists fifteeen A6Ms destroyed, for the loss of one Seafire pilot shot down and killed by an A6M, so my rough approximation of 10:1 erred very much on the side of caution. These figures do not include probables or damaged, or combats with other Japanese aircraft. But as I also said, these are based on pilots' combat reports.

If you can't get hold of a copy of Brown, I could try scanning the relevant pages into a doucument and attaching it, but I'm afraid playing with our scanning programme usually involves a great deal of time and blasphemy, so I cannot guarantee to succeed with it soon or indeed at all.

 

[parsifal]

The trouble with many of the western based sources is that trhey have relied on claimed kills rather than going into the japanese source(s) about confirmed losses. More recent researchers that have started to cross check the Japanese confirmed lossdes to the claimed losses, have realized that the immediate post war accounts are quite innaccurate.

But thats not the end of it. Unfortunately, many of the japanese records are innaccurate, in that they are incomplete, so the true extent of Japanese losses, from the japanese side cannot always be pinpointed accurately from that direction either.

In short, the true extent of Japanese losses is one of the most least understood, and most innacurately documented subject areas of WWII that there is.

 

[renrich]

My question on Seafire kills versus "Zeros" come from a fact that Allied pilots were well known for identifying any Japanese aircraft as a "Zero." Incidently, when the USN first actually encountered the A6M in combat, some of them misidentified it as a bomber because of the longish canopy. If one looks at a cutaway diagram of a liquid cooled engined fighter it is easy to see that there are a great many spots mainly in the cooling section for the engine that a shell fragment or rifle caliber round can cause damage that will cause the engine to overheat and fail. The liquid cooled engine has most of the vulnerabilities of the radial engine plus all that cooling system. The other advantage of the radial type for the USN was that for a given horsepower the radial was lighter. Of course, that weight advantage was somewhat offset by the superior streamlining of the inline engine.

 

[John Davies]

Brown's Appendix 3 does distinguish between combats between Seafires vs Zeroes, and Seafires vs other Japanese types. Combats are recorded individually, in some detail, noting area, mark and serial number/codes of Seafire involved, name of pilot, type of enemy aircaft, and outcome.

However, we could be moving into difficult territory here. Accepting that information based on pilots' combat reports may not be completely accurate, what is to be done? If we are only to accept victory statisitics which are validated both by the claim records of one side and the loss records of the other, we are going to get into some very real difficulties

You've already pointed out that Japanese records are not all complete. But if we try to apply this criterion consistently across the board, we are going to have to ask all sorts of awkward questions. To suggest only one possible example, now that parts of the Kremlin archive are open to Western researchers, has anyone checked Hartmann's total? This sort of thing opens up a real can of worms!

 

[JoeB]

These seem contradictory to me Joe.

10:1 you cite is a claim. I don't see how one claim can measure or validate the accuracy of another claim.

For comparison, the FM-2, which was mostly also used for carrier (CVE) defense in late war claimed 18[3] fighter type a/c for 7 air combat losses, 26:1, Sept '44-Aug '45 (Naval Aviation Combat Statistics).

Those specific points maybe you think are contradictory? I don't. The post I was responding to seemed to say the claimed 10:1 ratio of Seafires over Zeroes in 1945 indicated that the *actual Zero losses* over Darwin in 1943 were perhaps close to what the Spitfires claimed. But there's no logical relationship between the *level* of claims of one unit and the *accuracy* of claims of another unit.

In contrast I was comparing too like things, claims v claims. Seafires claimed 10:1 in 1945, so what were some other ca. 1945 claimed ratio's by older type Allied fighters?, let's put the Seafire claims into context, that's all. FM's claimed 26:1 fighter-fighter, ie. a 10:1 claim wasn't particuarly high for an older type fighter in 1945 usually defending carriers, often against kamikazes. I wasn't inferring anything about how many enemy a/c Seafires and FM's *actually* downed.

On Japanese losses being a difficult subject in general, yes, but in part IM frank O because of resistance to what their records tell us even when pretty clear. In Darwin again the losses are from the orginal combat reports (kodochosho in JNAF terminology) of the only unit involved per many sources. And, with a 500 mile trip back to base and no air-sea rescue function to speak of, it's hard to imagine a lot of other Zero losses without pilot losses. Who ever failed to record disappeared pilots in their own then-secret records? And why did no other evidence of those pilots' existence and loss ever surface since (there's a lot of stuff written in Japan, and on internet too, about individual pilots). At some point a historically rigorous approach requires postive evidence of significant errors in apparently complete sources or they have to be accepted as the most probable facts, and we've passed it in the Darwin case. For example, in the whole Pacific War, not just Darwin area, there's no case I know of where Japanese accounts specifically cover a mission* (like the details given for each of the JNAF Darwin raids) but fail to mention a loss for which there was positive wreck/POW/body evidence on the Allied side. Shouldn't there be at least one such case if those records are really so 'uncertain' (and it's implied 'understated')?

And, when we compare Darwin 1943 to eg. Guadalcanal, Darwin 1942, Port Moresby 1942, etc. we're comparing against the same kind of Japanese Navy records, it's apples and apples, unless we further assert that the 202nd's combat reports were less complete in 1943 than the same unit's reports in 1942, or other similar units in '42-43.

In the August 15 1945 case as I said there's a bit more room for doubt, because of multiple units involved both sides, more room for interpretation on 'loss' v. 'damage' of planes close to their bases, and I don't happen to know if those published 252nd and 302nd accounts are from actual combat reports. But if one reviews more such cases (1945 over Japan) there's no doubt Allied (almost all US actually) fighters still were credited with substantially more enemy planes than they downed. *Every* published Japanese account of Homeland defense combats can't be incomplete or mistated. It's quite believable, given other incidents, that the FAA Seafires August 15 only shot down that one 252nd AG Zero and hit but didn't down a 302nd machine, though credited with 7. But it's only one combat either way. I agree as was stated that *if* there had been a lot more combats Seafire v. Zeroes flown by 1945 JNAF pilots, the Seafire probably would have done well, as did every other Allied fighter in 1945.

*there's a case in Malaya 1942 where a wreck/body of JAAF fighter doesn't correspond to any loss given in the Japanese official history, but in that case the original records themselves aren't available, so no details of that mission are mentioned: sharp contrast to Darwin where each combat the Allies recorded is also described in fair detail in the JNAF combat reports.

Joe

 

[HoHun]

Hi Renrich,

>If one looks at a cutaway diagram of a liquid cooled engined fighter it is easy to see that there are a great many spots mainly in the cooling section for the engine that a shell fragment or rifle caliber round can cause damage that will cause the engine to overheat and fail.

For an actual analysis, you'd also need to add the probability of the vulnerable spot to be actually hit in a damaging way by said shell fragment or rifle calibre round.

Rifle-calibre machine guns definitely were badly lacking in effectiveness against liquid-cooled engined fighters in the air-to-air role, and almost completely replaced by heavy machine guns or cannon by the end of the war.

As rifle-calibre machine guns were quite light in comparison to other weapons and were fairly efficient at firing a high number of small projectiles, I think we can safely rule out the hypothesis that hitting vulnerable spots with individual rounds was an efficient way of bringing down enemy fighters in air-to-air combat. Else we'd have seen fighters increasing the number of rifle-calibre machine guns when they were facing enemy types with liquid-cooled engines instead of reducing them.

For example the Luftwaffe might have considered to equip the Me 109 with small underwing gondolae with MG 81Z machine guns against the P-51 top cover ... 6400 rifle-calibre rounds per minute for a weight penalty equivalent to that for a single 12.7 mm Browning M2.

That this version never saw combat, never was tested, and even never was considered at all shows that the "vulnerable to rifle bullets" hypothesis - or the related "volume of fire" hypothesis - does not accurately describe the reality of WW2 air combat.

Regards,

Henning (HoHun)

 

[HoHun]

Hi Kookitty,

>Sorry, but I can't seem to find the sourse for that. (it was from another discussion on navy a/c)

Ah, too bad. I think such decisions influencing the long-term policy of a service branch are quite important for the technical development, so I try to learn as much about them as possible when the opportunity presents itself. Still interesting even without a source, though

Regards,

Henning (HoHun)

 

[HoHun]

Hi Koolkitty,

>Roll rate is also an important component in maneuverability (in many ways more important than turning ability) and was something the Zero was lacking in. (particularly at high speeds) (though the Ki 43 is a different story)

Hm, do you have any data on the Ki-43 roll rate? I believe I haven't seen anything in this regard yet.

As far as the A6M roll rate is concerned, note that the NACA chart does not indicate a stick force for the A6M, so it's difficult to compare this graph to those of the other fighters.

At low speeds, I'd expect the A6M to have a rather aerobatic roll rate as it was designed for manoeuvrability in that speed regime. Note that the ailerons had aerodynamic booster tabs that re-configured into damping tabs when the flaps were extended to keep the aircraft controllable for landing. This seems to be an expression of a design intended for unusally high roll rates. (See Robert Mikesh's "Zero", or John Deakin's article in his "Pelican's Perch" online column.)

Regards,

Henning (HoHun)

 

[renrich]

Obviously, the rifle caliber MG was not as well suited to take down WW2 AC as the .50 cal or the various cannon. I can't remember the exact number but the RAF determined that a certain number of 303 rounds had to hit a bomber to bring it down which with a two second burst which meant that they needed 8 guns with a certain rate of fire. Seems like it was around 161 hits. My point is that if Bob Johnson had been flying a liquid cooled engined fighter rather than a P47 in his famous flight where the FW sprayed him with rifle caliber rounds in several firing passes, he probably would not have made it home because his coolant would have leaked out. If one reads Lundstrom, "The First Team," the Wildcat fighter pilots learned that a Zero on their tail, if he had run out of 20 mm rds, did not pose a great threat. It was called the "pin cushion" tactic. They would not have felt that way if their engine had been liquid cooled.

 

[John Davies]

As well as preference, there is also the question of availability. American engine builders produced a whole series of excellent, sturdy, reliable, high-powered radial engines. But they did not produce an inline equivalent of the Merlin until Packard started building them under licence. The closest, the Allison, was a decent engine at low to medium levels, but tended to run out of breath higher up, and was not a real rival to the Merlin, the Griffon, or indeed the Daimler-Benz or Jumo series of inline power plants.

So American airframe builders designed to use the engines which were available from American engine builders. The results were usually very successful. The question of what was available (quickly, under war conditions, without a long development and gestation period) almost certainly had more influence than any purely theoretical considerations.

On a seperate but related point, by late war, rifle-calibre machine guns were indeed considered quite ineffective. According to Brown, some FAA Seafire pilots did not use theirs, for this reason, and were occasionally required to explain, in official returns, why not.

As for the general question of carrier fighter design, my opinion is that we did not produce a good carrier fighter until the Sea Fury, which came on the scene very late. The Seafire was an effective aircraft in the air, but a horribly fragile aircraft to deckland.

It demanded considerable precision on the approach, because with its low wing loading (especially when returning from a sortie with empty tanks), it could easily float over the wires and into the barrier. Just when you needed to see exactly what you were doing, that big engine would block all view of the deck. The hook was placed under the rear fuselage in the Merlin-engined Seafires, not right at the tail as in American designs. This was a consequence of the Spitfire airframe's chronic centre-of-gravity problem (Jeff Quill explains this very clearly in "Spitfire"), but it did mean it was easier to fail to pick up the wires than with an American aircraft. Panels which were slightly bent out of shape due to poor shipboard maintenance conditions could begin to vibrate, giving a false impression of a pre-stall buffet when in fact airspeed was still comfortably above the stall, making the pilot reluctant to reduce speed, and thus setting the aircraft up for a float. The ASI was not positioned so as to easily allow a quick glance. All things considered, it is a tribute to the pilots that the Seafire deck-landing accident rate was not higher than it was.

One FAA pilot said he liked the instrument panel layout of American aircraft, and in contrast considered many British panel designs looked as if they had been laid out by the office charwoman!

This was a consequence, of course, of the pre-war situation. RN Admirals who were mostly interested in battleships, and naval aviation under the control of the RAF, which saw it very much as a side-line, and devoted its efforts to land-based designs. Why do you think we were so glad to use so many Wildcats, Hellcats, and Corsairs?

Indeed, the FAA took the Corsair to sea before the USN considered it ready, and learned to tame it, basically because at that point the FAA was absolutely desperate for anything that would fly, fight, and had a decent performance. And BTW if you read Hanson's "Carrier Fighter", you'll see the FAA developed a considerable affection for the "bent-winged bast*rd" ! But that's another story, and posssibly a bit off-topic for this thread.

 

[HoHun]

Hi Renrich,

>My point is that if Bob Johnson had been flying a liquid cooled engined fighter rather than a P47 in his famous flight where the FW sprayed him with rifle caliber rounds in several firing passes, he probably would not have made it home because his coolant would have leaked out.

If an attacker can aim at his leisure at point-blank range at a defenseless target flying straight and level without any defensive manoeuvring ... maybe, but that's hardly representative of typical WW2 air combat.

>the Wildcat fighter pilots learned that a Zero on their tail, if he had run out of 20 mm rds, did not pose a great threat. It was called the "pin cushion" tactic. They would not have felt that way if their engine had been liquid cooled.

Oh, well - that's a guess about a feeling ... you'll probably admit that this is not really the genuine scientific approach

I believe that there might be data around somewhere that could help us to get a more reliable impression of engine survivability. Loss rates of differently engined aircraft types under comparable conditions ... that's a much better way towards an accurate assessment than anecdotes.

So far, I've not seen any actual data on radial vs. inline engine survivability, and unfortunately conventional wisdom and myth are hard to tell apart in the absence of data.

Regards,

Henning (HoHun)

 

[renrich]

It may not meet your standards of statistical evidence but at the 1944 fighter conference, a large group of service and company test pilots and there were British pilots present voted on which American engines inspired the most confidence-79% voted R2800, 17% voted Merlin, 1% voted V1710. Quote from "America's One hundred Thousand" "There is no question pilots worried about vulnerability of cooling systems in liquid cooled engines especially in the face of heavy fire directed at them during ground attack missions." Look at the coolant radiator assembly in the P51, how large it is and where it is located with no protection and remember that most hits on an AC either from the ground or from the air took place in the after part of the AC (because of not enough lead.) Couple that with all the coolant lines running to the engine. One 30 cal ball round either hitting a coolant line or that radiator can put that engine out of action. Look at the statistics of the P51 losses in Korea flying air to ground missions versus those of the F4Us and ADs. Look at a cutaway of the P38 and plot the area of fragile, unprotected and essential cooling parts versus that of a P47. I hope one does not need to be a statistician to intuitvely grasp which aircraft is most vulnerable to enemy fire.

 

[John Davies]

You are absolutely right, air-cooled radial engines were more resistant to damage than liquid-cooled inlines. The problem was that they also had more drag, which meant higher power was needed to achieve the same level of performance, which meant higher fuel consumption. So while an airframe designed for an inline could in theory be adapted for a radial, the result was likely to be either degraded performance or reduced range or both.

Hawkers did some design studies about fitting the Hercules to a Hurricane airframe, in case the supply of Merlins was interrupted by bombing of the factories, but took it no further than the drawing-board. I don't think they built a prototype. A series of Lancasters fitted with the Hercules showed no worthwhile improvement in performance over the Merlin-based marks, in spite of the higher nominal horsepower of the Hercules.

The solution, of course, is to make the whole airframe bigger, so you finish up with a fighter the size of a P-47 or a Hellcat, which can both absorb the power of a big radial, and carry the necessary tankage. Here American designers had a great advantage over their European counterparts.

Aircraft like the Spitfire, Hurricane and Bf-109 were designed with no practical knowledge of what their combat environment was likely to be. Indeed, around 1936, any kind of high-performance monoplane was a huge innovation for most fighter squadrons. By the time the USA came into the war, they had at least had the opportunity to observe for two years how things were working out in practice, and to draw the necessary conclusions.

 

[kool kitty89]

If you also look at the (late) pre war US aircraft, most are radial engines up to the advent of the V-1710. For fighter designs, predominantly the R-1820 and R-1830. This includes the only operational "modern" monoplane fighters in service up to 1940. (prior to the P-40 being introduced) For the USAAC the P-36 was their highest performance fighter. (the P-35 behind that) And the Navy had the F2A, the F4F soon superceding it around the same time the P-40 was introduced)


And you also have to remember that the Hercules engines used on RAF bombers had significantly porrer altitude performance than the contemporary Merlins used on the same design. (even though the low altitude rated merlins Merlins)


And the problem with the V-1710 being that it was designed to be either used in low-medium altitude aplications, or with turbocharging. (the only production fighter to use such being the P-38 ) With which it was quite compeditive with the Merlin, but not all designs could practically adapted incorporate such a sustem though. (the P-51 probably could have been modified to use a turbo, but switching to the Merlin was far simpler)

Eventually the folly in ignoring conventional supercharging for high alt aplications (an AAC policy) was realized and was developed for the Allison, first being a simple 2-stage (auxiliary) supercharger being added to the excessories section, with no intercooler. The first of these types were available in small numbers farily early after the US entrance in the war (in early 1942) and were used experimentally, notably on the XP-39E/XP-76 design. And later utilized on the P-63, the P-63's engine (while still lacking an intercooler) encorporated Water injection which boosted WEP form 1,500 hp to 1,800 hp. Similar engines were used experimentally on the XP-40Q and XP-51J.
Finally more advanced engines were introduced with improved 2-stage supercharging with intercooling. These were used on late model P-63's and some experimental designs, but didn't see service with the US durring WWII.

 

[HoHun]

Hi Renrich,

>It may not meet your standards of statistical evidence but at the 1944 fighter conference, a large group of service and company test pilots and there were British pilots present voted on which American engines inspired the most confidence-79% voted R2800, 17% voted Merlin, 1% voted V1710.

It's certainly interesting in showing that the good reputation of radial engines was in fact already established during WW2. However, of course it doesn't tell us if they were any more survivable in combat.

>One 30 cal ball round either hitting a coolant line or that radiator can put that engine out of action.

Rifle-calibre rounds were found to be badly lacking effectiveness in actual combat - both as fixed forward firing armament and as flexible defensive armament.

One .30 ball round might be able to put an liquid cooled engine out of action, but the actual combat experience shows that this was so unlikely to happen that the rifle-calibre machine turned out to be a rather poor weapon.

That means that the liquid-cooled engine practically proved to be rather insensitive against rifle-calibre fire in actual air-to-air combat. The theoretically assumed vulnerability did not translate into a practically relevant factor in air-to-air combat.

(Rifle-calibre machine guns were mostly used in the surface-to-air role because they were available on the battlefield for other purposes, so no similar observation is possible for surface-to-air combat.)

>Look at the statistics of the P51 losses in Korea flying air to ground missions versus those of the F4Us and ADs.

Hey, actual statistics? Where can I find them?

>Look at a cutaway of the P38 and plot the area of fragile, unprotected and essential cooling parts versus that of a P47. I hope one does not need to be a statistician to intuitvely grasp which aircraft is most vulnerable to enemy fire.

It's easy to see how one might arrive at the impression that the radial is a more survivable engine, but that doesn't mean that first impression will be realistic.

The survivability advantages of the sturdily-built B-17 over the B-24 with its thin, flexible wing and the constantly leaking gasoline lines in its bomb bay are just as obvious - and yet, if you look at the actual combat results, the B-24 was more survivable than the B-17, albeit only by a small margin. Similarly, the advantages of the robust landing gear of the Fw 190 over the flimsy construction of the Me 109's appears obvious, but again a look at the available data sets shows that this had no discernible impact on accident rate or maintenance status of the operational units.

I'd not be suprised if the reputed survivability advantage of the radial engine would be far less important than the books repeating the WW2 pilot opinion would have us believe. We shouldn't forget that due to the larger frontal area of the radial engine, it's more susceptible to damage after all - great if the radial can come home with a cylinder shot away, but if we take into account that the same flak shell might have missed the smaller inline engine altogether, which engine really holds the advantage?

(Maybe all of this should go into the current "engine survivability thread"?)

Regards,

Henning (HoHun)

 

[kool kitty89]

The radial may be larger in diameter, but is far shorter than an inline, and the vulnerablie areas are simply spread out differently. Obvioulsy when comparing a large engine like the R-2800 to the Merlin etc, it will be more extreme, but for a more comperable engine like the R-1830 Twin Wasp it's a bit different.

But this discussion belons more in the thread Ho Hun mentioned perviously in the P-40E vs F4F-3 thread. http://www.ww2aircraft.net/forum/engines/engine-survivability-13581.html

 

[Glider]

Hi Renrich,

>
I'd not be suprised if the reputed survivability advantage of the radial engine would be far less important than the books repeating the WW2 pilot opinion would have us believe. We shouldn't forget that due to the larger frontal area of the radial engine, it's more susceptible to damage after all - great if the radial can come home with a cylinder shot away, but if we take into account that the same flak shell might have missed the smaller inline engine altogether, which engine really holds the advantage?

I think the difference is that the frontal area of a large proportion of the in lines is similar to the Radial when you include the frontal area of the cooling system. Typhoon and P40's are two first class examples, late P38's are another and those such as the Mossie had a lower frontal area but looked at from above have a larger cross section than a radial.
The cooling systesm was very vulnerable to any small piece of flak, debris or small calibre bullet.

 

[John Davies]

Air-to-air combat was a dangerous occupation, but ground attack against massed light flak was plain murder. Hanson, in "Carrier Fighter", writes of carrying out ground attack missions in his Corsair, against well-defended Japanese airfields, at a height between five and ten feet. One new pilot simply could not make it, and kept ballooning up to about thirty feet (low enough, in all conscience). He was killed on his first sortie. In contrast, Hanson seems to treat his unit's few encounters with Japanese aircaft in the air as light relief; opportunities for some entertaining target practice.

I'd expect the vulnerability of a liquid-cooled engine to be far more important in ground attack than in fighter vs fighter combat. It might be possible to establish a fairly accurate comparison here. Does anyone know the comparative attrition rates of Typhoons and P-47s on ground attack duties in Northern France in 1944? Same enemy, similar duties, one aircooled engine, one liquid-cooled. I confess I do not have the figures; but they'd certainly be interesting if anyone does.