Spitfire mk VB/Seafire vs Zero

[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/eng...ity-13581.html (Engine Survivability)

[Glider]

Originally Posted by HoHun

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.

[kool kitty89]

The arrangement of the cooling system, radiator, and oil cooler on the P-40 (seen above) is one of the best on liquid cooled-engined fighter designs in the war with the entire group packed under the engine making a very small target, the entire vulnerable engine area is limited to the immidiate vicinity of the engine, unlike other designs with long cooling kines running to spread out (wing or belly mounted) radiators.
(and similarly the P-39.P-63, albeit inside the rear fusalage allong with the engine, but in a similarly compact layout)

THe ultimate of this bing the Il-2 with the radiator mounted directly behind the engine within the nose and heavily armored. (strangely the oil cooler was mounted in a very vulnerably position on the belly, something finally corrected in the Il-10)

[renrich]

Interesting that all this discussion of vulnerability of engines leaves out the german BMW radials versus the liquid cooled DBs. JD, you make some excellent observations. However, earlier you intimated that the FAA solved the problems of operating the Corsair off of carriers before the USN. Perhaps you did not mean it exactly as I have stated but that is a myth. If one examines the chronology of the Corsair history, the FAA did not even get any Corsairs to familiarise with at Quonset Point, RI, much less deploy on carriers, until after the USN had identified and pretty much rectified the various factors which hampered the early Corsairs. By the time that was done the preparations to deploy Hellcats on carriers were already well underway so the Corsair with it's superior performance was delayed in use on carriers for about a year. As far as radials being less apt to succumb to battle damage because of the absence of the liquid cooling system. I have been a homebuilder since 1962. I don't need statistical evidence for me to know that a single family or multi family residence is more likely to burn down because of external causes if it has a wood shingle roof than if it has a fire resistant composition roof. To me, that is a direct analogy. As far as Mustang losses in Korea, I have read that somewhere but won't bother to try to find the exact source. I have a golf course to explore. Pinon Hills in Farmington, NM. Supposed to be one of the best public courses in the US.

[JoeB]

see next

[JoeB]

Originally Posted by renrich

As far as radials being less apt to succumb to battle damage because of the absence of the liquid cooling system.

As far as Mustang losses in Korea, I have read that somewhere but won't bother to try to find the exact source.

It is intuitive that liquid cooled planes would generally have higher loss rates, the question is how much.

On F-51 and F4U in Korea, suprisingly there isn't AFAIK an accurate complete tally of F4U sorties. The standard stat of F-51 is 341 combat losses (almost all to AA or unknown/flying into terrain counted as 'combat') in 62,607 combat sorties, .54%, quoted in McLaren "Mustangs over Korea", among other places.

But here's a more micro comparison adding up sorties and losses from the monthly and semi-annual reprots of the 4 Marine F4U sdns in Korea early in the war, using August and September 1950, the most intense period of combat in the first phase of the war. They lost 10 F4U's in action in 3,170 total combat sorties, .32%. In same two months 36 F-51's were lost to AA and 4 to 'enemy action unk' in 9,688 'effective' sorties (FEAF Monthly Summary Dec 1950), .41%. It's higher but not dramatically so. The total war F-51 loss rate was higher than early war rate because enemy AA became more formidable in the static phase of the war later on. Different statistic keeping (which sorties and losses to count as combat) might affect the above comparison somewhat.

The big discrepancy in loss rates in Korea was between jets and props. The F-80's total combat loss rate was only .15%, and even excluding air superiority missions early in the war, still a lot less. That was also the comparison that F-80 pilots were accurately predicting when forced to convert back to F-51's early in the war, their reluctance often quoted. The same thing was seen in F9F v naval props, perhaps they were more rugged than piston planes, but most obviously they simply moved faster and were therefore harder to hit for the AA typically encountered.

Another thing to remember though is that the F4U had a significantly higher loss rate to AA than the F6F in apples v apples carrier operations in 1945 as has been discussed before, it wasn't the best example of rugged radial plane.

Another set of stats to put air v liquid cooled in some context is a USN loss survey for Sept '44-Aug 45, single engine radial losses (not all fighters). Overall 501 a/c were hit and 193 of them lost. 23 of 37 hit in the engine were lost, of course air cooled in all cases ("WWII Fighter Conflict" by Price, p.59). So, even an increase to 37 out of 37 wouldn't have affected the overall losses much in that sample. Of course a plane like the P-51 had a cooling system which substantially increased the area of the 'engine incl cooling system' compared to a radial, so the 37 could also have gone up, but still the impact on overall losses might not be dramatic.

On F4F 'pin cushion' tactic, that's mentioned in enough places, sourced back to quotes and reports of the time, to be more than an 'anecdote'. OTOH in that case like most there isn't a set of rigorous scientific statistics establishing the exact effect of such a tactic, or how much such a tactic explains of the substantial superiority in realworld (w/ everything as it was, not 'woulda shoulda coulda') combat effectiveness F4F's displayed over P-40's, v Zeroes, in 1942.

Joe

[renrich]

JB, Good stuff in your post. other factors that might affect the stats are, did Marine and Navy pilots press their attacks lower and longer because their operations were more dedicated or trained for ground support than AF pilots and did prop plane pilots do likewise because of having more fuel endurance and because of slower speeds and maneuverability issues? I was under the impression that Marine and Navy pilots flew the majority of ground support missions in the early going in Korea.

[JoeB]

Originally Posted by renrich

JB, Good stuff in your post. other factors that might affect the stats are, did Marine and Navy pilots press their attacks lower and longer because their operations were more dedicated or trained for ground support than AF pilots and did prop plane pilots do likewise because of having more fuel endurance and because of slower speeds and maneuverability issues? I was under the impression that Marine and Navy pilots flew the majority of ground support missions in the early going in Korea.

Strike altitude and tactics (especially whether planes went back for multiple runs on the *same target*, a proven good way to get shot down) is a potential issue in comparing ground strike loss rates between any different air arms, I agree. The same would potentially be true comparing Typhoon and P-47 loss rates as someone suggested.

But, non-rigorously but reading a lot of original combat reports I don't see evidence of a big difference there between naval services and AF early in the Korean War. Both tended to raise altitudes later in the war to keep losses under control against proliferating Communist AA. The same was actually true in 9th AF in WWII, too high losses resulted in more closely enforced instructions to stay higher. Very low altitude strafing wasn't viable day after day against field forces well equipped with AAA.

Marine air in Korea was always on a smaller scale than AF. I'm not comparing Navy air because their mission profiles tended to be different on average, whereas Marine F4U and F-51 tasking was pretty similar (in fact later on 1st Marine Air Wing was under the operational control of 5th AF and F4U and F-51tasking was pretty much identical). Early on, the Marine task organization for close support was superior (and well publicized in the press, as Marine successes often are); in terms of coordination but what F4U's and F-51's were trying to do was pretty similar. Also as you suggested early criticism (ca. July 1950) of AF close support was also because it was mainly performed by F-80's which had limited payload and little endurance over the battlefield, being based in Japan. By August-September the 5th AF had converted more sdns back to F-51's, based in Korea. However later on F-80's were based in Korea, carried similar payloads to F-51's, and F-80 losses were still a lot lower. Also, at least some Communist POW's voiced the opinion F-80's were more effective because there was less warning of their approach.

Joe

[John Davies]

Renrich, thanks for your comments. A comparison between the surviveability of inline and radial-engined German fighters would be interesting. The reason I suggested comparing the attrition rates of the P-47 and the Typhoon in Northern France in 1944 is that it is as close as one can get to an “other things being equal” test; similar duties, same enemy, different type of power plant. If anyone has the figures, I’d be very interested.

I agree with you that a liquid-cooled power plant intuitively ought to be more vulnerable; all those radiators and pipes just waiting for something to cut them. My suspicion (and I confess it is no more than that) is that this was much more of a factor in ground attack than fighter-vs-fighter combat.

There is probably a simple reason for this. In fighter-vs-fighter combat, the vast majority of rounds fired missed. Johnnie Johnson, in his autobiography “Wing Leader”, expressed a low opinion of Fighter Command gunnery. He considered the average pilot was capable of bringing off a no-deflection shot from dead astern at medium range, but could not be relied upon to achieve anything more demanding. In his opinion, except in the case of a few good marksmen, deflection shooting was largely a waste of time.

This may be the reason why there were so few aces. Admittedly, Johnson raises this in the context of a conversation with Beurling, who was an exceptional marksman, but it does give pause for thought. In typical English country style, Johnson suggests shooting for the pot with a twelve-bore was excellent training for a fighter pilot. He says that someone who could “bring down a curling widgeon in the dusk” would have no trouble hitting an enemy aircraft!

I suppose the reasons are pretty simple. A fighter pilot had to concentrate on a lot more than just shooting. He also had to fly his own aircraft, (a fairly high workload in itself) and most important of all, pay attention to not getting shot down himself. In contrast, a ground-based gunner simply had to lay off his deflection and let fly. Even if the relative speeds were much faster, so he did not have long to aim at a small, fast-moving target, it still looks like an easier task. Also, there were often an awful lot of them. Bob Stanford Tuck hated flying against light flak. He considered that a lone fighter had a fair chance against one light flak emplacement, little against two, and this was how he was shot down in 1942. I do not know what he would have thought of the massed batteries both the Germans and Japanese used to defend airfields late in the war.

Turning to the Corsair, I admit I do not know its full development history, so your comments are very interesting. Thanks.

I do recommend “Carrier Fighter” by Norman Hanson, if you can get hold of a copy. It is a quite splendid book. Hanson flew with one of the FAA Corsair squadrons. Although much of their work was appallingly dangerous, it is clear he was an aggressive optimist, and coped well. Mind, if you were not an aggressive optimist, I suppose you would not be a fighter pilot. He absolutely loved flying this big powerful brute of an aircraft.

At the end of the war he and his fellow-pilots were planning to take their carrier’s entire air wing of Corsairs in formation under the Sydney harbour bridge. They reckoned that compared with the sort of thing they had been doing on a daily basis on operations, this would be dead easy. Senior brass got wind of it, and threatened mass court-martials, so they never did. Pity about that.

Hanson mentions two problems with the early Corsairs; a low canopy which unduly restricted vision, later replaced by something much better, (and the FAA certainly had some of those early canopied aircraft, I’ve seen pictures), and an undercarriage with too much bounce in it, necessitating a modification to the oleos. My impression from Hanson is that neither problem was fully solved by the time the FAA took its first Corsairs into action, but they were sorted shortly afterwards.

I’m quite prepared to accept that the USN had solved most of the Corsair’s problems fairly early on, but delayed taking them to sea. But there is a whole world of difference between solving problems under test conditions, and trying the beast out under operational conditions and finding out how it works in such an environment.

I don’t think the FAA deserves especial credit for commissioning the Corsair for carrier operations before the USN. The FAA had a very powerful incentive. Desperation. The FAA had a very urgent need for adequate numbers of high-performance aircraft, and would basically take anything and everything that would fly and fight.

Desperation was also the reason for the Seafire. The Merlin 32 powered LIIC, and the FIII and LIII, both powered by versions of the Merlin 55, were very effective aircraft in the air. Combat reports show they were more than a match for most of their opponents, both Japanese and German, and were even just about a match for the Fw190. But it was an absolutely horrible carrier aircraft. Take the difficulties of deck landing it, making accidents more likely than with aircraft properly designed for carrier operations. (Which I’ve covered in detail in another post). Add the fact that when an accident did occur, the Seafire’s comparatively fragile structure was much more likely to sustain severe damage than, for instance, one of the products of the Grumman Ironworks. It was basically an aircraft that should never have been taken to sea, and would not have been, if British industry had produced a credible alternative in adequate numbers. For that we had to wait for the Sea Fury.

And that, as everyone knows, is because the FAA entered WW2 with some good carriers, more building, and no high-performance naval aircraft whatsoever. As a piece of purely mutton-headed thick-witted “planning”, that takes some beating!

[renrich]

JD, good stuff in your post, again. What you are saying about poor marksmanship by fighter pilots is, I suspect, the rule rather than the exception. The USN pilots were exposed to a lot more gunnery training, especially full deflection shooting, than probably any other flyers. Just like with wing shooting, though, some have the aptitude for it and many don't. That poor marksmanship is the very reason, I believe, that a radial engined airplane was somewhat less likely to sustain crippling damage than the other liquid cooled engine AC. During the BOB, I would bet that the HE111s brought down, especially because of the rifle caliber weapons used by the Brits, succumbed often to damage to the cooling systems of the inline engines. If the British pilot got lucky, one 303 ball round, in the right place could put an engine out of use, even if the pilot was a poor shot and could not hit the enemy with the prescribed number of bullets that statistics dictated. Re, Corsair, the fifth production Corsair, in Nov. 42, has the seat raised and a new canopy fitted. Those changes are implemented on the 689th production AC. Sep 25, 42, initial carrier tests are performed by the 7th production AC with 4 landings made on CVE26, USS Sangamon. Problems noted are: cowl flap actuators leak, engine oil leaks from valve push rods, forward view is poor, AC bounces on landing and swings because low tail wheel puts flaps close to deck. June 1, 1943, RN squadron #1830 is formed at Quonset Pt RI using Corsair Is. July 15, 1943, VF17 is aboard the new carrier, Bunker Hill with F4U1s, for it's shakedown cruise, they are promised the new raised cockpit F4Us upon return to Norfolk. As you can see the USN already had a full squadron operating off a carrier only 45 days after the RN began familiarising it self with F4Us off a land base. The problem was that even though a fix for the problems was found in short order, it took a while for that fix to become incorporated into the production line. As you said, the RN and the USN were desperate to get the airplanes into the fight and they had to make do with early production AC and with field modifications. How would it have been to have been the pilot of that first F4U with it's deck landing problems lining up for that first landing on that tiny CVE flight deck? I bet his A-hole was puckered up so tight you couldn't drive a hat pin up it with a sledge hammer!

[HoHun]

Hi Glider,

>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.

Good point, and interesting picture! I have actually toyed with the thought of measuring out areas of comparable fighters' systems in threeviews, but I'm afraid I don't really have sufficiently detailed threeviews.

>The cooling systesm was very vulnerable to any small piece of flak, debris or small calibre bullet.

That small calibre bullets were generally considered ineffective shows that this was not a significant vulnerability in air-to-air-combat at least.

I'd agree with John that air-to-ground actions might have a different threat profile. However, bomber defensive guns would tend to face the attacker at similar aspects as ground-based guns, and small-calibre bullets were considered ineffective in that role, too.

Regards,

Henning (HoHun)

[HoHun]

Hi Renrich,

>I don't need statistical evidence for me to know that a single family or multi family residence is more likely to burn down because of external causes if it has a wood shingle roof than if it has a fire resistant composition roof. To me, that is a direct analogy.

I don't doubt the cause-effect relationship between a piercing hit by a rifle-calibre bullet on the cooling system and the resultant loss of the engine

However, the question really is how likely it was to achieve such a piercing hit with a rifle-calibre bullet. The historical answer is: so unlikely that the warring parties gave up on trying, and replaced the rifle-calibre guns with heavy machine guns or even cannon wherever possible.

It's possible that the heavier guns used had a higher chance of achieving that critical piercing hit so that the cooling system was indeed a significant area of vulnerability again, but lacking data, we can't tell for sure. (I just point this out to avoid the impression I consider the cooling system invulnerable - it most definitely was not

Regards,

Henning (HoHun)