Spitfire mk VB/Seafire vs Zero

[kool kitty89]

Yes, that ~4,500 ft/min figure is wrong for max sustained climb, but fairly commonly stated. (including some history TV programs) Similar to the claims of the Curtiss-Wright CW-21 Demon being sometimes listed with a 4,500-5,000 ft/min initial climb. (probably acheived with zoom) Actual initial climb for the A6M-2 should be ~3,000-3,200 ft/min. (the CW-21 and Ki-43 being similar)

Some performance figures from US testing may be high (both speed and climb) due to use of high octane fuel, not available to the Japanese.

[parsifal]

Originally Posted by ponsford

Hi parsifal: After reading Dunn's article I presume your figures are from Francillion? That 4517 ft/min must be a typo. That can't be right. It's just too far removed from other available data sets to be believable.

My sources probably were Francilion, but to be honest, I am not sure. But to double sheck my figures, I just pulled oput two of my general refereences, to confirm if I was correct, or not

The sources are

"Zero A6M", H. P. Willmott, Bison Books, 1980
"Combat Aircraft Of WWII", Iain Parsons, Ure Smith Books 1978

I have attached the relevant extract from the first source FYI. Can do the same for the second, if you need confirmation.

Both sources list the initial climb as 4500 ft per min. There are some slight differences in max speed, and some of the other stats, which i am not sure of

[HoHun]

Hi Ponsford,

>Here’s an interesting online article on Zero performance:
ZERO-SEN Model 21 Performance: Unraveling Conflicting Data by Richard Dunn

I found this article quite interesting, and it made me go and look for A6M data myself. Interesting to see that Mike has included A6M data on his site in the meanwhile, I'm going to have to check it out to see if there is anything I haven't seen yet

Here is a summary of the various data sets on the A6M I found ... obviously, there is a lot of variation in performance between the individual tests, illustrating why I'm not overly suprised by possibly contradicting data on the Zero.

Regards,

Henning (HoHun)

[HoHun]

Hi Ponsford,

>Thanks for the links HoHun. I appreciated your analysis of the F4F and P-40. Have you done a similar analysis for the F4F versus Zeke? I would find that of interest.

Roger, here it is ... A6M2 data based on the TAIC (Akutan Zero) data, F4F-4 data based on the Buerau of Aeronautics Standard Aircraft Characteristics.

F4F-4 data is for MIL because this is the highest power setting for the type I'm aware of. A6M2 data is for WEP for the same reason :-)

Regards,

Henning (HoHun)

[HoHun]

Hi Parsifal,

>"Zero A6M", H. P. Willmott, Bison Books, 1980

Hey, I like that book Since you're quoting the publishing year 1980, is it the original edition with the number "6" on the dust jacket? I thought the entire series was pretty good - I have "1" through "6", but I don't know if there were more ...

Regards,

Henning (HoHun)

[parsifal]

Originally Posted by HoHun

Hi Parsifal,

>"Zero A6M", H. P. Willmott, Bison Books, 1980

Hey, I like that book Since you're quoting the publishing year 1980, is it the original edition with the number "6" on the dust jacket? I thought the entire series was pretty good - I have "1" through "6", but I don't know if there were more ...

Regards,

Henning (HoHun)

Nah, its not a "6". But it seemed like a pretty good book just the same, I like it as a dependable and interesting "general" reference for the zero. The appendices are the best bit.

Its the only one I have, though I have a similar sort of reference for the Hellcat.

Also like the squadron/signal pubs, have a few of them.

I didnt think the 4500' per minute fugure was all that outrageous, but then I am not that good a student. Without having thought about it too much, I just assumed that the zeke with its ultra light construction, would be a top notch climber. Conversely, it also made sense to me, in my school boyish way of looking at these issues, that it would be a poor diver for pretty much the same reason....bit like the feather you see floating down from the ceiling, as compared to the piece of lead that might represent the Wildcat. No doubt I will stand corrected by the time we are all done here, but thats okay....I am here to learn

[kool kitty89]

For 1941 3,200-3,400 ft/min is pretty darn good. And comparing the power loading, the A6M-2 has decent power loading, but not as good as many european contemporaries ie Spitfire and Bf 109. (Zero is ~.179 hp/lb normal loaded, compared to Bf 109F-2 at ~.205 which managed around 3,850 ft/min)

[parsifal]

Originally Posted by kool kitty89

For 1941 3,200-3,400 ft/min is pretty darn good. And comparing the power loading, the A6M-2 has decent power loading, but not as good as many european contemporaries ie Spitfire and Bf 109. (Zero is ~.179 hp/lb normal loaded, compared to Bf 109F-2 at ~.205 which managed around 3,850 ft/min)

Im no expert, but it occurs to me that the 3285 figure is remarkably close to the "time to height" figures, than initial climb. The 4500 ft per min appears to be for the first 5000 ft or so, when the lift is at a maximum.

Perhaps the 4500 ft per minute is the initial climb rate, and not comparable to a sustained climb rate? Even so IMO it would the most appropraite number to quote for the Zeke, since the combat that it would be most likley to engage in would be against torpedo bombers, or Dive Bombers, both of which are at some stage going to be below 5000 ft in their attack runs.

Do you have figures for the Initial climb, that is climb to say 4500 ft. If so, are they in conflict with that quoted figure?

Regards

Parsifal

[HoHun]

Hi Parsifal,

>Nah, its not a "6". But it seemed like a pretty good book just the same, I like it as a dependable and interesting "general" reference for the zero.

Absolutely! I just asked for the "6" out of curiosity, I'm pretty sure the content is exactly the same.

>I didnt think the 4500' per minute fugure was all that outrageous, but then I am not that good a student. Without having thought about it too much, I just assumed that the zeke with its ultra light construction, would be a top notch climber.

That's actually a good thought - climb rate is dominated by power and weight.

You could make a rough estimate like this:

Engine power: 1050 HP maximum, or roughly 770 kW.

Weight: about 2500 kg mass, meaning roughly 25000 N weight.

If all of the power were converted to climb rate directly, we would get:

Power = Force * Speed, or

770 kW = 25000 N * v, so that

v = 770 kW / 25000 kN = 30.8 m/s

That's extremely fast and of course unrealistic, but we know the upper limit now.

Two considerations can give us a more realistic figure:

1) Some of the power is required to keep the aircraft going against the drag at the relatively low speed at which it climbs. Let's guess this is 300 HP.

2) The useful power delivered by the propeller is always less than the power delivered to the propeller. Let's guess our efficiency is 80% here.

So we get:

(Engine Power - Drag Power) * Efficiency = Force * Speed, or

(770 kW - 220 kW) * 0.8 = 25000 N * v, so that

v = (770 kW - 220 kW) * 0.8 / 25000 kN = 17.6 m/s

This is roughly 3500 fpm, or 1000 fpm less than the 4500 fpm we were discussing.

Of course, we were required to guess two figures here, but you can see that power is an important parameter, and adding for example 10% extra power gives more than 10% climb rate increase because the power lost to drag will not increase. You can also see that climb rate is inversely proportional to weight, so if your aircraft is only half as light, it will climb twice as good.

(If you look into the details, you'll find that the power lost to drag depends on weight too - that's why a big wing can be an advantage in a climb. The calculation I posted accounts for this, and for a fair number of additional complications not mentioned here.)

Regards,

Henning (HoHun)

[renrich]

According to Eric Brown the Condor(Kurier) had a very weak spine as well as vulnerable gasoline lines and was not a very robust AC and very susceptible to gunfire. The early F4F3s had an initial rate of climb of more than 3000 fpm.

[Soren]

The A6M2 climbed at around 3,250 to 3500 ft/min, which is higher than any Allied fighter of the period.

As for turn performance, the Zero, throughout its versions easily outturns any Allied fighter.

Now a highly boosted Spitfire V should be able to follow the Hap through a sustained turn at high speed, no problem, there are other a/c capable of that as-well, but all the Hap pilot has to do is pull in tighter the stick and he's away, the Spitfire simply can't hope to follow.

The Zero turns a LOT tighter than any Spitfire, which is what the Japanese pilots took advantage of when fighting it, pulling such tight turns that the Spitfire pilots were forced to utilize energy tactics if they were to survive. Now unfortunately the British hadn't developed efficient tactics against a fighter like the Zero when they came to fight it in the pacific, and were forced to learn it the hard way just like the US years before.

[HoHun]

Hi Renrich,

>The early F4F3s had an initial rate of climb of more than 3000 fpm.

According to my calculation, it arrives at 3000 rpm almost spot-on, almost matching the A6M2 ... but this favourable comparison is due to the power peak the R-1830-86 provides at low altitude with the supercharger in "neutral" gear.

Still, the F4F-3 due to its lighter weight (I used the 7065 lbs from the table accompanying Kohn's article) has more of an advantage over the heavy F4F-4 than one might think at first ... here are the graphs.

Regards,

Henning (HoHun)

[John Davies]

Originally Posted by Soren

The A6M2 climbed at around 3,250 to 3500 ft/min, which is higher than any Allied fighter of the period.

As for turn performance, the Zero, throughout its versions easily outturns any Allied fighter.

Now a highly boosted Spitfire V should be able to follow the Hap through a sustained turn at high speed, no problem, there are other a/c capable of that as-well, but all the Hap pilot has to do is pull in tighter the stick and he's away, the Spitfire simply can't hope to follow.

The Zero turns a LOT tighter than any Spitfire, which is what the Japanese pilots took advantage of when fighting it, pulling such tight turns that the Spitfire pilots were forced to utilize energy tactics if they were to survive. Now unfortunately the British hadn't developed efficient tactics against a fighter like the Zero when they came to fight it in the pacific, and were forced to learn it the hard way just like the US years before.

I'm very sorry, but that's quite simply incorrect. Brown in "The Seafire", (Ian Allen, London, 1973), quotes the rate of climb figures for the Seafire LIII (the main variant used in the Pacific) as 4,160 fpm at sea level and 4,310 fpm at 6,000 feet, this powered by a Merlin 55M with its boost sytem optimised for low to medium levels. The FIII, the other version used in the Pacific, climbed at 3,650 fpm at sea level. Climb for 6,000 feet is not given. But anyway, the FIII slightly outperforms the climb figures for the Zero you give, and the LIII well outperforms them. The Seafire was remarkable not only for its high rate of climb, but its steep angle of climb, and was one of the very few allied fighters to nullify one of the Zero's main advantages; the Japanese pilots could no longer out-climb an opponent.

To add a little context to those figures, the Seafire LIIC, which as far as I know was only used in the European theatre, had a maximum rate of climb of 4,600 fpm, using a Merlin 32 with +18 lbs boost, which suggests a short life and a merry one for the engine!

The Zero did NOT out-turn the Seafire, easily or otherwise. What FAA pilots found was that the Zero had a tighter radius of turn, but the Seafire had a much higher rate of turn; i.e it was going around a larger circle, but going round it sufficiently faster to keep safely ahead of the Zero. In a full 360 degree circle, the Seafire would get all the way around first, but the Zero would travel a shorter distance, going around a smaller circle; but going around it more slowly.

Of course, this was not ideal. The Seafire pilot's aim was to get behind the Zero, to acheive a firing position, not hurtle merrily along in front. So the FAA used the tactic of alternate climbing and diving turns, in efect a series of near-stall turns, to get behind the Zero. These tactics worked from the first, so I am not sure why you suggest the British forces "had not developed efficient tactics".

Also, the Zero's best fighting speed was found to be about 180 knots. The Seafire's was anywhere between 220 and 280, which was a nice broad range giving lots of room for manoevre. FAA doctrine was to keep speed up into their own range. If the Zero pilot attempted to match this, his own manoeverability would degrade, and again give the Seafire the edge. The Zero was only really a very manoeverable aircraft at its best fighting speed. Controls, and especially ailerons, became much heavier at higher speeds. This greatly increased the effort needed to horse the aircraft about, and reduced rate of roll, vital in combat. In contrast, the Seafire excelled in the rolling plane. I'm sorry I do not have degree per second figures, but Brown does comment that it was exceptional in its ability to enter a hard roll sharply and positively, and reverse its turn quickly. The only enemy fighter which had an advantage was the Fw190, and even there, the advantage was not a large one.

"Proof of the pudding"? FAA Seafires shot down either 15 or 16 Zeroes for the loss of one of their own. The loss was because the pilot, Sub-Lt Hockley, suffered a radio failure, and was not aware of the need to break until it was too late. He had the appalling bad luck to be killed on the last day of the war.

BTW I know those kill figures are based on pilots combat reports. Brown's Appendix Three lists every Seafire combat individually, so I suspect when he was doing his research he simply went down to the Public Record Office and got the original squadron documents out. And I know everyone over-claimed, which does NOT imply dishonesty. In the heat and confusion of battle, it is impossible to be completely accurate, and all fighter pilots were optimists. If they weren't, they would never have been fighter pilots in the first place. But even allowing for a bit of over-claiming, it is clear that the variants of Seafire deployed in the Pacific enjoyed a decisive superiority over the Zero.

It has been suggested that a kill should only be regarded as authentic if it is confirmed by the documents of BOTH sides; one side's combat reports, and the other side's loss records. I'm sorry, but I am not going to go there. Even assuming that everyone's records are complete, accurate and available (a VERY large assumption), if we applied that consistently, we'd have to revise the combat totals for everyone; Hartmann, Kojedub, Bong, Johnson, Boyington, the lot. Safer, I think, to simply say that all combat reports overclaim a bit, and leave it at that.

Seafires did have some real weakenesses. They were a poor deck-landing aircraft, and short of range. Both these disdavatages were because the design was an adaptation of a land-based design. But by early 1945, FAA squadrons in the Pacific had to some extent overcome both problems. Deck-landing accidents were down to well under 2% of sorties, and by scrounging some 89 gallon drop tanks designed for P-40s, they had got the strike radius up to over 200 nautical miles, and patrol endurance on station up to over three hours; respectable figures by any standards.

The Seafire's reputation had been crucified by the fiasco at Salerno, where they were badly misused, resulting in a casualty rate of 10% of aircraft written off per sortie in deck-landing accidents, plus many more minor accidents. Understandably, it took a long time to recover.

As for what the RAF and RAAF's experience was with their Spitfires against the Zero; sorry, I haven't a clue! I'd suspect a lot had to do with the Mark (the Mark VIII, deployed late in the Pacific war, had a much higher performance than the Mark V), and the tactics used. I think the title of this thread can lead to some confusion, as it is about comparing both the Spitfire Mk V and the Seafire with the Zero. The fact is, the Sptifire Mk V and the Seafire LIII/FIII were very different aircraft; different performance, different tactical enviroments, different services, and very probably different tactics too. So comparisons which are valid for one will not be valid for the other.

The Seafire LIII and FIII were specifically optimised for performance at low to medium levels. They were very effective aircraft. Also, the FAA learned very fast, and as a "poor relation" service, was usually very good indeed at improvisation. It had to be; but in a war where the ability to learn and adapt fast often made the difference between life and death, this was no bad thing.

[Glider]

Interesting post, I knew that they used P40 tanks but didn't know how much difference it made.
Thanks

[HoHun]

Hi John,

>The Zero did NOT out-turn the Seafire, easily or otherwise. What FAA pilots found was that the Zero had a tighter radius of turn, but the Seafire had a much higher rate of turn; i.e it was going around a larger circle, but going round it sufficiently faster to keep safely ahead of the Zero.

Hm, I guess this is a bit like the turn rate comparison I posted earlier in the thread ... a bit difficult to interpret. I have prepared a new turn rate comparison for the A6M2 and the Seafire LIII - it doesn't seem to leave much room for the Seafire LIII out-turning the Zero by turn rate if both go for the optimum rate turn.

>The Seafire LIII and FIII were specifically optimised for performance at low to medium levels.

The Seafire LIII certainly was a pure low-altitude aircraft. The A6M2 would seem to have an advantage above 4000 m altitude in all of the main performance criteria, though the medium-altitude FIII would compare more favourably at these altitudes.

I guess it would be more meaningful to see a comparison against the heavier but more powerful A6M3 and A6M5 variants, but I'm afraid I have no good engine data on these aircraft as the TAIC data seems a bit suspect ...

Regards,

Henning (HoHun)