Spitfire mk VB/Seafire vs Zero

[John Davies]

While we're on the subject of the Wildcat, here's a bit of light relief……

All taildraggers swing a bit on takeoff, but the Wildcat more than most. This was due to a combination of a big torquey radial, a narrow undercarriage, a short fuselage and a fin ("vertical stabiliser" in American) and rudder that could have been bigger, and indeed were enlarged in the later ones.

So before you open the throttle you wound in a lot of rudder trim to compensate. Now the fun starts….

The rudder trimmer in the early Wildcats (and for all I know in all of them) worked in the opposite to the natural sense; i.e you wound the wheel to the left to apply right trim and vice versa. There was also a trim indicator, which did go round the right way, which meant that when the trim wheel was being wound one way, the indicator was going the other way. Are you confused yet?

Of course, from time to time the inevitable happened, and some luckless sprog wound in a handful of trim not to compensate for but to accentuate the swing. Once the throttle was opened, no pilot in the world had a leg strong enough to force the rudder pedal over against the combined forces of swing and mis-trim, and he would very soon find himself facing the way he had just come.

Some very spectacular incidents resulted. Apparently some pilots actually managed to take off in this manner. I never heard of an accident in which anyone was killed. Grumman built their aircraft very strongly! However, it was a bit unfair on other users of the airfield. It never, to my knowledge, happened afloat, because no pilot is going to do that more than once, so it tended to happen during training ashore.

In a way, it's kind of comforting. It shows that British designers did not have a monopoly of mutton-headed anti-ergonomic cockpit design.

 

[Glider]

I've read through this thread twice now and was unable to find any figures on the Zero or Spitfire V from flight tests or manufactures' data bearing on aircraft performance characteristics such as speed, climb, roll rate (excepting the NACA chart) turn.

This may help with the Spitfire V for speed and climb

Spitfire Mk VB W.3134 Report

 

[renrich]

I have read that the Wildcat was very easy to groundloop in a landing on dry land but the arresting gear on a carrier helped in that respect. According to Lundstrom, I believe, the design of the F4F4 was undertaken after the USN knew about the Zero performance. Some of the USN pilots said the F4F4 flew like a loaded torpedo plane! No question that the folding wings was the correct decision so as to get more VFs on board. The FAA may have been well trained but again according to Lundstrom the prewar gunnery training of the USN was superior to all other air forces and the overall training of the USN and IJN was the best in the world. Lundstrom-" In terms of actual flying hours, the Navy's aviation program in the mid 1930s probably offered the most comprehensive training schedule of all the world's air forces." In the USN, the 1935 syllabus was a one year course involving 465 hours of ground school and 300 hours of flight. In 1939, it was recommended that the syllabus be shortened to seven months with 207 flight hours. The syllabus began after a month at a flight school with ten hours of instruction where if the student was apt, he soloed. ( I soloed after ten hours of dual. When I got up in the air, I looked at the empty right seat and asked the Lord to please let me get back on the ground again safely.) The VF wings before 1940 averaged from 3500 to 1500 flight hours. The VF wings in 1940 averaged 1000 to 600 flight hours. The VF wings 1941 averaged 600 to 300 hours. The VF wings in 1942 averaged 300 flight hours. If the six guns was the correct decision for the F4F4, why did they go back to four guns on the FM2 and why the four guns on the F8F?

 

[HoHun]

Hi Parsifal,

>So according to these sources, I think you are right, the performance is better in the older mark. The exceptions appear to be max ceiling.

I'd say this is probably a misquoted data point then. Ceiling is tied rather closely to flying weight, with the lighter aircraft enjoying a clear advantage if everything else is unchanged.

Regards,

Henning (HoHun)

 

[HoHun]

Hi John,

>On the other hand, if you are an FAA pilot keeping the Fw200 Condors off the North Atlantic convoys in winter, manoerverability doesn't matter so much. Firepower, however, does.

Good point - from Brown's books, I'd say the British were really impressed by the Fw 200's fighting abilities early in the war, so the six guns might have been necessary (or at least highly desirable) from their point of view.

>Adding an extra gun and its ammunition, on each side, in effect increasing the weight devoted to armament by 50%, will greatly increase the roll inertia that a control input from the ailerons has to overcome in order to initiate or stop a roll.

Hm, this would be right only if the six-gun fighter had indeed had 150% of the ammunition supply of the four-gun fighter, but it seems that the lightly-armed variant carried more ammunition, so the difference was not as great as it might have been.

But you hit the nail on the head with the differentiation between roll rate and roll acceleration - this is an important detail often missed in performance discussions!

Regards,

Henning (HoHun)

 

[HoHun]

Hi Ponsford,

>I've read through this thread twice now and was unable to find any figures on the Zero or Spitfire V from flight tests or manufactures' data bearing on aircraft performance characteristics such as speed, climb, roll rate (excepting the NACA chart) turn.

With regard to Spitfire data, see:

WWII Aircraft Performance

F4F data:

Untitled Document

A6M data is hard to find - the best guess would be the TAIC intelligence summary for which I don't have an online resource. It seems that climb rate does not match the published engine ratings in that TAIC chart, though.

In general, there is only so much you can learn from un-processed data because of the variability of data from multiple sources, or even contradictions within a single source occassionally. That's the reason for conducting a quantitative analysis that leads to "generic" data, like this one:

http://www.ww2aircraft.net/forum/polls/f4f-wildcat-versus-p-40e-tomahawk-13281.html#post364448

(If the direct link doesn't take you right to the correct post, it's #25 in the linked thread. The P-40 data is from Perils P40 Archive Data )

>Frankly I think the Spitfire – Zero comparison is less interesting than a F4F – Zero comparison.

I don't know how the F4F came to play such a big role in this thread, but it's in fact a Seafire vs. Zero discussion

Regards,

Henning (HoHun)

 

[JoeB]

1. Since Joe decided not to accept my offer to consider his post never

2. In reality, the markedly inferior performance of the F4F vs. the A6M is a well-documented fact, and the good combat record of the USN was achieved in spite of that inferior performance.

3. Note that Joe uses the term "combat effectiveness" as if it were a property of the aircraft on the same level that performance is a property of an aircraft. As the results of combat - the only way to measure "combat effectiveness" - are dependend both on men and machines, and on the men and machines of the opposing side as well -, this is a misconception,

4. So how comes he thinks he can get away with a poorly-hidden insult on my honesty here?

With regard to possibly contradicting data ... those who have actually sorted through different data sets while analyzing performance are aware that there is much conflicting data around, and that it is a routine occurrence to have something contradicting something else. Quantitative analysis is an excellent tool to sort out such contradictions.

1. Huh?
2. No actually 'markedly inferior" is not documented. To again refer to a reference you've been told about, have said 'maybe I should read' but obviously haven't read, see Lundstrom's discussion of the early informal and formal F4F v captured (Ryujo's from the Aleutians) Zero in late 1942 ("First Team in the Guadalcanal Campaign" p 534-5). The first tests concluded the F4F was slightly faster. The next ones, probably more carefully conducted, gave the general result with which we're famillar now (or should be): the two were around equal in speed at sea level, then Zero relatively slightly faster up to 19k ft (best speeds less than 20mph apart); both trials agreed the Zero was somewhat better in a continuous turn (not a lot, not as much of an advantage as over the P-40), Wildcat rolled substantially better at high speed, F4F dived a little better or same, Zero climbed substantially better in general. Not markedly inferior even in those basic stats.

Anyway you made that comment wrt to F4F v P-40 not F4F v Zero. It's definitely not 'well documented' that the F4F was 'markedly inferior' in performance to the P-40E, that depends what area of performance you emphasize between two a/c more dissimilar than the F4F and Zero were.

3. There are separate individual plane factors. Those consist in turn of measureable aerodynamic performance (speed, sustained turn rate, radius, etc) and other (armament, ruggedness, cockpit visibility behind or for gunnery, favorable handling for gunnery? etc). There is overall combat effectiveness of the plane. There is combat effectiveness of a fighter unit equipped with the plane.

The second thing, overall combat effectiveness of the plane itself, would be illustrated as follows: randomly select similarly trained test pilots of similar background. Assume you could convince them to seriously try to kill each other in real air combat in various scenario's, not a race, and not just a mock dogfight. Let them go at it and see what happens. The more the effectiveness difference, the higher the kill ratio. The separate individual plane characteristics will determine which plane is more effective in that 'all else equal' situation but there is no way to calculate the kill ratio upfront just using the performance stats. IOW a single index of effectiveness and the individual stats are related things but not the same thing. Of course the effectiveness of a unit equipped with the plane is another thing, no confusion or misconception about that except maybe by you.

4. If your graphs say the F4F turned a lot worse than the Zero and head to heads said not as well but not big difference, I'll go with the trials (though trials of captured a/c aren't 100% certain either). And again if you really don't want to debate don't, but 'I'm on ignore' then you launch into another long response with lots of ad-hominem, what does 'ignore' mean then ?

Joe

 

[ponsford]

Thanks for the link Glider:

Spitfire VB
Max speed: 371 mph at 20,100 ft.
Climb: 3250 ft/min at 15,200 ft.
Time to 20,000 ft. 6.4 minutes

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.

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

Speeds summarized fwiw:

Zero 21:
(1) 316 m.p.h. at 16,570 ft. (Taylor, p.253);
(2) 316 m.p.h. at 16,400 ft. (General View, appended chart)
(3) 321 m.p.h. at 20,000 ft. (Mikesh, p. 123)
(4) 326 m.p.h. at 16,000 ft. (Reardon, p.113)
(5) 331.5 m.p.h. at 14,930 ft. (Francillion, p. 16)
(6) 332 m.p.h. at 16,570 ft. (Caiden, p. 158)
(7) 336 m.p.h. at 19,685 m.p.h. (Green, p.46)
(8) 345 m.p.h. ( Sakai , p.48).

Dunn is pushing Sakai's figures. I'm not entirely convinced by his argument.

More US Zero data below:

Informational Intelligence Summary No. 85: Flight Characteristics of the Japanese Zero Fighter
Max speed sea level: 270 mph
Max speed critical height: 326 mph
Climb sea level: 2750 ft/min.
Climb 15,000 ft: 2380 ft/min.

Zero-2 A6M2, USAAF Material Command (Actually Navy figures from San Diego)

Vmax sea level 277 mph
Vmax 16,000 ft 335 mph
Climb sea level 2710 ft/min
Climb 15,000 ft 2480 ft/min

Mitsubishi Type 0 MK2-SSF Hamp Airplane, AAF No. EB-201 Flight Test Engineering Branch

All flight tests were performed at rated power and no data is available at maximum emergency power, 2600 RPM and 40" Hg. manifold pressure.

Maximum speed at high critical altitude = 15,300 ft. (2400 RPM and 36" Hg. man. press.) = 308 MPH

Rate of climb at sea level (2400 RPM and 36" Hg. man. press.) = 3260 ft/min.
Rate of climb at low critical altitude, 7000' (2400 RPM and 36" Hg. man. press.) = 2980 ft/min.

TAIC Report No. 17, Combat Evaluation of Zeke 52 with F4U-1D, F6F-5, and FM-2
Max speed: 335 mph at 18,000 ft.

TAIC 38: Zeke 52

Max speed at sea level: 291 mph 44" HG
Max speed at critical alt. 19,400 ft.: 326 mph 44" HG.

 

[ponsford]

Which leads me to the obvious conclusion that if the pilots of a pretty advanced development of the Merlin-engined Seafire had to work hard at it to get a decisive advantage over the Zero, then anyone who went up against a Zero in a Wildcat had to be a real hero!

Hi John: I take your point and tend to agree with the gist of it. It would take balls... or numbers, discipline and good tactics.

 

[ponsford]

The zero Mk 2 had the following statistics

Specification of A6M2 Navy Type 0 Carrier Fighter Model 21:

Performance: Maximum speed 331 mph at 14,930 feet. Cruising speed 207 mph. Initial climb rate 4517 feet per minute.

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.

 

[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]

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]

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]

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.