Do we have any encounters of P51s with A6Ms?

[parsifal]

Either somebody's pulling your leg or you made a math error.

180 mph is 264 feet per second (Actually 236.989 feet per second, but you get the idea).

A circle with a diameter of 612 feet has a circumference of 3,845.3 feet, so the distance around 180° is 1,922.7 feet.

My maths, and it is wrong, but so too is your calculation, i would respectfully submit, because, as is often the case, diameter and radius are mixed up. The circumference is 3.142 x diameter, or 6.284 x radius. If the figure given for the zeke is indeed a radius, then your figures are correct. if however the figure is a diameter and this circle being described by the zeke is a diameter of 612feet, not a radius, that means the full circle being described by the zeke is 1922.5 feet. A semicircle is half that or 961 feet. At 180mph is 264 feet per second as you point oput, but the distance to cover is a lot less than your calculations (except if its a radii). To cover that 961 feet, it would take the Zeke 3.6 seconds to complete. So, depending on whether the turn radius is a radius, or a diameter, you get 3.6 or 7.2 seconds.

At 264 feet per second, and assuming he doesn't decelerate at all, it takes 7.28 seconds to cover the distance and complete the turn.

Your calculation is wrong because youve mixed up radius and diameter.

Besides that, VERY few aircraft could exceed 20° per second turn rate, and 180° divided by 3.5 seocnds is more than 51° per second, which has NEVER been done in a fixed wing aircraft in a level unstalled turn, even by a Harrier using VIFFing.

There are plenty of accounts during the war of zekes being able to turn inside allied fighters and be on their tail in less than 5 seconsds. thats why all the tactical instructions given during the war say never get into a slow turning fight with a zeke. the RAAF trials between a Spit and a Zeke, undertaken in 1943, starting with the two aircraft at 180 degrees from each other, had the zeke on the tail of the spit, inside of 8 secs. and thats with the spit turning as fast as he can. And the spit was known for its turning ability.

The math says your above figures are a tall tale that sounds good but doesn't wash. Physics doesn't lie. I'm assuming a typo in your figures since you are usually spot on. This is NOT an attack. Just trying to get it straight.

I stand by those figures, more or less, on the basis that the turn radius is in fact a diameter. if not, it is 7.2 secs as you say.

About the P-38, since maneuvering flaps aided the turn. they were routinely used by P-38 pilots in combat once fitted. Another trick they could use was asymmetric thrust to help the turn rate. It works in a P-38. Didn't turn it into a world-class dogfighter, either, but did surprise many Japanese pilots.

P-38 was an outstanding fighter, but it was never a fantastic dogfighter. Using the right tactics, it had it allover the Zeke, but this was not the right tactic to use.

As far as being all over a P-38 like a dog in heat goes, it was quite the reverse in the real war. P-38's shot down 1,700 Japanese aircraft with very few losses in the PTO. That tells P-38's they didn't dogfight with Zero at 180 - 250 mph or the results would have been quite dfferent

.

Could not agree more. Though when the figures for US claimas over sekes are added up, they exceed the actual number of zekes lost by about 2 or 3:1. P-38s achieved their kill rates, not by dogfighting with a zeke, they did by dive, shoot and scoot.

 

[GregP]

Sorry Parsifail, I didn't mix up anything.

The P-38J, flaps up, had a power off stall speed of 99 mph and a power-on stall speed of 74 mph. Let's assume the aircraft would be in a power-on condition in a dogfight. That means that at 180 mph (264 feet per second), the aircraft could just sustain a bank of 80.2° and have the stall speed be right at 180 mph. To be safe, let's give the pilot a 10 mph cushion in stall speed. That puts his power-on stall speed at 170 mph, where he can sustain a bank angle of 79°.

A level 79° bank produces a g-load of 5.24 g's which produces a turn radius of 421 feet and time to complete the turn of 5.0 seconds. I doubt the P-38 could do this, meaning it probably could not sustain a 180 mph level turn. After some checking, I found one place where it was stated the P-38's best level sustained turn was at 165 mph. If we again give the pilot a stall speed cushion, he could sustain a 77° turn (stall speed is 156 mph), resulting in a 77° bank. This produces 4.4-g's and results in a turn radius of 420 feet with a time to complete the turn of 5.4 seconds, power-on.

That seems altogether unreasonable since it would mean a turn rate of about 33.3° per second and the best I have seen for a P-38 WITH maneuver flaps is about 21.6° per second, and that was at the corner speed of 165 mph At that rate, the turn at 165 mph would take 8.33 seconds, and that IS reasonable or close to it, and in line with the known turn rate for a P-38J with maneuver flaps. That puts the P-38 at 3.01g's and a turn radius of 642 feet.

I have seen the A6M5 quoted at being very nearly 30° per second at low altitudes, one of the best numbers ever recorded for a fighter of any sort. Assuming a low altitude and 30° per second, this mean the A6M5 might complete the same 180° turn the P-38J did in 8.33 seconds in 6.0 seconds (5.999 actually). Assuming the Zero is also turning at 165 mph, this would mean the Zero is sustaining a 4.06-g turn at a bank angle of 75.7° with a 462 foot turn radius.

So, at 165 mph we have the Zero turning at 72% of the turn radius of a Zero and pulling about 1/3 more g's. The g's calculated are well within the Zero's structural limits and within the stall speed increase of a 75° bank for the Zero.

That sounds reasonable to me and tells me why the P-38's didn't DO that in combat ... they'd be out-maneuvered. Since they avoided this condition like the plague, the Zero were almost never all over the P-38's. Never fight to your opponent's strengths.

Now if we had a P-38 pilot who DID try to maneuver with a Zero at low speed, he'd probably be toast as you stated. But no Zero EVER turned at over 50° per second. Nothing else did either except maybe a bulldozer at full power.

 

[parsifal]

According to the aircraft performance trials (Mike Williams' site), a zeke 52 could circle an F4U within 3.5 turns (that is, starting parallel). A Hellcat is not stated but ive read elsewhere it would take 4 turns for the zeke to "circle' the hellcat. FM-2 needed 8 circuits to be "lapped", and the P-38 was more than twice the radius of the FM-2. These trials were below 10000 ft and at airspeeds of around 175 knots

Flight test repots for the P-38G make the following recommendations/observations (WAR DEPARTMENT AIR CORPS, MATERIEL DIVISION Wright Field, Dayton, Ohio)


"Inasmuch as the general maneuverability of this aircraft is probably the lowest of any type of current fighter aircraft, and in view of the competition facing the P-38G in the European Theatre, all possible effort should be made to improve its rate of climb and high speed.

c. The P-38G turns much better than the P-38F (will close 180° in 360° circle) due to maneuver flaps.

d. Buffeting was noticeable but at higher speeds and accelerations than in the P-38F.

e. The P-38G will outzoom the P-38F.

f. The P-38G will hold its altitude in turns at thirty-five-thousand (35,000) feet, whereas the P-38F loses altitude.

g. The P-38G holds its advantages over the P-38F at all altitudes.

h. The lack of sufficient intercooling holds down the performance of the P-38G as well as the P-38F"

 

[parsifal]

So, if the p-38 had a turn radius of about twice that of an FM-2, and the turn radius of the FM-2 is about 1/8 worse than the Zeke, very roughly (because i dont know the turn radius for a P-38), we can estimate the P-38 as having a turn radius at 250mph and 10000 feet of about 2500feet. Compare that to 1118feet for the zeke. if these figures are anywhere near right, the Zeke will travel 7025 feet @250 mph to describe a full circle, whilst the Lightning will need to move 15807 feet. The problem is, we dont know the speeds of the two aircraft...optimum turning sppeed i believe will be higher for the P-38. but if they do travel at the same speed, the Zeke will do 2 turns for every one turn done by the P-38. Thats roughly twice as sluggish as an F6f

 

[GregP]

C'mon Parsifal, get ressonable/ Your number is about right above, but you fail to state the F4U was turning about 1260° while the Zero was turning about 900°.

Let's say the Zero turned 3.5 turns (1,260°) at 30° per second (the max turn rate I have EVER seen for a Zero at it's best altitude). That takes 42 seconds. If it circles an F4U in that time, the F4U completes 2.5 turns (900°) in that same time. That is a turn rate of 21.4° per second and is quite in line with the expected value. I believe it.

So what is your point?

It STILL can't complete a 180 turn in 3.5 seconds. Your statement makes my point almost exactly. I already said that the Zero would out-turn a P-38 at 165 mph since it can make the turn in about 6 seconds to the P-38's 8.22 seconds. That's why the P-38 and all other fighters avioded combat with the Zero at low speeds. It's in the combat reports, too.

I didn't dispute the Zero was more maneuverable; it was ... I disputed the Zero being able to make a 180° turn in 3.5 seconds, and still do say that.

We are BOTH saying the Zero was more maneuverable ... we're disagreeing on the turn rate of the Zero.

Tell you what, if you can get Bill (Drgondog) to go along with a turn rate of 50° per second for the Zero, I'll be really impressed and simultaneously amazed.

 

[parsifal]

I was using the Mike Williams test results. there are more than one report, but the best is

http://www.wwiiaircraftperformance.org/japan/ptr-1111.pdf

The relevant quote is on Page 2. The important thing that these reports say is that the Zeke at low speed (up to 250 mph) at low to medium altitudes was far superior to any American fighter, under any conditions. provided the fight was 10K and the speed was below 250 mph, the zeke was going to get the better situation


I dont think the zeke can turn 180 degree in 3.5 secs either at 180 mph or 250mph, but 7.22 secs is on the cards at those speeds. Dont know what happens at 150 or 130 mph which is what it has to do to turn at 612 feet.

The last post was about how many turns the zeke could do in comparison to any US fighter you care to nominate. And remember how this discussion started. it was claimed the p-38 was the most manouverable fighter in the US inventory, its wasnt, it was claimed the P-38 under some conditions could out turn a Zeke, it never could, so long as the speed remained below 250mph. Even at speeds of 300mph, against most US aircraft, it was still competitive, if not superior. Given that most dogfights were at speeds below 300mph, this makes the zeke the preferred dogfight sircraft. The US did not win the fighters war using manouvre tactics. they won it using dive, speed, protection flying as you say to their own strengths, and not those of the Zeke

my response was the claim that the p-38 could out turn a Zeke....not your claim, but a claim made close to here.

 

[GregP]

The P-38 absolutely CAN out-turn a Zero, but not a low speeds. Put them both at 320 mph and the P-38 will be on the Zero's tail in short order.

And at some speeds, the P-38 will out-turn almost any other US fighter. Conversely, use the other fighter's best turn rate velocity and the situation will be reversed. So if all you wan to do is trash the P-38, you can find conditions where that is the case. If you want to prove the other case, you can ALSO find conditions where that is true.

I cannot agree that the P-38 was a slug of a fighter, and neither would our top two Aces in WWII, both of whom scored their victories in a P-38.

I can admit the Zero was the king of maneuverability at low speeds, though, as any turn graphs will show, and I like the Zero even if it was outclassed by 1944. To me it is the best-looking fighter of WWII. But I like radials.

 

[parsifal]

P-38 is one of my favourite US aircraft. and that makes it one of my favourite aircraft.

we are not that far from the same page in this. No argument that at higher speeds, the zeke rapidly lost its manouverability. at 320 mph it turned like a number 9 bus. Though Sakai during his fight with the Hellcats in 1945, was travelling and out turning them (actually it was a half roll and pull the stick back turn he used) at speeds just under 351 mph.

but what i would say is that the curve under which the zeke was most manouverable was the speeds that most dogfights would occur. Most dogfights, i am told tended to happen at speeds below 300 mph. thats arguable, but seems logical to me. If you think about the context of when a Zeke might be used as a fighter, usually to intercept US bomber strikes, against all except the B-29 (and possibly the Mosquito and A-20), most of those raids would occur at speeds of you guessed it, 200-250 mph. Same applies when its employed as an escort itself. Sure as an escort fighter, they would tend to need to fight at the interceptors choice of height, speed etc, but it just shows that fighters dont work in isolation, they are part of a team effort, and the team generally moved at around 200-250 mph.

Even today,, gunnery dogfights tend to be below Mach, and thats in jets

Surely you would agree, the US tactics against the Zeke were not to engage in a turning fight. boom and Zoom are in all the tactical analyses Ive seen, the results (dare i say it) of wargaming and testing of the zeke with the principal mounts ranged against it.

If the Zekes had been able to maintain some semblance of pilot skill, they would have maintained a better record than they did. But the weakneses of the Zeke and the falling pilot standards fed off each other in an ever worsening power dive. the vulnerability and weakness of the Zeke made it an easy target to shoot down, which increased pilot wastage. increased pilot wastage meant that standards fell quicker. Quicker falls increase the loss rate, and so on. it was a vicious circle, from which there was no escape.

 

[GregP]

Yup, agree. I think that even in something like an F-15, a hard-turning dogfight would wind up under Mach 1, as you said.

Actually I'm not too sure what the average speeds for a dogfight would be, but I tend to agree they'd at least start out realtively slow. I assume the fighters would both be at cruise speed when one side saw the other side. They would probably accelerate and initiate an ambush. If the other side saw them, the'd accelerate with somewhat less time to do it and try to counter.

The P-38 was our fastest-accelerating fighter, but I would not be surprised if the initial pass was below 300 mph. The rest of the fray would depend on whether or not they climbed, dived, or stayed level. The P-38's wanted it fast and the Zero wanted it medium to slow. Somebody would get their wish.

About Sakai, I think he was an exceptional pilot and if the planes were reversed, he still might get out of the way and survive.

I'm not a very big fan of the Buffalo but, in the proper hands, it shot down a lot of Russian planes. Didn't exactly do that in US service. Thank the Finns for it.

The P-38 did quite well if not quite at the top of its class. There can only be one validictorian. That went to the P-51 in US service. But the Hellcat, Corsair, and Lightning weren't taken lightly by any opponent unless he was in the middle of a surprise ambush. Even then, the victim's friends might not take that without trying their best to kill him in return for the deed.

 

[Garyt]

Tomo Pauk wrote:

I'm not sure that it was designed for 100 oct fuel, standard Japanese fuel was 91 (or 92) octane. The lack of better fuel was to be circumvented via using water injection, in order to delay the onset of detonation.

This is from the link to the thread on the Homare, which seems to indicate the Homare was indeed designed for 100 octane fuel - apparently the designers were about to optimistic as to what fuel would be available after the start of the war.

Quote Originally Posted by rinkol View Post
I have a reference written by the designer, Ryoichi Nakagawa, that I am sure says that the original design was intended for 100 octane fuel, but with the start of the war, the engine had to be modified to run off 92 octane fuel. The low quality of the available oil was another issue. Unfortunately, the document seems to be buried amonst others.

Robert
Thank you. Found what is probably the same reference online, for a fee. It appears the Homare was originally designed for 100 octane but had to be modified by IJA decree to take 87-92 octane fuel due to predicted wartime restrictions.

 

[tomo pauk]

Thanks for that info.

 

[Shortround6]

Problem is that we really don't know much about Japanese fuels. Maybe somebody does but any reports/analysis seems not to have made it in to most commonly available books/web sites.

The Japanese would certainly have been aware of 100 octane fuel as it existed in small quantities for a number of years (Howard Hughes used it in 1935) it was certainly no secret in 1940 (Rolls Royce had given out performance figures for Merlins using A 100 octane fuel at the Paris Air show of 1938 ). However the actual performance of "100" octane fuel carried quite a bit. Were they measuring lean or rich response? It might be quite possible to make 92/100 fuel given a suitable base stock. Early US 100 octane (1938-40 at least) was 100 octane lean and around 98-103 octane rich mixture (yes, some lots were actually under 100 octane when operated rich but since NO TESTS existed nobody KNEW which lots were which when they were produced and not tests existed for acceptance.
We do know that Dutch East Indies fuel was rich in aromatics which tend to help rich response but I sure don't know enough about any other characteristics of DEI fuel to even have a guess as to how well ( or badly) it compared to south east Asian fuel. Or what the production break down would be ( how many gallons of which type fuel per barrel of crude oil).

Japanese 92 octane may or may not have been better than US 91/96 commercial fuel.

 

[Balljoint]

Problem is that we really don't know much about Japanese fuels. Maybe somebody does but any reports/analysis seems not to have made it in to most commonly available books/web sites.

The Japanese would certainly have been aware of 100 octane fuel as it existed in small quantities for a number of years (Howard Hughes used it in 1935) it was certainly no secret in 1940 (Rolls Royce had given out performance figures for Merlins using A 100 octane fuel at the Paris Air show of 1938 ). However the actual performance of "100" octane fuel carried quite a bit. Were they measuring lean or rich response? It might be quite possible to make 92/100 fuel given a suitable base stock. Early US 100 octane (1938-40 at least) was 100 octane lean and around 98-103 octane rich mixture (yes, some lots were actually under 100 octane when operated rich but since NO TESTS existed nobody KNEW which lots were which when they were produced and not tests existed for acceptance.
We do know that Dutch East Indies fuel was rich in aromatics which tend to help rich response but I sure don't know enough about any other characteristics of DEI fuel to even have a guess as to how well ( or badly) it compared to south east Asian fuel. Or what the production break down would be ( how many gallons of which type fuel per barrel of crude oil).

Japanese 92 octane may or may not have been better than US 91/96 commercial fuel.

The high octane fuels were the result of reforming feed stocks –cat cracking for the most part I think- rather than the feedstock constituents. Bit of irony that the basic reformation concept is a Russian (pre Bolshevik) invention.

 

[Shortround6]

You could get the high performance fuels from certain feed stocks without cat-cracking, just not anywhere near the the numbers of gallons per barrel that cat cracking delivered, Cat cracking did allow more marginal feed stocks to be used also. Please note that Cat-cracking is different than distilled "straight run" gasoline. Amount of allowable lead also entered the picture. And the same amount of lead added to different "blends" of gasoline gave different peak results even if the "unleaded" but different "base" mixture tested the same.

91/96 is about as good as gets for gasoline found in the ground as part of the crude oil. You can get up to 125 PN from straight run gasoline. Higher performance requires blending and the use of aromatics ( which can be produced by cat-cracking base stocks)

Lead does have rather diminish returns but tipping the lead "can" a bit more did allow for some significant increase in production at certain times without having to relax the performance of the fuels.

 

[sgtleehead]

Gentlemen,

According to the book, Possum, Clover Hades, The 475th Fighter Group in World War II by John Stanaway, McGuire and his flight actually engaged a Ki-43 Oscar and not an A6M. However, initially the flight identified the Japanese aircraft as an A6M5.

The Ki-43 was flown by A/O Akira Sugimoto of the 54th Sentai. McGuire stalled his Lightning trying to get the Oscar off the tail of Capt Ed Weaver's P-38. McGuire's aircraft crashed with his drop tanks still attached.

Eagledad

Your right actually - sorry poor memory. But the point I was trying to make was about the danger factor, because the Zero was more maneuverable then the KI-43. When we look at the ability to maneuver the figures quoted more commonly or compared, are generally based on low combat speeds as already alluded to by GregP. At higher speeds the ability to turn can be completely changed. The Tempest or the corsair were classic examples. The Tempest could still maneuver well at high speeds so it had a consistent threshold of agility throughout the speed envelope. The Zeros flight performance drastically changed as the speeds increased. That's what made the Tempest such a good plane. Some observers would overlook the performance throughout the whole spectrum and just concentrate on say, the maximum turn at low speed. Even the British initially did the same in the initial flight trials of the Tempest.

I have to say - the maths here is confusing!

 

[tomo pauk]

Your right actually - sorry poor memory. But the point I was trying to make was about the danger factor, because the Zero was more maneuverable then the KI-43.
....

Do we know for sure that Zero was more maneuverable than Ki-43?

 

[GregP]

I had always read the opposite, that the Ki-43 was actually more maneuverable than the Zero, but was very lightly armed.

Getting real comparisons is tricky since the Ki-43 was IJA and the Zero was IJN ... and the Imperial Japanese Army and Navy hated each other. The last thing they'd do would be to run trials against each other.

It would have turned into a Kamakaze demonstration of ramming.

 

[VBF-13]

Do we know for sure that Zero was more maneuverable than Ki-43?

I wouldn't know, tomo pauk. But the thing to me is both required tactical thinking "outside the box" to deal with.

 

[parsifal]

Ki43 was fitted with special manouvre flaps that apparently that gave it greater a tighter turning ability than a Zero, however I think the Zeke was able to compete its turn quicker at certain speeds and heights. The Zeke as statefd previously at 180 mph under 10K was repotedly able too complete a 180 degree turn in about 5.7 seconds. some aources say 7.22 seconds. I suspect the former is a single turn manouvre, whilst the latter is a sustained turn rate.

Converting that to an (estimated) 360, I get 11.4s max turn and 14.4secs sustained turn rate

The problem with turn rates is that they can be highly variable depending on pilot skill, weather conditions and other variables, so i need to preface this comparsion by stating up fron that they may not be necessarily comparable. i have absolutely no way of knowing one way or the other

Im skeptical, but one source from a magazine that i have gives the following figures for the Ki43

@ entry speed of 300mph
a 360 deg turn
1,000ft 11.1s
5,000ft 12.4s
10,000ft 12.3s

2 x 360 deg turns
1,000ft 21.6s
5,000ft 23.4s
10,000ft 25.0s

@ entry speed 250mph
One 360
1,000ft 9.3s
5,000ft 10.1s
10,000ft 10.8s
15000ft 12.4s
9.3s 10.1s 10.8s 12.4s

Two 360s 21.1s 22.5s 25.4s 28.9s
1,000ft 9.3s
5,000ft 10.1s
10,000ft 10.8s
15000ft 12.4s


Sustained turn rates
No Flaps 12.6s 13.6s 15.9s 18.9s
Full Flaps 12.3s 13.6s 15.0s 18.0s

At the stated altitudes (speeds not specified)

Best Flap in all situations was to apply full flaps

Stall speeds in these tight tiurns could fall ewell belowe 100mph without risk of a stall

If those figures are true, and i doubt it, the Ki43 was one hell of a turn fighter

 

[parsifal]

As a comparison I looked up the turn characteristics of the Me 109e and Spitfire I from Mike Wiliams. i should preface this by saying apparently the turn radius at best speed and altitude, without significant loss of altitude for the Ki43 was listed in the above used article as 360feet


According to Mike Willams (who quotes the RAE test results), the RAE determined in Report No. B.A.1640 that "The minimum radius of turn without height loss at 12,000 ft., full throttle, is calculated as 885 ft. on the Me 109 compared with 696 ft. on the Spitfire." and that the corresponding time to turn through 360 deg is 25 seconds for the Me 109 and 19 seconds for the Spitfire. Compare that to 360feet and 10.8 secs for the Ki43. This is where my maths is going to go down in a big way, but what the heck....If the Spt and the Ki43 start parrallel and get into a turning fight, the Ki43 should be on the tail of the Spit pretty quickly. In just under 11 secs the Ki43 would have done a full 360, whilst the spit has done a bit over 180 degrees. another 5.4 secs and the Ki43 has done 180 degrees, the Spit about 90 degrees (only doing this roughly). Another 2.7 secs and the Ki43 has done a further 90 degrees, the Spit about 50.....I think by then the Ki43 would well and truly be in a really good firing position. adding that up and the Japanese fighter has gone from parrallel to astern in about 19 secs. if that is even anywhere near right, that is impressive.