Am I the only person in the world who's a fan of the Ki-43

[Ivan1GFP]

One reason they were used as synchronized guns was because nobody wanted to put a Vickers gun in the wings

Since when were we discussing Vickers guns?
The Ho-103 and Ho-5 are both Browning designs and I thought this discussion was about how poorly the Ho-103 synchronized and how pilots had it replaced with the Type 89 which was the Vickers.

Number of blades shouldn't have a lot to do with anything. Sakae engine did 2600rpm and used a 0.69 reduction gear? (corrections welcome) so prop was turning 1794rpm (?), with a 900rpm machine gun that is one shot every two full revolutions of the prop, regardless of number of blades. A slightly slower gun may run into more trouble. Machine guns also don't fire real evenly unless a lot of care is used setting them up and the ammo is very, very good. Gun is advancing the belt and depending on weight of belt and arrangement (lots of short layers or a few long layers) that can slow the guns down. US rather famously didn't test prewar installations with full belts and ran into all sorts of problems. You may average 14 shots per second but that doesn't mean the the time between shots doesn't vary.

Synchronizers often fired the gun when the blade was clear vs stopping the gun when the blade was in the way. It may not sound like it but that is a distinct difference. Look at the example again, a 3 blade prop on a Sakae is going to swing 8 or 9 blades past a 7.7mm gun for every time the gun fires in theory.

I believe I have a pretty good idea of how a synchronizer works as per this post which I will reproduce below for ease of reading.
FW-190 - How Good Was It, Really?

Gentlemen,
I believe there is a serious misconception about how guns are fired through a propeller arc.
First of all, there is a difference between an "interrupter" and a "synchronizer" mechanism.
The interrupter may have been used in the early days of he Great War, but in general not much later.
It works by "interrupting" the firing cycle of the gun which would be firing free between the propeller blades.
The synchronizer is much different. It triggers the gun to fire. If the gun is ready to fire and if the trigger is pulled, the gun fires.
A typical synchronizer would trigger the gun once in each gap between blades.
For some typical (and simple) numbers, figure that an engine might be turning 2500 RPM with a reduction ratio of 0.500:1 to the propeller.
For a 3 blade propeller that would be 1250 x 3 = 3750 times per minute that the synchronizer would attempt to fire the gun.
We know of course that a typical MG / Cannon cyclic rate is much lower than that, so many times when the synchronizer connects, the gun is not ready to fire.
The reduction in firing rate happens because sometimes the gun IS ready to fire but the synchronizer has not reached the proper position yet.

There are plenty of aeroplanes with synchronized guns and 4 blade propellers, especially in Japanese service. Think N1K1-J and Ki 84.

Two 12.7 guns may have been good armament in the late 30s or even 1940 but it was falling behind in in 1941/42. Japanese pilots in Ki 43s did bring down a number of B-24s but the most favored tactic was to attack from the front (pre nose turret) and use 3-4 fighters, one behind the other to attack a single bomber in the formation. In other words they were using 3-4 planes to bring the same firepower to bear as an single American or British fighter could.

I never claimed that Ki 43's 2 x 12.7 mm Ho-103 even with explosive shells was heavy armament.
I just claimed that it was better than the 2 x 7.7 mm Type 97 which is all the A6M2 would have after the 60 rounds of 20 mm were gone.
At a cyclic rate of 520 rounds per minute, the 60 rounds was good for slightly less than 7 seconds of firing time!

- Ivan.

 

[Greyman]

I have hit some information that seems to indicate that the Japanese bought 2 million rounds of 12.7mm HE ammo from the Italians but it is a gaming site so.....

As far as I know the Japanese used two types of Italian HE/Incendiary 12.7-mm rounds and two types of their own manufacture.

 

[tomo pauk]

...
I never claimed that Ki 43's 2 x 12.7 mm Ho-103 even with explosive shells was heavy armament.
I just claimed that it was better than the 2 x 7.7 mm Type 97 which is all the A6M2 would have after the 60 rounds of 20 mm were gone.
At a cyclic rate of 520 rounds per minute, the 60 rounds was good for slightly less than 7 seconds of firing time!

The Ki 43 with two 12.7mm was not that a frequent occurance. Mostly it was one 7.7 and 12.7.link
Cannon was crucial for the success of the Zero, we can try to imagine IJN trying with Ki 43s to stop Allied bombers of different types attacking their carriers - not a good proposal for the Japanese. The 100 rd box was introduced some time ater Midway, and in 1943 the long barreled 20mm cannon was introduced.

 

[Shortround6]

Since when were we discussing Vickers guns?
The Ho-103 and Ho-5 are both Browning designs and I thought this discussion was about how poorly the Ho-103 synchronized and how pilots had it replaced with the Type 89 which was the Vickers.

we were discussing gun placement and the evolution of Japanese fighter armament. Unlike the Americans who put a one or two .50s in the fuselage and additional .30s in the wings the Japanese almost never put their 7.7 guns in the wings. I am not sure if poor rate of fire was the only reason that some Ki 43s had one of their 12.7s replaced by a 7.7mm. The rate of fire of the 7.7 wasn't all that great either. Some people have suggested it was supply problems, either guns or ammo or both.

I believe I have a pretty good idea of how a synchronizer works as per this post which I will reproduce below for ease of reading.
FW-190 - How Good Was It, Really?

https://ww2aircraft.net/forum/threads/fw-190-how-good-was-it-really.47877/page-5#post-1377498

Thank you.
WW I engines were rarely geared so even a 1500rpm engine had a prop rotating well in excess of the rates of fire of contemporary machine guns (usually about 600rpm)
The Germans on the MG 131 used electric priming and also used it on the wing root MG 151/20 guns of the FW 190. Me 109s and indeed all non-synchronized MG 151/20s got percussion primed ammo. This helped keep the rate of fire of the German synchronized guns closer to the free gun rate of fire (approaching only a 10% reduction).

Browning machine guns (and clones) are easy to synchronize. This is due to the basic mechanism. Some guns are impossible to synchronize.
The Basic Browning fired closed bolt. Round is already in the chamber and synchronizer only has to release the firing pin. Please note the British modified their Brownings to fire open bolt due to change to cordite propellent. Synchronizer has to release the bolt from the rearward position and it travels forward chambering the round and then firing. Aside from the Gloster Gladiator I don't think the British ever synchronized their Brownings ?
This does not mean the Brownings kept a high rate of fire when synchronized. The US .50 dropped from a nominal 600rpm pre war to around 450rpm when synchronized. I haven't seen a good figures for what happened when the US raised the rate of fire on the .50 from 600rpm to 800 rpm. But then the only US fighters that continued after 1941 with synchronized guns were the P-39 and P-63. At least production versions. depends on how you count the A-36

I never claimed that Ki 43's 2 x 12.7 mm Ho-103 even with explosive shells was heavy armament.
I just claimed that it was better than the 2 x 7.7 mm Type 97 which is all the A6M2 would have after the 60 rounds of 20 mm were gone.
At a cyclic rate of 520 rounds per minute, the 60 rounds was good for slightly less than 7 seconds of firing time!

- Ivan.

The Zero had, for all practical purposes, the same armament as a Bf 109E, I would also note than any French fighters with 20mm guns used 60 round drums and the early Spitfire VBs used 60 round drums. Granted the Zero was a bit later in timing. However from the link Tomo posted it seems that very few Ki 43s had twin 12.7mm guns, at least in the part of the war where the Japanese were on the offensive. The majority of Ki 43s were built after Jan 1943 and even if all the later ones had twin 12.7s it is too late.
I would note also that for those 7 seconds the Zero has 3-4 times the fire power of a twin 12.7mm Ki 43 and about 6 times the firepower of a split armament Ki 43.
The Zero has much less need of repeated firing passes to score a kill on average.

 

[tomo pauk]

Hello Gentlemen,
I had just been searching for data on the Ki 43-II and stumbled upon yet another interesting thread.
I don't suppose anyone here would know what the capacities of the fuel tanks were on the Ki 43-II?
I already have the numbers for the Ki 43-I.
Anyone happen to know where I can find what the throttle settings and RPM were for Military, Normal, and Emergency Power?
The numbers from TAIC documents don't seem to match up with the Sakae 21, so I am not inclined to trust them for the Ha 115.
...

The Ki-43-I was supposed to hold 564L of fuel internally, the -II and -III having 528L, if I'm correctly decyphering the figures from the Bunrin Do book about it.

Table with Nakajima engines, I believe Shinpachi provided the translation. My contribution is the '1st speed, 2nd speed' remark. Please note that there is no mention of 'WER' or 'military power' in Japanese nomenclature.

 

[Ivan1GFP]

The Ki 43 with two 12.7mm was not that a frequent occurance. Mostly it was one 7.7 and 12.7.link
Cannon was crucial for the success of the Zero, we can try to imagine IJN trying with Ki 43s to stop Allied bombers of different types attacking their carriers - not a good proposal for the Japanese. The 100 rd box was introduced some time ater Midway, and in 1943 the long barreled 20mm cannon was introduced.

Hello Tomo Pauk,
From a couple of accounts (I believe one was about the CAP over the fleet carriers at Midway), the MG armament is all they had after the first engagements. I will need to find some references to be sure.
Agreed that the ammunition load for the cannon was increased in the A6M3 series and the Type 99-2 long barrel cannon were also introduced. The initial Type 99-2 had its issues as well. Its cyclic rate was even lower than for Type 99-1 at only 480 rpm and its muzzle velocity was only a bit better at 625 m/sec (2050 fps).
The A6M2 fighter bomber series by Nakajima also had increase ammunition loads from the original A6M2. I picked the original A6M2 because it was a great example to illustrate my point and also because it served throughout the war even after later versions were introduced.

Regarding the Ki 43 with two 12.7 mm being not so frequent, please observe that your link is describing the Ki 43-I with the two blade propeller.
My original theorizing was that there was some rather poor interaction between the two blade synchronizing mechanism and the Ho-103's less than regular cycle times which was causing issues because there don't seem to be accounts of Ki 43-II and Ki 43-III pilots having one of their 12.7 mm guns replaced by a 7.7 mm.
I have also seen references that state the Ki 43-I had a two pitch propeller and others that say it was "variable pitch" and others that state "constant speed". I do not know which is correct; I have only recently been collecting data on the Ki-43 series (with particular interest in the late Ki 43-II).
Some time ago, I wrote up a little spreadsheet to calculate the reduction in rate of fire based on propeller RPM and weapon cyclic rate that included a couple other variables for percentage of missed firing cycles. It was useful for discussions on another thread but I wasn't smart enough to keep a copy. It wasn't complicated, so perhaps I should write another version.

- Ivan.

 

[Ivan1GFP]

Thanks for the data, Tomo Pauk,
I actually have the same reference from FAOTW 65.
From a diagram, I found that the Ki 43-I had a 132 liter tank and a 150 liter tank in each wing which adds up to match the 564 liter total.
What I am trying to find is the change in volumes of the tanks in the Ki 43-II to get down to 528 liters.
It is probably in the manual, but I don't read Japanese.

From TAIC data on Ha-115, the Take Off rating is shown as 41.7 inches Hg and Military is shown as 37.8 inches Hg.
It is the same for the Sakae 21 but the manual for A6M5 states that Take Off is +300 mm while 41.7 inches Hg converts to +310 mm.
The question is whether the settings are the same as the Sakae 21 and TAIC just was a little off or was the rating really higher for the Ha-115.
I suspect the actual number is really +300 mm but that would be 41.34 inches Hg and the difference is an error in conversion but this is just a suspicion and not fact....

- Ivan.

 

[tomo pauk]

Hello Tomo Pauk,
From a couple of accounts (I believe one was about the CAP over the fleet carriers at Midway), the MG armament is all they had after the first engagements. I will need to find some references to be sure.
Agreed that the ammunition load for the cannon was increased in the A6M3 series and the Type 99-2 long barrel cannon were also introduced. The initial Type 99-2 had its issues as well. Its cyclic rate was even lower than for Type 99-1 at only 480 rpm and its muzzle velocity was only a bit better at 625 m/sec (2050 fps).

The result of expanded ammo by the Zeros were slaughtered US torpedo bombers. Zero have had good/excellent firepower, but during the crucial battles of 1942 the ammo count for cannons was too low. The Type 99-2 was with MV of 750 m/s (~2500 fps), it used a bigger cartridge with more propellant. link1 , link2

The A6M2 fighter bomber series by Nakajima also had increase ammunition loads from the original A6M2. I picked the original A6M2 because it was a great example to illustrate my point and also because it served throughout the war even after later versions were introduced.

Regarding the Ki 43 with two 12.7 mm being not so frequent, please observe that your link is describing the Ki 43-I with the two blade propeller.
My original theorizing was that there was some rather poor interaction between the two blade synchronizing mechanism and the Ho-103's less than regular cycle times which was causing issues because there don't seem to be accounts of Ki 43-II and Ki 43-III pilots having one of their 12.7 mm guns replaced by a 7.7 mm.

We can pick and choose exactly this variant of fighter A and exactly that version of fighter B, and arrive on some conclusions. My point was that Zero, on aggregate, was a better armed fighter, and from mid-1943 on it was a much better armed fighter than Oscar.

 

[taly01]

In the USSBS survey posted by Micdrow on this site Japanese air weapons and tactics they describe the MA round developed during 1943, it was a fuzeless "impact" ignition round that carried 3 times more HE than fuzed 12.7mm, as the fuze space was replaced by HE! It was designed as an incendiary surface burster for use against protected fuel tanks and airframe and was admired by the USSBS authors for its ingenuity and effectiveness. It was developed for all JAAF guns and the JNAF was in the process of adopting it at wars end. I think this was one reason why the Ki-43 kept its 12.7mm rather than going to 20mm, the extra power of the 20mm would have been balanced against the fewer 20mm rounds you could fit into a ki-43.

 

[Ivan1GFP]

The result of expanded ammo by the Zeros were slaughtered US torpedo bombers. Zero have had good/excellent firepower, but during the crucial battles of 1942 the ammo count for cannons was too low. The Type 99-2 was with MV of 750 m/s (~2500 fps), it used a bigger cartridge with more propellant. link1 , link2

We can pick and choose exactly this variant of fighter A and exactly that version of fighter B, and arrive on some conclusions. My point was that Zero, on aggregate, was a better armed fighter, and from mid-1943 on it was a much better armed fighter than Oscar.

Hello Tomo Pauk,
Thanks for the data correction. I have updated my notes. Turns out the listing for MV on Type 99-1 was a bit off as well though not quite as much.
My original intent on picking those versions was for early war variants but skipping the Ki 43-I which definitely had some serious problems with armament and structure.

The general lack of respect for the firepower of the A6M (2?) series was indicated by tactics I have seen described in a few places.
In a one versus one fight, the A6M2 wins over the F4F-4 pretty easily.
In a many versus many fight, a non intuitive tactic was to ignore the fellow that was on your tail and shoot the zero that was chasing your squadron mates. Have you also heard about this?

- Ivan.

 

[tomo pauk]

In the USSBS survey posted by Micdrow on this site Japanese air weapons and tactics they describe the MA round developed during 1943, it was a fuzeless "impact" ignition round that carried 3 times more HE than fuzed 12.7mm, as the fuze space was replaced by HE! It was designed as an incendiary surface burster for use against protected fuel tanks and airframe and was admired by the USSBS authors for its ingenuity and effectiveness. It was developed for all JAAF guns and the JNAF was in the process of adopting it at wars end. I think this was one reason why the Ki-43 kept its 12.7mm rather than going to 20mm, the extra power of the 20mm would have been balanced against the fewer 20mm rounds you could fit into a ki-43.

I'm not sure that was why the 20mm was installed too late on the Ki 43, the round that is being designed in 1943 will have no impact on deceisions made in 1941-43. And we have the 1945 prototypes that were supposed to carry 20 mm cannons.
One can wonder how much of an increase in capability for the Ki 43 would've been installation of extra two HMGs in the wings.

...
The general lack of respect for the firepower of the A6M (2?) series was indicated by tactics I have seen described in a few places.
In a one versus one fight, the A6M2 wins over the F4F-4 pretty easily.
In a many versus many fight, a non intuitive tactic was to ignore the fellow that was on your tail and shoot the zero that was chasing your squadron mates. Have you also heard about this?

The 'Thach weave' was roughly that - once the enemy fighters were to come into firing range, the pairs of a flight were to converge towards each other so the would-be-attackers will be subject to a head-on attack. It represented a lack of respect for the protection of the Japanese fighters (Zero mostly), though that maneuver was probably envisionaged before that lack was widely known
I'm not sure that A6M was regarded as lacking in firepower by Allies, it was the best armed Japanese 1-engined fighter for perhaps 2 years.

 

[Greyman]

For what it's worth (re: armament) here is some info from some crash reports:

Army '1' S/E Fighter
crashed 5 December 1942 at Gandarama, Bengal
1 x 12.7-mm, ammo: explosive (only 2 rounds remained/survived)
1 x 7.7-mm, ammo: explosive, armour-piercing, incendiary

Army '1' S/E Fighter
crashed 10 December 1942 3 1/2 miles N.W. Chunati
1 x 12.7-mm, ammo: mostly explosive with a few armour piercing interspersed
1 x 7.7-mm, ammo: explosive, incendiary and armour piercing

Army '1' S/E Fighter
crashed 15 December 1942 1/2 mile S.E. of Ruma Village
1 x 12.7-mm, ammo: 3 types of explosive, 2 types of ball
1 x 7.7-mm, ammo: 1 type of explosive, 2 types of ball

Army '1' S/E Fighter, Mk.II
belly landed 2 April 1943 near Hpayabin
2 x 12.7-mm

Army '1' S/E Fighter, Mk.II
crashed 21 May 1943 at Signall Hill, Cox'a Bazar, East Bengal
2 x 12.7-mm

 

[Ivan1GFP]

I'm not sure that was why the 20mm was installed too late on the Ki 43, the round that is being designed in 1943 will have no impact on deceisions made in 1941-43. And we have the 1945 prototypes that were supposed to carry 20 mm cannons.
One can wonder how much of an increase in capability for the Ki 43 would've been installation of extra two HMGs in the wings.

I believe Shortround6 made the observation that there simply wasn't the room for installation inside the wing of the Ki 43 without compromising structural integrity or redesigning the wing.

Why no wing armament for the Ki-43?

The 'Thach weave' was roughly that - once the enemy fighters were to come into firing range, the pairs of a flight were to converge towards each other so the would-be-attackers will be subject to a head-on attack. It represented a lack of respect for the protection of the Japanese fighters (Zero mostly), though that maneuver was probably envisionaged before that lack was widely known
I'm not sure that A6M was regarded as lacking in firepower by Allies, it was the best armed Japanese 1-engined fighter for perhaps 2 years.

Regarding Thach Weave: It was a nice conjectural exercise of "What can we do if these guys really are much more maneuverable than we are?" It was more or less evening the odds as much as possible if the factors of performance and maneuverability were conceded to the enemy. What I was describing was tactics that evolved AFTER initial encounters with the Zero.

Regarding the Zero as the best armed Japanese single engine fighter: Perhaps it was, perhaps it was not.
"....although the Type 99 Mk.1 cannon was effective when it could be used correctly, most of the aerial victories achieved by A6M2 Zero pilots during the crucial first six months of the war were being attained with the cowl-mounted 7.7mm types." - Saburo Sakai in an interview with Osamu Tagaya (from Zero by Robert Mikesh).

- Ivan.

 

[tomo pauk]

I believe Shortround6 made the observation that there simply wasn't the room for installation inside the wing of the Ki 43 without compromising structural integrity or redesigning the wing.

Make a hole in the spars, so the HMG can fit, of course reinforce the spars so they are not weakened.

Regarding Thach Weave: It was a nice conjectural exercise of "What can we do if these guys really are much more maneuverable than we are?" It was more or less evening the odds as much as possible if the factors of performance and maneuverability were conceded to the enemy. What I was describing was tactics that evolved AFTER initial encounters with the Zero.

Okay. I still doubt that Wildcat's pilot can choose to ignore the (faster) Zero that is on his tail and carry on with his business. Regardless to pilot's anecdotes.

Regarding the Zero as the best armed Japanese single engine fighter: Perhaps it was, perhaps it was not.
"....although the Type 99 Mk.1 cannon was effective when it could be used correctly, most of the aerial victories achieved by A6M2 Zero pilots during the crucial first six months of the war were being attained with the cowl-mounted 7.7mm types." - Saburo Sakai in an interview with Osamu Tagaya (from Zero by Robert Mikesh).

- Ivan.

I'm open to the suggestions re. Zero not being what I've claimed for it.
There at least 4 things WRT Sakai's statement.
- The 'when it could be used correctly' qualifier.
- He also said that he tried once to down a Wildcat with MGs only. After hosing out hundreds of rounds, Wildcat still flew. After closing to it, he saw the tail shredded to pieces, so he reverted to cannons to make a kill.
- Zero didn't saw a reduction of cannons down to multiple guns at any give time, but it got improvement in cannon armament and switch from LMGs to HMGs
- Multiple references from 'Shattered Sword' noting that US A/C will succumb to cannon fire, but not MG fire.

 

[Ivan1GFP]

I'm open to the suggestions re. Zero not being what I've claimed for it.
There at least 4 things WRT Sakai's statement.
- The 'when it could be used correctly' qualifier.
- He also said that he tried once to down a Wildcat with MGs only. After hosing out hundreds of rounds, Wildcat still flew. After closing to it, he saw the tail shredded to pieces, so he reverted to cannons to make a kill.
- Zero didn't saw a reduction of cannons down to multiple guns at any give time, but it got improvement in cannon armament and switch from LMGs to HMGs
- Multiple references from 'Shattered Sword' noting that US A/C will succumb to cannon fire, but not MG fire.

Hello Tomo Pauk,
There really isn't much competition for best armed Japanese single engine fighter. Besides A6M and Ki 43, there was the Ki 27 and probably a stray A5M in a few places. It is interesting that the Me 109E had basically the same armament.

Regarding Sakai's statement, it really comes down to whether you believe it is an accurate account of the event of the time.
Assuming his statement was accurate:
Considering the relative destructive power of the 20 mm shell as compared to the 7.7 mm bullet, it says a lot about how ineffective the 20 mm Type 99-1 actually was.

As others have already pointed out:
Consider also that the Ki 43 was never armed with more than 2 x 12.7 mm Ho-103 and still accounted for over half the number of kills credited to Japanese fighters.

- Ivan.

 

[parsifal]

At the time the type 99-1 was in widespread service, the JAAF fighters were still generally equipped with no more than 2 x 7.7mm lmgs. One exception was the single (9 plane) sqn equipped with the KI44 Shokis

By the time the JAAF began upgrading its Ki-43s to carry 2 x 12.7 HMGs, the Navy was already introducing the much improved Type 99-2. The Type 99 Mark 2 was a heavier weapon with a stronger recoil, and was put into service in the IJN from the latter part of 1942. It was used exclusively in fixed installations, i.e., either in fighters or in power-operated turrets. The Type 99 Mark 2 was carried by later models of the A6M, starting with the A6M3a Reisen Model 22 Ko (introduced from the end of 1942) and on later Navy fighters such as the George

The Model 4 of this weapon adopted the same belt-feed mechanism as the Type 99 Mark 1 Model 4. The Type 99 Mark 2 Model 5 resulted from attempts to increase the rate of fire. By modifications that included the addition of strong buffer springs, the rate of fire was raised to between 670 and 750 rpm. But the Model 5 was formally adopted only in May 1945. IJN fighters fought most of the war with the Type 99-2

Type 99-2 was a weapon that in my view was not far behind the MG 151/20. Problems with the Type 99-1 were its relatively low MV. However it was still comparable to the MGFF in other characteristics. Its biggest disadvantage was the drum feed ammunition supply. The limited ammunition capacity was an important disadvantage. The Type 99 Mark 1 Fixed Model 3 could be equipped with a 100-round drum, but the size of the drum was itself a problem in fighter installations, although the Model 3 guns were installed on the initial production versions of the A6M2. A more practical solution was provided by the Type 99 Mark 1 Fixed Model 4, which featured a Kawamura-developed belt feed mechanism.

 

[tomo pauk]

Hello Tomo Pauk,
There really isn't much competition for best armed Japanese single engine fighter. Besides A6M and Ki 43, there was the Ki 27 and probably a stray A5M in a few places. It is interesting that the Me 109E had basically the same armament.

Thank you.

Regarding Sakai's statement, it really comes down to whether you believe it is an accurate account of the event of the time.
Assuming his statement was accurate:
Considering the relative destructive power of the 20 mm shell as compared to the 7.7 mm bullet, it says a lot about how ineffective the 20 mm Type 99-1 actually was.

As others have already pointed out:
Consider also that the Ki 43 was never armed with more than 2 x 12.7 mm Ho-103 and still accounted for over half the number of kills credited to Japanese fighters.

- Ivan.

The Ki 43 was the most produced Japanese fighter, in it's prime it clashed with Western and some Soviet heardware that was obsolete in between 1942 and some time of 1944. Rarely a 4-engined bomber or other next-gen Western A/C were deployed against the IJA fighters in that time. Coupled with trained and experienced pilots, there is no wonder that kills were just piling up. From 1944 to 1945, the new types were flown against much better A/C with well trained and experiencced pilots, while the Japanese could not keep up with pilot's quality themselves.
Similar thing happened to the German pilots - it was one thing to rack kills when having upper hand in A/C and pilot's quality, another thing was when those aces were pitted against well trained pilots flying equal and better A/C.

The Type 99-1 cannon was not ideal, with low MV and low ammo capacity. However, methinks that substituting the Zero's cannons with MGs (1 cannon vs. 2 LMGs) would've been an self inflicted wound.

 

[Vincenzo]

talking of sinchronization, this is from a italian forum, i don't remember the name EDIT 150gct.it

Macchi_C202_Breda_127mm

• Vincenzo
• Feb 15, 2018

we have also for other italian fighter, the rate of fire of synchronized weapons varied with engine revolution

 

[Juha2]

Hello Vincenzo
thanks a lot for sharing!
Do you know the meaning of the red and green dotted lines?
Do you have same sort of info on Fiat G.50?

Juha

 

[tomo pauk]

In the USSBS survey posted by Micdrow on this site Japanese air weapons and tactics they describe the MA round developed during 1943, it was a fuzeless "impact" ignition round that carried 3 times more HE than fuzed 12.7mm, as the fuze space was replaced by HE! It was designed as an incendiary surface burster for use against protected fuel tanks and airframe and was admired by the USSBS authors for its ingenuity and effectiveness. It was developed for all JAAF guns and the JNAF was in the process of adopting it at wars end. I think this was one reason why the Ki-43 kept its 12.7mm rather than going to 20mm, the extra power of the 20mm would have been balanced against the fewer 20mm rounds you could fit into a ki-43.

There was also fuse-less ammo for the Ho-5 20mm cannon, per docs Paul posted.