Heaviest armed Japanese single seat, single engine fighter?

[Admiral Beez]

Did Japan ever field a single engine, single seat fighter with a cannon or machine gun armament on the level of the late war allies? Two cannons and two .303 mgs isn't bad in 1940, but won't cut it later.

 

[wells]

Yes, the N1K2-J had 4 x 20mm in the wings, possibly others as well. That's the one that immediately comes to mind.

 

[Admiral Beez]

Yes, the N1K2-J had 4 x 20mm in the wings, possibly others as well. That's the one that immediately comes to mind.

That's competitive with the Allies. A good pick. The Nakajima Ki-44 was also armed with four 20mm Ho-5 cannons.

 

[MIflyer]

The N1K1-J George 11 had two 7.7Mm cowl guns and four wing mounted 20MM cannon. The N1K3-J George 21 was to have four 20MM wing mounted cannon and two 13.2 MM cowl machine guns but apparently never went into production.
The J2M4 Raiden 32 Jack had four 20MM wing mounted cannon and two more 20MM cannon in the aft fuselage in a "jazz music" installation, and while they only built a couple of them I'd guess that is the winner.

 

[J.A.W.]

I've seen the Kawasaki Ki 61 listed as the most successful fighter for B-29 kills, but I don't know if
this result was due to other inherent characteristics - rather than just weight of gunfire - as carried?

 

[MIflyer]

The Ki61 had a Japanese copy of a DB601 engine, chosen for it having superior high altitude performance to other Japanese fighter engines. So the Tony could get to the B-29's on their high altitude daylight missions better than most other Japanese fighters.

Ironically the success the B-29's had in bombing Japanese engine factories led to the replacement of the DB601 copy with a radial engine, producing the Ki100, possibly the best Japanese fighter of the war.

 

[J.A.W.]

The Ki61 had a Japanese copy of a DB601 engine, chosen for it having superior high altitude performance to other Japanese fighter engines. So the Tony could get to the B-29's on their high altitude daylight missions better than most other Japanese fighters.

Ironically the success the B-29's had in bombing Japanese engine factories led to the replacement of the DB601 copy with a radial engine, producing the Ki100, possibly the best Japanese fighter of the war.

A 'shotgun marriage' sure, but did the Ki 100 have the altitude performance?

(Or, by the time the Ki 100 entered service, General Le May had already stopped the B-29 high-altitude attacks?)

 

[Shortround6]

The Japanese 20mm guns were not really in the first rank.

The Ho-5 was sort of fast firing, 750-820rpm, (for wing guns) but a little on slow side for MV and a lot on low side for shell weight.
79 gram HE shells compared to the 128-130gram shells from a Hispano.

The Navy had two guns, the later type 99-II used shells about the same as the Hispano/Oerlikon but fired them at less velocity (750ms instead of 880ms) and fired fewer shells per second/minute. about 480-500rpm, there was a model 5 version in the last few months of the war that got up to 750rpm but it is not certain that it saw combat (or not much).
But the British were fielding MK V Hispanos in Europe in the Spring of 1945 that also fired at 750rpm. The MK V Hispano dropped velocity to 850ms.

The Japanese guns were firing about 75% of the shell weight per second and were firing the shells about 85% as fast.

 

[J.A.W.]

The Japanese 20mm guns were not really in the first rank.

The Ho-5 was sort of fast firing, 750-820rpm, (for wing guns) but a little on slow side for MV and a lot on low side for shell weight.
79 gram HE shells compared to the 128-130gram shells from a Hispano.

The Navy had two guns, the later type 99-II used shells about the same as the Hispano/Oerlikon but fired them at less velocity (750ms instead of 880ms) and fired fewer shells per second/minute. about 480-500rpm, there was a model 5 version in the last few months of the war that got up to 750rpm but it is not certain that it saw combat (or not much).
But the British were fielding MK V Hispanos in Europe in the Spring of 1945 that also fired at 750rpm. The MK V Hispano dropped velocity to 850ms.

The Japanese guns were firing about 75% of the shell weight per second and were firing the shells about 85% as fast.

About the Mk V Hispano, shorter barrel = loss in MV? They were firing the same ammo, surely?

The Tempest units that were returned to 2nd TAF control (after shooting down ~800 V1s during the main cruise-missile assault)
were sent to European continental bases in Sept' 1944, & all were Hispano V equipped, IIRC.

 

[Shortround6]

About the Mk V Hispano, shorter barrel = loss in MV? They were firing the same ammo, surely?

When you cut 30cm off the barrel you are going to get lower velocity.
They chopped about 12% length off the barrel and got about 3.5% less velocity.
TANSTAFL
Although in this case the price is minimal.

 

[J.A.W.]

When you cut 30cm off the barrel you are going to get lower velocity.
They chopped about 12% length off the barrel and got about 3.5% less velocity.
TANSTAFL
Although in this case the price is minimal.

Not quite 'a free lunch', but a deal you wouldn't leave on the table, either - not with a weight/drag reduction sweetener to go...

 

[marathag]

The Japanese 20mm guns were not really in the first rank.

The Ho-5 was sort of fast firing, 750-820rpm, (for wing guns) but a little on slow side for MV and a lot on low side for shell weight.
79 gram HE shells compared to the 128-130gram shells from a Hispano.

The Navy had two guns, the later type 99-II used shells about the same as the Hispano/Oerlikon but fired them at less velocity (750ms instead of 880ms) and fired fewer shells per second/minute. about 480-500rpm, there was a model 5 version in the last few months of the war that got up to 750rpm but it is not certain that it saw combat (or not much).
But the British were fielding MK V Hispanos in Europe in the Spring of 1945 that also fired at 750rpm. The MK V Hispano dropped velocity to 850ms.

The Japanese guns were firing about 75% of the shell weight per second and were firing the shells about 85% as fast.

From Tony Williams archived 20mm page

Designation	Rim Dia.	Nation	Projectile	Velocity	Name
20 x 72 RB	19.0	CH / J	HE / 128	600	1930s Oerlikon FF and SSG, Type 99-1
20 x 80 RB	19.0	D	HE / 92	700	WW2 Ikaria MG-FF/M
20 x 82	25.2	D	HE / 115	710	WW2 Mauser MG 151/20, Vektor GA-1
20 x 94	24.9	J	HEI / 79	730	WW2 Ho-103
20x100/101 RB	19.0	CH / J	HE / 128	675-750	1920s Oerlikon F, FFL, Type 99-2

20 x 110	24.8	F / UK / USA	HE / 130	850-880	WW2 HS 404, Hispano, AN-M2, HS 804
20 x 120	28.9	DK	HE / 126	840	1930s Madsen
20 x 125	28.5	J	HEI / 127	820	WW2 Type 97 AT rifle, Ho-1, Ho-3

 

[MIflyer]

The Japanese 20mm guns were not really in the first rank.

Well, after US "experts" said there was no way to scale up the .50 cal M2 they forget to tell the Japanese, who went ahead and did it. At the Smithsonian they have an HO-5 and a .50 cal side by side, sectioned to show the insides. We'd have been so much better off if we could have had a 20MM version of the M-2 .50 cal.

 

[J.A.W.]

Well, after US "experts" said there was no way to scale up the .50 cal M2 they forget to tell the Japanese, who went ahead and did it. At the Smithsonian they have an HO-5 and a .50 cal side by side, sectioned to show the insides. We'd have been so much better off if we could have had a 20MM version of the M-2 .50 cal.

If the US-Hispano was de-bugged sooner, that would still be better, but jeeze, just imagine if all those .50 cal in groundwork for the past 80 years had been 20mm jobs, Woohoo boy, I'll tell ya!

 

[Shortround6]

Well, after US "experts" said there was no way to scale up the .50 cal M2 they forget to tell the Japanese, who went ahead and did it. At the Smithsonian they have an HO-5 and a .50 cal side by side, sectioned to show the insides. We'd have been so much better off if we could have had a 20MM version of the M-2 .50 cal.

Be careful of what you wish for, you just might get it.

US .50 cal M2 Ammo....................................46Grams projectile...............17,800 joules ME
Japanese Ho-5 cannon ammo .................79Grams projectile...............21,000 joules ME
German MG 151/20 ammo.......................115Grams projectile..............29,000 joules ME
British 20mm Hispano.................................130Grams projectile..............50,300 joules ME

Not all 20mms are created equal.
Maybe a US 20mm Browning would have been useful, but the Japanese army 20mm gun was only about 70% as powerful as the Hispano and that is rather dependent of the rate of fire.
On a per shot basis it is about 50% as powerful. These are also averages that are somewhat dependent on the belt load out.
A Browning scaled up to use 20mm Hispano ammo would have been a rather impressive beast, Now the question is would it have been as light, compact and as reliable as the Hispano itself?

Also note that the US .50 used a higher MV than the Japanese and German guns which made it a bit easier to hit with (deflection shooting).

 

[J.A.W.]

Be careful of what you wish for, you just might get it.

US .50 cal M2 Ammo....................................46Grams projectile...............17,800 joules ME
Japanese Ho-5 cannon ammo .................79Grams projectile...............21,000 joules ME
German MG 151/20 ammo.......................115Grams projectile..............29,000 joules ME
British 20mm Hispano.................................130Grams projectile..............50,300 joules ME

Not all 20mms are created equal.
Maybe a US 20mm Browning would have been useful, but the Japanese army 20mm gun was only about 70% as powerful as the Hispano and that is rather dependent of the rate of fire.
On a per shot basis it is about 50% as powerful. These are also averages that are somewhat dependent on the belt load out.
A Browning scaled up to use 20mm Hispano ammo would have been a rather impressive beast, Now the question is would it have been as light, compact and as reliable as the Hispano itself?

Also note that the US .50 used a higher MV than the Japanese and German guns which made it a bit easier to hit with (deflection shooting).

So in effect, Browning .50" vs Nippon Ho-5 20mm is like when were kids, & deciding if we wanted a more accurate .177 slug gun,
or the heavier hitting, but arched trajectory .22 type?

Edit: Slug gun in local vernacular refers to an air rifle (or BB gun which shoots out lead pellets) rather than a solid round shotgun piece.

 

[Shortround6]

Close, the Japanese 20mm ammo does explode though.

However it seems to have had mixture of HE and incendiary that was different to what just about everybody else used.
One type of shell used 3 g of PETN and 9 g incendiary ( compressed air fuse?) and another used 4 g cyclonite and 3.7 g incendiary.

Hispanos also used a number of types but most the HE held around 10.5g depending on exact explosive, There was another version that used 7 grams of He and 4.3 grams of incendiary
and another that put just over 10 g of incendiary behind a hardened steel cap (no fuse).

The Japanese rounds probably didn't have much explosive effect as we think of it. The Explosive may have just burst the shell open to scatter the incendiary material.

That 79 gram shell also slowed down more quickly than most other projectiles which didn't help longish range gunnery.

Now for the Japanese Army this was not a hard choice. The Japanese Army 12.7mm machine gun used 33-35.4 gram projectiles at over 100ms slower than the US .50 for about 9,800-10,600 joules of ME. So the US .50 was rather more powerful which made the need for even a light 20mm more critical.

 

[Shortround6]

A point of information is weight. The Japanese were not stupid.

Japanese 12.7mm Ho-103............................23kg
US .50 cal Browning........................................29kg
Japanese 20mm Ho-5....................................37kg
20mm Hispano..................................................50kg.

The ammunition shows a somewhat similar increase in weight.
The Japanese army guns/ammo were pretty good for the weight.
But a Japanese army fighter with two 12.7s and two 20mm guns was not really carrying "heavy" armament. In target effect in may have been only 5-10% more effective than six .50s and then we could argue about the amount of ammo/firing time.

Now compared to a Ki-43 the armament was a huge improvement

 

[MIflyer]

The Japanese rounds probably didn't have much explosive effect as we think of it.

When my friend Bob Berry's PB4Y-2 was attacked by George II fighters, making head on passes, one explosive round hit the inside armored back of the seat of the radio operator that was on the other side of the cabin from his position. The round exploded on contact with the seat back and sent shrapnel into the man's back. They made it back to Okinawa with one engine shut down due to a throttle that had been shot away and the injured crewman was sent up to an aid station that supported the ground troops. He came back after a while, saying the wounded up there were in much worse shape than he was. They sent him to Iwo Jima the next day. So the effect of the explosive round was not terribly bad.

Bob said that they REMOVED some of the armor in their airplanes because they found that with those head-on passes the armor tended to make the rounds rattle around more.

 

[Shortround6]

When my friend Bob Berry's PB4Y-2 was attacked by George II fighters, making head on passes, one explosive round hit the inside armored back of the seat of the radio operator that was on the other side of the cabin from his position. The round exploded on contact with the seat back and sent shrapnel into the man's back. They made it back to Okinawa with one engine shut down due to a throttle that had been shot away and the injured crewman was sent up to an aid station that supported the ground troops. He came back after a while, saying the wounded up there were in much worse shape than he was. They sent him to Iwo Jima the next day. So the effect of the explosive round was not terribly bad.

Bob said that they REMOVED some of the armor in their airplanes because they found that with those head-on passes the armor tended to make the rounds rattle around more.

I have tried to be careful to say Japanese Army rounds/ammunition as in true WW II Japanese fashion the Army and Navy not only didn't use the same ammo, they did not use the same projectiles. Japanese Navy 20mm projectiles were very similar to Hispano (or Oerlikon) projectiles. 127-128g compared to 130g and with very similar construction (wall thickness. etc) with about 10 g of HE in the HE shell. Japanese Navy also used HE/T and HEI shells. The HE/T held about 1/2 the amount of HE due to space needed by the tracer compartment.
A Japanese Navy shell with 10g of HE is going to have more target effect than a Japanese Army shell with 3-4g of HE.

There was a considerable difference of opinion as the effects of 20mm Shells. The German 20mm mine shell held about 20g of HE for a lot more blast. However the 30-40 grams less steel for fragments changed the entire nature of the damage. Pages of reports and discussions have been written about the differences.
A lot depends on how far away from the explosion the item/s, people are. Just a few feet can matter or one/two barriers (even sheet metal).