Best Japanese B-29 'Killer'

The Ki 44 IIc retained for home island defence had 4 - 20mm and some had 2 12.7 mm MGs along with a pair of Ho.301 40mms. The Ki 44 IIIa with 4- 20mms flew in June 1943 and a submodel was the IIIb. It did carry a pair of 37mms along with 2 20mms. Some were delivered into servicce.

Twitch said:

The Ki 44 IIc retained for home island defence had 4 - 20mm and some had 2 12.7 mm MGs along with a pair of Ho.301 40mms.

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source?
you skipped url i gave with discussion about lack of 20mm?

The armament references are all stated in these for sure and probably more-

Thorpe, Donald, W.
Japanese Camouflage Markings of WW II
Aero Publishers, Fallbrook, CA 1968

Green, Wm.
The Complete Book of Fighters
Smithmark Publishers, NY, 1994

Green, William
Fighters Vol. 3
Doubleday Co., 1962

Francillon, Dr. Rene J.
Japanese Aircraft of the Pacific War
Naval Institute Press, Annapolis, Maryland, 1988

Gunston, Bill
Fighting Aircraft Of WW II
Salamander Books Ltd, London 1988

Sharpe, Michael, Scutts, Jerry March, Dan
Aircraft of WWII
PRC Publishing Ltd, London, 1999

imho this error comes from francillon - requoted miscellaneous times.
highly probably sources of sources lead to francillon.

i have a similar myth of 28g of explosive in ShVAK shell. it appeared in Shavrov's book "History of Aviation weapons" and spread wide. actual weight is 2.8g.

Some years ago, when writing Flying Guns – World War 2: Development of Aircraft Guns, Ammunition and Installations 1933-45 with Emmanuel Gustin, I had a long debate with American and Japanese experts on Japanese aircraft armament, concerning the armament of the Ki-44. More misinformation about this appears to be around than for any other plane. Much of it is down to Francillon, who did a great pioneering job with his book, but several decades of research have taken place since.

The information supplied to me was based on original Japanese documentation and must be considered the best available evidence, unless and until someone comes up with something absolutely definitive which contradicts it.

First, the 37mm/40mm issue. No Ki-44 ever carried a 37mm gun. In any case, the Ho-203 was a big gun with a huge hoop-shaped "squirrel cage" magazine above it (it never came with anything else). No way could that fit into any fighter wing. See the photo of the Ho-203 in the nose of a twin-engined Ki-45below:



The Ki-44-IIc and Ki-44-III were fitted with two 40mm Ho-301. This was a light and compact weapon with a flat magazine which easily fitted in the wing. However, the muzzle velocity was extremely low and there were only ten rounds in the magazine. To stand any chance of hitting, you had to get so close to the target before firing that it was almost a suicide weapon. Many of the guns were removed and replaced by 12.7mm Ho-103.

No version of the Ki-44 carried any 20mm guns. This has been the hottest debate, but the original Japanese documentation is clear. Photographs are unlikely to prove otherwise, since both the 12.7mm Ho-103 and the 20mm Ho-5 were based on the Browning M2 and looked very similar apart from a marginal difference in size.

Apart from the 40mm versions mentioned, and the early Ki-44-1a which had two 7.7mm Type 89 Fixed and two 12.7mm Ho-103, all models of the Ki-44 were armed with four Ho-103.

Tony Williams: Military gun and ammunition website and discussion forum

And before everyone gets rabid about height of operations.

Why did they move the B29 operations to lower levels, incendiary attacks etc.

And why was it done?

And who was the rocket signtist behind that plan?

All asked as a non American myself of course.

k9kiwi said:

Why did they move the B29 operations to lower levels, incendiary attacks etc.

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3.6% loss ratio and 10% hit ratio at days.
they (curtiss lemay?) decided to fly at nights to avoid interceptors and to fly low to avoid bomb dispersion and to drop incendiaries due to wooden material of buildings.

Exec hit the nail on the head... Improved accuracy....

I read through this old topic and am surprised no one mentioned the main Japanese fighter ... the Ki-84 ???


Kris

What is needed is:
- speed at altitude
- armour
- armament
- sustained climb rate

All Japanese fighters except for the Ki-61 had single-stage radial engines which lost power at high altitude. Japanese fighter aircraft were all slow except for the Ki-84.

The N1K-1J had strong armament but the Homare engine (also used by the Ki-84) performed badly at high altitude. The J2M had a Kasei engine which was better at altitude. The J2M also had a strong armament and decent armour. Speed for both was below 600 kmh which means it could not catch up with a B-29 but had to intercept head-on and dive from a higher altitude.

Ki-61 was also too slow. The Ki-61-II would have been the best option: inline-engine, decent armour and armament, sufficient speed. The Ki-100 was an excellent dogfighter but for an aircraft whcih entered service in 1945 one could expect a better speed than 590 kmh. Absolutely useless against the B-29.

Kris

Civettone, are you implying that the B-29 cruised at it top speed with full fuel and bomb load? Ever heard of the term "cruising speed", which for B-29 was ~350 km/h, making it easier to catch for fighters.

Anyway, in my opinion the order would be like this:

J2M5, 3-speed supercharger, decent armament, but only ~50 produced
Ki-84, fastest IJAAF fighter and well armed, but unreliable because of the engine
Ki-45, well armed and probably the most durable IJAAF fighter
J2M3, 2-speed supercharger, well armed and a good climber, ~200 produced
Ki-61-II, good at high altitudes, very few made
Ki-44, best climbing IJAAF fighter, but lacking in armament
Ki-100, overrated but reliable, good dogfighter but not really the best interceptor
N1K1-J, NIK2-J, same as above and unreliable Homare engine
Ki-61-I, only barely adequate, vulnerable V12 engine

Ki-27, Ki-43 and A6M were totally unsuitable against B-29

They had more advanced types flown as prototypes, for example:

Ki-87 Ki-94-II, turbo-equipped interceptors, and a real bomber killer armament (including 30 mm cannons), top speed 700+ km/h
Ki-83, same as above but two engines
Ki-102 (even saw some service but only as a ground attacker), improved Ki-45, some turbo-equipped prototypes
A7M, Zero successor, performance comparable to Hellcat Corsair

If the above types had been in service when the B-29s first appeared, the loss rates would have been higher. But the reality is that IJAAF and IJN, while able to fight against "normal" fighters, ground attack and bomber aircraft, were not prepared equipment-wise for the B-29.

Good post.

Three things: - fighters need speed surplus to catch the bomber. And closing in with 20 mph is not exactly heartwarming
- and what did you mean by the vulnerable engine of the Ki-61? And wouldn't this also apply to the Ki-61-II?
- The multi-speed Kasei engines were also very unreliable

Kris

FLYBOYJ said:

Great list Dan - I count 124 claims by the Japanese - that actually is about right because the site I posted has a listing of 19 aircraft shot down by flak AND fighters - with the totals of that list being off by 24 I'd say the USAAF stats against the Japanese claims aren't that far off considering the theater and mission being flown.

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This is a old thread - but the list Dan presented was for 'confirmed' Japanese Aces - our own experience has aces accounting for pehaps 30% of total claims and awards - which implies that the numbers are seriously inflated re: actual credits to claims... and the credits air to air already exceeded actual losses by 60%.

Second note: I haven't seen the breakout but so many of the post February 1945 missions by the 20th were at night and low altitude - so any Japanese fighter pilot with the balls to jump into a night bombing attack could fly anything in the inventory - so pick a twin with radar as the primary choice for effectiveness..

exec228 said:

3.6% loss ratio and 10% hit ratio at days.
they (curtiss lemay?) decided to fly at nights to avoid interceptors and to fly low to avoid bomb dispersion and to drop incendiaries due to wooden material of buildings.

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LeMay was in fact the sole 'decider' and he reported directly to the Joint Chiefs - not anyone in the PTO.

Stripped all the guns except tail guns. His thing was a.) the winds aloft and the strain on the engines to climb to altitude and the fuel used to climb were adversely impacting bomb load, aborts and accuracy on target, b.) the airwar in Japan was diametrically opposite ETO - Wooden structures vs concrete and mortar, - lack of effective and co-ordinated night fighter capability as well as far fewer radar directed AAA, c.) the fire departments and containment was not equipped to fight massive distributed fires.

Results? - double the bomb load, far fewer aborts, faster ingress and egress from the targets, much more difficult for fighters to plan and co-ordinate attacks as the B-29s were not in mass formation and flying at varying altitudes from different headings. Oh, and burned out 13 (IIRC) square miles to the ground at center of Tokyo, dwarfing even Dresden.

His wing commanders believed they were all gonna die on the first mission but it was arguably one of the most succcessful attacks by 20th Air Force and set the pace for improved techniques and future successes.

To add to Bill's post because it seems that some believe that LeMay's decision was not well thought out. I knew a fellow who was a B29 navigator on missions over Japan. He said that when the B29s tried to bomb in daylight from high altitudes, the jet stream at their altitudes was so strong the accuracy of bombs dropped was abysmal. Thus the switch to low altitude, night, area bombing.

exec228 said:

3.6% loss ratio and 10% hit ratio at days.
they (curtiss lemay?) decided to fly at nights to avoid interceptors and to fly low to avoid bomb dispersion and to drop incendiaries due to wooden material of buildings.

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The daylight loss rate was nothing like 10% on average. The max loss rate was in January 1945, around 5%of total sorties for the Marianas based B-29's (B-29's still operating from China in same period had a lower loss rate v generally easier targets), of which 2.2% were due to fighters (though one by one examination of 'other cause losses' would reclassify some as originating in fighter damage). The total loss rate in March dropped to 1.26%, rose again somewhat as daylight raids resumed, peaking at almost 2% again in May, but then dropped drastically after that as the B-29 force became overwhelmingly large, and Japanese began to hoard their remaining a/c and gas to resist an invasion. In July the total number of sorties was 2.5 times as many as in March and 12 times as many as January, and the total loss rate had declined to 0.3%. This is a factor often neglected, that the B-29 force was continually growing. Also, the operational loss rate dropped as the B-29 became more technically mature, and the ability to make emergency landings at Iwo Jima also cut losses.

Henry Sakaida's "B-29 Killers JAAF" book mentioned earlier in thread clearly describes 24 B-29 loss incidents to fighters, for one mission of China-based a/c over Manchuria, otherwise Marianas based a/c, through Feb '45. Of those, 14 were due to ramming or included ramming, sometimes of a/c which dropped from formation because of gun attacks. Assuming pilots willing to ram, a/c like early series Type 3's (Tony) could get the job done. The 244th Sentai of JAAF had many B-29 kills, and its a/c in that period were mostly early Type 3's, with just 2*12.7mm and 2*7.7mm in the wings, those produced before 20mm wing guns were introduced. Extra weight like armor was stripped out to improve climb.

The issue in switching (temporarily) to all night fire raids in March '45 was perceived ineffectiveness of high altitude precision bombing attacks, mainly v Japanese a/c industry. In fact those raids were more effective than believed, had a much bigger impact on the Japanese a/c industry in a much shorter time than was the case v the German industry. The raids caused the Japaense to start a crash program of dispersal which miscarried and a/c output and quality dropped drastically after early 1945, though it was also affected by blockade (materials shortages) and general disruption caused by the fire raids. In any case it was a major strategic/political decision to do area bombing, not about B-29 losses. Again, many raids after March were again in daylight, some precision, some tactical (many v airifields on Kyushu during Okinawa campaign) also some incendiary bombing in daylight, as well as night raids incendiary raids and then mining, night precision radar (by 'Eagle' radar equipped groups), and of course eventually nuclear raids, a much wider variety of mission profiles by the larger force of spring-summer 1945.

Joe

renrich said:

To add to Bill's post because it seems that some believe that LeMay's decision was not well thought out. I knew a fellow who was a B29 navigator on missions over Japan. He said that when the B29s tried to bomb in daylight from high altitudes, the jet stream at their altitudes was so strong the accuracy of bombs dropped was abysmal. Thus the switch to low altitude, night, area bombing.

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Remarkable! I thought the jet stream was like a narrow corridor.

Kris

Civettone said:

Remarkable! I thought the jet stream was like a narrow corridor.

Kris

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Visualize the 'jet stream' as being muliple shear layers with slightly different to diverse velocities and directions - with winds aloft of up to 200+ mph.

Allegedly the jet stream complexity over Japan was the very worst.

it starts at what alt?


Kris

I had read the main reason why they bombed at that altitude was it being an awkward height for the Japanese AAA, either too low for the long range guns and a little too high for the short range ones.