Nakajma Ki-44-III?

[blockhaj]

Something i put together quickly but i assume this is how it would have looked

 

[CherryBlossom]

Something i put together quickly but i assume this is how it would have looked

Thanks for sharing Block, i see more clearly what you mean.

if you have anytime perhaps include the individual exhaust stacks and the four blade propeller B)

 

[blockhaj]

Something i put together quickly but i assume this is how it would have looked

Thanks for sharing Block, i see more clearly what you mean.

if you have anytime perhaps include the individual exhaust stacks and the four blade propeller B)

Well the blueprint i used isnt very accurate nor straight and i have no blueprint of the ho 203 nor its size but if someone could give me that i would try to make a very realistic blueprint.

 

[Sherman Tank]

Something i put together quickly but i assume this is how it would have looked

Thanks for sharing Block, i see more clearly what you mean.

if you have anytime perhaps include the individual exhaust stacks and the four blade propeller B)

Well the blueprint i used isnt very accurate nor straight and i have no blueprint of the ho 203 nor its size but if someone could give me that i would try to make a very realistic blueprint.

Something is better than nothing in a lot of cases!

 

[blackkite]

Hi! Ho-203 data
Length : 1, 500mm, Weight : 80kg, Caliber : 37mm, Barrel length : 800mm, Muzzle velocity : 570m/S,
Firing speed : 100 rounds per minute, Warhead weight : 400g, Ammo Theme Weight : 838g,
Mechanism : Recoil use, Manufacturing Country : Japan, Manufacturing : Japan Special Steel

https://ja.wikipedia.org/wiki/%E3%83%9B203

 

[windswords]

Hi Block,

I like what you did with the Ki-44-III speculative drawing. If you want to refine it further try to add individual exhaust stubs (see the previous images in this thread). Also you can double check the scale of your drawing with the dimensions of the Ho-203 that Blackkite provided. Welcome to the forum!

 

[blockhaj]

Hi Block,

I like what you did with the Ki-43-III speculative drawing. If you want to refine it further try to add individual exhaust stubs (see the previous images in this thread). Also you can double check the scale of your drawing with the dimensions of the Ho-203 that Blackkite provided. Welcome to the forum!

Thx i think i will, though ive been on this forum for almost a year.

 

[blackkite]

Hi!

Source

https://twitter.com/ija_fighter_bot

 

[blackkite]

Hi! Ki-44Ⅲ.
Four blades propeller, increase wing area, increase vertical tail stabilizer area. HA-45 2000hp engine.
Source : MILITARY CLASSICS VOL.71, IKAROS PUBLICATION

This book says that Ki-44Ⅲ was only a paper plan.

 

[Conspirator]

after looking at all this i can say that the guns on this wouldnt be hardly bigger than a 7.62 so i mean it probably wouldnt have the punch of a browning machine gun like the ones that were used in the supermarine spitfire mk 2.

 

[blackkite]

This is a excellent table by CherryBlossom-san.
https://www.secretprojects.co.uk/attachments/bbbbbbb-png.535891/

And Ho-301 40mm cannon for Ki-44-ⅡOtsu.
https://wikiwiki.jp/warthunder/Ki-44-II otsu

 

[Conspirator]

This is a excellent table by CherryBlossom-san.
https://www.secretprojects.co.uk/attachments/bbbbbbb-png.535891/

And Ho-301 40mm cannon for Ki-44-ⅡOtsu.
https://wikiwiki.jp/warthunder/Ki-44-II otsu

interesting. with the unit being so large and bulky i thought they would do this

 

[Justo Miranda]

Nakajima Ki.44

​

During the 30s, the Western powers that constrained the Japanese territorial expansion were developing four engine heavy bombers. The Tupolev TB.3, capable of reaching Tokyo taking off from Soviet territory, flew for the first time in 1930. In 1932 the French Farman 222 also performed its first flight; although ugly as all of its kind, it was very effective to control navigation in the area to the south of Formosa, operating from Saigon. The Boeing B-17 prototype was on the air in 1935 and the British Sunderland and Stirling prototypes, capable of transatlantic flights, followed in 1938 and 1939. Even the Dutch worked on a four engine version of the Fokker T-IX, named T-VI /115.

The B-17 had a 2,000 miles range, turbocharged engines and such a powerful armament that allowed this airplane autonomous defence. When the IJA was aware of these excellent performances, they realized that the American bomber was above the interception capabilities of the standard fighter Ki.27 and possibly exceeded its successor Ki.43, that had not yet entered service.

Given the potential threat that the B-17s based in Philippines could represent, the IJA requested Nakajima the design of the Ki.44, a point defence interceptor with high climb rate and twice the armament of the Oscar. Realities of war showed that this effort would not be enough though, since the US industry was able to design, test and mass-produce a new aircraft in the third time than the Japanese.

On November 1, 1944, the first American bomber flew over Tokyo, but it was not the expected B-17 but a giant B-29 F-13 42-93852, of the 3rd Photo Recon Sqn, ironically named ‘Tokyo Rose’. When the Ki.44-II-Otsu of the 47th Sentai tried to intercept it, they discovered that the Superfortress flew so high and fast that they could not reach it. It turned out that the Japanese plane used for the intended interception, equivalent to the Starfighter of the time and with an astonishing climb rate of 5,000 m in four minutes, was not good enough to do the work for which it had been designed.

The psychological impact caused by this realisation on the Japanese pilots had important consequences. The IJA needed interceptors equipped with turbo superchargers, but the Japanese industry was unable to build them or even replicate enemy bombers that had been shot down. They also needed more powerful weapons with wider range, whose usefulness was not foreseen until it was too late.

In 1944, the Luftwaffe had two types of guns of 30 mm to fight against the B-17 and B-24:

The MK 103, a potent and heavy weapon, with great effective range and low rate of fire, difficult to install in single engine fighters given its powerful recoil that damaged the airframes.

The MK 108, light and with high rate of fire, but with low effective range that forced the fighters to come dangerously close to the self-defence formations of American bombers.

Across the world, the Japanese interceptors fighting against the B-29 had similar problems with their weapons. The IJA had the Ho-203 cannon of 37 mm, weighted 89 kg, and had a rate of fire of 120 rpm and an effective range of 1,000 m. As was the case with the German Mk 103, this gun was difficult to integrate in the fragile airframes of the Japanese fighters because of their excessive recoil. The alternative seemed to be the new Ho-301 of 40 mm, weighing about half of what the Ho-203 weighs, had a moderate recoil and increased rate of fire of 450 rpm, although only 150 m range because the ammunition used was propelled by small spin-stabilised rockets.

It was determined during its design that the warhead should at least contain 65 grams of High Explosive (HE) to be effective against the B-29s, but this could only be achieved by reducing the amount of rocket propellant and thus the range of the weapon. The manufacturing of the Venturi nozzles at the base of this type of rockets, that generated both propulsion and spin, required an accuracy that the Japanese industry could not achieve for large production runs. As a consequence, the trajectory of the rockets was not precise enough for air-to-air combat.

Under pressure from the bombings and the proven futility of the weapons of 12.7 and 20 mm, the IJA decided to carry out a series of operational tests with two Ho-203 guns, with belt magazines of 25 rounds installed in the wings of some Ki.44-II-Hei of the 70th Sentai, based in Manchuria.

On September 8, 1944, ninety B-29s from the 58th BW made an attack on the Showa Steel Works at Anshan. The aircraft of the70th Sentai attempted interception, but the extra weight of the guns prevented them to reach the flight altitude of the bombers in time. Meanwhile, the aircraft of the 59th and 104th Sentai, equipped with standard armament, could only manage to damage three B-29s, after losing in combat eleven Tojo to the powerful American defensive fire.

Some tests were also carried out with the Ho-301, using some Ki.44-II-Otsu of the 1st Field Reserve Squadron, without suffering any structural damages. Afterwards, some Ki.44s of the 47th Sentai were transformed to test these 40mm cannons in combat. The 47th was an elite squadron whose pilots have had some success fighting against the Liberators at a medium altitude.

But the flight altitude of the B-29 made the extra weight of the Ki.44 difficult to manoeuvre. Above 8,000 m the small wings generated little lift and the plane uncontrollably fell several hundred meters when trying any combat manoeuvring. Its only effective tactic was diving at 45 degrees, frontally attacking the ‘bomber box’ to avoid the dangerous effect of the 20mm cannon at the B-29 tail, firing against the vulnerable bomber cockpit and then increasing the falling angle to avoid collision.

These manoeuvres were already difficult with the Tojo standard, but with the extra weight of the guns, the flight controls barely responded due to the low air density at high altitude. It is therefore possible that some registered rammings were actually accidental collisions. After shooting, the two aircraft crossed just a few meters away, with a combined speed of 1,000 kph. Considering the limited range of the Ho-301, the Japanese pilot could either shoot four rounds and escape, or shoot six rounds and die.

The Ta-Dan bombs used by the IJA for air-to-air bombing were also not effective. Some pilots as Capt. Yasuro Masazaki, of the 47th Sentai, developed a special skill using these weapons and achieving some hits. However, their experience was not transferable and generally speaking the Ta- Dan only proved useful in combat at lower altitudes.

On February 4, 1945, the Ki.44 of the 70th Sentai destroyed the B-29 42-24608 over Kobe and six days later the 42-24867 over Ota, using air-to-air bombing tactics. Some Ki.43 and Ki.44 of the 1st Field Reserve Squadron based in Singapore were used in experiments with the new spin stabilised rockets Ro-San Dan that proved to have too erratic flight paths for use in air-to-air combat. Three types of spin-stabilised rockets were built for the IJA during World War II:

Ro-San Dan (Ro-3) of 10 cm and 10 kg

Ro-San Dan (Ro-5) of 20.2 cm and 76 kg

Ro-Sichi Dan (Ro-7) of 30.3 cm and 280 kg



All stabilized in flight rotating at 3,600 rpm thanks to the spin effect produced by six 25 degrees angled nozzles, had incendiary and shrapnel warheads, time fuses and percussion primers and could be fired from simple iron tubes. Some tests were also performed with an unknown type of fin stabilised rocket, possibly a modified Ro-3, using a Ki.43 with underwing rails, but there is no record that it were used in combat as happened with the efficient German R4M.

After all these failures, only the Tai-Atari (head-on ramming) tactics remained, using the plane as a weapon to destroy the B-29 in deliberate collision course. On September 26, 1944, a Tojo of the 9th Sentai piloted by Sgt Mamoru Taguchi rammed the first B-29 during a raid against Showa Steel Works in Manchuria. In November 1944, a group of pilots of the humiliated 47th Sentai began to make rammings against the B-29 on a volunteer basis.

These practices were widespread until December 5, when the IJA ordered the creation of a Shinten Seiku Tai (Air Superiority Company) built into every Sentai of fighters. They were initially formed by four planes stripped of weapons, armour and any other unnecessary equipment for ramming, in order to improve manoeuvrability at high altitude. The number of Shinten fighters was increased up to eight per each Sentai of air defence during the last months of the war.

The Shinten pilots received special training in the 1st Advanced Training Unit where tail and belly approaches to the B-29s were not recommended. On November 24, 1944, hundred and eleven B-29's of the 73rd BW attacked the Nakajima-Tokyo factory flying at an altitude between 9,100 and 8,200 m. They were intercepted by the Ki.44-II-Otsu of the 47th Sentai, with the ‘Lucky Irish’ 42-24622 being destroyed after its ramming by the Tojo of Yoshio Mita.

On December 7, the B-29 ‘Humpin’ Honey’ 42-6299 was rammed over Manshu-Mukden by the Ki.44-II-Hei of Sgt. Tadanori Nagata and the 42-6390 by the Yoshihiro Akeno airplane, both of them from the 104th Sentai. On December 22, during a raid over Nagoya, ‘The Dragon Lady’ 42-63425 was rammed by the Ki.44 of Yoshi Hirose, from the Akeno Flying School, but the B-29 managed to return to its base despite resulting severely damaged in the tail section.

On January 9, 1945, two B-29 bombers were rammed over Tokyo by fighters of the 47th Sentai, during a new attack to the Nakajima factories. ‘Miss Behavin’ 42-24655 was rammed in engine No. 2 by a Ki.44-Otsu piloted by Masumi Yuki. ‘Tail End Charlie’ 42-24772 was rammed by Takashi Awamura airplane. On the 27th, the B-29 repeated the attack with the ‘Irish Lassie’ 42-65246 being rammed by the Ki.44 of Isamu Sakamoto and the ‘Shady Lady’ 42-24619 resulting rammed by the airplane of Kiyoshi Suzuki, both from the 47th Sentai. On February 10, during the bombing of the Nakajima-Ota factory, the B-29 ‘Battlin' Betty’ 42-24760 was rammed by a Ki.44-II of the 47th Sentai piloted by Heikichi Yoshizawa.

There are no records indicating the assignment of the Ki-44 to any Tokko unit as these aircraft were considered indispensable for air defence of the Japanese mainland. The structure of the Ki.44-II-Ko only supported the installation of a 150 kg bomb fixed for close-range attacks, instead of a centreline 200 litres fuel tank. The Ki.44 of the following series could transport two fuel tanks under the central section of the wing, in a rather rear position, to not interfere with the deployment of the landing gear. Under the outer wings, it could carry two Ta-Dan bombs of only 52 kg.

At the end of 1944 there were three Sentais in the Philippines, the 22nd, 29th and 246th equipped with Ki.44-II-Otsu fighters. They were used for air defence of Clark and Nicholls airfields as well as to carry out escort missions of the Ki.43 suicide and Ki.46 reconnaissance airplanes that tried to locate the Allied Task Forces. During the Battle of the Philippines, the Ki.44 suffered heavy casualties in air and ground combat because of the TF-38 attacks. The 246th Sentai lost all its aircraft.

On 28 November, two Ki.44s in strafing mission over San Pedro Bay were shot down by the naval AA and one of them voluntarily impacted against the destroyer USS Ross (DD-563). During the Battle of Okinawa, on April 13, 1945, the British fleet reported the presence of a Dinah escorted by Tojos on a reconnaissance mission. On May 12, a Ki.84 kamikaze of the 120th Sei squadron escorted by a Ki.44, attacked the battleship USS New Mexico (BB-40) off Yomintan

 

[Conspirator]

wow okay so.. kamikazies. but still mitsubishi never (as far as i know) had any plans for a new revolutionized "zero". it had performed so well they never bothered to create new versions. i mean with the bf109 they made at least 12 versions of it (b109-g is the best)

 

[windswords]

wow okay so.. kamikazies. but still mitsubishi never (as far as i know) had any plans for a new revolutionized "zero". it had performed so well they never bothered to create new versions. i mean with the bf109 they made at least 12 versions of it (b109-g is the best)

A6M1 - prototype
A6M2 - two versions (-11) and (-21), which had folding wing tips for carrier operations.
A6M3 - two versions (-32) with more engine output and squared wingtips for better dive and roll but shorter range, and (-22) with the older wing (better range) still with more powerful engine.
A6M4 - Turbo supercharger for better high altitude performance, but development was problematic and abandoned.
A6M5 - three versions (-52a), (52-b) and (-52c), each one having more protection and armament, including CO2 fire extinguishers in the wing fuel tanks, and behind the cockpit.:
52a - individual exhaust for greater speed. Improved 20 mm cannon with more rounds per gun. Thicker wing skinning was installed to permit higher diving speeds.
52b - 7.7 mm machine gun in the right forward fuselage was replaced by a 13.2 mm gun. armored glass 45 mm (1.8 in) thick was fitted to the windscreen.
52c - Armament increased to 3 13.2mm machine guns (1 in the cowling and 1 in each wing) and 2 20 mm cannons. Four racks for rockets or small bombs were installed outboard of the 13 mm gun in each wing. A 55 mm (2.2 in) thick piece of armored glass was installed at the headrest and an 8 mm (0.31 in) thick plate of armor was installed behind the seat. Wing skin was thickened further to permit even higher diving speeds.
A5M5-S - To intercept B-29s and other night-flying aircraft, armed with one 20 mm Type 99 cannon behind the pilot, aimed upward, similar in intent to the Luftwaffe's Schräge Musik installation.
A6M6 - to use improved engine, featuring water-methanol engine boost and self-sealing fuel tanks in the wings. Due to the unreliability of the fuel injection system, testing continued but the end of war stopped further development.
A6M7 - designed to meet a requirement for a dedicated attack/dive bomber version that could operate from smaller aircraft carriers. It featured a reinforced vertical stabilizer, a special bomb rack, provision for two 350-litre drop tanks and fixed bomb/rocket swing stoppers on the underside of the wings. Hhad a similar armament layout to the A6M5c.
A6M8 - New powerplant (Mitsubishi Kinsei 62 (1,560 hp)). Extensively modified cowling and nose for the aircraft. Armament: two 13.2 mm machine guns and two 20 mm Type 99 cannons in the wings. In addition, two 150 l (40 US gal) drop tanks on either wing in order to permit the mounting of a 250 kg (550 lb) bomb on the underside of the fuselage. Two prototypes were completed in April 1945 but it did not enter production.
A6M2-K - Two seat trainer version based off the A6M2. Also used as a target tow.
A6M5-K - Two seat trainer version based off the A6M5.
A6M2-N - Nakajima-built floatplane fighter (based on the A6M2-11 with a slightly modified tail).

So counting all the major versions plus the sub types shows 16 versions, although 3 of those versions were not put into production.

As for a "new" Zero, that would be the A7M Reppu, superior to the Zero in every way. It was almost ready for production when the war ended. The story of why it took so long to develop is too much to go into here.

 

[windswords]

The challenges of attacking a B-29 at high altitude are illustrated in a translation of a statement by 2nd Lt Oishi Sozo, a Ki-44 pilot of the 47th Sentai originally printed in Maru Mechanic #33:

"On November 1, 1944 B-29s from Saipan came over the Kanto area on a reconnaissance mission. Maybe all the fighter aircraft in the Kanto area took-off. The three B-29s formation flying at 12,000 meters managed complete their mission and fly away. On that day I took-off too but gradually my oil pressure got lower and at 7,000 meters it was almost zero. The engine barely run. Exactly at that time I saw the three B-29s flying above me but I was not able to do something because the altitude difference was too high. But I just couldn't sit there and watch them go so I lifted the nose and was about to hit the machine cannon button. At exactly that moment my poor "aiki" (beloved plane) stalled.

After that incident, when a young lieutenant brought the combat report to the headquarters, the staff officer there shouted 'why the hell didn't you ram the enemy bombers with your planes?' With such staff officers with next to no knowledge about aircraft there was virtually no way to win the war.

The US planes with their superchargers were able to fly at very high altitude but our planes were lagging behind in technology. The maintenance crew did their best to fix the problem with the oil pressure during high altitude. They used a larger diameter oil pipe and we could fly as high as 9,500 meters.

Contrary to reconnaissance missions, the B-29 formations flew at 9,000 meters during bombing missions and so were finally able to catch up with them. But when we reached the 9,000 meters, it was always individually, not as a group, so we had to deal with the rain of defensive fire a ten B-29 formation was throwing at each one of us."

 

[riggerrob]

after looking at all this i can say that the guns on this wouldnt be hardly bigger than a 7.62 so i mean it probably wouldnt have the punch of a browning machine gun like the ones that were used in the supermarine spitfire mk 2.

Browning, Colt and Farbrique Nationale built M1919 aircraft machine guns in a variety of calibres including: Argentina 7.65 x 55 mm, USA .30-06 Springfield, .303 British, French 7.5 x 54 mm, German 7.92 x 57 mm, Russia 7.62 x 54 mm, Swedish 6.5 X 55 and 8 x 63 mm.

After the Korean War the Canadian Army converted large numbers of M1919A4 to fire NATO 7.62 x 51 mm ammo. I fired both the .30-06 and 7.62 NATO versions during the 1970s.

 

[blackkite]

Hi! Ki-44-ⅡOtsu with 40mm cannon.(Nine bullet per cannon.)
The bullet of the Ho-301 40mm cannon is not fired with a cartridge case like a normal cannon, but the bullet itself is packed with explosive charge for propulsion, and gas is ejected from the 12 nozzles at the bottom of the bullet.
It is a rocket that pops out.
Although this 40 mm gun has a large caliber, it has the advantage of having a simple mechanism and being lightweight.
However, the initial velocity was as slow as 240 m / s, the trajectory was unstable, and it was difficult to hit unless the target was shot very close.(50m)

In a situation that everyone was watching, a pilot who died in a ramming attack over the airfield is seen on the left side of the lower propeller blade.(Third picture)

Source : FAMOUS AIRPLANES OF THE WORLD No.16 ARMY TYPE 2 FIGHTER SHOKI.

 

[blackkite]

Hi!

 

[Conspirator]

wow okay so.. kamikazies. but still mitsubishi never (as far as i know) had any plans for a new revolutionized "zero". it had performed so well they never bothered to create new versions. i mean with the bf109 they made at least 12 versions of it (b109-g is the best)

A6M1 - prototype
A6M2 - two versions (-11) and (-21), which had folding wing tips for carrier operations.
A6M3 - two versions (-32) with more engine output and squared wingtips for better dive and roll but shorter range, and (-22) with the older wing (better range) still with more powerful engine.
A6M4 - Turbo supercharger for better high altitude performance, but development was problematic and abandoned.
A6M5 - three versions (-52a), (52-b) and (-52c), each one having more protection and armament, including CO2 fire extinguishers in the wing fuel tanks, and behind the cockpit.:
52a - individual exhaust for greater speed. Improved 20 mm cannon with more rounds per gun. Thicker wing skinning was installed to permit higher diving speeds.
52b - 7.7 mm machine gun in the right forward fuselage was replaced by a 13.2 mm gun. armored glass 45 mm (1.8 in) thick was fitted to the windscreen.
52c - Armament increased to 3 13.2mm machine guns (1 in the cowling and 1 in each wing) and 2 20 mm cannons. Four racks for rockets or small bombs were installed outboard of the 13 mm gun in each wing. A 55 mm (2.2 in) thick piece of armored glass was installed at the headrest and an 8 mm (0.31 in) thick plate of armor was installed behind the seat. Wing skin was thickened further to permit even higher diving speeds.
A5M5-S - To intercept B-29s and other night-flying aircraft, armed with one 20 mm Type 99 cannon behind the pilot, aimed upward, similar in intent to the Luftwaffe's Schräge Musik installation.
A6M6 - to use improved engine, featuring water-methanol engine boost and self-sealing fuel tanks in the wings. Due to the unreliability of the fuel injection system, testing continued but the end of war stopped further development.
A6M7 - designed to meet a requirement for a dedicated attack/dive bomber version that could operate from smaller aircraft carriers. It featured a reinforced vertical stabilizer, a special bomb rack, provision for two 350-litre drop tanks and fixed bomb/rocket swing stoppers on the underside of the wings. Hhad a similar armament layout to the A6M5c.
A6M8 - New powerplant (Mitsubishi Kinsei 62 (1,560 hp)). Extensively modified cowling and nose for the aircraft. Armament: two 13.2 mm machine guns and two 20 mm Type 99 cannons in the wings. In addition, two 150 l (40 US gal) drop tanks on either wing in order to permit the mounting of a 250 kg (550 lb) bomb on the underside of the fuselage. Two prototypes were completed in April 1945 but it did not enter production.
A6M2-K - Two seat trainer version based off the A6M2. Also used as a target tow.
A6M5-K - Two seat trainer version based off the A6M5.
A6M2-N - Nakajima-built floatplane fighter (based on the A6M2-11 with a slightly modified tail).

So counting all the major versions plus the sub types shows 16 versions, although 3 of those versions were not put into production.

As for a "new" Zero, that would be the A7M Reppu, superior to the Zero in every way. It was almost ready for production when the war ended. The story of why it took so long to develop is too much to go into here.

okay well i did not know that thanks.

 

[blackkite]

A few Ki-44-Ⅲ were made.
Wing span : 10.15m, Gross weight : 2886kg.
The planned armaments were as follows.
(1) Ki-44-ⅢKoi : 20mm cannon×4
(2) Ki-44-ⅢOtsu : 20mm cannon×2, 37mm cannon×2
Source : FAMOUS AIRPLANES OF THE WORLD No.16, ARMY TYPE 2 FIGHTER "SHOKI".

 

[Tony Williams]

The Ki-44-IIc and Ki-44-III were fitted with 40 mm Ho-301 cannon as already described. None of these planes were fitted with 37 mm guns - this is a much-copied error.

 

[windswords]

The Ki-44-IIc and Ki-44-III were fitted with 40 mm Ho-301 cannon as already described. None of these planes were fitted with 37 mm guns - this is a much-copied error.

Yes, some Ki-44-IIb and IIc were fitted with the Ho-301 and never the Ho-203 37 mm cannon (too big for the wing I believe). The Ki-44-III prototype had a bigger wing and according to Japanese sources were to have 37 mm cannons as an alternate armament (standard was 4x20 mm). Whether any of the Ki-44-III prototypes were fitted with them I don't know.

 

[Tony Williams]

The Ki-44-IIc and Ki-44-III were fitted with 40 mm Ho-301 cannon as already described. None of these planes were fitted with 37 mm guns - this is a much-copied error.

Yes, some Ki-44-IIb and IIc were fitted with the Ho-301 and never the Ho-203 37 mm cannon (too big for the wing I believe). The Ki-44-III prototype had a bigger wing and according to Japanese sources were to have 37 mm cannons as an alternate armament (standard was 4x20 mm). Whether any of the Ki-44-III prototypes were fitted with them I don't know.

The problem with the Ho-203 wasn't the size of the gun, but that it was designed around a hoop-shaped endless belt magazine, which was far too bulky to fit in any fighter's wing. It was reserved for installation in the nose of twin-engined planes (e.g. Ki-45KAI). See below:



There was a later 37mm gun, the Ho-204 (which was a scaled-up Browning design) but the only installation was in the Ki-46-III-KAI, in which it was mounted in the fuselage pointing obliquely upwards. It was a massive beast, nearly 2.5 m long and weighing 130 kg (see below), so I am doubtful that it would have been considered for wing-mounting. The 30 mm Ho-155 was much more likely - the second, trimmed-down version of that was 1.5 m long and weighed 44 kg. It was installed in about 30 Ki-84-Ic.

 

[Tony Williams]

Just a PS about the 40mm Ho-301 - it did not fire rockets, but caseless gun ammunition. A rocket is propelled forwards by the escape of high-velocity gases to the rear, and it continues to accelerate after launch. In the Ho-301 the propellant is burned up before the projectile leaves the barrel; the propellant gases are trapped inside the barrel between the bolt and the projectile. In fact, the mechanism most closely resembles an Oerlikon-pattern Advance Primer Ignition blowback, in that the gun fires as the bolt is travelling forwards at high speed, so the recoil first has to bring the bolt to a standstill before pushing it back again. This means that the recoil pulses are relatively smooth. The gun mechanism generated quite a high rate of fire for the calibre, but the major weaknesses were the low muzzle velocity (limited by the small quantity of propellant) and the small magazine capacity (10 rounds).

 

[windswords]

blockhaj earlier in this thread said

The gun itself isn't too big, it would probably have been fitted in under wing pylons or gunpods. For the magazine though a straight mag would have been needed. I bet around 20-30 rounds per gun.

I think the ammo feed would be too big even for a gunpod, and that would mess with the aerodynamics. But an alteration of the ammo feed to a straight feed would not be a difficult task. It's curious they did not simply go with the Ho-150 or Ho-155.

 

[Justo Miranda]

Kayaba had planned to manufacture its own version of the Ho-301, 40 mm recoilless rocket-gun, modifying it to fire 30 mm rounds.

speculative drawings

 

[Skyraider3D]

There is a lot of misinformation about Ki-44 'Tojo' armament. Please see the variant listing on the Wikipedia page for an accurate description of what armament was used on what version (I wrote it):

Nakajima Ki-44 - Wikipedia

en.wikipedia.org

 

[windswords]

There is a lot of misinformation about Ki-44 'Tojo' armament. Please see the variant listing on the Wikipedia page for an accurate description of what armament was used on what version (I wrote it):

Skyraider,
I have seen pictures and references to both the Ki-44-IIb and -IIc models with the Ho-301 cannons. I wonder if in some cases either or both models were retorfitted with the cannons in the field as opposed to in the factory? I have also see printed material that says some were equiped with Ho-20 20 mm cannons. Again I don't know if this was a factory implementation, done in the field, or is false. Any further info would be appreciated.

 

[blackkite]

Hi!
https://en.topwar.ru/33157-yaponskaya-aviacionnaya-pushka-ho-301.html

 

[Rbakerj]

Nakajima Ki.44

​

During the 30s, the Western powers that constrained the Japanese territorial expansion were developing four engine heavy bombers. The Tupolev TB.3, capable of reaching Tokyo taking off from Soviet territory, flew for the first time in 1930. In 1932 the French Farman 222 also performed its first flight; although ugly as all of its kind, it was very effective to control navigation in the area to the south of Formosa, operating from Saigon. The Boeing B-17 prototype was on the air in 1935 and the British Sunderland and Stirling prototypes, capable of transatlantic flights, followed in 1938 and 1939. Even the Dutch worked on a four engine version of the Fokker T-IX, named T-VI /115.

The B-17 had a 2,000 miles range, turbocharged engines and such a powerful armament that allowed this airplane autonomous defence. When the IJA was aware of these excellent performances, they realized that the American bomber was above the interception capabilities of the standard fighter Ki.27 and possibly exceeded its successor Ki.43, that had not yet entered service.

Given the potential threat that the B-17s based in Philippines could represent, the IJA requested Nakajima the design of the Ki.44, a point defence interceptor with high climb rate and twice the armament of the Oscar. Realities of war showed that this effort would not be enough though, since the US industry was able to design, test and mass-produce a new aircraft in the third time than the Japanese.

On November 1, 1944, the first American bomber flew over Tokyo, but it was not the expected B-17 but a giant B-29 F-13 42-93852, of the 3rd Photo Recon Sqn, ironically named ‘Tokyo Rose’. When the Ki.44-II-Otsu of the 47th Sentai tried to intercept it, they discovered that the Superfortress flew so high and fast that they could not reach it. It turned out that the Japanese plane used for the intended interception, equivalent to the Starfighter of the time and with an astonishing climb rate of 5,000 m in four minutes, was not good enough to do the work for which it had been designed.

The psychological impact caused by this realisation on the Japanese pilots had important consequences. The IJA needed interceptors equipped with turbo superchargers, but the Japanese industry was unable to build them or even replicate enemy bombers that had been shot down. They also needed more powerful weapons with wider range, whose usefulness was not foreseen until it was too late.

In 1944, the Luftwaffe had two types of guns of 30 mm to fight against the B-17 and B-24:

The MK 103, a potent and heavy weapon, with great effective range and low rate of fire, difficult to install in single engine fighters given its powerful recoil that damaged the airframes.

The MK 108, light and with high rate of fire, but with low effective range that forced the fighters to come dangerously close to the self-defence formations of American bombers.

Across the world, the Japanese interceptors fighting against the B-29 had similar problems with their weapons. The IJA had the Ho-203 cannon of 37 mm, weighted 89 kg, and had a rate of fire of 120 rpm and an effective range of 1,000 m. As was the case with the German Mk 103, this gun was difficult to integrate in the fragile airframes of the Japanese fighters because of their excessive recoil. The alternative seemed to be the new Ho-301 of 40 mm, weighing about half of what the Ho-203 weighs, had a moderate recoil and increased rate of fire of 450 rpm, although only 150 m range because the ammunition used was propelled by small spin-stabilised rockets.

It was determined during its design that the warhead should at least contain 65 grams of High Explosive (HE) to be effective against the B-29s, but this could only be achieved by reducing the amount of rocket propellant and thus the range of the weapon. The manufacturing of the Venturi nozzles at the base of this type of rockets, that generated both propulsion and spin, required an accuracy that the Japanese industry could not achieve for large production runs. As a consequence, the trajectory of the rockets was not precise enough for air-to-air combat.

Under pressure from the bombings and the proven futility of the weapons of 12.7 and 20 mm, the IJA decided to carry out a series of operational tests with two Ho-203 guns, with belt magazines of 25 rounds installed in the wings of some Ki.44-II-Hei of the 70th Sentai, based in Manchuria.

On September 8, 1944, ninety B-29s from the 58th BW made an attack on the Showa Steel Works at Anshan. The aircraft of the70th Sentai attempted interception, but the extra weight of the guns prevented them to reach the flight altitude of the bombers in time. Meanwhile, the aircraft of the 59th and 104th Sentai, equipped with standard armament, could only manage to damage three B-29s, after losing in combat eleven Tojo to the powerful American defensive fire.

Some tests were also carried out with the Ho-301, using some Ki.44-II-Otsu of the 1st Field Reserve Squadron, without suffering any structural damages. Afterwards, some Ki.44s of the 47th Sentai were transformed to test these 40mm cannons in combat. The 47th was an elite squadron whose pilots have had some success fighting against the Liberators at a medium altitude.

But the flight altitude of the B-29 made the extra weight of the Ki.44 difficult to manoeuvre. Above 8,000 m the small wings generated little lift and the plane uncontrollably fell several hundred meters when trying any combat manoeuvring. Its only effective tactic was diving at 45 degrees, frontally attacking the ‘bomber box’ to avoid the dangerous effect of the 20mm cannon at the B-29 tail, firing against the vulnerable bomber cockpit and then increasing the falling angle to avoid collision.

These manoeuvres were already difficult with the Tojo standard, but with the extra weight of the guns, the flight controls barely responded due to the low air density at high altitude. It is therefore possible that some registered rammings were actually accidental collisions. After shooting, the two aircraft crossed just a few meters away, with a combined speed of 1,000 kph. Considering the limited range of the Ho-301, the Japanese pilot could either shoot four rounds and escape, or shoot six rounds and die.

The Ta-Dan bombs used by the IJA for air-to-air bombing were also not effective. Some pilots as Capt. Yasuro Masazaki, of the 47th Sentai, developed a special skill using these weapons and achieving some hits. However, their experience was not transferable and generally speaking the Ta- Dan only proved useful in combat at lower altitudes.

On February 4, 1945, the Ki.44 of the 70th Sentai destroyed the B-29 42-24608 over Kobe and six days later the 42-24867 over Ota, using air-to-air bombing tactics. Some Ki.43 and Ki.44 of the 1st Field Reserve Squadron based in Singapore were used in experiments with the new spin stabilised rockets Ro-San Dan that proved to have too erratic flight paths for use in air-to-air combat. Three types of spin-stabilised rockets were built for the IJA during World War II:

Ro-San Dan (Ro-3) of 10 cm and 10 kg

Ro-San Dan (Ro-5) of 20.2 cm and 76 kg

Ro-Sichi Dan (Ro-7) of 30.3 cm and 280 kg



All stabilized in flight rotating at 3,600 rpm thanks to the spin effect produced by six 25 degrees angled nozzles, had incendiary and shrapnel warheads, time fuses and percussion primers and could be fired from simple iron tubes. Some tests were also performed with an unknown type of fin stabilised rocket, possibly a modified Ro-3, using a Ki.43 with underwing rails, but there is no record that it were used in combat as happened with the efficient German R4M.

After all these failures, only the Tai-Atari (head-on ramming) tactics remained, using the plane as a weapon to destroy the B-29 in deliberate collision course. On September 26, 1944, a Tojo of the 9th Sentai piloted by Sgt Mamoru Taguchi rammed the first B-29 during a raid against Showa Steel Works in Manchuria. In November 1944, a group of pilots of the humiliated 47th Sentai began to make rammings against the B-29 on a volunteer basis.

These practices were widespread until December 5, when the IJA ordered the creation of a Shinten Seiku Tai (Air Superiority Company) built into every Sentai of fighters. They were initially formed by four planes stripped of weapons, armour and any other unnecessary equipment for ramming, in order to improve manoeuvrability at high altitude. The number of Shinten fighters was increased up to eight per each Sentai of air defence during the last months of the war.

The Shinten pilots received special training in the 1st Advanced Training Unit where tail and belly approaches to the B-29s were not recommended. On November 24, 1944, hundred and eleven B-29's of the 73rd BW attacked the Nakajima-Tokyo factory flying at an altitude between 9,100 and 8,200 m. They were intercepted by the Ki.44-II-Otsu of the 47th Sentai, with the ‘Lucky Irish’ 42-24622 being destroyed after its ramming by the Tojo of Yoshio Mita.

On December 7, the B-29 ‘Humpin’ Honey’ 42-6299 was rammed over Manshu-Mukden by the Ki.44-II-Hei of Sgt. Tadanori Nagata and the 42-6390 by the Yoshihiro Akeno airplane, both of them from the 104th Sentai. On December 22, during a raid over Nagoya, ‘The Dragon Lady’ 42-63425 was rammed by the Ki.44 of Yoshi Hirose, from the Akeno Flying School, but the B-29 managed to return to its base despite resulting severely damaged in the tail section.

On January 9, 1945, two B-29 bombers were rammed over Tokyo by fighters of the 47th Sentai, during a new attack to the Nakajima factories. ‘Miss Behavin’ 42-24655 was rammed in engine No. 2 by a Ki.44-Otsu piloted by Masumi Yuki. ‘Tail End Charlie’ 42-24772 was rammed by Takashi Awamura airplane. On the 27th, the B-29 repeated the attack with the ‘Irish Lassie’ 42-65246 being rammed by the Ki.44 of Isamu Sakamoto and the ‘Shady Lady’ 42-24619 resulting rammed by the airplane of Kiyoshi Suzuki, both from the 47th Sentai. On February 10, during the bombing of the Nakajima-Ota factory, the B-29 ‘Battlin' Betty’ 42-24760 was rammed by a Ki.44-II of the 47th Sentai piloted by Heikichi Yoshizawa.

There are no records indicating the assignment of the Ki-44 to any Tokko unit as these aircraft were considered indispensable for air defence of the Japanese mainland. The structure of the Ki.44-II-Ko only supported the installation of a 150 kg bomb fixed for close-range attacks, instead of a centreline 200 litres fuel tank. The Ki.44 of the following series could transport two fuel tanks under the central section of the wing, in a rather rear position, to not interfere with the deployment of the landing gear. Under the outer wings, it could carry two Ta-Dan bombs of only 52 kg.

At the end of 1944 there were three Sentais in the Philippines, the 22nd, 29th and 246th equipped with Ki.44-II-Otsu fighters. They were used for air defence of Clark and Nicholls airfields as well as to carry out escort missions of the Ki.43 suicide and Ki.46 reconnaissance airplanes that tried to locate the Allied Task Forces. During the Battle of the Philippines, the Ki.44 suffered heavy casualties in air and ground combat because of the TF-38 attacks. The 246th Sentai lost all its aircraft.

On 28 November, two Ki.44s in strafing mission over San Pedro Bay were shot down by the naval AA and one of them voluntarily impacted against the destroyer USS Ross (DD-563). During the Battle of Okinawa, on April 13, 1945, the British fleet reported the presence of a Dinah escorted by Tojos on a reconnaissance mission. On May 12, a Ki.84 kamikaze of the 120th Sei squadron escorted by a Ki.44, attacked the battleship USS New Mexico (BB-40) off Yomintan

Hi, Justo, this news item just appeared. SSG Birman was on Crowell’s aircraft, Miss Behavin’, on Jan 9. What is your source for SGT Yuki’s Ki-44 hitting their B-29? Thank you very much. Ray Bakerjian.

The Journal News: Purple Heart awarded to Spring Valley soldier in WWII lost, found.https://www.lohud.com/story/news/lo...ng-valley-soldier-wwii-lost-found/8574669002/

 

[HoHun]

Hi Justo,

Thanks a lot for sharing the great overview!

The MK 103, a potent and heavy weapon, with great effective range and low rate of fire, difficult to install in single engine fighters given its powerful recoil that damaged the airframes.

This is somewhat tangential, but I don't think I've ever read about recoil being an actual problem. The MK 103 was installed experimentally under the wings of the Fw 190A, and it was found that the combination of lower rate of fire and higher dispersion in comparison to the same parameters of the MK 108, made the larger MK 103 less effective against bombers than the MK 108.

An installation of the MK 103 in the Me 109 was initally prevented by the size of the muzzle brake, though towards the end of the war a redesign was done that would have allowed fitting of the MK 103 as motor cannon.

One case in which an airframe was actually damaged by the firing of the weapons was the He 162, but this was a case of the smaller MK 108's muzzle blast (not the recoil) causing damage to the sheet metal nose cone of the aircraft. While this is often quoted as the reason the He 162 was armed with 20 mm cannon instead of the originally planned MK 108, Heinkel actually designed a stronger nose cone that would have withstood the blast, and I suspect that the real reason the MK 108 wasn't fitted to the production aircraft is that the factory producing the MK 108 was overrun by Soviet ground forces.

The MK 108 due to its operation principle had a fairly low dispersion and thus could be considered an accurate weapon, though the low muzzle velocity lead to the trajectory falling off fairly steeply at longer ranges. However, in a theoretical study the Luftwaffe undertook late in the war, aimed at finding out which weapons to use against allied jet bombers which were expected to be encountered in the future, the probabilities for hitting targets at different ranges under different conditions were assumed to be fairly similar to those of the MK 103 with its flatter trajectory, possibly because the study also assumed that the Luftwaffe aircraft by that time would be equipped with lead (and drop) computing gunsights like the EZ 42.

In an earlier study, the Luftwaffe compared anti-bomber weapons on a figure of merit, based on the total weight of the weapons installation, including ammunition, required to deliver a certain amount of explosive at the target in a certain amount of time. Basically, only 20 mm and 30 mm cannon made sense according to these criteria, with the MK 108 being a clear winner due to its excellent weight efficiency. Smaller calibres didn't deliver worthwhile amounts of explosives, and larger calibres didn't have the rate of fire, in addition to being excessively heavy in relation to the firepower they offered.

Regards,

Henning (HoHun)

 

[Tony Williams]

Nakajima Ki.44​

Across the world, the Japanese interceptors fighting against the B-29 had similar problems with their weapons. The IJA had the Ho-203 cannon of 37 mm, weighted 89 kg, and had a rate of fire of 120 rpm and an effective range of 1,000 m. As was the case with the German Mk 103, this gun was difficult to integrate in the fragile airframes of the Japanese fighters because of their excessive recoil. The alternative seemed to be the new Ho-301 of 40 mm, weighing about half of what the Ho-203 weighs, had a moderate recoil and increased rate of fire of 450 rpm, although only 150 m range because the ammunition used was propelled by small spin-stabilised rockets.

It was determined during its design that the warhead should at least contain 65 grams of High Explosive (HE) to be effective against the B-29s, but this could only be achieved by reducing the amount of rocket propellant and thus the range of the weapon. The manufacturing of the Venturi nozzles at the base of this type of rockets, that generated both propulsion and spin, required an accuracy that the Japanese industry could not achieve for large production runs. As a consequence, the trajectory of the rockets was not precise enough for air-to-air combat.

Under pressure from the bombings and the proven futility of the weapons of 12.7 and 20 mm, the IJA decided to carry out a series of operational tests with two Ho-203 guns, with belt magazines of 25 rounds installed in the wings of some Ki.44-II-Hei of the 70th Sentai, based in Manchuria.

On September 8, 1944, ninety B-29s from the 58th BW made an attack on the Showa Steel Works at Anshan. The aircraft of the70th Sentai attempted interception, but the extra weight of the guns prevented them to reach the flight altitude of the bombers in time. Meanwhile, the aircraft of the 59th and 104th Sentai, equipped with standard armament, could only manage to damage three B-29s, after losing in combat eleven Tojo to the powerful American defensive fire.

Some tests were also carried out with the Ho-301, using some Ki.44-II-Otsu of the 1st Field Reserve Squadron, without suffering any structural damages. Afterwards, some Ki.44s of the 47th Sentai were transformed to test these 40mm cannons in combat. The 47th was an elite squadron whose pilots have had some success fighting against the Liberators at a medium altitude.

But the flight altitude of the B-29 made the extra weight of the Ki.44 difficult to manoeuvre. Above 8,000 m the small wings generated little lift and the plane uncontrollably fell several hundred meters when trying any combat manoeuvring. Its only effective tactic was diving at 45 degrees, frontally attacking the ‘bomber box’ to avoid the dangerous effect of the 20mm cannon at the B-29 tail, firing against the vulnerable bomber cockpit and then increasing the falling angle to avoid collision.

There seem to be some errors in this article. The 40mm Ho-301 did not fire rockets, but caseless ammunition in which the propellant was contained in the base of the projectile. The difference is that the propellant was all burnt by the time the projectile reached the muzzle, and the recoil generated drove the API Blowback operating mechanism. Spin-stabilisation was achieved by conventional rifling in the barrel (venturi not used - just a dozen holes in the base-plate).

Also I do not believe that any aircraft had wing-mounted 37mm Ho-203 cannon. The only magazine I am aware of for this gun was an endless belt forming a hoop above the gun, making the installation far too tall to fit in a wing (see below). I believe that the only installation of this gun was in the nose of a twin-engined plane.