Nakajima Ki-43 Hayabusa / OSCAR
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Nakajima Ki-43 Hayabusa / OSCAR

With its relatively low-powered radial engine, two-blade propeller and twin rifle-calibre machine-gun armament, the Nakajima Ki-43 Hayabusa (peregrine falcon) was the most dangerously underestimated Japanese fighter of the early months of the Pacific war; yet, with its outstanding manoeuvrability, it gained complete mastery over Brewster Buffalos and Hawker Hurricanes in Burma. It was the result of a 1937 design which emerged as a light- weight fighter-bomber that required no more than its 709kW to meet its speed demands. In common with other Japanese fighters of the time, however, its armament was puny by RAF standards, and it possessed neither armour nor self-sealing fuel tanks. As the Allied air forces pulled themselves together after the first shock of defeat, the Ki-43-I's weaknesses were discovered and increasing losses suffered, resulting in the introduction of the Ki-43-II (codenamed 'Oscar' by the Allies), with pilot armour, rudimentary self-sealing fuel tanks and reflector gunsight; the engine was also changed to the 858kW Nakajima Ha-115 radial which increased the top speed to 530km/h, roughly the same as that of the Hurricane Mk II. The Ki-43-IIb entered mass production in November 1942, first with Nakajima and six months later with Tachikawa. Final variant was the Ki-43-III with 917kW engine and a top speed of 576km/h, but relatively few examples reached operational units. The Ki-43 was numerically the most important of all Japanese army air force aircraft, production totalling 5,886, plus 33 prototypes and trials aircraft.

Nakajima Ki-43 Hayabusa / OSCAR

 ENGINE1 x Nakajima Ha-115, 858kW
    Take-off weight2590 kg5710 lb
    Empty weight1910 kg4211 lb
    Wingspan10.84 m36 ft 7 in
    Length8.92 m29 ft 3 in
    Height3.27 m11 ft 9 in
    Wing area21.4 m2230.35 sq ft
    Max. speed530 km/h329 mph
    Ceiling11200 m36750 ft
    Range w/max.fuel3200 km1988 miles
 ARMAMENT2 x 12.7mm machine-guns, 2 x 250-kg bombs

Nakajima Ki-43 Hayabusa / OSCARA three-view drawing (752 x 1003)

Comments1-20 21-40 41-60
ron, 18.03.2016

When the Ki 43-II debuted, it should have added a 20mm cannon under the cowl with a long barrel and the ammo on the cg.
More than one would be better but the power would need a serious upgrade. I'd be curious about testing a 40mm H0-301 in the tail to give assailants pause if they get on it's 6.
The range of 150m would be perhaps compensated for by the speed of the Allied plane closing from behind. In any case it could force lower % deflection fire. At best, one 40mm hit from the stinger could kill an Allied plane.
Failing that, any normal range rear firing gun would be a deterrant. After the tide of war turned, it needed some defensive measure. At least I'd be curious to test it.

The IJA lost so many pilots in NG and the Solomons, these Oscars needed more firepower but without losing the advantage in agility altogether. If the 20mm was too big for the upper cowl, why not just put it down under?

No other WW 2 fighter still had only 2 MGs till the end of the war in front line service like the Oscar!

GUD, 17.03.2016


francis dec, 13.03.2016

nearly 2000 mile range! me109 had 400 mile range and lost battle of britain as a result

Ron, 26.12.2015

Let me quote an excerpt:
"And here is the special thing - armament.
Guns : Two 20 mm cannon. Airplanes of PW's unit (5001st Toku - Tokko Tai Dokuritsu Chutai) had been originally equipped with two 12.7 mm MG;s but these were replaced by 20 mm at Gifu before departure for SWPA, to test suitability of 20 mm. Other Type 1F Oscar Mark 2, as far as he knew, did not have 20 mm cannon.
Ammunition : 200 rounds per gun.

From the other section.
"He was then shown three different types of 20 mm cannon viz: Oerlikon type, old and improved models (most likely Navy Type 99-I and Type 99-II - Hiro), and the MG 151/20 from Tony. He doubted that cannon installed in his airplane were similar to any of these. He showed great interest in the MG 151/20 and was definitely of the opinion that it was not of Japanese manufacture. He explained that cannon in his airplane were operated hydraulically and therefore could not possibly have been MG 151/20s. However, throught his statements he frequently added that he had never inspected his cannon very closely and therefore could never be positive should he be shown one.
He explained that the muzzles of the guns of his plane protruded approximately 3-4 inches forward of the top portion of the blast tubes.
When shown smaples of 20 mm amunition from the older type Oerlikon and from the high velocity 20 mm cannon installed in Type 2EB Helen, he stated that the ammunition used by the cannon in his airplane was a size between these.
(PW was definite in his statements regarding installation of cannon in Type 1 fighter Oscar Mark 2).

This is sort of revelation, however not all his descriptions were accurate or true. For instance the top speed of his Ki-43 was largely exaggerated, even Model 3 was not supposed to reach the speeds of 600 kph TAS in level flight. His dive limit was also exaggerated, as Model 2 Oscar was not supposed to exceed 650 kph Indicated. Lastly the fuel capacity exceeded that given in the manual by 200 liters. He either did not know his aircraft, which does not seem probable considering he was educated person, with a great flight experience but also important duties. As a flight instructor he most certainly knew his aircraft.

In this case the question about 20 mm armed Oscar is open. As we know Model 3 to be equipped with Ho-5 20 mm cannon required a construction changes, namely increasing the length of the nose to accommodate larger armament and ammunition boxes. Could ordinary Oscar 2 be equipped with those ?
Do we know anything about 5001st Special Attack Unit and its aircraft ? If all Oscars of his unit were equipped with 20 mm cannon as PW claims than it would be a very important unit at that time.

PW informed that 5001st Special Attack Unit, Independent Squadron was formed at Kagamigahara, Gifu on 25th December 1943. It was sent to SWPA as a test unit which if unsatisfactory, would be dissolved and pilots and airplanes sent to other units. Unit was equipped with 15 Oscar 2 fighters - four flights of three airplanes each, and three airplanes in reserve.
On 8th January 1944 entire unit flew to Tachiarai and stayed one hour for refuelling. Same day they proceeded to Kagi, Formosa. They left it on January 9th and arrived Nielson Airfield, Manila where they remained for 3 days.
On January 12 they arrived Manado, only to leave it next day stopping for a few hours at Babo to finally arrive to Wewak on January 14, 1944.

In his day when shot down (January 16, 1944) 12 airplanes left Wewak at 09:00, and were joined over Boram by 18 Oscars and Tonys. Together they proceeded toward Saidor to engage Allied fighters protecting Allied landings. He flew at approx 4500 meters at speed of 350 kph. At some point they were intercepted by 24 P-40s rising from a height of 2500/3000 meters. Four Allied airplanes broke formation to attack Japanese flank, Pw intercepted and shot down one of them and hit another which he claimed, he saw smoking badly. During combat PW was hit and crashed."
-J-aircraft site.

650 kph= 404 mph.
600 kph= 373 mph.

15 custom armed Oscars. Piloted by pros. Special indeed!

TORBJÖRN KAMPE, 18.10.2015

this aircraft has lot of good maneuverability.
better than the Spitfire.

Ron, 23.09.2015

J-aircraft Forums General Category Japanese Army Aircraft Message Board Topic: 5001st Special Attack Unit Oscar Mark 2 armament

Ron, 23.09.2015

1150 hp Ki 43-II is said to stall at 81 mph, max level TAS 373 mph, 311 mph IAS, 404-435 mph dive.
15 service test fighters with 2x20mm cannons @ 200 rpg. Early 1944.
Make of this what you will. It sounds to me like Ki 44 info was mixed in, perhaps translation was a factor as well.
404 mph is more credible to me than 435 mph for dive, unless stress of interrigation got this crossed with the Ki 44 Dive and Max level speed which matches up.
This was unofficial info from a captured instructor who piloted one of these 15 special cannon armed Oscars that got shot down.

Ron, 13.12.2014

Axis History Forum is where I got the 8 g fill for the Ho-103 HE shell. I see 0.8 g everywhere else, so I may be wrong. It could be a typo. Sorry.
2.2 g and 2.2% can also be found. Also 2.0 PETN is given for the HE in the HEI shell. Incendiary fill weight not given. So, if it's 0.2 g, that could be the 2.2 g mentioned. As for the 2.2%, it equals 0.8 g of 34.2-37.5 g HE shell, approx. So, it could be either way, 2.2% or 2.2 grams - given incomplete numbers.
For comparison, the A6M5b Type 3 13.2 mm 44.18 g HEI shell has 2.28 g of filler.
The Breda-SAFAT 37.5 g HEIT shell has 0.6 g of fill.
A captured Ki 43 had APT, HE,I belting.
I bet the APT is really an APIT @ 36.7 g @ 760 mps.
The only Ho-103 APT I found is on the Axis site @ 34.2 g @ 760 mps, but it gives that same weight for the APIT and HEIT as well. Perhaps it's the average.
The HE shell could be 33 g or 37.5 g 796 mps.
The I shell is 36.5 g but filler weight isn't given.
Another belting is AP, HE, HET, AP.
AP is 35.4 g @ 760 MPS.
HET must mean the HEIT shell 37.5 g (Breda) @ 770 mps.
HE see above.
Warthunder shows a belting of AP, APIT, HE, HE, I.
Air combat: APIT, HE, I.
There are others too. I don't know what these are based on.
Game modeling is often revised for the players.
So much for my previous simplified post.

Ron, 06.12.2014

This fighter screams for more bite.

The LMG Type 89 was fast enough synchronized but range was only 600 m and was only able to add to the damage done by the HMG Ho-103 which was too slow by itself when synchronized.
So, the vast majority of Ki 43s were of mixed armament in combat.

Type 89-2 7.7mmx58mm
RoF: 657 rpm
M/V: 810-820 mps
10.5 gpr
Range: 600 m
Ammo: 500 rpg

Ho-103 12.7mmx81mm
RoF: 425 rpm
M/V: 760-780 mps
35.4 gpr APT
33 gpr HE (8 g PETN)
Range: 750 m
Ammo: 270 rpg

Once the Italian ammo was made in Japan, it no longer tended to jam (or worse) in the Ho-103 gun.
It had very high chemical content for a 12.7mm HE round.

Ron, 23.10.2014

(A short digest of data on the Ki 43)

Ki 43-I Oscar was accepted after Combat flaps were installed so that it could out-turn the Ki 27 Nate. Wing loading was 19 lb/sq ft and a full turn to the left took 10.8 sec at about 2,000' and 205 mph; radius was around 302-308' left or right.
It could do a double-double Immelmann (4 in quick sequence)!
It could go as slow as 50 mph during aerobatics. It could roll in a dive up to 300 mph.
Care had to be taken on pullout or the wings may fold. Top level speed was only 308 mph /5Km altitude which was attained in 5 min 30 sec climb. P/L was 4.6 lb/hp for excellent acceleration.
Though the pre-production prototype had pilot armor and 12.7mm HMGs these were stripped for production. 716 Ki 43-I Oscars were biult until Feb 1943. Most were armed with twin Type 89 synchronized 7.7mm MGs firing 657 rpm each, mounted in the cowl.
Some 12.7mm Ho-103 HMGs were used but proved unreliable using Italian ammo. These rounds were fine in Italian guns, but eventually this was solved by Japanese manufacture of this ammo. No more miss-firing! These had a synchronized RoF between 400-450 rpm.

From Nov 1942 the Ki 43-II was produced until Oct 1944, Perhaps about 3,440 were biult. It's new engine improved speed to 329 @ 4 Km; 341 mph @ 6 Km; 372 mph in a dive. P/L slipped to 5 lb/hp and climb to 5 Km took 5 min 49 sec. 6 K;m took under 6 min 30 sec. Initial climb rate was 3290 fpm @ SL and about 3400 fpm @ 5 km.
Loaded weight had increased nearly 1200 lbs and the stronger wings were clipped so W/L increased to 28 lb/sq ft! Still good agility and acceleration vs the Allies.
In Nov 1943 pilot armor and fuel tank protection was installed as another reason for the extra weight besides more powerful HMGs and hp...etc.

The final Version to see action in WW 2 was the Ki 43-III. From the prototypes in May 1944 to the end, about 1,727 were built (production: July 1944-Aug 1945). A new engine for better altitude performance now gave a P/L 4.6 lb/hp again and time to climb 5Km took only 5 min 19 sec. Top speed @ 22,000' was now 358 mph (faster than the rival A6M5c or A6M7 Zeros). And W/L improved to 24.5 lb/sq ft. But still no cannons!!
The cannon armed Ki 43-IIIb never entered production.

Can you imagine if the Japanese had made their own version of the imported Mauser MG 151/20 cannon for synchronized RoF superior to the Ho-5? Most Japanese fighters had cowl guns, Army and Navy. The Ki 43 was most in need of something like this mid-war. The Ki 61 had them. But can you picture over 4,000 Oscars armed with Mauser derived nose cannons, 2 or more each? Not to mention the slow Navy cannons might get a second look, after all the Army fighters are refitted. Just what if?

Ron, 04.10.2014

The Allied pilots spoke in awe of Oscars performing double-double Immelmanns (that's 4 consecutively), horizontal spins, flip-rolls, snaking vertical climbs, as well as extremely tight turns.
Some moves even a Zero couldn't follow much less any of them.

Ron, 16.09.2014

I'll paste this Ki 43-I turn data:

1969'/Left/205 m.p.h./307.4’/10.8/2700/37.8
1969’/Right/205 m.p.h./301.5’/11.0/2700/37.8"

It could do aerobatics to a slow point of 50 mph!

That 11 second 360 degree turn is close to the A6M2 as well.

But the Ki 43-I could roll with a foe up to 300 mph unlike the Zero 21. Both full span.

Ron, 07.07.2014

I'm now leaning more toward 400 instead of 700 rpm for the Type 3 HMG, synchronized, to correct my last post. 700 is not in line, especially with a heavier 13.2mm ammo belt than the 12.7mm Ho-103 HMG.

The reliability of the Ho-103 suffered when using Italian made ammo but this changed when the ammo was made in Japan.
The Italian Breda-SAFAT was not Browning based like the Ho-103.
The Italian ammo was reliable in their own HMG and the RoF synchronized was 575 rpm.

As for the Ki 43, I would put another pair of Ho-103s in the cowl if not in the wings. Worst case, 1 more in the cowl at least. It had enough agility in excess vs America for 3 guns or more. Granted the wings might need strengthening for a pair of wing-guns but that was needed anyway for improved dive (another glaring weakness). If there was room in the bottom of the nose, I'd put 1 or 2 there. Can you imagine a 6 gun Oscar! It would still be more agile than the 6 gun A6M5c Zero. Heck, put an Ho-5 under the nose! That would leave a mark, even at 400 rpm. Then 3 guns might do it.
The A6M5c had double that. Why should the Oscar start the war with 2 MGs and end the war with only 2 MGs?
The Ki 43-IIIb with 2 Ho-5 cannons missed the war. It should have been in service with the first Ho-5 mid-war! And then 3 or 4 Ho-5s. It had enough agility to spare unlike the Ki 44 or Ki 61.

Ron, 22.04.2014

The TAIC lists the dive limit for the clipped Ki 43-II at 372 mph. Noticeably less than the 400+ mph clipped Zero 32.

Another inferior comparison:
7.7 mm Type 89 MGs synchronized rate of fire: 657 rpm.
12.7 mm Ho-103 MGs " : 425 rpm.
(A touch less than I posted before)

The slow rate of the Ho-103 was disliked for dogfighting. Especially when compared to the A6M5b 13.2 mm synchronized Type 3 MG: 700 rpm. Therefor, many returned one 12.7 mm Ho-103 MG for one faster more reliable 7.7 mm Type 89 light MG, preferring mixed guns (the A6M5b likewise had mixed nose-guns).
This is curious since unsynchronized, the tables are turned with 900 rpm vs 800 rpm respectively. (Approx)53% vs 13% reduction. Go figure! Both guns are Browning style designs, am I wrong?

The Ki 43 combat flaps were a plus, good for at 1 or 2 less lb per square foot of wingloading, in effect. Unfortunately, it hooked the Japanese pilots on slow close-in tactics to fight the last war, against the other side who eventually showed up with powerful WW2 planes and energy tactics. Like they were addicted to this fighter, fighting planes with double their hp and triple their guns. It's a wonder the Oscars faired as well as they did.
At least Nakajima had the forsight to follow up with the Tojo and Frank in strong numbers while Mitsubishi stuck with Zero production too much at the expense of the Jack and Sam fighters.

Ron, 14.04.2014

I was just wondering about the margin of improvement the 'butterfly' combat flaps gave the turn performance of the Nakajima fighters.
They enabled an Oscar pre-service test plane with more features than the typical production model of 19 lbs/sq ft wingloading to turn at least as well as a Ki 27 Nate (unknown version) typically with 16.4 lbs/sq ft wingloading but without the new combat flaps. Those wingloadings are for production versions but the planes in the comparison should be relatively close to these. If anything the loaded down test Oscar is even more remarkable to turn so tight.
I don't know the non production figures.
But in broad terms the flaps were good for equalling at least 2.6 lbs/sq ft difference in wingloading.
Enough to go from a thumbs down to a thumbs up by the test pilots.

Think what this means for the Tojo and Frank wingloadings. They had these flaps too. Subtract in effect 2.6 lbs/sq ft from theirs too. 37.7 is effectively 35.1 for the Ki 44-IIb
and 35.1 is like 32.5 for the Ki 84-Ia in a turn... more or less. Again these are based on typical known production loaded weights unlike the test comparison.

Point is you can't judge the turn performance merely by their wingloading or they may surprise you.

Ron, 14.04.2014

Hey Hiroyuli,
You're right. They say about 1,000 Ki 43-IIIa Oscars were made in WW2.

Too bad it just had the 2 MGs.
No mass production of the 20 mm cannon armed Ki 43-IIIb seems to have occurred in time.

Ron, 24.12.2012

Hi X,
Anyone would agree at least at first.
But bear in mind most Hayabusas had light machine guns or a mix of one reliable 7.7-mm and one 12.7-mm that was less reliable. Only later did they improve to the point of twin heavy machine guns. Still they had claimed more allied planes than any other Jap fighter! And mostly US planes tough as any in the war. The difference that I suspect accounts the most for this would be that no allied plane could shake one on their tail close-in (short of diving away) like they could a Luftwaffe plane. If the Ki 43 pilot (and his buddies) had all day to shoot at you, it had enough ammo to do damage; but if you tried the same on his six, its like trying to swat a fly (or a swarm of flies). Anyway, that's my opinion.
Too many Allied pilots were slow to learn not to give the Oscar the firing time on target required.
Overclaiming is another factor but not so much more so than with any other Japanese fighter type.
Also the Ki 43 and Ki 84 confused Allied pilots who mistook one for the other with favorable consequences for the Nakajima pilots. Just take the death of ace Tom McGuire for instance.

Of course by mid-war, the slow (max. speed) but quick (accelerating) Oscars were losing the battle left and right despite many above average pilots, but that's true also in the rest of the Axis. Against the Japanese (especially Oscars and Zeros), US pilots learned their lesson and kept up their speed with hit and run tactics only.

X, 07.07.2012

2 x 12.7mm machine-guns are totally useless in fierce battles like the ones over Europe

Ron, 14.04.2012

I want to make a slight correction to my last post.
The Ki 43-II got the more powerful engine and the IIa got the armored seat etc.. in Nov. 1943 as I said but the A6M5b entering production in June only had the armored glass. The armored seat came in the A6M5c starting production in Oct. 1944 - 11 months after the Hayabusa and furthermore the Zero did not get a more powerful engine and performance was degraded compared to the Ki 43-IIa. So for whatever it's worth, the Zero needed the new 1560 hp MK8P Kinsei-62 by then as planned by the design team (A6M5 in time for autumn 1943 combat) but nooo! Only the postwar A6M8 got that thanks to the Navy higher-ups.
So the armor issue makes the Oscar look good when compared to the Zero at least.
So the Zero became the kamakazi standard.

Ron, 11.04.2012

I believe the last pre-series Ki 43 had the experimental 1150 hp Ha-105, pilot armor, and 12.7 mm cowl guns in 1940 and still surpassed the Ki 27 (Nate) in maneuverability due to the new combat flaps. Unfortunately on January 9, 1941 it began production with the old but plentiful 7.7 mm guns and the underpowered 975 hp Ha-25 radial and you guessed it, armor protection was thus all unloaded as a result!
Why make things difficult to mass produce? Right?
Thus it didn't have to be obsolete off the bat but it was for expediency. Big mistake!
The cost in pilots lost proved too high and those missing upgrades were slowly restored over the years. In the Ki 43-Ib had mixed armament of one 12.7 mm and one 7.7 mm. The Ki 43-II had the Ha 115 type 2 motor with 1150 hp at just under 10,000 ft. By November 1943 the Ki 43-IIa had it's armor back. 2 years gone and we're almost back to 1940 prototype level! It had TWO 12.7 mm guns though. That was on it's way too. Patience...
I must admit that the A6M Zero was still without any armor until mid 1944 by comparison. And after that it's performance constantly fell while that of the Ki 43 surpassed it. The Hayabusa only progressed... then the Ki 84 Hayate replaced it (Ki 44 as well) and in good numbers too. It's Mitsubishi rival was the ill fated A7M Reppu (Sam) no show. Credit Nakajima!

1-20 21-40 41-60

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