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
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!

Ron, 31.12.2011

Itokawa and his design staff were not proud when they built the first Nakajima prototype to the unrealistic requirements of the JAAF. It was rejected by the Army as a result. Demoralized, the Itokawa's team set their own more realistic goals, trying different variations of construction, engines, and so on, unhampered by the initial contract specs and design concessions. By the 12th prototype, it was accepted. After the next 10 experimental craft, combat flaps were added for phenomenal turns. Production was now begun.
I found that interesting, compliments of Richard M. Bueschel's Military History.

y.k, 18.12.2011

After the end of WW2 captured Japanese planes were operated in Indochina.

Naga, 14.12.2011

My limited knowledge of this aircraft does not cover users, but somewhere I heard that France operated a small number of the type. Is this true?

Aaron, 10.07.2011

The A6m2 compared to the Ki.43-1 was only more maneuverable over all in the vertical plane. The Ki.43s tighter/faster turn, quicker roll rate and faster acceleration gave it dominance on the horizontal plane. Fire power and top speed being the A6m's only advantage. Top speed does not come into play in swirling dogfight.

Ron, 04.07.2011

"As compared to the Mitsubishi A6M2 Reisen, the Ki-43-Ic had a substantially lower wing loading but was nevertheless slightly inferior to the carrier-based fighter in overall maneuverability. The A6M2 was superior to the Ki-43-Ic in zoom climbing speed, although the Ki-43-Ic had a slight edge over the A6M2 in steady climbing rate to 16,400 feet. The primary weakness of the Ki-43-Ic was its light armament..."(Parker
It had twin 7.7-mm cowl guns at first.
The Nakajima fighters were known to be more work for the pilot in aerobatics than the Zero. The Ki 43-I did 308 mph max. The A6m2 did 331 mph and at a higher altitude despite the higher ceiling of the Oscar. This is before either plane clipped it's wingspan for roll rate.

The record shows Buffalos of Malaya etc.. did make aces against more Hayabusas than Zeros. And my former post wasn't my invention. It's what I read.
I suggest they utilized it's dive advantage for hit and run and steered clear of the cannon armed Zeros (my guess).
Pilot quality is probably a big factor between the Japanese navy and army pilots too. Remember the incident with Russia?

Aaron, 26.06.2011

All facts aside, I am very currious as to why you believe a Buffalo could hang on the tail of and Oscar but not a Zero.?
The Ki-43 can outroll, outturn, out accelerate and over distance can out climb the contemporay A6M.

Aaron, 23.06.2011

I almost forgot the most important features of the Japanese fighters. The large ailerons of the Zero and the combat flaps of the Peregrine Falcon. These features made these two aircraft the tightest turning monoplane fighters of WW2 with one sole exception. The Ki.27 (Nate). (Not real sure about the A5M2-4 Claud)...?

1-20 21-40

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