Nakajima Ki-84 "Hayate" / "FRANK"
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lxbfYeaa, e-mail, 14.03.2024 06:49


lxbfYeaa, e-mail, 14.03.2024 06:46


lxbfYeaa, e-mail, 14.03.2024 06:36


Anonymous, 01.03.2024 10:32

I believe 5 G limit is from one of the translated manuals, but I’ve never seen 8 or 13 before. 5 G’s is pretty low, so I wouldn’t be surprised if it could pull 8 or more, especially looking at some of its other stats.

There’s a note in the translated manual about snap rolls being potentially damaging to the fuselage, which would indicate they weren’t very confident in the strength of the airframe, perhaps from the build quality or material quality at the time. So it could be that the 5 G number was just really conservative to prevent pilots from damaging the later, somewhat poorly built Hayates. But a well-built one could perhaps pull more.

Either way, a source on the 8 and 13 G numbers would be great to see.

Jean Stravinsky, e-mail, 16.04.2023 00:40

The details available in this thread allowed me to create the Ki-84 Data Card for my board game variant "Advanced Air Force" (a variant of Avalon Hill's "Air Force"), which you can find in the "files" section after searching "Air Force" in the Boardgamegeek site search window. 14 colour Data Cards and 4 pages of rules that are the result of 27 years of research. All free to download or print.

The Ki-84 in "Advanced Air Force" exists entirely due to this thread, so many thanks to everyone involved, particularly the OP.

Jean Stravinsky, e-mail, 15.04.2023 23:23

I realize now the too small prop diameter penalized performance, especially in climbs... The figures here are credible.

640 km/h top speed without shackles is probably typical, with 660 km/h the outer end for better examples. Sustained Climb is about that of a FW-190A-8, which is surprisingly low, but not out of line with the small prop and it's tendency to over-rev in dives. 17 seconds is for left 360s, with right ones around 20 econds, which would match the Japanese idea of lesser maneuverability, but in right Turns only. This thread does have extremely valuable data that illuminates the true reality of this aircraft: Good but not spectacular. The low climb explains why the Ki-100 out-climbed it in mock combat... In short it performed similarly to the FW-190A in climbs, but had diving limitations more akin to the Me-109G or less. It was equal or better to either in speed and in left turns, but not in right Turns... For the Japanese, any parity with German types is extremely good, but the Ki-100 was better except for one thing: Wing mounted Ho-5s zipped at 800-900 rpm, but only 500 inside the prop. Just for that the Ki-84 was better outside of mock combat, at least in my view... Great thread!

Anonymous, 05.01.2023 15:02

I'm not sure where he gets his figure but the American report of the ki84 stated "slightly inferior turn to Zeke52" Japanese standards of "poor turn" was much stricter than the rest of the worlds

Anonymous, 05.01.2023 14:59

where do you get 13Gs and 8Gs from?

Anonymous, 12.11.2022 22:48

The Ki-84 was immensely strong, stressed to 13 Gs limit 8 Gs in flight, probably 6-7Gs were practical. Where does the 5G limit figure come from?

Jean Stravinsky, e-mail, 12.11.2022 22:44

In test the Japanese ran, related in 2005 airplane magazine, the Ki-100 so badly out maneuvered the Ki-84 in turning tests that 1 Ki-100 could defeat 3 Ki-84s, switch pilots and do it again...

Anonymous, 12.11.2022 22:38

The Ki84 had full time automatic water injection. It could not fly without it. It had 1900 hp on 90 octane IJA fuel. 680 to 700 km/h are minimal credible figures, and at least the lower has no time limit... Because of its lower critical altitude it left P-51s behind below 20.0. Even 660 km/h is way too low, and the engine was better made than many think. Maneuverability was not that great in sustained turns, and these mattered a lot however. This is why the Ki-100 was better even though only about 590 km/h...

Jean Stravinsky, 12.11.2022 22:30

17 seconds? The Japanese thought it turned poorly, and yet this is close to A6M5. Where does this figure come from?

Jean Stravinsky, e-mail, 12.11.2022 22:25

In a comparison with the Ki-100, where the Ki-100 could defeat the Ki-84 even one against 3 through maneuverability and climbing alone, the only advantage listed for the Ki-84 was its dive speed.

If you really think the Ki-100 could reach 500 mph in a dive (it was significantly below the Ki-84's 460 mph ias limit at 5 000 feet, which is well below 500 mph), where did you get this information?

Darren, e-mail, 11.11.2022 20:16

Maximum speed in War Emergency Power would be about the same as when utilizing Military Power, maybe 1 or 2 mph faster at best. Water injection will reduce the critical altitude only, which allows faster level speeds at lower levels, maybe 2,000 feet less than what was attained without it's use.

So 392 mph at 20,000 feet under Military Power will equate to roughly the same speed but at around 18,000 feet instead. Hope this helps understand real world results while using WEP.

ron, e-mail, 13.12.2021 20:41

Ki 84-Ib: 4x20mm Ho-5 with 120 shells per cannon.
P/L: 4.1 lb/hp; Max speed: 410 mph/20,000'
Initial Climb: 3,787 fpm; Climb to 16,405': 6'54”
W/L: 35.5 lb/sf
Ceiling: 34,449
Normal Range: 1,025

ron, e-mail, 13.12.2021 20:21

Ki 84-Ic: 80 shells per 30mm Ho-155-II cannon + 110 shells per 20mm Ho-5 cannon ammo.

RS, 27.03.2021 00:21

McGuire was shot down by an Oscar before the Ki-84 in this battle entered the engagement and shot down a second P-38 with cannon fire. The story of this mission has been well researched by David J. Mason.

TORBJRN KAMPE, e-mail, 20.03.2018 02:15


ron, e-mail, 13.07.2017 03:41

If the Ki 84 turned a 360 in 17.05 sec, and a 180 turn in 8.55 sec, the Ki 116 would turn a 360 in perhaps 14.46 sec, and the 180 in 7.25 sec. based strictly on the weight difference. So it is only an estimate. Presumably with combat flaps.

The controls got heavy at 350 mph.

Jam, e-mail, 08.03.2017 21:19

Ki-84 had 624km/h @ 6000m top speed (Japanese stated top speed at military power whereas the Germans, Americans and British stayed the top speed of their planes at War Emergency Power) with its first Ha-45-11 engine. At WEP you're looking at about 645km/h at 6000m with Ha-45-11.

Then in late 1944 the Ha-45-21 1990hp engine was introduced. The US TAIC report used this engine. However the TAIC report is just calculations. The drag coefficient is too generous when you compare the drag to the Japanese tests. Ha-45-21 Ki-84 had about 665km/h at 6000m at WEP top speed. (Not 687km/h that is stated in TAIC).
In late 1945 the Ha-45-25 engine came which had 2000hp and lost less HP as it gained altitude. At 6000m it would of gave the Ki-84 about 680km/h @ 6000m at WEP

ron, e-mail, 02.06.2016 07:37

More detail on the 20mm Ho-5 cannon ammo (on fighters):

The fuseless black soft APT was 112.7g with 7g of tracer.

The hard APT was (118g) 119.5g with 7g of grn-white tracer.
It was black with green and white bands and fuseless.

The HEI 'incendiary' was 78.2g (82.5g);3.2g PETN/RDX;8.7g I.
It was black with a brass nose, fuseless.

The HEI 'explosive' was (65.2g) 77.4g; 3.4 RDX; 3.7g I.
It was black too, but fused.

Other ammo also used by IJAAF:

Medium APT was 116.7g (118.5g) and 7g red tracer.
It was black with a green band and fuseless.

A silver-grey HEI 'special incendiary' was (70.9g) 77.4g; with 0.4g RDX and 3.7g I. It had a 2 piece fuse.

The numbers in parenthesis come from converting (ounces vs) grains to grams. I favor grains since the OZs are more rounded off. It is curious how the results go back and forth though. I got it from the RAAF leaflet on scribd.

M/V slipped from 820mps to 700mps for the APT and 740 for HEI late in the war.

Ron, e-mail, 27.12.2015 23:01

So if a 8300 lb Ki 84 can turn full circle in 17 seconds, what can a 7039 lb Ki 116 do?
17 is already A6M5 territory! In time if not radius.
It may approach Ki 43-IIIa turn performance. Who knows?
If I were an Oscar ace in 1945, I would petition for the
385 mph Ki 116 Frank!

Ron, e-mail, 27.12.2015 00:17

853' radius turn time is 17 sec 360 deg left, 20 to the right. 236+ mph start.

Ron, e-mail, 26.12.2015 13:00


"1.This plane can perform each special flight easily, it doesn't have any bad characteristics.

2.Quick turn or roll maneuvers (such as quick roll, spins, etc) would give bad effect on the plane so it shouldn't be performed.

3.Oil pressure will be zero when at inverted flight, so do not try the inverted flight.

4.When pulling up on highspeed, the acceleration have to be within 4G.

5.When trying the special flight, because of this plane`s characteristics, try to always keep the altitude and speed before starting.

6.Because for being kind to the engine, do it on 2600RPM when at training.

7.With exception for when deep (vertical) dive, elevator tab should be in cruise mode.

8.Spin characteristic is good, and it doesnt enter to bad spin. When you`re at the spin, it will stop immediately if you place all rudders in neutral position.

9.To perform a loop, start at the speed of 400km/h, 2600RPM, Manifold pressure (+)100mmHg.

10.The point for chandelle is same as looping.

11.To perform a Immelmann turn, start at the speed of 400km/h, 2600RPM, Manifold pressure (+)200mmHg.

12.When at upsending invert roll , from the speed of 350km/h, rise in the angle of about 80degrees, open the Manifold pressure till (+)100mmHg, when you reach 150~160km/h start them as the usual process.

13.To perform slow turnover, switch the "pitch lever"to 2600rpm and keep the speed at 250(300)km/h and start them as usual process. The altitude loss is about 900m and the speed when returning at horizontal would be about 400km/h

14.To perform quick turnover, switch the "pitch lever"to 2600rpm and keep the speed at 250(300)km/h and when pulling the stick enough to the left(right) back, simultaneously stomp the rudder to left(right) enough and heading the nose swiftly to lower side, try not to invert the plane. The altitude loss is about 650(800)m and the speed when returning at horizontal would be about 350(400)km/h

15.To perform slow roll, try them from 2600RPM, speed 320km/h and start them as the usual process.

16.To perform quick turn, try them from 2600(2900)RPM, Manifold pressure (+)100mm Hg(+250), speed 380(400)km/h and start them as the usual process. left turn will force the nose down easier because of torque effect, right turn will force the nose up easier. When you keep turning, the speed defers by its tilt, horsepower, plane`s load, etc. The turn radius and time is as follows:
800~700 Altitude
360 degree 180degree Turn
Right Left Right Left Turn heading
20.00sec 17.05sec 8.55sec 9.15sec Turn time
260m 260m 260m 270m Turn radius(about)
2900RPM, Manifold pressure (+)250mmHg Notes

17.To perform quick ascend, you need a slow 3G to do this. If pull up were too rough, it will drastically decrease your gaining speed and lose your gaining altitude so be careful. So when you keep 2900RPM and maximum intake pressure when climbing, you can gain almost same climb as the descending altitude.

18.When diving in deep angle, do not over-use the elevator tab(trim?). The push for stick will be related against the speed and inversed getting heavier against the dive angle but, unless it is required you have to keep the tab within 5 degree down. When performing a dive, you have to take enough altitude and increase your speed slowly so you can learn enough, and then dive deeper within the limit speed. Here we have a sample for the deep dive.
Start roll and dive with angle of 60degree, tab down 5 degree, Altitude 5000m, 2900RPM, Manifold pressure(-)100mmHg, Speed 350km/h
-2.While diving
Open the Manifold pressure up to (+)250mmHg
-3.Pulling back to horizon
Altitude 1300m, 2900RPM, Manifold pressure(+)250mmHg, Speed 750km/h

-1.Do not overrev the props unless when malfunctioning.
-2.Close the gas valve controller for about half
-3.Elevator tab are required to check severely before piloting.
-4.If the plane starts to vibrate when diving, full close the gas valve control and slowly pull up.

19.Vertical dive have to be done with the process of dive and these cautions. The speed increase when vertical diving is very fast and altitude loss required for pull-up is big so it need with caution.
Here we have a sample for vertical dive.
Altitude 5000m, 2900RPM, Manifold pressure (-)100mmHg, Speed 300km/h
-2.While diving
Open the Manifold pressure up to (+)250mmHg
-3.Pulling back to horizon
Altitude 1300m, 2900RPM, Manifold pressure(+)250mmHg, Speed 750km/h

This is about as much as I have. It's 53 pages after all and I cant force anyone to do this for free as a friends request.

Hope that is interesting and helps, and as I said, it was not done by a fluent english speaker so can be hard to understand.
Last Edit: December 13, 2014, 07:09:30 am by Hiromachi Logge ...

Ron, e-mail, 26.12.2015 12:50

A translation of a Ki 84 test:
"A function and the handling of Ki-84 fighter. 3rd January 1944 (Showa 19).

Chapter1 - Main Specification

Section 1 - Main Specification
This plane is All metal low wing single seat monoplane, here we have a spec:
Wingspan - 11.238m
Length - 9.870m
Height(horizontal) - 3.385m
Wing area - 21 m2
Dihedral angle - 6.0
Aspect ratio - 6.08
Flap area - 2.436 m2
Aileron area - 1.376 m2
Horizontal stabilizer area - 3.079 m2
Elevator area - 1.074 m2
Vertical stabilizer area - 0.761 m1
Rudder area - 0.889 m2
Empty load - 2712 kg
Full load - 3763.5 kg
Wing loading - 178kg/m2
Powerloading - about 2.5kg/hp
Fuel - Aviation 92 gasoline ( 697 l )
Methanol and Water - 130 l
Engine oil - 50l (Full capacity 80l)
Armament - 20mm x2, 13mm x2

Name - Ha-45
Type - Air cooled twin row radial 18cyl
Output - 1500hp/8500m

Name - "Pe-32" electical constant speed propeller
Diameter - 3.10m

Max speed - 624km/h
Climb time - 12min 16sec to reach 8000m
Service ceiling - 11000m
Landing speed - 140km/h

Chapter 2 - Construction Functioning

Section 1 - Aircraft

@@ Subsection1 - Aerodynamic characteristics
The wing is capable of sustaining speeds of about 700km/h. The wing`s square shape is considered for stall and stability, contraction ratio 1.81 straight downhill tapered. To improve stall characteristic, as tip border to prevent early stall of wingtip we added 2 degree of twist down.

Vertical and Horizontal stabilizers both have thickest point at 40% chord length. The stabilizer area and position of balance is decided by consideration to the stability at high altitude and stability when controlling the flap.
The movement of horizontal stabilizer is mouted above the fuselage and angled + 3 degrees to improve the angle of attack against the draft from main wing.

The maximum width is decided from the engine`s diameter 1.180m, it is tapered smoothly to the tail.
Overall the shape of fuselage is shaped with simple curve, unlike straight shape so it can reduce drag.

The chord length of ailron`s back is reaching 20% of main wing, its balance is 25%. controllable angle is 15degrees down, 20 degrees up.
Elevator is decided considering to the effectiveness at landing and takeoff, controllable angle is 30degrees for pull, 20 degrees for push, also have trim.
Rudder is decided considering to the effectiveness at takeoff, controllable angle is 30degrees for left and right.

To improve the landing and takeoff performance of this plane which have high wingload, this plane is designed to use butterfly flap effectively enough to improve lift. The control angle of flap is 15degrees at takeoff, 30degrees at landing, Here we have the estimated maximum lift coefficiency:

Flap angle 0 degree: Max lift coefficient 1.46

Flap angle 15 degree: Max lift coefficient 1.70

Flap angle 30 degree: Max lift coefficient 1.92

Section 2 - Structure

Wing is all metal one side held single frame monocoque constructed, it have single wing, and its wingtip and cranial border tank can be dismounted.
For the center part of wing, it have 217L fuel tank, left and right wing have 173L fuel tank each, also split by 20mm cannons its outer cranial border it have 67L fuel tank.
Center wing cranial border have landing gear inside.
Ailerons are constructed with metal frame and fabric outer, it is perfectly balanced by counterweight placed on cranial border, and it have a correction rudder.
Flaps are fully metal constructed and it actuates by hydraulic, only used at takeoff and landing.

2.Tail stabilizers
Both the vertical and horizontal stabilizer are all metal construction.
Elevators are constructed with metal frame and fabric outer, and it have a metal constructed correction rudder. And it is perfectly balanced by counterweight placed on cranial border.
Rudder are also constructed with metal frame and fabric outer. And it is balanced by counterweight placed on lower cranial border. and it have a correction rudder on its caudal border.

3. Fuselage
It is metal constructed half monocoque construction, it can be separated into front and back part at 9th semicircle from the back of the seat.
Frontal fuselage is connected to wings by its lower mount base, and it have a pipeframe weld engine mount on front.
On the back of the cockpit the 12mm steel board is mounted to defend from bullet, and canopy have a emergency opening device.
It have a meintenance hatch on the bacl left side of the fuselage.

4. Landing gear
Main landing gear is completely retracted inside the wing`s cranial border by hydraulic, also it is fixed by hook at both the completely retracted and extended position.
Gear tower have a air/hydraulic absorber, it have a wheel and 650 x 170mm high pressure tyre. Brake is hydraulic.
Tail wheel have air/hydraulic absober tower, wheel and 200 x 75mm tyre, it can be both in fixed ...

Ron, e-mail, 23.12.2015 12:41

Initial climb of the Ki 116 Hayate was 1,000m/min.= 3280fpm.

Ron, e-mail, 10.12.2015 08:06

30.3 and 4.45 lb are the W/L and P/L for the 1560 hp Ha-112-II powered Zero A6M8 for comprison. But the Hayate Ki 116 is almost 30 mph faster for the same or better aerobatics with it's combat flaps!

Ron, e-mail, 10.12.2015 07:30

The W/L of the Ki 116 was 30.1 lb/s.f., 4 lb lighter than the Ki 84!! 35.8 for the Ki 100!!
Acceleration however was off a touch. P/L was almost 4.7 lb/hp, 0.7 heavier. 5.1 for the Ki 100!!

So it should easily narrow the gap with the Ki 100 in a dogfoght, namely in turn and climb performance.

Ron, e-mail, 22.11.2015 12:27

The unavailability of engines forced the decision to use the reliable Ha-112-II with a 3 blade prop (same as Ki 100). The prototype flew before the war ended. It's weight was 1,000 lbs lighter, improving agility; but speed dipped to 385 mph @ 19,000', 342 @ 12,000'. Still faster than the Ki 100-Ib by 25 mph with the same power!
Loaded weight was just over 7,000 lbs.
The end of the nose was more blunt like the Ki 100. Tail area was larger than the original.

I wonder how it would do in a mock dogfight with the Ki 100 or anything else.

TORBJRN KAMPE, e-mail, 18.10.2015 22:57

this aircraft has lot of good maneuverability.
better than the Spitfire. and snabare and more armed.
a mix of BF-109 and FW-190.
I think lot of good for this aircraft.
for its flight characteristics.
it is betere a zero zen.

Ron, e-mail, 04.03.2015 22:13

The Ki84's test dive was interrupted at 497 mph due to the pilot's oxygen malfunction. It probably could do much better since the Ki 44 (with slower level speed by about 15 mph) could dive to 528 mph! I wouldn't be shocked if the Frank could outdive the Tojo by the same margin of 15 mph or so in the 540s I would guess.
Perhaps not, depending on dive stability and vibration etc... since the Ki 44 engine was more reliable. Unless someone has better data, we can only speculate. Maybe my former posts are in question where I compared the Frank's 497mmph dive with that of the Ki 100 at 528 mph limit (matching the Ki 44). The limit of the Frank is still a mytery.

Percy, e-mail, 06.12.2014 14:14

The Japanese produced some fine aircraft during WW2, A Royal navy official had said that if the British navy had Japanese naval air craft on its aircraft carriers both the Italian and German navies would have ceased to exist .

Ron, e-mail, 25.09.2014 05:00

I think the 5g turn limitation of the Ki 84 hurt it in comparison with the much better Ki 100 in horizontal combat and inferior zoom-climb but better initial dive in the vertical.
The Hayate had sluggish controls vs the Kawasaki Goshiki-sen as well.
The type 4's more powerful 18 cylinder engine faded faster above 21,000' than the modest 14 cylinder motor of the Type 5 fighter.

Ron, e-mail, 22.05.2014 03:33

The Ki 84-Ic added 2 wing-mounted Ho-155 30 mm not 37 mm cannons (Ki 44-IIc), to augment the 2x20s in the cowl. It was barely in service but not likely in combat.

Also, if we factor in the 120g AP round that not all sources do, the 4x20 mm Ho-5 salvo for the Ki 84-Ib was 3.8-4.3 Kg/s!

The standard mixed gun Ki 84-Ia salvo was somewhere over 3 Kg/s even without that heavier AP cannon shell in the ammo belt composition.
My math is only in the ballpark considering that the data
reflects the degradation of the Ho-5 as the war ended.
When it was new it was a better contender.
The Monogram publication by Leszek A Wieliczko includes the 120g AP with the other rounds (Pg 68).

Ron, e-mail, 22.05.2014 00:31

The Ki 84-Ib with the 4x20s (Ho-5) was something over 94 built, while the -Ic was far fewer. That would still be decent firepower without the 37 mm cannons, with 4 ho-5s of the -Ib:
Upwards of 3.2+ Kg/sec. dispite over 50% synchronized penalty and g/round on the light side. The 750-850 ROF per Ho-5 was cut to 400 each, firing through the prop. The muzzle velocity had degraded from 820 m/s to about 700-750 toward the end. So, more than 2 is better even if 4 cannons are perhaps effectively 3. At least the cowl guns are long range, while fighters like the Raiden and Shiden have 4 cannons all wing-mounted limiting them all to convergence range. Range was 900 m for the Ho-5 cannon.
APT was 112-113g and had 7g of Tracer. Some AP was 120g.
HEI was only 79g and had 4g of HE and 4g of Incendiary.

The Ki 116 Hayate was tested with the lighter 1500 hp engine used by the Ki 100, and still managed 384 mph top speed and 497 mph dive redline like the Ki 84. It was about 1,000 lbs lighter than the standard Ki 84 and had a longer nose to maintain cg. Agility and reliability were much improved as expected. Alas, it was too late for production.

Ron, e-mail, 10.10.2013 15:11

Good match for the P-51 in a dogfight.
It was right up there with the best from Japan.
A 20-mm projectile from a Frank was found in the wreckage of Tommy McGuire's P-38L. The Oscar that was also in that fight did't have cannons. 4 P-38Ls vs 1 Ki 43 and 1 Ki 84. Scratch 2 P-38s. I know the cover story is a little different. The Ki 84 was new at the time and was initially confused with earlier less deadly Nakajima fighters. This gave the Frank an added advantage. You can't say that about the Mitsubishi A6M and J2M or the Kawasaki Ki 61 and Ki 100.
Another advantage was the larger numbers the Frank enjoyed compared to other newer fighters from Japan like the J2M, Ki 100, or even the NIK 'George'.
It also was faster in level max speed than these were. In fact faster at some altitudes than Allied fighters too.

percy, e-mail, 03.12.2012 00:46

there were some problems with the Bristol Centuras air craft engine but these were ironed out and as it turns out these engines had one of the longest intervals between major overhauls ,how ever these engines may have been slightly more difficult to service and maintain than the conventional poppet valve radial engine .the British authorities obviously thought the 20% gain in power was worth the extra effort.A KI 84 Frank fitted with one of these engines would be superior to all allied and German contempory fighter planes

Ron, e-mail, 26.11.2012 21:53

I do know the Sea Fury was active in the Korean war but didnt the sleeve valve tend to distort? Thus I believe serviceability was an issue.

percy, e-mail, 01.10.2012 14:20

Ron ,the Hawker Tempest Mk 2was used very late in the last war,mainly to distroy the v1 flying bomb sharing these duties with its sister ,the tempest Mk 5.THE Mk 2 was powered by a colossal Bristol centuras radial engine capable of producing over 3ooohorse power and because this engine used sleeve valves this engine had a smaller diameter than any convential radial of the same power.this allowed the tempest Mk2 to retain the slim lines of the Mk5 with no increase in frontal area ,so the Mk2Tempest was not only faster than redoubtable Mk5 but its air cooled engine was less vunerable to battle damage .If the Tempest Mk 2s engine could be fitted to the Hayate then this remarkable Japanese fighter would be the superior machine

percy, e-mail, 01.10.2012 14:18

Ron ,the Hawker Tempest Mk 2was used very late in the last war,mainly to distroy the v1 flying bomb sharing these duties with its sister ,the tempest Mk 5.THE Mk 2 was powered by a colossal Bristol centuras radial engine capable of producing over 3ooohorse power and because this engine used sleeve valves this engine had a smaller diameter than any convential radial of the same power.this allowed the tempest Mk2 to retain the slim lines of the Mk5 with no increase in frontal area ,so the Mk2Tempest was not only faster than redoubtable Mk5 but its air cooled engine was less vunerable to battle damage .If the Tempest Mk 2s engine could be fitted to the Hayate then this remarkable Japanese fighter would be the superior machine

Ron, e-mail, 15.05.2012 03:33

The Ki 84 was tested against the Fw 190A-5 in Japan and the Focke-Wulf had quicker dive.
I say quicker instead of faster because the terminal dive speed isn't the same as dive acceleration on the way there.
I welcome more info on this.
It's like the dive of the Ki 84 being better than the Ki 100 even though the maximum terminal speed is about 497 mph Ki 84) vs 528 mph (well built Ki 100) respectively.
The strength of the plane comes into play as well as the weight, power, drag, compressibility and so on.
It's not so simple as level maximum speed.

Ron, e-mail, 27.04.2012 03:34

Percy, could you elaborate please.
I believe the Mark V was the only production Tempest in WW 2 action.

percy, e-mail, 14.04.2012 14:41

the only allied fighter plale that was clearly superior to the japanese ki-84 was the hawker tempest mark 2

Ron, e-mail, 09.04.2012 04:36

I ran across something about the Ki 84 from a Russian author.
I didn't realize the cylinder block had to be replaced during an engine overhaul after only a few flights! In fact EVERY flight the Ha-45 had to be cleaned and rebiult!
It's no wonder specially qualified mechanics were necessary to keep the fleet maintained and serviceable. Finally the model 11 was replace by the improved 12, then the 21, and then the 23 engine was much better but not as powerful, only 1900 hp. But high altitude was still trouble.
The turbocharged 2000 hp Ha-45Pu was too late.

Ron, e-mail, 09.04.2012 03:49

I believe so. I've seen a photo of a bare metal Frank with US insignia flying in formation with allied fighters including a Seafire. It could have been the one you speak of.

Jim Reynolds, e-mail, 06.04.2012 18:03

Was the captured Frank ( that was in the Phillipines) repainted in US stars and bars ??? Thanks. Jim

Ron, e-mail, 25.03.2012 08:55

Good work Aaron,
Now if we only we had that much on all the fighters, Oh and of course control harmony, turn time (wing-loading doesn't tell the whole story) and deg/sec roll rate, and stall, terminal dive speed, stall recovery and dive pullout (compressibility) ...etc. Maybe the mystery keeps us digging.

Aaron, e-mail, 29.01.2012 23:51

Hey Ron are you still out there?
For Christmas my wife bought me the TAIC MANUAL No.1 on Japanese aircraft.
Mick Dunne, while the Frank could outclimb the average P-51D, it did not outclimb the P-51B when pushed to 75" engine boost pressure that was cleared in 1944 (about the time the Frank showed up).
For all those that are interested, the figures on the Ki.84 with the Ha.21 engine when it was properly constructed and maintained were:
2,040hp./7,940 lbs.combat weight/226sq.ft.wing area.
The following is SPEED mph/CLIMB fpm/TIME TO HEIGHT minutes:
362/4,275/S.L. 379/4,350/.8/1,000m. 389/3,890/1.65/2,000m.
389/3,570/2.6/3,000m. 388/3,590/3.65/4,000m. 414/3,610/4.6/5,000m. 426/3,350/5.7/6,000m. 427/3,250/5.8/6,098m. 426/2,870/6.8/7,000m. 416/2,280/8.25/8,000m. 403/1,720/9.6/9,000m. 387/1,175/10,000m.

wanshan, 21.06.2011 05:03

Only let down by dismal production standards at the 'wrong' end of the war!

Ron, e-mail, 16.12.2010 05:57

The straight leading edge of Nakajima fighters helped initial climb and entering a turn, but dive was highly prone to buffeting and control loss approaching compressibility, from the shock wave. So terminal dive didn't quite breach 500 mph (only 496 or 7). Flight stability in a dive was thus inferior to the Kawasaki Tony, both inline and radial models (Ki 61/100) which did well over 500 mph. So level maximum speed advantage doesn't always translate to dive speed performance.

Ron, e-mail, 09.11.2010 08:06

They should have kept the Ha-109 motor from the Tojo and split the Frank like the USSR did with the Yak-9U.The engine was unreliable at first so the early -9U was powered by the previous motor which was mature and still reached 420 mph.
If the Frank had 2 lines of power plant maybe it would have given up 10 or 15 mph with the less powerful Ha-109 but it would have been a much needed reliable Frank while the bugs got worked out of the new unreliable one. It could replace the role of the Tojo and Oscar early by cutting back on internal fuel or cut the ammo supply respectively for the interceptor or dogfighter roles. The Frank could have twice as many produced in place of Oscars and Tojos with their deficiencies. And the Frank with the reliable Ha-109 would have no drawbacks in 1943. It could still be as fast as most any Japanese fighter and out maneuver any Allied fighter and rival the Zero in production output. And if the newer Ha-45 beast couldn't be tamed, supe-up the Ha-109 or Ha-112 (of Ki 100 fame). These reliable motors were around since before mid-war with 1500 hp. Perhaps the Ha-112 is slimmer than the Ha-109, I don't know.

ore kimi no tame ni koso, e-mail, 29.09.2010 21:02

The Frank was the more powerful fighter of IJA

Aaron, e-mail, 19.09.2010 17:46

In a confidential report listing titled COMPARATIVE PERFORMANCE AND CHARACTERISTICS REPRESENTITIVE ENEMY AND ALLIED AIRCRAFT the FRANK 1, Nakajima is listed as follows:
Engine: Nakajima Ha.45: 1970hp/S.L. 1695hp/21,000ft. Armament: 4x20mm. Range: 1795mls/156mph/359gallons of fuel.
Performance at the test weight of 7940lbs.: Climb: 3780fpm/S.L. 3290fpm/21,000ft. 10,000ft/2.7min. 20,000ft/5.8min. Service Ceiling: 39,000ft. Maximum Speed: 348mph/S.L. 422mph/21,000ft.
Due to all the problems it encountered in production, but taking into account the ingenuity of some chief mechanics in the field, IMHO it was likely the Ki.84 the Allied pilot would meet in combat would be capable of 325-350mph/S.L. and 384-425mph/20,000ft. Just an opinion though. I have read that the performance of the Ki.84 varied greatly in the field durring 1945.

Aaron, e-mail, 17.09.2010 07:42

The Ki.84 is the most contraversal Japanese fighter to evolve from WW2. It definitely had the potential to be a world beating contender if it hadn't been for its constant failure of exhaust stacks due to poor materials, inefficient welding and problems with the hydraulics.
According to Wright Field Report No. F-1IM-1119B-ND released in January 1947, a Ki.84-1 with the Ha.45 Model 21 engine, Serial No. 302, performance was found to be as follows: Speed: 350mph/S.L. 389/10,000ft. 412/20,000ft. 426/23,000ft. 400/30,000ft. 370/35,000ft. This was listed under Normal Fighter, Military Power.
Climb Normal Fighter: 3790fpm/S.L. and 3195fpm/20,900ft under Military Power. 3615fpm/17,900ft under W.E.P. Service Ceiling: 38,800ft. No test weight or engine power settings given.
On another official PERFORMANCE AND CHARACTORISTIC sheet 156A-2 the following performance is listed: Engine at T.O. and WEP: 1970hp/S.L. 2040hp/3000ft. 1850hp/17,900ft. The following performance is at 7,940lbs.: Speed: 369mph/S.L.
427mph/20,000ft. Climb: 4275fpm/S.L. 3615fpm/17,900ft. Maximum Range: 1,815mls/173mph/1500ft./359gallons of fuel.
These test figures are under ideal situations and using USA high grade fuel. However, quoting Richard Dunn:
" I have a copy of a translation of a captured document of unknown reliability which indicates two maximum speeds for the Ki.84-1 (light) and Ki.84-1 (improved versions). The two speeds apparently relate to the Ha 45 rating of 2000hp at 4,020ft and 1800hp. at 19,680ft: Ki.84-1 (light): 412mph and 430mph respectively. Ki.84-1 (improved): 409mph and 427mph respectively. The light version is listed at 7885lbs. and the improved is listed at 8507lbs.

Ron, e-mail, 01.08.2010 02:17

It's interesting to read the first impression that U.S. pilots had of the Ki 84 'Frank'. That powerful long nose with 4 props, overhauling them to point-blank range like a thoroughbred! No toothless Oscar here. Unmistakably a Nakajima though. Survivors of those first encounters doubtless had their share of clean underwear changes afterward. It's no wonder the svelte 2,000 hp Hayate became the biggest worry to Allied airmen fighting Japan. Some later packed 30-mm cannon to compliment their 20-mm guns. At a fighting weight under 8,000 lbs, it was the most feared fighter, pound for pound. At the same time, it was long legged and tough by Japanese standards. The fastest they had and tight-turning too. Superlative design all-around, potentially.

GARY, e-mail, 07.05.2010 17:56


jeddizon, e-mail, 03.03.2010 16:45

Dam good plane!The frank was left at Clarkfield in the Philippines in 1945, where I live nearby and was captured,tested by the Technical Air Intelligence Unit.Brought to the USA where it endedup with collector Ed Maloney.

paul scott, e-mail, 10.09.2009 23:37

Nice little Japanese fighter. The Japanese turned out some good ones, probably ironically too many to mention, but as good as the allied fighters nonetheless - pilots weren't wonderful against the USA's ones they mostly encountered.

Frank Hitoshi, 07.02.2009 19:40

Everybody know the sad story of the Hayate of this photo?
After testing by US air force, the Hayate was owned by one collector. After that, the owner presented it to FUJI HEAVY INDUSTRY which used to be 'NAKAJIMA AIR PLANE". That time, the Hayate was full flying condition. However, one day FUJI H.I. gave up to maintain it and sold the Hayate to one museum. It was the start of this sad story. The new owner set it outside where rain came. The Hayate had become not to fly by being exhibited under this condition. After that, the new owner sold the Hayate to next owner. Then, the main bone of legs was cut for moving it to new museum. It means that the plane become the never flying. The sad Hayate has been exhibiting in Chiran museum in Kagoshima Japan now.

Dora09, e-mail, 09.01.2009 22:41

Agreed! I've always loved Nakajima fighters the best, in particular love Nakajima's wing design from ki27 to ki84. It is a thing of beauty really. The wing on the ki43 is one of the most attractive designs in aircraft history... IMO.

Mick Dunne, e-mail, 23.11.2008 07:54

I agree with you Mike...the Japanese A/C designers were as good as any in the world! The Ki48 was a gem...great engine too (2,000hp out of a short stroke engine only slightly bigger than the Nakajima Sakae!!!) Only let down by dismal production standards at the 'wrong' end of the war!

Mike Kaier, e-mail, 18.09.2008 16:28

It's fascinating to see information about late-war Japanese aircraft; with all the setbacks they had during the war, as late as 1944 they were building competative aircraft like the KI-84; the Germans really had nothing on the Japanese.

Ronald, e-mail, 18.09.2008 07:40

Ever since the Frank and Mustang first met in China the dogfights that ensued were reputed to be among the most ferocious of WW2!
The Ki 84 potentially had everything a balanced air superiority fighter needed except reliability. It was fast, far ranging, light on it's feet, fast climbing, armored and hard hitting, and in strong numbers. Only lacking high altitude performance to the degree of the USAAF or RAF. However it had the agility to turn inside all of them. It's like a Bf 109K or Yak-3 but with long range. Terminal dive was good at 495 mph. Initial climb was in the 4,000ft/min class and level speed was better than any mass produced fighter from Japan at 427 mph (with high octane fuel). But as the war was ending, factory quality was fading - even muzzle velocity of it's fast (850 rpm unsynchronized!) world beating 20mm cannons decreased.

Mick Dunne, e-mail, 29.12.2007 05:35

Yes! Rebuilt by Bud Mahurin in the USA and restored to full flying condition, it was 'repatriated' to Japan and is owned by a collector there who maintains it as a 'flyer'. Incidentally, this same aircraft, when filled up with some decent fuel and the engine 'plumbing' attended to, the plane reached 420 mph and easily outperformed the P51 and P47 in in climb and maneuverability! Imagine what the little sucker could have done with a decent propellor!

simon, e-mail, 28.09.2007 23:03

are there any original aircraft of this type left today?

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