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Posted 03 September 2013 - 11:10 PM

Nakajima Ki.84-1a Hayate (Gale/Hurricane) Frank 1

When discussing the best all round fighter A/C to come out of Japan, the Ki.84 will definitely have to be a considered candidate.

The following information comes from T.A.I.C 156A report dated March 1945.

Engine: Nakajima Ha 45 Model 21 / 1,970 hp. @ Take off./ 2,040 hp. @ 3,000 ft. (W.E.P.)/ 1,850 hp. 17,900 ft. (normal/W.E.P.*) (*note: that is how the power is listed...?)

Altitude.Speed/Climb/Time to height.
Meters...mph/fpm/minutes to altitude.
Feet.....mph/fpm/minutes to altitude.


FTH in low s/c: 390 mph./524.4 m.

Switch low/high: 389 mph./3,353.7 m.

FTH in high s/c: 427 mph./6,097.6 m.

Switch WEP/military: 422 mph./6,707.3 m.

FTH in high military: 426  mph./7,012.2 m.


Critical altitude low s/c: 4,400 fpm./853.7 m.

Switch low/high: 3,550 fpm./2,743.9 m.

Critical altitude high s/c: 3,620 fpm./5,457.3 m.

Switch WEP/military: 3,200 fpm./6,219.5 m.

Critical altitude high military: 3,200 fpm./6,341.5 m.

Note: See  the next post for the rate of climb and ceilings at military power.

Combat Weight: 7,940 lbs.

Combat Ceiling: 33,755 ft.
Operation Ceiling: 36,560 ft.
Service Ceiling: 38,800 ft.

Wing area given: 226 sq.ft. (Actual: 226.041 sq.ft.)

Wing Loading: 35.13+lbs./sq.ft.

Power Loading: 3.892+lbs./hp.

Range Clean: 1,025 mls./178 mph./1,500 ft./185 gallons fuel.

Range Maximum: 1,815 mls./173 mph./1,500 ft./359 gallons fuel.

Armament: 2 x 12.7mm/350rpg. in cowl + 2 x 20mm/150rpg. in wings.


NOTE: I believe all these performance figures and power output figures could only

     be attained if the aircraft was assembled well and the engine was tuned within

     specifications and on 100 octane fuel.


Edited by CORSNING, 09 January 2017 - 08:01 PM.



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Posted 03 September 2013 - 11:47 PM

The following information comes from the C. P. & C. Japanese Fighters chart. They only give two reference points on this chart so all the rest of the figures have to be calculated. The performance curves are based on the curves of the T.A.I.C. 156A report graphs.


Engine: Nakajima Ha 45 / 1,970 hp. @ Take off. / 1,695 hp. @ 21,000 ft. (No W.E.P or Combat power is listed.)

Feet.....mph/fpm/minutes to altitude.


Speed (military power):

FTH in low s/c: 389 mph./2,439 m.

Switch low/high: 388 mph./4,54.9 m.

FTH in high s/c: 422 mph./6,402.4 m.

Climb (military power):

Critical altitude low s/c: 3,990 fpm./1,798.8 m.

Switch low/high s/c: 3,145 fpm./3,658.5 m.

Critical altitude high s/c: 3,200 fpm./6,341.5 m.

Combat Weight: 7,940 lbs.

Combat Ceiling: 33,920 ft.
Operational Ceiling: 36,745 ft.
Service Ceiling: 39,000 ft.

Wing area given: 226.041 sq. ft.

Wing Loading: 35.13+lbs./sq. ft.

Power Loading: 4.030+lbs./hp.

Armament: 4 x 20 mm + 1 x 37 mm (Yep, that's what's on the chart).


NOTE: I believe these figures better represent the performance in the field

     of a well constructed and well tuned late model Ki.84 on at least 92 octane.

Edited by CORSNING, 08 January 2017 - 07:41 PM.



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Posted 04 September 2013 - 01:16 PM


From 'Nakajima Ki-84 Hayate:

"The performance and reliability of production Hayates was seldom as good as that of the service test machines."

"By June of 1945, the lowering of manufacturing standards had cut the climb rate of the fighter so severely that the aircraft was virtually useless at altitudes over 30,000 ft."

From Aces High BB - Ki84:

"The use of 100 octane fuel in the captured Ki-84 may have been used to simulate water/methanol."

On j-aircraft sight from 'Return to Fraq':

"So while the ki84 design had a 420mph potential, elements of reality (poor fuel, faulty engines, rough airframe finish, etc) often limited its performance to a lower level. Maybe the 388mph figure is about right

after all."

"Two POW reports comment on Ki84 performance. One POW (who flew the Ki-43-II) says max speed for the Ki 84 is 404 mph true and 342 mph indicated at 5,000 meters. Another POW, a Ki84 pilot, says max speed is 700kph/435 mph true and 600kph/373 indicated. He gives no altitude and says he has never flown faster than 550kph/342 mph indicated."

"My impression (not just for the Ki 84) is that many Japanese fighter pilots flew their aircraft in combat beyond "book" specifications and got away with it."

The following is a quote from ww2aircraft.net:

"I have a copy of a translation of a captured document (hand written notes) of unknown reliability which indicates two maximum speeds for the ki 84-1 (Light) and Ki 84-1 (Improved). The two speeds apparently relate to the Ha 2,000 hp. at 1,500 meters and 1,800 hp. at 6,000 meters.

Ki 84-1 (Light) 664 kph (412.5 mph) and 693 kph (430.5 mph).

Ki 84-1 (Improved) 658 kph (409 mph) and 688 kph (427.5 mph).

Fully equiped weight of Light: 3,576 kg. (7,885 lbs.); Improved: 3,858 kg. (8,507 lbs.)."

The following quotes are from the ARMY AIR FORCES AIR MARTERIEL COMMAND MEMORANDUM REPORT ON Frank I, T-2, Serial No. 302, dated July 16, 1946:

"Power is supplied by a Nakajima Ha 45 Homare Model 21, twin row, radial, air-cooled, 18 cylinder engine developing 1,970 brake horsepower at sea level with 3,000 RPM and 49.6" Hg."

"In general the pilots agree that the maneuverability of the Frank I is slightly inferior to that of the Zeke 52, while level flight speeds are much higher with less vibration at comparable velocities. Control forces are lighter than those of most American aircraft even though elevator forces on the Frank I are heavier than those of the Zeke 52."

"In general the handling and control characteristics of the aircraft are definitely superior to comparable American fighters, especially in the low-speed range; however, rate of roll and radius of turn are slightly inferior to those of the Zeke 52........No flat spots or control reversal tendencies were noticed over an I.A.S. range of from 74 to 350 mph. The rudder control is extremely sensitive to 300 mph I.A.S. slightly less sensitive above this speed with little change in directional trim from 150 to 350 mph I.A.S."

"CONCLUSION - ......its lack of pilot protection and short range leave much to be desired in the light of present fighter standards."

Edited by CORSNING, 06 January 2017 - 09:34 PM.



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Posted 05 January 2017 - 08:01 PM

     All the following quotes and phrases are from 'F4U CORSAIR vs Ki-84 "FRANK"

Pacific Theater 1945' Osprey Duel 73 by Edward M. Young.


Note: Type 1 Fighter (Ki.43), Type 2 Fighter (Ki.44), Type 3 Fighter (Ki.61) , Type 4

Fighter (Ki.84) & Type 5 Fighter (Ki.100).


Page 21: " The Ki.84 demonstrated a better harmony between speed and turning ability

than the Ki.43. It was faster, had heavier armament and enjoyed superior performance

at high altitudes than the Shoki (Ki.44)."


Page 54: "The Type 4 Fighter was ideally suited to the newer hit & run tactics. Heavier,

sturdier & faster in the dive than the Type1 Fighter, with more firepower at altitude and

maneuverability than the Type 2 Fighter, the Hayate had the ability to dive down on

American fighter formations at speed, fire a burst from its machine guns & cannon and

climb back to altitude with a rate of climb superior to the F4U Corsair, F6F Hellcat, P-47

Thunderbolt or P-51 Mustang. And if the combat broke up into a turning fight, the Hayate

was more maneuverable than the American fighters and could execute the standard

split-S evasive maneuver more readily."


Page 51: "Once in the air, the poor quality of Japanese aerial radios made communications

between a leader and his formation difficult."

Edited by CORSNING, 07 January 2017 - 05:41 PM.



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Posted 07 January 2017 - 04:04 PM

     All the following quotes and phrases are from 'F4U CORSAIR vs Ki-84 "FRANK"

Pacific Theater 1945' Osprey Duel 73 by Edward M. Young.


The Nakajima Ha-45 Homare engines and fuel:


Pages 24: "The Early prototypes and pre-production Ki.84s used the Ha-45 Model 11 (capable

of 1,800 hp. take-off and emergency power). Early production Ki.84s used the Ha-45 Model 12

(capable of 1,825 hp.). Late production Ki.84s had Ha-45 Model 21, 1,990 hp or Ha-45 Model

23, 1,900 hp. that solved some of the problems with the fuel system. The last production Ki.84s

received the Ha-45 model 25 (capable of 2,000 hp.).


Page 21: "The engines of the first few prototypes were effectively hand-built &  apparently

worked well. Later prototypes with mass-produced Homare engines encountered

increasing problems with excessive cylinder temperatures at full power. The cylinders

functioned smoothly when operating at less than full power. There were additional problems

with the oil pressure dropping at high altitude and a malfunctioning fuel system that were'

not resolved until later versions of the Homare engine were introduced near war's end."


Page 24: "Serviceability and maintenance remained a problem throughout the Ki.84s

operational life. The Homare would function well with regular and careful maintenance, but

problems with the engine became even more pronounced in the field, where operating

conditions, shortages of skilled ground crew and lack of spare parts made regular

maintenance problematic."


Page 21/22: The following statements are from Nakajima's test pilot Yoshizawa:

     "The Ki.84 used 92 octane gasoline. When we used 100 octane gasoline that the Navy

stored in Taiwan, all engine problems stopped. It was obvious that the troubles were caused

by the fuel, but it was not easy to obtain such high octane fuel then."

     " The Ki.84's weak point was the engine...,and it never worked properly right until the end.

It was really disappointing that we could only operate it by tricking the engine to work, and to

gain speed that way."

Notes: Yoshizawa in this book did not expand on how they tricked the engine. Octane rating

of late war Japanese fuel sometimes fell to 85.

Edited by CORSNING, 07 January 2017 - 04:04 PM.



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Posted 07 January 2017 - 04:19 PM

     All the following quotes and phrases are from 'F4U CORSAIR vs Ki-84 "FRANK"

Pacific Theater 1945' Osprey Duel 73 by Edward M. Young.


Flight Experience of JAAF Pilots:


Page 23: "At last the Japanese had a fighter that could, in experienced hands, match the

performance of its Allied counterparts. However, while the Ki.84 showed a definite qualitative

improvement over other JAAF fighters, at this stage of the war it was quantity and pilot skill

that mattered almost as much, and here the JAAF fell short."


Page 42: "During the course of the Pacific War, JAAF pilot training underwent significant

changes in both organizational structure and duration as a result of attrition and growing

shortages of aircraft & fuel. As the war went on, shortened flying training and inadequate

flying practice led to a steady deterioration in pilot quality. When the JAAF was finally able

to introduce a superior airplane in the Type 4 Fighter, its training system was not able to

produce pilots with the skills needed to take advantage of its flying and fighting qualities."


     The number of hours of flight experience for a JAAF pilot trainee before he entered combat

declined as the war progressed. In 1941 it was 500 hrs. or more. In mid-1942 if fell to about

350 hours. In mid-1943 it fell to 250 hours. In mid-1944 it fell to 125 hours and about 100 hrs.

in 1945.

Edited by CORSNING, 07 January 2017 - 05:39 PM.

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Posted 07 January 2017 - 04:31 PM

     All the following quotes and phrases are from 'F4U CORSAIR vs Ki-84 "FRANK"

Pacific Theater 1945' Osprey Duel 73 by Edward M. Young.


VS the Vought F4U Corsair:

     "The Corsair's higher speed, excellent acceleration and rate of roll gave US Navy and

US Marine Corps pilots and advantage in combats with the Ki.84, but the lighter weight

Hayate's superior maneuverability and rate of climb, coupled with its heavy armament,

made the Nakajima fighter a dangerous opponent in the hands of an experience pilot.

Note: The poor quality of production of aircraft and flight training of JAAF pilots were the

critical factors in the actual outcome of the combats between the two fighters.




Edited by CORSNING, 08 January 2017 - 07:42 PM.

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Posted 07 January 2017 - 06:57 PM

                                                          Nakajima Ki.84 Hayate Timeline


December 1941: The Koku Hombu directs the Nakajima Co. to begin work on a replacement

     for the Type 1 Fighter. Requirements require top speed in the 400-420 range. Climb to

     5,000 m. under 5.0 minutes and armament of 2 x 12.7mm + 2 x 20 mm.


Spring 1942: Nakajima's chief designer, Yasushi Koyama and his team had completed a

     design for an all metal, low-wing monoplane with the specified armament, an enclosed

     cockpit providing excellent visibility and widely spread landing gear. The tail-wheel was



27 May 1942: The Koku Hombu approves the Nakajima design study for a new all-purpose

     fighter, which it designates the Ki.84.


November 1942: Nakajima had built a full scale wooden mock-up for JAAF evaluation. Maj

     Yoshitsugu Aramaki, from the Koku Hombu's Experimental Division, recommended 100

     test examples be produced. The Koku Humbu agreed and ordered 125 test and pre-

     production Ki.84s be built.


April 1943: 1st flight Ki.84 01 prototype with a Nakajima Ha-45 Model 11, 1,800 hp. engine

     capable of 387 mph.


June 1943: The 2nd prototype Ki.84 02 was completed.


August 1943: The Ki.84 is ordered into production. The 2nd prototype is flight tested.


December 1943: Some of the original  83 Ki.84s from the first pre-production batch went to a

     special operational test unit.

     Engine: Nakajima Ha.45 Model 11

     Armament: 2 x 12.7 mm. Ho-103 machine guns /350 rpg. Rate of Fire: 800-900 rpm.

                        Duration = 23 to 26 seconds.

                       2 x 20 mm. Ho-5 cannons/150 rpg. Rate of Fire: 750-850 rpg.

                       Duration = 10 to 12 seconds.

Note: According to Edward M. Young's book, F4U vs. Ki.84, the Ho-5 cannon was considered

     one of the best 20 mm aircraft cannons fielded by either side during the war.


March 1944: 22nd Hiko Sentai began receiving Ki.84s.


April 1944: The first production Ki.84 Ko is completed as the Type 4 Fighter Model 1 Hayate.

     Three more fighter sentais were established, three more in may & 3 more in August.

     The fuselage held a 35 gallon water-methol tank ahead of the cockpit. There was a 65 mm.

     armored glass block behind the windscreen and 13 mm. armor plate behind the pilot's seat

     providing protection for the pilot.

     Engine: Nakajima Ha-45 model 12, 1,825 hp.


June 1944: 42 aircraft of the second pre-production batch had been completed. Ha-45 model 11.


August 1944: The 22nd Hiko Sentai deploys to China.


September 1944: 1st combat operations of the Ki.84 over China and Burma.


24 October 1944: The Ki.84's 1st combat over the Philippines. This was the first encounter in

     significant numbers by the Allies.


December 1944: The Ki.84-Ib enters service. Armament 4 x 20 mm. Ho.5 cannons.


Early 1945: The Ki.84-Ic enters service with 2 x 20 mm. Ho.5 + 2 x 30 mm. Ho.105 cannons.


25 February 1945: Carrier strikes on Tokyo are the first combats between the Corsair and the 

     Hayate. Task Force 58 launched carrier strikes against Tokyo area airfields and factories.


Note: The last production model Ki.84 Otsu/Ki.84b Type 4 Model B was probably several

     hundred aircraft. Engine: Ha-45 model 25: 2,000 hp. Armament: 4 x 20 mm. Ho-5 cannon.



F4U Corsair vs. Ki.84 'Frank' Pacific Theater 1945, Osprey Duel 73 by Edward M. Young

Edited by CORSNING, 14 January 2017 - 09:15 PM.

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Posted 07 January 2017 - 08:31 PM

Cheers Jeff, I was just requesting info re the KI-84 performance in another section, that's perfect ,Thankyou for your input,and for sharing your reasearch,much appreciated...
God bless.



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Posted 14 January 2017 - 04:51 PM

The following statement concerns the first pre-production Ki.84 with a Nakajima Ha.45-11 engine:


     " Rushed over to Fussa in September 1943, the new model was flown in mock combat with its brother Ki.44 Shoki as

well as one of the JAAF's proudest possessions, a German Focke-Wulf Fw 190A/5 that had arrived in Japan earlier that

summer. Test pilot Major Yasuhiki Kuroe, a former Shoki combat pilot now assigned to Fussa, rated the Nakajima Ki.84

higher than both competitive aircraft in maneuverability, but worriedly reported that the German fighter decidedly had the

advantage in speed and dive tests. "


     " The Ha.45/11 and Ha.45/12 engines of the Ki.84-Ia model proved to be almost totally unreliable under field

maintenance conditions. Flying aircraft they had only recently acquired, many Hayate pilots found the powerful

aircraft getting away from them. Propeller wake, hitting the dropped landing flaps, often snapped the aircraft's nose

down, and only a skilled pilot could prevent an accident. Many didn't, and the aircraft were washed out. Landing

itself was always a minor miracle. for the metallurgy of the landing gear legs depreciated as production rates increased.

Poor heat-treated made the main members so brittle that the Hayate pilots often cynically joked about the ' 4-Sen's easy breaking legs.' "


     " Replacement aircraft received from Japan had consistently lower top speeds than the previous batch. Rated at over

600 km./hr. when the Hayate was introduced, by the end of 1944 only rare Ki.84-Ia could reach a speed of

(600 km./hr.)* Climb rates and service ceilings also suffered, with pilots drawing straws to get a "good" Hayate

instead of one of the "lemons" delivered to the combat units. " *Note: The figure printed in the book was actually

(400) km./hr. I substituted 600 km./hr. because I had read elsewhere that the Ki.84-Ia speed had fallen off to the

360 mph. (547-579 kph.)range.



Nakajima Ki.84a/b Hayate in Japanese Army Air Force Service by Richard M. Bueschei.

Edited by CORSNING, 14 January 2017 - 09:22 PM.

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