Kawasaki Ki-78 and Kogiken Series
-- Kawasaki Ki-78 introduced radical concepts (05/1941); Kogiken Series immediately after may have helped to disperse them (summer 1941)
-- The goal is to track technological advancement with precision to see how that might be reflected in the tech tree beyond simple placement at each tier.
-- These details are not revealed through specifications but rather through close reading and cross-referencing of development narratives.
Summary:
"Correlation does not imply causation" but a chronological relationship may drive further inquiry
1938 -----------------------------------------------------1941------------------------------------------------------------------------------------------ 1944
Kawasaki Ki-38 --------------> Ki-45------------------------------------------------> Ki-45 KAI---------------------------------------------------> Ki-45 KAIc/d
| --------------> Ki-66 -----> Ki-48-II
| ---------------> Ki-96 -------------------------------------> Ki-108
L-------------------------------------------------------------> Ki-102
Mitsubishi Ki-39/40 ---------> Ki-46-I ------------------------------------> Ki-46-II --------------> Ki-46-III--------> Ki-46-IV ---------------------------> Mitsubishi Ki-83
LKi-46 III KAI --------------------------------------> Mitsubishi Ki-83
Messerschmitt Me 209 -------------------------> Ki-78 --------------------------------> J2M
Messerschmitt Me 209 -------------------------> Ki-78 -----------------> Ki-60 ----> Ki-61 -----> Ki-64 -----> Ki-73 ---------------------------------> Mitsubishi Ki-83
L---------->Ki-61-II --> Ki-100 --> Ki-100-II --> Ki-119
-------------------------------------------------------------------> Kogiken Plan I Type A -------------> Ki-88
Proof 1: Me-209 --> Ki-78 --> Ki-60/61 and J2M
Messerschmitt Me 209 (__/___ - __/1938)
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-- Me 209 V1 established World Air Speed Record on April 26 1939 [755.138 km/h]; record held for nearly 30 years; finally surpassed by a highly modified Grumman F8F-2 on August 16 1969 [776.449 km/h]. (Myhra, 3)
-- Me 209 V4's challenges with the evaporative cooling system (Myhra, 15) are remarkably similar to those experienced by Takeo Doi with the Kawasaki Ki-64.
-- Me 209 V4's later use of two low-drag radiators to remedy the situation was also trialed by Kawasaki Ki-78. Kawasaki Ki-60 and Ki-61 instead use a ventral radiator.
Kawasaki Ki-78 Kensan III (__/1938-01/1944)
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Notes:
-- "...introduced several advanced design features not previously used by the Japanese aircraft industry." (Francillon, 125)
-- "Begun [1938] as a civil project for use in a high-speed research program and for a contemplated attempt to break the world air speed record ... taken over by Imperial Japanese Army [as Ki-78] upon Japan's entry into the war." (Francillon, 125)
-- "Designed by a team of the Aeronautical Research Institute of the University of Tokyo... [before transfer to Kawasaki]." (Francillon, 125)
-- First use of water-methanol injection in Japan ... "momentarily boost power to 1550hp." (Francillon, 125)
-- "... [1st flight on] December 26 1942. It was found extremely difficult to fly at low speeds, and take-off and landing speeds were respectively 205 km/h (127 mph) and 170 km/h (106 mph). Furthermore, loaded weight and wing loading exceeded calculated values and elevator flutter was experienced at 635 km/h (395 mph)." (Francillon, 125-126)
-- "... [31st flight on] December 27 1943 ... reached a maximum speed of 699.6 km/h @ 3527m (434.9 mph @ 11539 ft). This was considerably less than the [ultimate goal of] 850 km/h (528 mph) ... To achieve the calculated performance too many airframe and engine modifications were required and the flight trials of the Ki-78 were suspended after 32nd flight, on January 11 1944." (Francillon, 126)
-- image 1 / image 2 / 3-view (Docavia #7)
Engineer/Designer | Role | Details | Technology appearance elsewhere |
Shoroku Wada Isamu Imashi |
Project Leader (1938) Project Leader (~1941) |
Aeronautical Research Institute of the University of Tokyo Kawasaki |
|
Mineo Yamamoto | Fuselage Design | minimum cross section | Ki-46, Ki-73, Ki-83 ... |
Eichiro Tani* | Wing Design |
laminar flow wing 11m2 wing area combination Fowler, split flaps, drooping ailerons to reduce landing speed |
J2M, N1K1-J, Ki-64, Ki-93, Ki-94-II laminar flow wing Ki-60 low wing area (15.9m2)
|
Seichi Kurino | Engine Installation |
DB.601A 1175hp
water-methanol injection system |
Ki-60, Ki-61, Ki-64 inline engine [more info here] D4Y, M6A inline engine J2M, A6M6, Ki-84, Ki-43-III H2O-methanol injection |
Shojiro Nomura | Engine Installation |
radiators of small frontal area mounted to each side of rear fuselage fan to improve cooling driven by 60hp turbine |
concept abandoned? J2M |
Data: Francillon *Eichiro Tani was later involved in development of Kawanishi Baika (Dyer, 61)
Timeline relative to other projects: (all dates from Francillon unless otherwise indicated)
11/1936 -- Aichi granted a license by Daimler-Benz as early as November 20 1936, to manufacture the DB 600A--D. (Mikesh, 9)
03/1937 -- Kawasaki Ki-28 loses IJA fighter contract to Nakajima Ki-27
12/1937 -- specification issued for what would become Tomio Kubo's Ki-46; December 12 1937
early 1938 -- Japanese Navy acquired from Germany the Heinkel He 118 V4, along with its production rights (Mikesh, 9)
___ 1938 -- Kawasaki Ki-78 project start
04/1939 -- Me 209 V1 established World Air Speed Record on April 26 1939 [755.138 km/h]
late 1939 -- Kawasaki to produce Daimler-Benz under license agreement
09/1939 -- J2M specification issued and preliminary designs completed by Jiro Horikoshi; Aichi Atsuta evaluated but Kasei chosen; work begun 03/1940 (Peczowski, 5)
11/1939 -- Ki-46 prototype completed at Mitsubishi's Nagoya plant; first flight late November at Kagamigahara in Gifu Prefecture north of Nagoya
02/1940 -- Army issues contract to Kawasaki for Ki-60 and Ki-61
03/1940 -- J2M work begins under J. Horikoshi ... assisted by Yoshitoshi Sone and Kiro Takahashi (Peczowski, 5)
04/1940 -- three DB.601A engines imported for Ki-60 project (Bueschel, 4)
12/1940 -- Ki-61 given priority over Ki-60 project
03/1941 -- Ki-60 first prototype complete (15.9m2 wing area) and flown ... 550 km/h; meanwhile Ki-46-II completed.
05/1941 -- Ki-78 wooden mockup complete; production of 2 prototypes entrusted to Kawasaki
summer 1941 -- 'Kogiken Series' studies begin under the direction of engineer (and LCDR) Ando Sheigo of Kokugijutsu Kenkyujo (Army's Air Technical Research Laboratory); Tachikawa and Kawasaki also invited to attend; designs nearing completion by 09/1941. (Dyer, 43-44); [sidenote: coincides with Ki-45 development as Ki-45 KAI]
summer 1941 -- Ki-60 second prototype complete (16.2m2 wing area) ... lighter ... improved cowling streamlining ... 560 km/h
07/1941 -- Kawasaki Ha-40 first Japanese-built DB 601 complete (Nijboer, 18)
09/1941 -- Ki-78 construction of first prototype begins at Kawasaki Gifu plant (Francillon); 'Kogiken Series' designs nearing completion (Dyer, 43-44)
12/1941 -- Ki-61 prototype first flight
02/1942 -- J2M prototype complete
03/1942 -- J2M prototype first flight March 20 1942 at Kasumigaura
05/1942 -- specification issued for what would become Ki-46-III
06/1942 -- Messerschmitt Chief Test Pilot Willi Stor's Me109 E/2 fighters arrived in Japan in for evaluation
__/1942 -- "testing [of Ki-61] in 1942 proved it to be a better performer than the Ki-43 Model II prototype, a captured Curtiss P-40E, and even Bf109 E/2"
10/1942 -- Ki-61 cooling system modified and tested as proof of concept for Ki-64 [~620 km/h]; started 10/1942 and continued to the end of 1943 (Dyer); J2M2 accepted for production as the Navy Interceptor Fighter Raiden (Thunderbolt) Model 11.
12/1942 -- Ki-78 first flight December 21 1942 [see notes above]; meanwhile Ki-46-III completed.
04/1943 -- only 14 J2M aircraft delivered by this time (including the 3 J2M1 prototypes) due to refinement issues and production priority to A6M.
05/1943 -- specification issued for long-range escort fighter; in response Tomio Kubo assisted by Mizuno, Kato and Sugiyama begin the Ki-73 project; abandoned before construction to focus on Ki-83 [details here].
06/1943 -- Rikugun (Army Aerotechnical Research Institute) begins stopgap study for adaptation of Ki-46-III to serve as a high-altitude interceptor fighter; pursued actively from 05/1944 onwards.
12/1943 -- Ki-78 makes 32nd flight December 27 1943 [699.6 km/h @ 3527m]; Ki-61-II first flight; Ki-64 first flight [700 km/h @ 4000m]
01/1944 -- Ki-78 project suspended January 11 1944
05/1944 -- Rikugun actively pursues adaptation of Ki-46-III to serve as high-altitude interceptor fighter; modification program initiated at Tachikawa; meanwhile J2M5 begins flight trials
10/1944 -- Ki-46-III KAI (Army Type 100 Air Defense Fighter) adaptation completed; lacked climbing speed; further developed as Ki-46-IIIb (only a few built); Ki-46-IIIc remained on drawing board. Ki-83 prototype construction began; 4 Ki-83's complete by 05/1945.
11/1944 -- Ki-61-II conversion to radial engine and redesignation as Ki-100; Ki-83 first flight November 11 1944.
02/1945 -- Ki-100 first flight
02/1945 -- Ki-46-IV demsonstrates 700 km/h average speed with strong tailwind; two produced; Ki-46-IVb fighter version with nose-mounted cannon deleted from production priority.
05/1945 -- Ki-83 four prototypes complete by this time
08/1945 -- Surrender; advanced versions of Ki-83 in progress as Ki-95 and Ki-103.
Conclusions
-- Ki-78 contributed to the development of Ki-60, 61, 64 after Kawasaki lost the Army fighter contract to Nakajima Ki-27; concepts also show up in Mitsubishi J2M
-- Ki-64's enhanced model to generate 2800hp may refer to a water-methanol injection system to boost engine horsepower
-- movement of radiators from the sides of the fuselage (Ki-78) to the wings (Ki-64) appears to be an effort at streamlining in order to get closer to the 850 km/h goal, at the expense of operational range
-- coupling of DB.601A engines (Ki-64) appears to be an effort to get closer to the 850 km/h goal through raw horsepower; same concept employed by Tomio Kubo with Ki-73 but abandoned in favor of Ki-83
-- see also: Me 209, Kogiken studies
Me-209 | Ki-78 | Ki-60 | Ki-61 | Ki-64 | Mitsubishi Ki-83* | |
Engine | DB.601A 1175hp |
DB.601A 1100hp |
DB.601A as Ha-40 1175hp |
2xDB.601A as Ha-201 2350hp |
2xHa-211 Ru | |
Span (m) | 8 | 10.5 | 12 | 13.5 | 15.5 | |
Length (m) | 8.1 |
8.47 |
8.75 (Ki-61-Ib) 9.16 (Ki-61-II KAIa) |
11.03 | 12.5 | |
Height (m) | 3.07 | 3.7 | 3.7 | 4.25 | 4.6 | |
Wing area (m2) | 11 | 16.2 | 20 | 28 | 33.52 | |
Empty (kg) | 1930 |
2150 |
2210 (Ki-61-Ib) 2840 (Ki-61-II KAIa) |
4050 | 5980 | |
Loaded (kg) | 2300 |
2750 |
2950 (Ki-61-Ib) 3780 (Ki-61-II KAIa) |
5100 | 8795 | |
Wing loading (kg/m2) | 209 |
169.8 |
147.5 (Ki-61-Ib) 189 (Ki-61-II KAIa) |
182.1 | 262.4 | |
Power loading (kg/hp) | 2 |
2.4 |
2.51 (Ki-61-Ib) 2.52 (Ki-61-II KAIa) |
2.17 | 2 | |
Maximum speed | 700 km/h @ 3500m |
560 km/h @ 4500m |
592 km/h @ 4860m (Ki-61-Ib) 610 Km/h @ 6000m (Ki-61-II KAIa) |
690 km/h @ 5000m* |
655 km/h @ 5000m 686 km/h @ 8000m 704.5 km/h @ 9000m |
|
climb
ceiling (m)
|
|
...
8000 |
8:00 to 5000m
10000 |
5:31 to 5000m (Ki-61-Ib) 6:00 to 5000m (Ki-61-II KAIa)
11600 (Ki-61-Ib) 11000 (Ki-61-II KAIa) |
5:30 to 5000m
12000 |
10:00 to 10000m
12660
|
range (km) | 600 |
... |
1100 (Ki-61-Ib) 1600 (Ki-61-II KAIa) |
1000 | 1953 |
Data: Francillon *Ki-64 --> Ki-73 --> Ki-83 relationship established here.
Conclusions:
-- Ki-78's dimensions and weight were upscaled for Ki-60, Ki-61, Ki-64
-- Ki-64's top speed was attained through engine coupling and aerodynamic refinement. Dyer indicates that a higher top speed was hoped for with improvements to the engines, which may have been the water-methanol injection system used by Ki-78.
-- Ki-83 finally achieved a remarkable formula by way of Ki-73 (coupled liquid-cooled engine project which did not materialize).
Kawasaki Ki-60, 61, 61-II, 64
Mitsubishi J2M Raiden (Thunderbolt) 雷電 -- "Jack" (05/1942)
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Proof 2: Ki-46 --> Ki-83
-- see 10/1944 under Ki-78 timeline; both designed by Tomio Kubo.
Mitsubishi Ki-46 -- "Dinah" (11/1939, 03/1941, ~05/1942+, 10/1944+)
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Production | Airframe | Engine | Speed | Armament | |
34 (1939-1940) | Ki-46-I recon | IV 2x Mitsubishi Zuisei Ha-26-I 875hp | 540 km/h @ 4069m | 1x7.7mm Type 89 rear | |
1093 (1940-1944) | Ki-46-II recon | V 2x Mitsubishi Zuisei Ha-102 1080hp | 604 km/h @ 5800m | 1x7.7mm Type 89 rear | |
2 (~05/1942) 609 (1942-1945) |
Ki-46-III recon | VII 2x Mitsubishi Kinsei Ha-112-II 1500hp | 629 km/h @ 6002m | (added 13mm back/head armor plate for pilot) | |
(10/1944+) | Ki-46-III KAI interceptor | VII 2x Mitsubishi Kinsei Ha-112-II 1500hp | 629 km/h @ 6002m | VI 2x20mm Ho-5 (N) | VI 1x37mm Ho-203 forward-up 30-degrees* |
"a few" (03/1945+) Drawing board |
Ki-46-IIIb ground attack Ki-46-IIIc |
Ki-46-IIIb: oblique removed Ki-46-IIIc: 2x20mm Ho-5 oblique |
|||
4 (1943-1944) | Ki-46-IV recon | VII 2x Mitsubishi Kinsei Ha-112-II Ru 1500hp |
634 km/h @ 7202m 629 km/h @ 9997m |
||
Drawing board |
Ki-46-IVa Ki-46-IVb |
Ki-46-IVa: not specified Ki-46-IVb: "nose-mounted cannons" |
Data: Francillon All built by Mitsubishi Jukogyo K.K. at Nagoya and Toyama; 1742 total.
Notes:
-- design team led by Tomio Kubo; "...perhaps the most outstanding Japanese aircraft to serve its country during the Pacific War." (Francillon, 168-177)
-- streamlined reconnaissance aircraft; later adapted for high-altitude bomber interception; adaptation study began 06/1943, idea revived 05/1944 as U.S. B-29 bombers initiated high-altitude daylight bombing from foothold in China (Francillon, 168-177)
-- "[Kubo] obtained the cooperation of the Aeronautical Research Institute of the University of Tokyo which developed close-fitting cowling for the two Mitsubishi Ha-26 fourteen-cylinder radials, with resultant improvement in pilot's sideways vision and a reduction in drag, and which also contributed to the design of the fully retractable landing gear selected for the aircraft. To meet the stringent performance requirements Tomio Kubo adopted a thin wing section and a fuselage of small diameter in which a large fuel tank was mounted close the aircraft's center of gravity. The pilot and radio-operator/gunner were seated in two cockpits separated by the fuselage fuel tank. Design and construction of the first prototype progressed slowly as it was found necessary to conduct extensive wind-tunnel tests in the facilities of the Aeronautical Research Institute of the University of Tokyo ... [aircraft finally completed early 11/1939 at Mitsubishi's Nagoya plant]." (Francillon, 170)
Ki-46-I and Ki-46-II
-- Reconnaissance
Ki-46-III KAI
-- "Shortly before China-based B-29's ... initiated high-altitude daylight raids over Japan, the JAAF Headquarters became aware of the urgent need to develop an interceptor fighter with good performances at high altitude. The Army Aeronautical Research Institute at Tachikawa (Rikugun Kokugijutsu Kenkyujo) had, in [06/1943] studied the possibility of adapting the [Ki-46-III] which was one of the few JAAF operational aircraft to have required altitude performance ... [05/1944] project urgently revived and conversion lines were quickly set up at the Tachikawa Dai-ichi Rikugun Kokosho (First Army Air Arsenal at Tachikawa). The photographic equipment and forward fuselage were replaced by [see table above] ... canopy was modified to resemble that of the Ki-46-II ... known as the Army Type 100 Air Defense Fighter ... completed 10/1944. From [11/1944] aircraft of this type served in the defense of Japan, equipping 2 Sentais, 5 Dokuritsu Dai Shijugo Chutai and 1 Dokuritsu Hikotai. However ... not very successful, being too vulnerable to the concentrated fire of the B-29 and lacking the climbing speed required of an interceptor." (Francillon, 8)
-- [sidenote: Tomio Kubo's Ki-83 was in prototype stage at this time, completed 10/1944, first flown 11/1944]
-- [sidenote: adaptation of Ki-46 to interceptor role is concurrent with Ki-102b (10/1944-07/1945) which uses the same engine.]
-- [sidenote: the same institute produced Ki-93, prototype complete and flown 04/1945; the diamond-shaped horizontal tail surface, and vertical tail surface with leading edge and receding tip, bear strong resemblance to Ki-46, moreso than to any other heavy fighter; more details along those lines here]
-- "Development of 2 additional fighter versions, dispensing with the 37mm cannon, were begun by Mitsubishi [03/1945]. They were the Ki-46-IIIb (Army Type 100 Ground-Attack Aircraft) of which only a few were buit, and the Ki-46-IIIc, with obliquely mounted 20mm Ho-5 cannons, which remained on the drawing boards." (Francillon, 8)
Ki-46-IV
-- engine upgrade to improve capability of avoiding interception. (Francillon, 9)
-- "...intake air was methanol-cooled as the space available in the nacelles was too limited for using a normal intercooler." (Francillon, 9)
-- Ki-46-IVa flight tests commended [02/1944] ... "However, the production of the turbo-supercharged Ha-112-Ru was too slow to gain tempo and these engines were assigned in priority to high-altitude interceptor fighters such as the Kawasaki Ki-100-II, Ki-102a and Ki-102c. Consequently the Ki-46IVa never replaced the Ki-46-III on Mitsubishi's production lines and a fighter version, Ki-46-IVb, with nose-mounted cannons remained on drawing boards." (Francillon, 9)
Edited by J311yfish, 11 November 2014 - 04:34 PM.