Desperate War of Japan in the Pacific

Air cooled aircraft engine

New joint designation of aircraft engine

USN and IJN loved air cooled engines in the Pacific War. USN used engines of Wright and P&W. IJN used Nakajima and Mitsubishi. IJN and IJA supplied aircraft engine with aircraft makers. The makers had no option to select important engine. In the late of the Pacific War, Japan established Munition Ministry which gave the designation of IJA and IJN new ones.

Tbl.1 New joint designation of aircraft engine Taga, p312
Joint designationMakerIJNIJA


TG.52 of USN had 266 FM-2 in the Okinawa battle. The FM-2 was equipped with 9-cylinder Wright R-1820-56 which produced 1,350hp[3]. FM-2 had bigger power than type 52 of Zero, and had better zoom. I suppose FM-2 was superior than type 52 of Zero. How often did IJN and USN fighters aerial combats at high altitude? Fighters had to escort bombers. IJN bombers usually dived at 3,000m and torpedo bombers had to decend at sea level to release torpedos. Could a man find a wake of an aircraft carrier at 6,000m altitude?

Tbl.2 Engines for F4F and Zero F4F
TypeFM-2F4F-4FM-1F4F-3Zero type52
Take off power1,350hp1,200hp1,200hp - 1,130hp
hp/altitude 1,300/1,200m
- 1,100/2,850m
Charger1-stage, 2-speed2-stage, 2-speed2-stage, 2-speed2-stage, 2-speed1-stage, 2-speed
Climb [m/min]1,1136681,006701857

18-cylinder 2,000hp class of Nakajima and Mitsubishi

Nakajima and Mitsubishi were 2 big aircraft engine makers in Japan. Munition Ministry decided to adopt Nakajima product of 18-cylinder 2,000hp class engine. But Nakajima could not product on time. Nakajim tried to develop the smallest 2000 hp. Nakajima had better design a bigger radius engine so as to be in time. I do not know why IJA was cooperative with IJN. IJN and IJA always developed the aircraft weapon of guns and radars separately, and purchased manufacturing license of the same German engine independent.

Nakajima Ha-45

Nakajima purchased manufacturing license of Cyclone 9 Engine from Wright in 1934[1][6]. Wright could increase the 9-cylinder engine upto 1,350 hp. IJN ordered a trial in September 1940. The precedent of Ha-45 was Ha-35 of Nakajima. Ha-35 was 14-cylinder 27.9L two-row radial engine which was the production of 31,113 including Ha-25 and Ha-115 of IJA. But the power of Sakae was up only 1,100 hp from 950 hp.

Ha-45 had small 18-cylinder 35.8L displacement which was also called Homare[5]. Nakajima made them at Musashino Seisakusyo which was the most important target #357 of B-29. Nakajima was troubled to make Ha-45 in short of special steels.

Tbl.3 Ha-45

Mitsubishi Ha-43

Mitsubishi purchased manufacturing license of Hornet Engine from P&W in 1936[2][7]. Mitsubishi had begun to develop a 18-cylinder engine called A18 in 1939, which was originated from Kasei. The A18 was diameter 1,370mm, weight 944kg, displacement 54.1L and takeoff power 1,900hp. IJA adopted it for Ki-67 and designated Ha-104. And Ha-214 was developed from Ha-104, produced 2,300 to 2,500hp with a fluidic super charger or a turbo charger. The production of Ha-104 and Ha-214 was 2,860. While Ha-43 was developed from 14-cylinder 32.3L two-row radial engine Kinsei. Kinsei-50 got 1,300hp in 1940, and 1,500hp in 1941.

While P&W began to develop R-2800 in 1936. XF4U had already flown with P&W XR-2800 in May 1940, and recorded 651.8 km/h on 1 October. P&W developed a lot of varients of 18-cylinder R-2800 successfully[4]. It was too late to develop 18-cylinder engine for Japan. How Japan was competitve to develop?

Turbo charger production makers

Japan failed to product 2,000hp class engines working at high altitude. One of the reasons was supercharger. Japan could not make a 2-stage supercharger, nor turbocharger reliable. Mitsubishi tried development of turbo charger. In case of US, the chargers were developed by GE etc. GE was an electric maker which productioned turbines. Why could Mitsubishi depend on other companies like IHI, Hitachi and Toshiba for aircraft? We Japanese prefer to do our jobs ourselves, but sometimes it is not on time. P-38 was equipped with 2 turbo chargers. The photo shows them on the tops of 2 berries. A site shows that an engineer of Mitsubishi remembers a military turbo charger trial[8].

Fig.1 Turbocharger

Air cooled 14-cylinder radial engines for fighters

Russia, Germany and Japan developed air cooled 14-cylinder radial engines for fighers eagerly in WWII. The table shows ultimate production type of the engignes. Russian La-7 was competitive with German Fw190A-3, though the engine of the La-7 had smaller power than Fw190A-3. If IJN developed carrier fighters of 15,000 or 1,800hp engine in the Pacific War, IJN fighters might compete F6F in 1943. The production of Ha-32 was over 11,000 including all the sub types[10]. While the production of Ha-34-11 (Ha-109) was 3,554.

Tbl.4 Air cooled 14-cylinder radial engines
NationDesignationMakerWeightDisplacementTake off powerApplyYear

A trial of Ki-100 flew on 1 February 1945[9]. 57 La-7 of the first batch production were deployed in May 1944[11]. Fw190 adopted BMW139 of 18-cylinder at first, but the engine was over heat. BMW made a test of BMW801 in April 1939. RLM ordered 102 Fw190A-1 in 1941. Fw190A-1 was equipped with BMW801C of 1,600hp take-off power, and deployed in August 1941. Fw190A-3 was deployed in 1942. Fw190A-9 was roll out in February 1944. The production was 1,334[12].

Rare metal

The Government increased import of rare matals much in 1941 compared with 1936 rapidlly. Nickel increased 20.4 folds as shown in Tabl.6. The Government understood how Nickel is important to continue a war. But the result was miserable.

Tbl.6 Incerased import ratio


Japan began the Pacific War to get resources abroad. But she could not supply for even military use at all. Sales of rare metal was limited under control of government in WWII. The required index lowered as follows Tbl.2. I do not why Nickel was the bottle neck of war time production. At first, Government planned import of Celebes where Japan occupied in the beginning of the war. It seems to me that Nickel had been already very short before the Pacific War. So the index dropped to 30% from 60%. I think Japanese controlled economy did not work well.
Morimoto, p81, p191-192

Tbl.5 Required index [%]
Year194019411942 1943
Co502010 5
Ni603020 10
W, Mo--65 65
V--70 60
Cr--90 70

Vacuum tube

Ni is material of electrode of vacumn tubes. The tubes were used for wireless commnunicators and radars. Signal processing was done by a lot of vacumn tubes. IJN needed a lot of them and ordered makers. However, there were no such metals in the controlled domestic market. The makers, Toshiba, NEC and JRC were shortage of Ni.

Black Market

IJN and JRC developed a radar searching vessels which was called type 22 in 1942. IJN ordered JRC to make 100 sets at once. But IJN had not allocated Ni for JRC. So Mr. Mizuma of IJN inroduced to JRC black market. JRC bought Ni from the market, but police found the fact and arrested a manager and a director of JRC.[15][16] In those days, Japanese economy was under strict control of government alike of North Korea nowdays. A bureaucrat of Munitions Ministry proposed of captured nickel coins in Hong Kong. The coin was good for vacuum tubes. All the makers of vacuum tubes rushed into the coins.[17]

Aircraft engine

Nakajima was troubled to make aircraft engines because of shortage of speciallized steel. Two site show examples of crank shaft of SCM415 and SCM440 nowdays.[18][19]
  1. Ha-40
  2. Piston ring material
  3. Crome Kou

Gun material for IJN

IJN made guns with 1.2 to 2% Nickel.
Houshin no seizou-hou

Battleship Hyuga and Ise

Battleship Hyuga and Ise had stayed in Singapore in February 1945. Other battleship Yamato and Nagato had already returned home. Japan had operated to ferry strategic materials to Japan since January 1945. But only one thirds of 30 merchant ships reached to Japan. So IJN planned that warships ferry the materials. The warships were battleship Hyuga and Ise, cruiser Oyodo, destroyer Kasumi, Hatsushimo and Asashimo. They departed from Singapore in the evening of 10 February. They arrived at Muture Island near the Kanmon Strait on the evening of 19 February. They ferried gasoline of 2,000 kL, crude oil of 3,000 ton[13]. They ferried rubber, tin and tungsten of 3,700 ton. This amount was a capacity of medium size merchant ship.


Now, JOGMEC of Japan saves rare matal which are Ni, Cr, W, Co, Mo, Mn and V now. Japan imports Nickel from Indonesia that takes part of Japan's 45%.
Jpan's import nations of Nickel


NATO nations stay their armies in Afganistan. New York Times wrote that there might be a big mine of Li comparable to Bolvia[14]. Is this one of reasons why Western nations invaded Afganistan?

  1. Ikari, p220
  2. Ikari, p220
  3. Raito R-1820
  4. Pratt & Whitney R-2800
  5. Homare (Ha-45)
  6. Wright R-1820
  7. Pratt & Whitney R-1690
  8. Haiki turbine no omoide
  9. Hien, p231
  10. Gunzo, p84-95, No75
  11. Iiyama, p342
  12. Fw190, p25
  13. Gunzo, p168-177
  14. Bei-Afgan Senso no shi no Mokuteki
  15. Nakagawa p.154
  16. JRC
  17. Nakagawa p.200-201
  18. SCM415
  19. SCM440

© 2007-2015 Enoki