Showing posts with label Kawasaki. Show all posts
Showing posts with label Kawasaki. Show all posts

Sunday, March 13, 2011

Kawasaki Ki-61

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Ki-61 "Hien"
A Ki-61-I-Otsu
Role Fighter aircraft
Manufacturer Kawasaki Aircraft Industries
First flight December 1941
Introduced 1943
Retired 1945
Primary users IJA Air Force
Chinese Nationalist Air Force
Indonesian People's Security Force
People's Liberation Army Air Force
Number built 3,159
Developed into Kawasaki Ki-100
The Kawasaki Ki-61 Hien (飛燕, roughly "flying swallow") was a Japanese World War II fighter aircraft used by the Imperial Japanese Army Air Force. The first encounter reports claimed Ki-61s were Messerschmitt Bf 109s: further reports claimed that the new aircraft was an Italian design, which led to the Allied reporting name of "Tony", assigned by the United States War Department.[1] The Japanese Army designation was "Army Type 3 Fighter" (三式戦闘機).[2] It was the only mass-produced Japanese fighter of the war to use a liquid-cooled inline V engine. Over 2.500 Ki-61s were produced, first seeing action around New Guinea in 1943, and continuing to fly combat missions throughout the war.[3]

Contents

  • 1 Design and development
  • 2 Operational history
    • 2.1 Ki-61 Special Attack Unit
  • 3 Ki-61 units
  • 4 Variants
  • 5 Operators
  • 6 Specifications (Ki-61-I-KAIc)

Design and development

A factory fresh Ki-61-I-Ko being ferried to either the 68th or 78th Sentai in New Guinea; it has yet to receive the distinctive dark green "palm leaf" pattern which was usually applied by front-line units in the Southern theatre, nor does it have the usual black anti-glare panel forward of the cockpit.
The Ki-61 was designed by Takeo Doi and his deputy Shin Owada in response to a late 1939 tender by the Koku Hombu[N 1] for two fighters, each to be built around the Daimler-Benz DB 601Aa. Production aircraft would use a derivative of the DB 601, known as the Ha-40, which was to be manufactured by Kawasaki at its Akashi plant. The Ki-60 was to be a heavily-armed specialised interceptor, with a high wing loading; [N 2] the Ki-61 was to be a more lightly-loaded and armed general-purpose fighter, intended to be used mainly in an offensive, air superiority role at low to medium altitudes.[N 3]
Both single-seat, single-engine fighters used the same basic construction, being of all-metal alloys with semi-monocoque fuselages and three-spar wings, with alloy-framed, fabric-covered ailerons, elevators and rudders. Priority was given to the Ki-60, which first flew in April 1941, while design work on the Ki-61 did not begin until December 1940. Although the Ki-61 was broadly similar to the Ki-60, it featured several refinements exploiting lessons learned from the disappointing flight characteristics of the earlier design.[4]
The all-metal, semi-monocoque fuselage was basically oval in cross-section, changing to a tapered, semi-triangular oval behind the cockpit canopy, with a maximum depth of 1.35 m (4 ft 5 in). An unusual feature of the Ki-61 was that the engine bearers were constructed as an integral part of the forward fuselage, with the cowling side panels being fixed. For servicing or replacement, only the top and bottom cowling panels could be removed. A tapered, rectangular supercharger air intake was located on the port-side cowling. Behind the engine bulkhead were the ammunition boxes feeding a pair of synchronized 12.7 mm (.50 in) Ho-103 machine guns which were set in a "staggered" configuration (the port weapon slightly further forward than that to starboard) in a bay just above and behind the engine. The breeches partly projected into the cockpit, above the instrument panel. The Ho-103 was a light weapon for its caliber (around 23 kg/51 lb) and fired a light shell, but this was compensated for by its rapid rate of fire. The ammunition capacity was limited, having only around 250 rounds for each weapon. A self-sealing fuel tank with a capacity of 165 L (44 US gal) was located behind the pilot's seat. The windshield was armoured and there was a 13 mm (.51 in) armour plate behind the pilot. The radiator and oil cooler for the liquid-cooled engine were in a ventral location below the fuselage and wing trailing edge, covered by a rectangular section fairing with a large, adjustable exit flap.[4]
The evenly-tapered wings had an aspect ratio of 7.2 with a gross area of 20 m² (215.28 ft²) and featured three spars; a Warren truss main spar and two auxiliary spars. The rear spar carried the split flaps and long, narrow-chord ailerons, while the front spar incorporated the undercarriage pivot points. The undercarriage track was relatively wide at 4 m (13 ft 1.5 in). Each wing had a partially self-sealing 190 L (50 US gal) fuel tank behind the main spar, just outboard of the fuselage. A single weapon (initially a 7.7 mm/0.303 in Type 89 machine gun) was able to be carried in a weapons bay located behind the main spar.[4]
The first prototype of the San-shiki-Sentohki ichi gata (Type 3 Fighter, Model 1, the official IJAAF designation) first flew in December 1941 at Kagamigahara Airfield (now Gifu Air Field).[5] Although test pilots were enthusiastic about its self-sealing fuel tanks, upgraded armament, and good dive performance, the wing loading of 146.3 kg/m² (30 lb/ft²) at an all-up weight of 2,950 kg (6,500 lb) was viewed with scepticism by many of the senior officers of the Koku Hombu, who still believed in the light, highly manoeuvrable, lightly armed fighter epitomised by the then new Ki-43-I-Hei which had a wing loading of 92.6 kg/m² (19 lb/ft²) (and even that was considered borderline compared to the earlier Ki-27).[6]
To address these concerns, Kawasaki staged a fly-off between two Ki-61 prototypes and the Ki-43-I, a pre-production Ki-44-I, a LaGG-3 (flown to Manchuria by a defector), a Bf 109E-3, and a captured P-40E Warhawk. The Ki-61 proved the fastest of all the aircraft and was inferior only to the Ki-43 in manoeuvrability.[6][7][8][9]
The Ki-61 was the last of the fighters powered by the DB-601 or its foreign derivatives, and it was soon overshadowed by fighters with more powerful engines. By the time it first flew in December 1941 –one year after the Macchi C.202's first flight and three years after the first Bf 109E– the engine was already underpowered compared to the new 1,120 kW (1,500 hp) inline or 1,491 kW (2,000 hp) radial engines being developed (and already nearing the mass-production stage) to power the next generation of combat aircraft such as the Messerschmitt Bf 109 G, or the Republic P-47. Moreover the inline Ha-40 engine proved to be an unreliable powerplant.[10][11]
The DB-601 engine required precise and sophisticated manufacturing; the Ha-40 was lighter (by roughly 30 kg/70 lb) and required even higher manufacturing standards. Reaching these standards proved to be a "stretch" for Japanese manufacturers, an issue further complicated by the variable quality of materials, fuel, and the lubricants needed to run a sensitive, high-performance engine. The Japanese equivalent of the more powerful DB-605 engine was the Ha-140, which was fitted onto the Type 3 to produce the Ki-61-II high-altitude interceptor.[10][12]
Compared to the Ki-61-I, the Ki-61-II had 10% greater wing area, used more armour and was powered by the Kawasaki Ha-140 engine generating 1,120 kW (1,500 hp). After overcoming initial fuselage and wing stability problems, the new interceptor reverted to the original wing and was put into service as the Ki-61-II-KAI. However, the Ha-140 engine had severe reliability problems which were never fully resolved, and around half of the first batch of engines delivered were returned to the factory to be re-built. A US bombing raid on 19 January 1945 destroyed the engine factory in Akashi, Hyōgo, and 275 Ki-61-II-KAI airframes without engines were converted to use the Mitsubishi Ha-112-II radial engine, resulting in the Ki-100. While the Ha-112 solved the problems encountered with the Ha-140, the new engine still had a major weakness: a lack of power at altitude, which diminished its ability to intercept high-flying B-29s relative to the Ki-61-II.[10][13]
During testing, the Hien proved capable[14], but several shortcomings were subsequently revealed in operational service, namely lack of armor protection and a sub-standard engine that eventually led to a new engine being considered.[15]

Operational history

Unusual wartime photo of a captured Ki-61 being tested by the USAAF
The Ki-61 looked so different compared with the usual radial-engined Japanese fighters that the Allies at first, believed it to be of German or Italian origin, possibly a license-built Messerschmitt Bf 109. The first Ki-61 seen by Allied aircrew had been misidentified as a Bf 109 by USAAF Capt. C. Ross Greening during the Doolittle Raid. In early reports, when it was thought to have been a German fighter, the Ki-61 had been code-named "Mike".[16][17]. The final, and better known code name adopted was "Tony", because the Ki-61 looked like an Italian aircraft.[18][19]
The new Ki-61 Hien fighters entered service with a special training unit, the 23rd Chutai, and entered combat for first time in early 1943, during the New Guinea campaign.[20]. The first Sentai (Air Group/Wing) fully equipped with the Hien was the 68th in Wewak, New Guinea,[20] followed by the 78th Sentai stationed at Rabaul. Both units were sent into a difficult theatre where jungles and adverse weather conditions, coupled with a lack of spares, quickly undermined the efficiency of both men and machines. Because the Ki-61 was so new, and had been rushed into service, it inevitably suffered from teething problems. Almost all of the modern Japanese aircraft engines, especially the Ki-61's liquid-cooled engines, suffered a disastrous series of failures and ongoing problems,[11] which resulted in the obsolescent Ki-43 still forming the bulk of the JAAF's fighter capability.
Initially, this campaign went successfully for the Japanese Army Air Force (JAAF), but when the Allies re-organized and enhanced the combat capabilities of their air forces, they gained the upper hand against the JAAF.[11] High non-combat losses were also experienced by the Japanese during this campaign. For example, while in transit between Truk and Rabaul, the 78th lost 18 of its 30 Ki-61s.[21][22]
Even with these problems, there was some concern in Allied aviation circles regarding the Hien:
The new Japanese fighter caused some pain and consternation among Allied pilots, particularly when they found out the hard way that they could no longer go into a dive and escape as they had from lighter Japanese fighters. ...General George Kenney [Allied air forces commander in the Southwest Pacific] found his P-40s completely outclassed, and begged for more P-38s to counter the threat of the new enemy fighter.[citation needed]
However, the increasing numerical strength of Allied bomber units, along with inadequate anti-aircraft systems, imposed crippling losses on Japanese units. Approximately 100 out of 130 Japanese aircraft based in the Wewak area were lost during the attacks of August 17–21 1943. By the end of the campaign, nearly 2,000 Japanese aircraft had been lost in air attacks from up to 200 Allied aircraft at a time, around half of which were B-24s and B-25s armed with fragmentation bombs.[11] After the Japanese retreat, over 340 aircraft wrecks were later found at Hollandia.[11].
The Ki-61 was also utilised in Southeast Asia, Okinawa, China and as an interceptor during US bombing raids over Japanese home islands, including against Boeing B-29 Superfortresses. The Ki-61 was notable for many reasons: initially identified as of either German or Italian origin, these aircraft were capable of matching Allied aircraft such as the P-40 in speed, and as evaluation had already showed, were superior in almost every respect. However, the armament of the early Hien was lighter, but still sufficient for most purposes. Some authors claim that the Lockheed P-38 Lightning was measurably superior.[23] The Ki-61 carried a great deal of fuel, but due to having self-sealing fuel tanks, it did not have the reputation for being "easily flammable", as were many other Japanese aircraft.[10]
Due to the additional weight, the Ki-61's performance and agility suffered when its armament was increased, but it still remained capable with a 580 km/h (313 kn) maximum speed. The cannon armament was needed to counter the Allied bombers, which proved to be difficult to shoot down with only 12.7 mm (.50 in) machine guns. The empty and maximum weights for the Ki-61 prototype (2 × 12.7 mm/50 in + 2 × 7.7 mm/.303 in) were 2,238 kg (4,934 lb) and 2,950 kg (6,504 lb), respectively; for the Ki-61-I basic (4 × 12.7 mm/.50 in) 3,130 kg (6,900 lb); and for the Ki-61-KAI (2 × 12.7 mm/.50 in + 2 × 20 mm), 2,630 kg (5,798 lb) and 3,470 kg (6,750 lb).[10]
A number of Ki-61s were also used in Tokkotai (kamikaze) missions launched toward the end of the war. The Ki-61 was delivered to 15th Sentai (group/wing), as well as some individual Chutaicho (junior operational commanders) in other Sentai, and even to operational training units in the JAAF. The aircraft was largely trouble-free in service except for the liquid-cooled engine which tended to overheat when idling on the ground and suffered from oil circulation and bearing problems.[24]

Ki-61 Special Attack Unit

An ex-23rd Sentai, 2nd Chutai Ki-61 found and photographed at Inba airbase by USAAF personnel in 1946.
The tactic of using aircraft to ram American B-29s was first recorded in late August 1944, when B-29s from Chinese airfields attempted to bomb the steel factories at Yawata. Sergeant Shigeo Nobe of the 4th Sentai intentionally flew his Kawasaki Ki-45 into a B-29; debris from the explosion severely damaged another B-29, which also went down.[N 4][25] Other attacks of this nature followed, as a result of which individual pilots determined it was a practicable way of destroying B-29s.[26]
On 7 November 1944, the officer commanding the 10th Hiko Shidan (Air division) made ramming attacks a matter of policy by forming ramming attack flights specifically to oppose the B-29s at high altitude. The aircraft were stripped of their fuselage armament and protective systems in order to attain the required altitudes. Although the term "kamikaze" is often used to refer to the pilots undertaking these attacks, the word was not used by the Japanese military.[27]
The units assigned to the 10th Hiko Shidan included the 244th Hiko Sentai (Fighter group), then commanded by Captain Takashi Fujita, who organised a ramming flight called "Hagakure-Tai" ("Special Attack Unit"), which was composed out of volunteers from the three Chuatai (squadrons) of the 244th: the 1st Chutai "Soyokaze", 2nd Chutai "Toppu", and the 3rd Chutai known as "Mikazuki".
First Lieutenant Toru Shinomiya was selected to lead the Hagakure-Tai. On 3 December 1944 Shinomiya, along with Sergeant Masao Itagaki and Sergeant Matsumi Nakano, intercepted a B-29 raid; Shinomaya rammed one B-29, but was able to land his damaged Ki-61, which had lost most of the port outer wing, back at base. After attacking another B-29 Itagaki had to parachute from his damaged fighter, while Nakano rammed and damaged Long Distance of the 498th BG and crash-landed his stripped-down Ki-61 in a field. Shinomaya's damaged Ki-61 was later displayed inside Tokyo's Matsuya department store while Nakano's Ki-61 was displayed outside, alongside of a life-size cut-away drawing of the forward fuselage of a B-29.[28][N 5] These three pilots were the first recipients of the Bukosho, Japan's equivalent to the Victoria Cross or Medal of Honor, which had been inaugurated on 7 December 1944 as an Imperial Edict by Emperor Hirohito (there are 89 known recipients, most of whom fought and scored against B-29s).[29][30] The existence of the ramming unit had been kept confidential until then, but it was officially disclosed in the combat results announcement and officially named "Shinten Seiku Tai" ("Body Attack Detachment") by the Defense GHQ. On 27 January 1945, Itakagi survived another ramming attack on a B-29, again parachuting to safety, and received a second Bukosho; he survived the war as only one of two known double-Bukosho recipients.[31] Sergeant Shigeru Kuroishikawa was another distinguished member of the unit.
However, these pilots gained no reprieve and despite their successes they were obligated to continue these deadly and dangerous ramming tactics until they were killed, or else wounded so badly that they could no longer fly. They were regarded as doomed men and were celebrated among the ranks of those who were going to certain death as Tokkotai (kamikaze) pilots.[32]
Some other Ki-61 pilots also became well-renowned, among whom was Major Teruhiko Kobayshi of the 244th Sentai, who was credited by some with a dozen victories mostly due to conventional attacks against B-29s.[33]

Ki-61 units

The Hiko Sentai, usually referred to as Sentai, was the basic operational unit of the IJAAF, composed of three or more Chutai (companies or squadrons). A Sentai had 27 to 49 aircraft, with each Chutai having 16 aircraft and pilots plus a maintenance and repair unit. Several sentai had other units under their operational control, most notably the Hagakure-Tai ("Special Attack Units") of the 244th Sentai. By 1944, with the depredations of Allied attacks on supply lines and airfields, as well as the loss of pilots and aircraft through combat attrition and accidents, few sentai were able to operate at full strength.
Units operating the Ki-61 "Hien", data from[34][35]
Sentai Established Aircraft Type(s) Area of Operations Disbanded Notes Notable Pilots
17th 10 February 1944 at Kagamigahara, Gifu Prefecture[N 6] Ki-61, Ki-100 Philippines, Formosa, Japan End of War One of Kawasaki's main factories was located at Kagamigahara which, in 1944 was not yet a city.
18th 10 February 1944 at Chōfu from the 244th Sentai Ki-61, Ki-100 Philippines, Japan End of War
Lt Mitsuo Oyake won Bukosho for shooting down three B-29s (one by ramming) 7 April 1944 and damaging three others.
19th 10 February 1944 at Akeno Fighter School Ki-61 Indonesia, Philippines, Formosa, Okinawa End of War (Formosa)

23rd 11 October 1944 at Inba, Chiba Prefecture Ki-43, Ki-44, Ki-61 Iwo Jima, Formosa, Japan End of War (Inba)

26th Late 1944 Ki-51, Ki-43, Ki-61 Formosa End of War (Formosa)

28th June 1939 in Manchuria Ki-46, Ki-61, Ki-102 Manchuria, Japan July 1945

31st July 1938 in China Ki-10, Ki-43, Ki-61 Manchuria, Philippines 30 May 1945 at Singapore

33rd Late 1943 Ki-10, Ki-27, Ki-43, Ki-61 New Guinea, Manchuria (Manchoukuo), East Indies End of War, Medan, Dutch East Indies

53rd 23 March 1944 at Tokorozawa, Saitama Ki-61, Ki-45 Japan, Eastern Defence Sector
flew Ki-61 for a short time in Home Island Defence
55th 30 May 1944 at Taishō, Osaka Prefecture Ki-61 Philippines, Japan End of War at Sana, Nara Prefecture

56th August 1944 at Taishō Osaka Prefecture Ki-61 Japan End of War at Itami, Hyōgo Prefecture Unit claimed 11 B-29s for 30 pilots lost. Warrant Officer Tadao Sumi (five B-29s plus one P-51 destroyed, four B-29s damaged) Bukosho recipient.
59th 1 July 1938 at Kagamigahara, Gifu Prefecture Ki-27, Ki-43, Ki-61, Ki-100 China, Manchuria (Nomonhan), Indochina, East Indies, New Guinea, Okinawa, Japan End of War at Ashiya, Fukuoka Prefecture
1st Lieutenant Naoyuki Ogata Bukosho recipient. Warrant Officer Kazuo Shimizu flew with unit from February 1942 right through to August 1945; 18 victories, including nine bombers.
65th
Ki-32, Ki-51, Ki-43, Ki-61, Ki-45 Philippines, Formosa, Okinawa, Japan End of War, Metabaru, Saga Unit used Ki-61 from the summer of 1944
68th March 1942 at Harbin, Manchuria Ki-27, Ki-61 Rabaul (New Britain), New Guinea, Halmahera 25 July 1944 First unit to convert to the Ki-61. Unit was destroyed by Allied air forces in New Guinea. Most surviving ground and aircrew were used as infantry, with few survivors. A Ki-61-1-Otsu, manufacturer's No. 640 is one of the best preserved aircraft wrecks in New Guinea.[36] Captain Shogo Takeuchi transferred from 64th Sentai, April 1942. KIA 15 December 1943 30+ victories. Sgt. Susumu Kaijinami officially credited with eight victories plus 16 unofficially.
78th 31 March 1942 in China Ki-27, Ki-61 Manchuria, Rabaul, New Guinea 25 July 1944 Second unit to convert to the Ki-61. Unit was destroyed by Allied air forces in New Guinea. Most surviving ground and aircrew were used as infantry, with few survivors.
105th August 1944, Taichung, Formosa Ki-61 Okinawa, Formosa End of War (Formosa)

244th April 1942, reorganised from 144th Sentai Ki-27, Ki-61, Ki-100 Okinawa, Formosa End of War (Yokaichi, Shiga Prefecture) Nine Bukosho recipients. Major Teruhiko Kobayashi JAAF's youngest Sentai commander. Also had an air-to-air B-29 ramming unit. Sentai claimed 73 B-29s shot down plus 92 damaged. Most famous of the Home Defence Sentais. Captain Nagao Shirai considered the ranking ace of 244 Sentai and possibly leading B-29 "killer" of JAAF (11 B-29s plus two F6Fs destroyed, six other aircraft damaged using Ki-61 and Ki-100. Captain Chuichi Ichikawa nine B-29s plus one F6F destroyed, six B-29s damaged. Major Teruhiko Kobayashi, three B-29s plus two F6Fs destroyed.
Training Units




23rd Dokuritsu Dai Shijugo (Independent Chutai) Chōfu, 1941 Ki-61 Japan Became basis of 23rd Sentai Evaluation and conversion unit for Ki-61.
Akeno Fighter School Akeno, Mie Prefecture, 1935 Ki-10, Ki-27, Ki-43, Ki-44, Ki-45, Ki-61, Ki-84, Ki-100 Japan End of War Main flight training school for Army fighter pilots. Many of the instructors participated in missions in defence of Japan 1944-1945. Akeno Airbase still in operational use.
37th Kyoiku Hikotai (Flight Training Company) Matsuyama airfield, Formosa, 1943[37] Ki-43, Ki-44, Ki-45, Ki-61, Ki-84 Formosa End of War Flight training school for Army fighter pilots. Many of the instructors participated in missions in defence of Japan 1944-1945

Variants

Note: Ko, Otsu, Hei and Tei are the Japanese equivalents to a, b, c, d. Kai ('modified' or 'improved') was also used for some models of the Ki-61.
Ki-61
12 original prototypes.
Ki-61-I-Ko
The first production version. This version had a fully-retractable tailwheel and two 7.7 mm (0.303 in) Type 89 machine guns in the wings and two synchronized 12.7 mm (0.50 in) Ho-103 machine guns in the fuselage forward decking. The wings had racks outboard of the wheelwells, which were capable of carrying one 151 L (40 gal) drop tank or a light bomb. Weights: 2,238-2,950 kg (wing loading 147 kg/m2).[10]
Ki-61-I-Otsu
The second production fighter variant. As it was found the armament was too light against allied aircraft and the tailwheel retraction mechanism was unreliable, the aircraft was modified accordingly. Two 12.7 mm (.50 in) Ho-103 machine guns replaced the wing 7.7 mm (.303 in) machine guns, with modifications to the upper-wing bulges, and the tailwheel doors were removed and the tailwheel locked in the "down" position (although the mechanism was still intact). Max takeoff weight 3,130 kg.[10]
Ki-61-I-Hei
800 German-made 20 mm Mauser MG 151/20 cannons and ammunition supplies were imported to Japan by submarine. The Hei was built in conjunction with the Otsu variant on the Kawasaki production lines but some "conversion kits" were directly sent to New Guinea. In this variant, the wing machine guns were replaced by Mauser cannons. The fuselage was longer (engine bulkhead forwarded of 19 cm, added a small fuel tank). Trial fittings found that these could be placed into the existing wing if the gun was laid on its side and a fairing was provided on the underside of the wing for clearance of the breech mechanism. 388 Ki-61s were so modified;[38] the first of these was completed in September 1943[38] or January 1944.[10] The last was completed in July 1944.[38] Max takeoff weight 3,470 kg, max speed 580 km/h at 5,000 m, time to that height was seven minutes.
Ki-61-I-Tei
This machine featured two 12.7 mm (.50 in) Ho-103s in the modified (stronger) wings, provisions of external storage using fixed underwing pylons, and a non-retractable tail wheel. The forward fuselage was elongated by 190 mm (7.5 in) just after the exhaust line and forward of the windscreen to make room for the installation of Japanese 20 mm Ho-5 cannon in the fuselage decking (the same as with Hei version). The continued supply of MG 151's via submarine was not able to be guaranteed and the Ho-5 was ready. Several internal changes were also made. These included the simplification of several systems for increased dependability and ease of maintenance. The rear section of the fuselage was also made to be easily removable to further facilitate the ease of repair work.[39] There is now some doubt as to whether the Tei ("d") designation was used.[40]
Ki-61-I-KAId
Interceptor variant with 2 × 12.7 mm (.50 in) fuselage machine guns and 2 × 30 mm (1.18 in) wing cannon.
Ki-61-I- w.c.e.s.
An experimental aircraft with a wing cooling evaporation system, modelled on that used by the Heinkel He 100. It was the fastest Ki-61 built, achieving 630 km/h (395 mph), and the last with a retractable tail wheel.
Ki-61-II
Prototype with 10% greater wing area and a slightly different airfoil. An Ha-140 engine with 1,120 kW (1,500 hp) for takeoff was fitted; the cowling panels were redesigned and the supercharger air intake was longer. A redesigned windscreen incorporating an extra panel was mounted further forward. The transparency to the rear of the sliding canopy was redesigned to increase rearward visibility. The prototype was first flown in December 1943; flight trials showed that the new wing was unsatisfactory and only eight Ki-61-IIs were built. The Ki-61-II was one of only very few Japanese aircraft able to reach the operational altitude of the B-29s raiding Japan with decent firepower. Subsequently, the majority of B-29s lost to Japanese fighters were shot down by the Ki-61-II.
Note
Because of the unreliability of the Ha-140 and the destruction of the Akashi plant by a B-29 bombing attack the bulk of the Ki-61-II-KAIs built were airframes only, which were later converted to Ki-100-Is. ;Ki-61-II-KAI
Pre-production version which reverted back to the Ki-61-I-Tei wing, a 220 mm (8.7 in) fuselage stretch, enlarged rudder, and Ha-140 engine; 30 built.
Ki-61-II-KAIa
Armed with 2 x 12.7 mm (.50 in) machine guns in the wings and 2 x 20 mm cannon in the fuselage.
Ki-61-II-KAIb
Armed with 4 x 20 mm cannon.
Ki-61-III
One prototype only. This version had a cut-down rear fuselage and a canopy design which was later used by the Ki-100-II.
A total of 3,159 Ki-61 were built.[41]

Operators

 China
Operated some captured aircraft
 China
Also operated some captured aircraft
 Indonesia
  • In 1945, Indonesian People's Security Force (IPSF) (Indonesian pro-independence guerrillas) captured a small number of aircraft at numerous Japanese air bases, including Bugis Air Base in Malang (repatriated 18 September 1945). Most aircraft were destroyed in military conflicts between the Netherlands and the newly proclaimed-Republic of Indonesia during the Indonesian National Revolution of 1945–1949.[42]
 Japan

Specifications (Ki-61-I-KAIc)

Data from Japanese Aircraft of the Pacific War[43]
General characteristics
  • Crew: One
  • Length: 8.94 m (29 ft 4 in)
  • Wingspan: 12.00 m (39 ft 4 in)
  • Height: 3.70 m (12 ft 2 in)
  • Wing area: 20.00 m² (215.28 ft²)
  • Airfoil: NACA 2R 16 wing root, NACA 24009 tip
  • Internal fuel capacity: 550 l (121 Imp gal)
  • External fuel capacity: 2 x 200 l (44 Imp gal) drop tanks
Performance
Armament

Read More

Kawasaki Ki-100

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Kawasaki Ki-100
A Ki-100 in the RAF Museum at Hendon, London
Role Fighter
Manufacturer Kawasaki Heavy Industries
First flight 1 February 1945
Introduced 1945
Retired 1945
Primary user Imperial Japanese Army Air Force
Produced 1945
Number built 395 [1]
Developed from Kawasaki Ki-61
The Kawasaki Ki-100 was a fighter aircraft used by the Imperial Japanese Army in World War II. The Japanese Army designation was "Type 5 Fighter". No Allied code name was assigned to this type, although it may have been misidentified as a Tony due to the similar profile and appearance.
The emergency measure of adapting a Ki-61-II-KAI fighter to carry a Mitsubishi radial engine resulted in one of the best interceptors used by the Army during the entire war. It combined excellent power and manoeuvrability [2] and, although its high altitude performance against the USAAF B-29 Superfortress heavy bombers was limited by the lack of an efficient supercharger, it performed better than most other IJAAF fighters.[3]
Missions began in March 1945; from the first engagements the Ki-100 performed well against the B-29, and showed itself to be equally effective against U.S. Navy carrier fighters.[4] A new variant, the Ki-100-Ib, was constructed during the last weeks of the conflict in time to to equip five sentai for home defense duties.

Contents

  • 1 Design and development
  • 2 Operational history
  • 3 Variants
  • 4 Specifications (Ki-100-1a/b Goshikisen)

Design and development

In mid-1944, the Ki-61 was one of the best fighters of the IJAAF. It was the only production Japanese fighter to have an inline powerplant (the Kawasaki Ha-40, a Japanese adaptation of the German Daimler-Benz DB 601 engine) during World War II, as well as the first one with factory-installed armor and self-sealing fuel tanks. It also had respectable performance, more in line with contemporary American and European designs of the time, with a focus on speed and rate of climb instead of manoeuvrability and range. It was an effective design, but suffered from engine shortages and reliability problems.
These problems as well as the performance advantage of enemy fighters, especially the F6F Hellcat, led to the development of an improved model, the Ki-61-II (later Ki-61-II-KAI), powered by the new 1,120 kW (1,500 hp) Kawasaki Ha-140 engine, which was unfortunately heavier than the Ki-61-I-KAIc it replaced. Maximum speed increased from 590 km/h (370 mph) to 610 km/h (380 mph) and general performance (except rate of climb) improved as well. However, it was never able to perform as planned due to the continued degradation of quality of the engine's assembly line, with far fewer engines produced than were required, while many of the engines that were built were rejected due to poor build quality. At this point of the war, the IJAAF was in desperate need of effective interceptors to stop the enemy bomber raids over the Japanese mainland, so in October 1944 it was ordered that a 1,120 kW (1,500 hp) Mitsubishi Ha-112-II (Kinsei ["Venus"] 60 series), a 14-cylinder, two-row radial engine should be installed in those airframes. The need for the re-engined fighter was made yet more urgent on 19 January 1945, when a B-29 raid destroyed the engine's production plant,[5] leaving 275 finished Ki-61s without a powerplant.
The Mitsubishi Ha-112-II some 54 kg (120 lb) lighter than the Ha-140 and produced the same power more reliably. After the study of an imported Fw 190A, an example of an aircraft in which a wide radial engine had been successfully installed in a narrow airframe, three Ki-61-II-KAI airframes were modified to carry this engine and to serve as prototypes. Three engineers, Takeo Doi, chief engineer and head of project, his assistant Makato Owada and head of engine systems at Kawasaki Kagamigahara, Tomio Oguchi, worked through several concepts for redesigning the Ki-61 airframe to accept the new engine before, settling on a solution in which a second skin fairing was riveted to the fuselage, to smooth out the airflow behind the adjustable cooling flaps and multiple exhaust stubs of the new engine cowling.[6]. At first, there were problems with the aircraft now being found to be very tail-heavy, but the removal of a large lead counterbalance, which had been placed in the Ki-61-II-KAI's rear fuselage to balance the increasingly heavy Ha-140 engine, restored the center of gravity (cg).
As a result, on 1 February 1945, the new model was flown for the first time. Without the need for the heavy coolant radiator and other fittings required for a liquid-cooled engine, the Ki-100 was 329 kg (725 lb) lighter than the Ki-61-II, reducing the wing loading from 189 kg/m² (38.8 lb/ft²) to 175 kg/m² (35.8 lb/ft²). This had an immediate positive effect on the flight characteristics, enhancing landing and takeoff qualities as well as imparting increased manoeuvrability and a tighter turning circle.[6]
The army general staff was amazed by the flight characteristics of the plane, which surpassed the Hien's in all but maximum speed (degraded by a maximum of 29 km/h/18 mph by the larger area of the radial engine's front cowling), and the model was ordered to be put in production as the Goshikisen (Go = five; shiki = type; sentoki = fighter) or Army Fighter Type 5. The company's name was Ki-100-1-Ko. All of the airframes were remanufactured from Ki-61-II Kai and Ki-61-III airframes; the integral engine mount/cowling side panel was cut off the fuselage and a tubular steel engine mount was bolted to the firewall/bulkhead. Many of the redundant fittings from the liquid-cooled engine, such as the ventral radiator shutter actuator, were still kept. The first 271 aircraft, or Ki-100-1-Ko, with the raised "razorback" rear fuselage were rolled out of the factory between March and June 1945. A further 118 Ki-100 I-Otsu were built with a cut-down rear fuselage and new rear-view canopy from May through to the end of July 1945. This version also featured a modified oil cooler under the engine in a more streamlined fairing.[6]
The engine was reliable in contrast to the mechanical nightmares of the Nakajima Ki-84, Kawasaki Ki-61, and Kawanishi N1K-J that kept many aircraft grounded.[7] Although slow in level flight for 1945, Ki-100 could dive with P-51 Mustangs (unlike most Japanese fighters) and hold the speed on pullout. Two problems which hampered the effective employment of Japanese fighters towards the end of the war were unreliable electrical systems; that of the Ki-100 was less problematic than most other aircraft types, although the fuse-boxes caused problems; and poor radio communications, which was generic throughout the war.[8]
The armament was two fuselage-mounted 20 mm Ho-5 cannons, each with 200 rpg. These were complemented by two wing-mounted 12.7 mm (.50 in) Ho-103 machine guns with 250 rpg.[9]
Improvement of the basic model lead to the Ki-100-II, with a supercharged engine for high-altitude interception of the B-29 Superfortresses, but only three examples were built, and it never saw combat.[10]

Operational history

111th's Ki-100 I-Otsu.
Army units to be equipped with this model included the following Sentai: 5th, 17th, 18th, 20th, 59th, 111th, 112th, 200th and 244th and the 81st Independent Fighter Company. Along with the previously-named Army air units, pilots were trained through the Akeno and Hitachi (Mito) Army Flying Schools. Many of the Akeno and Hitachi instructors, who were often seconded from operational units, flew combat missions (this deployment was a notable spreading out of the very few fighters that were operational, but many of these wings were only partially re-equipped).[11]
The Ki-100 made its combat debut on the night of 9 March 1945[12][13] and suffered its first loss on 7 April 1945, when a Ki-100 flown by Master Sergeant Yasuo Hiema of the 18th Sentai was shot down by a B-29 after "attacking the formation again and again".[13] Allied aircrews soon realised that they were facing a formidable new fighter[14] Although far fewer Ki-100s were available than the Ki-84s, it was perceived to be one of the most important fighters in the inventory. However in intercepting the high-flying B-29s (at a point in the conflict, the B-29 raids became low-level missions), the new Japanese fighters struggled as the Ha-112-II engine performance decreased at high altitudes. The most effective way to attack the Superfortress was by making very dangerous head-on attacks, changing their approach path as they neared the bombers. A failure while attempting this was deadly, because of the concentration of defensive fire from the bombers. In this type of combat, the Navy's Mitsubishi J2M Raiden was superior.[15]
During March and April 1945 experienced instructors from the Akeno Army Flying School flew the Ki-100 in extensive tests against the Ki-84, which was considered to be the best of the JAAF fighters then in operational service. Their conclusions were that, given pilots of equal experience, the Ki-100 would always win in combat.[16] From Mid-April Major Yasuhiko Kuroe, a highly experienced combat veteran was placed in charge of a "flying circus" made up of captured Allied aircraft, including a Mustang which had been captured in China. This "circus" travelled to various operational fighter bases throughout Japan and was used to train pilots in the best ways to combat enemy aircraft.
On 25 July 1945, 18 Ki-100 fighters from 244th Sentai encountered 10 Hellcats of the light aircraft carrier USS Belleau Wood's Fighter Squadron 31 (VF-31) in an air battle where the Ki-100 pilots claimed 12 victories with only two losses. Claims and counter-claims regarding the "true" results still arise around this action. The real losses were two Hellcats and two Ki-100s, including Major Tsutae Obara's Ki-100 and Ensign Edwin White's Hellcat which collided, killing both pilots.[17]
After the bombing of the Kagamigahara plant and the slow deliveries of components by the satellite plants, production rates of the Ki-100 began to fall more and more, and in the period between May and July, only 12 examples were delivered. Finally, production ended due to the bombing, with only 118 examples of the Army Type-5 Fighter Model 1b delivered.
The last loss of a Ki-100 occurred on 14 August 1945, a day before the surrender of Japan, when Sergeant Major Fumihiko Tamagake of the 244th Sentai was shot down by a Mustang.[11]
An overall assessment of the effectiveness of the Ki-100 rated it highly in agility and a well-handled Ki-100 was able to out-manoeuvre any American fighter including the formidable P-51D Mustangs and the P-47N Thunderbolts which were escorting the B-29 raids over Japan by that time, and was comparable in speed especially at medium altitudes. In the hands of an experienced pilot, the Ki-100 was a deadly opponent and together with the Army's Ki-84 and the Navy's Kawanishi N1K-J, the only other Japanese fighters being able to defeat the latest Allied types.[18]

Variants

  • Ki-100 (prototypes): one batch of Kawasaki Ki-61 II KAI with radial engine. 3 built as such.
  • Ki-100 I-Ko: Fighter Type 5 of Army (Mark Ia) initial model of series, KI-61 II KAI modified. 271 built as such.
  • Ki-100 I-Otsu: (Mark Ib) full-vision canopy. 118 built as such.
  • Ki-100 II (prototypes): engine Mitsubishi Ha-112-II Ru with turbocharger, 1,120 kW (1,500 hp). 3 built as such.
  • Total production: 395 examples.[1].

Specifications (Ki-100-1a/b Goshikisen)

The same Ki-100 viewed from the front. Photograph at the RAF Museum at Hendon, London
Data from Japanese Aircraft of the Pacific War [19]
General characteristics
  • Crew: 1
  • Length: 8.82 m (28 ft 11 in)
  • Wingspan: 12.00 m (39 ft 4 in)
  • Height: 3.75 m (12 ft 4 in)
  • Wing area: 20 m² (215 ft²)
  • Empty weight: 2,525 kg (5,567 lb)
  • Loaded weight: 3,495 kg (7,705 lb)
  • Powerplant: 1× Mitsubishi Ha 112-II radial engine, 1,120 kW (1,500 hp) at take off
Performance
Armament

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Kawasaki Ki-102

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Ki-102
Kawasaki Ki-102b assault plane Model b
Role Fighter
National origin Japan
Manufacturer Kawasaki Aircraft Engineering
First flight 1944
Introduction 1944
Retired 1945
Primary user Imperial Japanese Army Air Force
Number built 238
Developed from Kawasaki Ki-96
The Kawasaki Ki-102 (Army Type 4 Assault Aircraft) was a Japanese warplane of World War II. It was a twin-engine, two-seat, long-range heavy fighter developed to replace the Ki-45 Toryu. Three versions were planned: the Ki-102a day fighter, Ki-102b ground-attack and Ki-102c night fighter. This aircraft's Allied reporting name was "Randy".

Contents

  • 1 Design and history
  • 2 Versions
  • 3 Specifications (Ki-102b)

Design and history

It entered service in 1944, but saw limited action. The main type (102b) was kept in reserve to protect Japan, although it did see some limited duty in the Okinawa campaign. It was kept out of front line service because it was hoped that it would be the carrier of the Igo-1-B air-to-ground guided missile when the Allied invasion of Japan occurred.

Versions

Ki-102
prototypes, 3 built
Ki-102a (Type Kō)
Externally similar to the 102b, but with turbosuperchargers that enabled the engine to maintain its rating at higher altitudes. 57 mm (2.24 in) cannon was swapped in favor of a 37 mm (1.46 in) cannon, and the 12.7 mm (.50 in) rear gun was deleted, 26 built.
Ki-102b (Type Otu)
Ground-attack variant similar to prototypes, except with revised tail wheel, 207 built.
Ki-102c (Type Hei)
Night Fighter version with lengthened fuselage and span. Radar under a Plexiglas dome, oblique-firing 20 mm cannons, and the 20 mm cannons in the belly replaced with 30 mm (1.18 in) cannons completed the package, 2 built.
Ki-108
High-altitude fighter prototype with pressurised cabin, two conversions from Ki-102b aircraft using the structural improvements used on the 102c.

Specifications (Ki-102b)

Data from Japanese Aircraft of the Pacific War[1]
General characteristics
  • Crew: 2
  • Length: 37 ft 7 in (11.45 m)
  • Wingspan: 51 ft 1 in (15.57 m)
  • Height: 12 ft 2 in (3.70 m)
  • Wing area: 366 ft² (34 m²)
  • Empty weight: 10,900 lb (4,950 kg)
  • Loaded weight: 16,000 lb (7,300 kg)
  • Powerplant: 2× Mitsubishi Ha-112-II Ru 14-cylinder radial engine, 1,500 hp (1,120 kW) each
Performance
Armament
  • Guns: * 1× 57 mm (2.24 in) Ho-401 cannon~replaced in the 102a with a 37 mm (1.46 in) cannon, deleted in the 102c
  • 2× 20 mm Ho-5 cannon~replaced in the 102c with 30 mm (1.18 in) cannons
  • 1× 12.7 mm (0.50 in) Ho-103 machine gun~deleted in the 102a and 102c
  • Bombs: 2 × 200 L (53 US gal) drop tanks or 2 × 250 kg (551 lb) bombs

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Kawasaki Ki-10

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Ki-10
Ki-10 Model 1
Role Biplane fighter
Manufacturer Kawasaki Heavy Industries
Designed by Takeo Doi
First flight March 1935
Introduced 1935
Retired 1942
Primary user IJA Air Force
Number built 588
The Kawasaki Ki-10 (九五式戦闘機 Kyūgo-shiki sentōki?, Army Type 95 Fighter) was the last biplane fighter used by the Imperial Japanese Army, entering service in 1935. Built by Kawasaki Kōkūki Kōgyō KK for the Imperial Japanese Army, it saw combat service in Manchukuo and in north China during the early stages of the Second Sino-Japanese War. Its reporting name given by the Allies was "Perry".

Contents

  • 1 Design and development
  • 2 Operations
  • 3 Variants
  • 4 Operators
  • 5 Specifications (Ki-10-II)

Design and development

Kawasaki Ki-10-II KAI prototype
The Ki-10 was designed by Japanese aeronautical engineer Takeo Doi[1], who had succeeded Richard Vogt as chief designer for Kawasaki. The design was in response to a requirement issued by the Imperial Japanese Army for a new fighter, and was the winner of a competition against Nakajima's Ki-11. Although the low-wing monoplane offered by Nakajima was more advanced, the Army preferred the more maneuverable biplane offered by Kawasaki. In order to overcome the speed disadvantage the Kawasaki team used a metal three-blade propeller in the third prototype, while flush-head rivets were used in an attempt to reduce drag[2].
The Kawasaki design had sesquiplane (unequal-span) wings, braced by struts, and with upper-wing ailerons[1]. The structure was of all-metal construction, which was then fabric-covered. Armament consisted of two 7.7 mm (.303 in) Type 89 machine guns, synchronized to fire through the propeller. The initial production version was powered by a liquid-cooled 633 kW (850 hp) Kawasaki Ha-9-IIa V engine.

Operations

The Ki-10 was deployed in Manchukuo (Manchuria) and in the initial campaigns of the Second Sino-Japanese War in northern China. It proved an excellent dogfighter against the Chinese air force, including those active at the Battle of Wuhan. However, by the time of the Nomonhan Incident (Battles of Khalkhin Gol) in 1939, against the forces of Soviet Russia, it was largely obsolete.
At the beginning of the Pacific War, the Ki-10 was retired to training and secondary missions, but later returned to front-line service, performing short-range patrol and reconnaissance missions in Japan proper and China in January-February, 1942.

Variants

Another picture of the Kawasaki Ki-10-II KAI prototype
data from Japanese Aircraft of the Pacific War[3]
  • Ki-10 : Prototype for Imperial Japanese Army Air Force (4 built in early 1935).
  • Ki-10-I (Army Fighter Type 95-I): Initial production version (300 built December 1935 - October 1937)
  • Ki-10-II : Prototype of modified Mark I, increased in length (1 built May 1936)
  • Ki-10-II (Army Fighter Type 95-2): Improved production version (280 built June 1937 - December 1938)
  • Ki-10-I KAI : Prototype Ki-10-I with modifications to engine and radiator (1 built October 1936)
  • Ki-10-II KAI : Prototype - Aerodynamic modification of Ki-10-II, now designated Ki-10-I-KAI, with 634 kW (850 hp) Kawasaki Ha-9-IIb engine (2 built November 1937)
Total production: 588 units[3]

Operators

 Japan
  • Imperial Japanese Army Air Force[3]
    • 1st Rentai IJAAF
    • 4th Rentai IJAAF
    • 5th Rentai IJAAF
    • 6th Rentai IJAAF
    • 8th Rentai IJAAF
    • 11th Rentai IJAAF
    • 13th Rentai IJAAF
    • 4th Sentai IJAAF
    • 9th Sentai IJAAF
    • 33rd Sentai IJAAF
    • 59th Sentai IJAAF
    • 64th Sentai IJAAF
    • 77th Sentai IJAAF
    • Akeno Fighter Training School

Specifications (Ki-10-II)

Data from Japanese Aircraft of the Pacific War[3]
General characteristics
  • Crew: one, pilot
  • Length: 7.2 m (23 ft 8 in)
  • Wingspan: 10.02 m (32 ft 10½ in)
  • Height: 3 m (9 ft 10⅛ in)
  • Wing area: 23 m² (247.569 sq ft)
  • Empty weight: 1,360 kg (2,998 lb)
  • Loaded weight: 1,740 kg (3,836 lb)
  • Powerplant: 1× Kawasaki Ha-9-IIa, 634 kW (850 hp)
Performance
Armament

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