Kawasaki Ki-61 Hien 飛燕
This aircraft was an incredible find back in the 1970’s and it’s so sad to see it in this state. Unfortunately because the PNG museum has been so neglected over the years it has been plundered by several private museum groups. The South Australian Museum even recently acquired at least two P-38 Lightnings from the museum with the aim of restoring them and returning at least one them back to the museum. Yeh right! Well all’s fair in love and war they say. When you see such a rare aircraft deteriorating in such away it’s hard to argue about what’s fair and what’s not.
Roy Worcester Historical Centre
Founder Roy Worcester
Fates of Artifacts
Ki-61 Tony Manufacture Number 379
Kawasaki Ki-61 Tony Manufacture Number 640
JAAF 68th Sentai
When the book Pacific Aircraft Wrecks was published, it stated:
Richard Dunn adds:
Richard Leahy recalls visiting the wreck:
Bruce Hoy adds:
RAAF Recovery & PNG Museum
The RAAF recovered the fuselage first, which arrived at the PNG Museum on November 23, 1984, and was displayed in a dolly built by Bruce Hoy. The wings and engine were delivered later, and were stored separate from the fuselage. It was displayed at the museum for twenty years: 1984 - 2004.
On July 29, 2004 this aircraft was packed into a container bound for Australia by Robert Greinert / HARS. The airplane remained property of the PNG Museum, and was exported under the agreement that it would be restored to static condition, and returned to the PNG Museum, along with P-38F 42-12647. According to Greinert: 'as part of the Minister for Culture and Tourism's plan to undertake a restoration program for the museum.'
Kawasaki Ki-61 Hien 飛燕
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 Allied code name assigned by the United States War Department was 'Tony'. The Japanese Army designation was 'Army Type 3 Fighter' (三式戦闘機). It was the only mass-produced Japanese fighter of the war to use a liquid-cooled inline 'V' engine.
Design and development
The Ki-61 which was designed by Takeo Doi and his deputy Shin Owada, was one of two parallel designs tendered for by Kawasaki to fulfill requirements framed by the Koku Hombu late in 1939 for two fighters. Each was to be built around the Daimler-Benz DB 601Aa, a derivative of which was to be manufactured as the Ha-40 by Kawasaki at its Akashi plant. The first design, known as the Kawasaki Ki-60, was for a heavily armed specialised interceptor, which would have a high wing-loading; the second, the Ki-61 was a more lightly loaded and armed general-purpose fighter to be used mainly in an offensive, air superiority role at low to medium altitudes. Both single-seat, single-engine fighters used the same basic construction being 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. Design of the Ki-61 did not begin until December 1940. Although the Ki-61 was broadly similar to the Ki-60 it featured several refinements using lessons learned from the disappointing flight characteristics of the earlier design.
The all metal, semi-monocoque fuselage was basically oval in cross-section, changing to a tapered, semi-triangular oval behind the cockpit, with a maximum depth of 1.35 m (4 feet 5 inches). 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 the top and bottom cowling panels only 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 12.7 mm caliber 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) 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 (36.2 Imp gallons) was located behind the pilot's seat. The windshield was armoured and there was a 13 mm armoured steel 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.
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 partially self-sealing 190 l (42 gallon) 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.
The first prototype of the San-shiki-Sentohki ichi gata (Type 3 Fighter, Model 1, the official IJAAF designation) first flew in December 1941. 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 (6,504 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) (even that was considered borderline).
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.
The Ki-61 was the last of the DB-601-powered fighters and it was soon overshadowed by fighters with more powerful engines. By the time it first flew in December 1941 – only one year after the Macchi's first flight and three years after the Bf 109E – the DB-601 was already underpowered compared to the new 1,500 hp inline or 2,000 hp radial engines being developed (and already nearing the mass-production stage) to power the next generation of combat aircraft: the P-47, Fw 190 and Bf 109 G. Moreover, the inline Ha-40 engine proved to be an unreliable powerplant.
The DB-601 engine on which the Hien was based was designed with very critical tolerance limits, and in the Ha-40 Japanese technicians developed a lighter version (by roughly 30 kg) that required even higher tolerances. Reaching these levels proved to be a 'stretch' for Japan's aviation manufacturing capabilities, which was further complicated by the variable quality of the materials, fuel, and the lubricants needed to run this sensitive, high-performance engine smoothly. 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.
Compared to the Ki-61-I, the Ki-61-II had 10% greater wing area, more armor, and – with the Kawasaki Ha-140 engine – an increased power of 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 reliability problems of its own which were never fully resolved, and around half of the first batch of engines delivered were returned to the factory to be re-built. Shortly after, 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 weakness: the lack of power at altitude, which diminished its ability to intercept high-flying B-29s relative to the Ki-61-II.
The first Sentai (wing) fully equipped with the Hien was the 68th in Wewak, New Guinea, 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; this was especially the case for new-design aircraft, which are particularly prone to teething problems, as the Ki-61s were. 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.
High aircraft losses were experienced in some incidents during this campaign. For example, while in transit between Truk and Rabaul, the 78th lost 18 of its 30 Ki-61s. Other units were involved and sometimes, even more unfortunate: only two of (possibly) 24 Nakajima Ki-49s reached Rabaul in June 1943. 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, which resulted in the obsolescent Ki-43 forming the bulk of the JAAF's fighter capability. At the end of the campaign, nearly 2,000 Japanese aircraft had been lost in continuous air attacks from up to 200 Allied aircraft at one time (among them, around half were B-24s and B-25s armed with fragmentation bombs After the Japanese retreat, over 340 aircraft wrecks were later found at Hollandia.
Even with these problems, there was a general Allied concern regarding this new fighter:
The Hien entered combat in the spring of 1943 in the New Guinea war zone, covering [mainland] New Guinea, the Admiralty Islands, New Britain and New Ireland. 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-40 Warhawks completely outclassed, and begged for more P-38 Lightnings to counter the threat of the new enemy fighter.
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 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. Of the allied fighters encountered at the beginning of World War II, only the P-38 was measurably superior. 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.
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 kt) maximum speed. The cannon armament was essentially needed to counter the Allied bombers, which proved to be difficult to shoot down with only 12.7 mm machine guns. The empty and maximum weights for the Ki-61 prototype (2 x 12.7 mm + 2 x 7.7 mm) were 2,238 kg (4,934 lb) and 2,950 kg (6,504 lb), respectively; for the Ki-61-I basic (4 x 12.7 mm) 3,130 kg (6,900 lb); and for the Ki-61-KAI (2 x 12.7 mm + 2 x 20 mm), 2,630 kg (5,798 lb) and 3,470 kg (6,750 lb).
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 (groups/wings), 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.
Ki-61 Special Attack Unit
The tactic of using aircraft to ram American B-29s was first recorded in late August 1944, during a raid when B-29s from Chinese airfields were sent to bomb the steel factories at Yawata. Sergeant Shigeo Nobe of the 4th Sentai intentionally sliced his Kawasaki Ki-45 into a B-29; debris from the explosion following this attack severely damaged another B-29, which was also went down. Other attacks of this nature followed, as a result of which individual pilots determined it was a quite practical way to destroy B-29s.
On 7 November 1944, the officer commanding the 10th Hiko Shidan made ramming 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.
The units assigned to the 10th included the 244th Hiko Sentai, then commanded by Captain Takashi Fujita who organised a ramming flight named 'Hagakure-Tai' ('Special Attack Unit'), which was composed of three sections: the 1st Chutai 'Soyokaze', 2nd Chutai 'Toppu', and the 3rd Chutai known as 'Mikazuki'.
First Lt. Toru Shinomiya was selected to lead the attack unit, he would became famous by ramming an American B-29 and living to tell the tale. Shinomiya attacked the B-29 on 3 December 1944, and brought himself and his damaged aircraft home; Shinomaya's Ki-61, which had lost most of the port outer wing, was subsequently put on display in a major department store in Tokyo. He would eventually lose his life as a Tokkotai pilot in the battle for Okinawa. Another 244th pilot, Corporal Masao Itagaki, performed a similar feat on the same occasion, but had to parachute from his damaged fighter. A third pilot, Sergeant Nakano, of the Hagakure-Tai of the 244th rammed another B-29 and crash-landed his stripped-down Ki-61 in a field. 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.) Sergeant Shigeru Kuroishikawa was another distinguished member in the unit.
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' ('Heart of Heaven Intercept Unit') by the Defense GHQ.
But 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.
Some other Ki-61 pilots also became well-renowned, among whom was Major Teruhiko Kobayshi who was credited by some with a dozen victories mostly due to conventional attacks against B-29s.
Source: Sakaida, Henry. Japanese Army Air Force Aces 1937-45. Bueschel, Richard M. Kawasaki Ki.61/Ki.100 Hien in Japanese Army Air Force Service.
Note: Ko, Otsu, Hei and Tei are the Japanese equivalents to a, b, c, d. Kai (modified) was also used for some models of the Ki-61.
Ki-61: 12 original prototypes.
A total of 3,159 Ki-61 were built.
China: Chinese Nationalist Air Force
Operated some captured aircraft
China: People's Liberation Army Air Force
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.
Japan: Imperial Japanese Army Air Force
Data from The Great Book of Fighters
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: Empty weight: 2,630 kg (5,800 lb): * Loaded weight: 3,470 kg (7,650 lb): * Powerplant: 1× Kawasaki Ha-40 liquid-cooled inverted V-12, 875 kW (1,175 hp)
Performance: Maximum speed: 580 km/h (360 mph) at 5,000 m (16,405 ft): * Range: 580 km (360 mi): * Service ceiling: 11,600 m (38,100 ft): * Rate of climb: 15.2 m/s (2,983 ft/min): * Wing loading: 173.5 kg/m² (35.5 lb/ft²): * Power/mass: 0.25 kW/kg (0.15 hp/lb): Time to altitude: 7.0 min to 5,000 m (16,405 ft)
Armament: 2x 20 mm Ho-5 cannon, 120 rounds/gun: * 2x 12.7 mm (0.50 in) Ho-103 machine guns, 200 rounds/gun: * 2x 250 kg (550 lb) bombs
Editor for Asisbiz: Matthew Laird Acred
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