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Kawasaki Ki-61 Hien (Swallow) 'Tony'

Kawasaki Ki-61 Hien (Swallow) 'Tony'


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Kawasaki Ki-61 Hien (Swallow) 'Tony'

Introduction
Development
Combat Record
New Guinea
The Philippines
Formosa and Okinawa
Defence of Japan
Variants
Stats (Ki-61-I KAIc)

Introduction

The Kawasaki Ki-61 Hien (Swallow) was the only inline-engined fighter aircraft to see service in Japan during the Second World War, and was designed around a licence-built version of the German Daimler-Benz DB 601A engine.

Development

The Kawasaki design team was lead by the German engineer Dr Richard Vogt for ten years, before he returned home in 1933 (where he became chief designer for Blohm und Voss). During this period Kawasaki negotiated the right to build a number of German liquid-cooled engines, and used them to power some of their most successful aircraft of the period. This tradition continued after Vogt's departure, and in the late 1930s Kawasaki purchased a licence to build the Daimler Benz DB 600 inline engine. This was soon followed by a licence for the DB 601, the engine that powered the Messerschmitt Bf 109E. In April 1940 a team from Kawasaki returned from Germany with a set of design drawings and several engines. Over the next year Kawasaki worked on producing a Japanese version of the engine, and the first Kawasaki Ha-40 was completed in July 1941. The new engine was slightly lighter than the DB 601A, and provided more power at take-off, but would also suffer from overheating problems, making it less reliable than the German original. The engine was quickly accepted by the Japanese army and entered production as the Army Type 2 engine.

During the 1930s all modern Japanese fighter aircraft were powered by radial engines, and were built with manoeuvrability in mind. By 1939 the Japanese Army was using the Nakajima Ki-27, a radial-engine powered monoplane, and the more advanced Nakajima Ki-43 Hayabusa was under development. However, in the west the most advanced fighters were powered by liquid cooled in-line V-12 engines, and in particular the DB 601 of the Bf 109 and the Rolls Royce Merlin of the Hurricane and Spitfire. Kawasaki believed that they could produce a superior fighter using their own version of the DB 601, and approached the Japanese Army with a number of different designs. In February 1940 (before the DB 601 plans and engines had reached Japan) Kawasaki were ordered to begin work on two of their designs, the Ki-60 heavy fighter and the Ki-61 all-purpose fighter, with the Ki-60 getting the higher priority.

The first prototype Ki-60 made its maiden flight in March 1941. The aircraft was designed to have a high top speed, a good rate of climb and to be more heavily armed than contemporary Japanese fighters. It had a comparatively small wing, and a narrow but quite tall fuselage. The new aircraft was unpopular with Japanese pilots - its small wings meant it had a high wing loading (by Japanese standards), which lowered its manoeuvrability and increased its landing speed. Most disappointing was its top speed, which even on the third, and significantly modified prototype, only reached 354mph, 20mph slower than expected. Work on the Ki-60 was abandoned and attention switched to the lighter Ki-61.

The Kawasaki design team, lead by Takeo Doi and Shin Owada, had already done some preliminary work on the Ki-61. It was similar to the Ki-61 in overall shape and length, but the fuselage was reduced in cross-section (and in height). A new longer wing was designed, with a higher aspect ratio (longer and thinner). The wingspan of the Ki-61 was five feet wider than that of the Ki-60. The new wing reduced the wing-loading, making the Ki-61 more manoeuvrable than the Ki-60 (and than the Allied fighters it would encounter when it first entered combat), but less manoeuvrable than other Japanese army and navy fighters.

The first prototype of the Ki-61 made its maiden flight early in December 1941. As expected, the Ki-61 was faster than the Ki-60, but the relative lack of manoeuvrability worried the Army's test pilots. Veteran pilots returning from the front were much more enthusiastic. The lighter, more manoeuvrable, fighters had won Japan control of the skies in late 1941 and early 1942, defeating both the out-dated Allied fighters in the Pacific in 1941 and the first of the more modern fighters that began to arrive in the area during 1942. This began to change as the Allies worked out how to fighter the nimble Japanese aircraft.

The newer Allied aircraft tended to be faster, more heavily armed, better armoured, have a better rate of climb and be faster in the dive than their more nimble Japanese opponents. The favoured Allied tactic was now to make 'hit and run' attacks on Japanese aircraft, diving on them from above, then climbing away without getting involved in a dog-fight. The Ki-61 promised to negate this tactic, allowing the Japanese pilots to dive away from the Allied fighters (or to catch Allied pilots attempted to dive away from trouble). The self-sealing fuel tanks and pilot armour were also popular, as was the increase in firepower.

The fate of the Ki-61 was decided by a series of competitive trials, flown against an imported Bf 109E-3, a captured Curtiss P-40E, and the Nakajima Ki-43-II and Ki-44-I. The Ki-61 was the fastest of these aircraft, and was only out-manoeuvred by the Ki-43-II. The Ki-61 was ordered into production, and given the designation Army Type 3 Fighter Model 1 Hien (Swallow).

When the Ki-61 was first encountered by Allied pilots it caused a certain amount of confusion. Every other Japanese-designed and built fighter used a radial engine. The new aircraft shared the same general shape as many DB-601 powered fighters, which gave it a slightly 'droopy' nose, with the propeller mounted in a distinctive low position, and a sloped upper fuselage running back to the cockpit. The Bf 109 had a similar, but more angular nose, and at first some believed that the new Japanese fighter was a licence-built version of the German fighter (this had been expected for some time, and a code-name, 'Mike', allocated to the Bf 109). After a few more sightings of the new fighter it became clear that it wasn't a version of the Bf 109, but it did resemble some of the Japanese fighters powered by the same engine, and in particular the Macchi C.202, which had a similar (although longer) smooth nose. In order to reflect this visual resemblance, the new fighter was allocated the code name 'Tony', short for Antonio.

Production of the Ki-61-I ended in January 1945, after somewhere between 2,654 and 2,734 aircraft had been built. The KAIc accounted for the vast majority of the 1,274 of the KAI models to be built. Although 374 Ki-61-II airframes were built, 275 of these didn't receive their inline engines and were instead completed as Ki-100s, while of the remaining 99 about two thirds reached front line units while the rest were destroyed by American bombing.

Combat Record

The Ki-61 entered service with the 23rd Dokuritsu Dai Shijugo Chutai (Independent Squadron) in Japan in February 1943. This was the equivalent of a British Operational Training Unit, and was used to give pilots experience with the new fighter. The first operational unit to receive the new fighter was the 68th Sendai, in March 1943, following in the next month by the 78th Sendai.

The overall Japanese plan for the war had been to conquer a large empire in order to push the fighting as far away from the Home Islands as possible. The hope was that the Allies could either be held at the outer edge of the Empire, or be forced to pay such a high cost to conquer this line of strongholds that they would come to terms. This meant that both the Japanese army and navy were forced to deploy most of their forces at a long distance from Japan, and would ultimately allow the Allies to chose where they attacked, bypassing many strong Japanese positions. It also meant that the Ki-61 would make its combat debut in an unexpected location - New Guinea.

New Guinea

The first Ki-61 units were allocated to the defence of the Southern Front. Here the Japanese held most of New Guinea, although their attempts to gain a foothold on the south coast of that vast island, facing Australia, ended in failure. It was clear that the Allies would soon go onto the offensive on New Guinea, and so in April 1943 the 68th and 78th Sendais began the move south to the major Japanese base at Rabaul.

Both units suffered high losses during the move to Rabaul. The Japanese Army Air Force was used to operating over China or other large land areas, and had little experience of flying long missions over water. The 78th Sendai was taken to Truk on aircraft carriers, before flying on to Rabaul. On the first delivery flight 18 out of 30 aircraft were lost when they got off course, while on another flight a problem with the wing-mounted ferry tanks meant that a large number of aircraft ran out of fuel. The 68th Sendai, which began to move in May, made the entire trip in the air, flying from the Ryukyu Islands to Formosa, the Philippines and along the northern coast of New Guinea, also losing large numbers of aircraft on the way. By the end of May the two units had reached Rabaul, but they were already under-strength (with around 30 aircraft each, instead of the 54 they were meant to have) and had lost some experienced pilots before even reaching combat.

The two units were part of the 4th Air Army, and moved to New Guinea in July-August 1943. They soon began involved in some one of the more prolonged and intense air battles of the Pacific War, with the two sides based comparatively close to each other, on the opposite sides of the mountain ranges in the centre of New Guinea. Large numbers of Japanese aircraft were destroyed on the ground by repeated Allied air strikes, but when the Ki-61 did get into the air it caused the Allies some problems. The Ki-61 was better armoured and more robust than the Nakajima Ki-43 or Japanese Naval fighters, could out-dive the P-38s, P-39s and P-40s in use with the American air force in the area, and could out-manoeuvre any Allied fighter until the P-51 Mustang and F6F Hellcat entered service.

Despite these limited successes the Japanese Army Air Force suffered very heavily on New Guinea. The jungle conditions caused as many problems for the Japanese as for the Allies, and vast numbers of Ki-61s were lost on the ground and in the air. By the time the Japanese withdrew in the spring of 1944 the Japanese had lost many of their most experienced pilots, along with large numbers of their best ground crew. Only 5% of the Army pilots with more than 300 hours flying time survived the fighting on New Guinea.

The Philippines

After the disasters in New Guinea the Ki-61 next saw combat in large numbers during the defence of the Philippines. The 17th and 19th Sentais were based around Manila from September-October 1944, and were joined by the 33rd Sendai from Malaya and the 18th and 55th Sendais after the American invasion began in October. Once again the Ki-61 units were overwhelmed, with the 55th Sendai losing all of its pilots by the end of November!

Formosa and Okinawa

The 19th, 37th and 105th Sentais were posted to Formosa and Okinawa, while the 59th Sentai took part in the defence of Okinawa. Once again the Japanese units suffered heavy losses.

Defence of Japan

The Ki-61 was used in large numbers in an attempt to defend the Japanese home islands. Japan was split into Easter, Middle and Western Defence Sectors. The 18th, 23rd, 28th, 53rd and 244th Sendais were posted to the Eastern sector, which included Tokyo. The 17th, 55th and 56th Sendais were posted to the Middle Sector, and the 59th and later 56th Sendais defended the Western Sector.

The Ki-61-I could only just reach the operating altitude of the B-29s, and even then only by having its weight reduced as much as possible. Most units thus struggled to inflict any damage on the Americans, although the 244th Sendai was an exception, proving itself to be a very dangerous opponent. The Ki-61 also used in an increasingly large number of suicidal ramming attacks against B-29s.

The Ki-61-II was a more capable aircraft, and could operate at the B-29's cruising altitude, but it never appeared in large numbers. It also entered service at about the same time as Allied fighter aircraft began to appear over Japan for the first time, with both US naval fighters and P-51 Mustangs from Iwo Jima entering the fray from February 1945.

Although the Japanese Army Air Force was suffering heavy losses over Japan, so were the B-29s. In March 1945 the high altitude day bombing campaign was replaced with low-level night raids, abandoning the idea of precision attacks. US losses dropped dramatically, and the Ki-61s were left to face Hellcats, Corsairs and P-51s. Although the Ki-61 could sometimes perform well against these aircraft, its pilots were almost always massively outnumbers and losses were very heavy. The radial-powered Ki-100, produced by fitting a radial engine to the airframe of the Ki-61-II performed a little better, but was never present in sufficient numbers to make any difference.

Variants

Ki-61

Twelve prototypes were produced with the designation Ki-61.

Ki-61-Ia

The Ki-61-Ia was the first production version of the Hien, and carried the same guns as the prototype, with two 7.7mm machine guns in the wings and two 12.7mm guns in the nose. Later aircraft were modified to carry imported 20mm Mauser MG 151 cannon in the wings, mounted on their sides.

Ki-61-Ib

The Ki-61-Ib was the second production version of the aircraft, and was armed with four 12.7mm machine guns, two in the wings and two in the upper fuselage. As with the Ia, some were later modified to carry 20mm Mauser cannon in the wings.

Ki-61-I KAIc

The Ki-61-I KAIc was the most common version of the fighter. It featured a modified fuselage (thus the KAI for Kaizo, or modified), and was armed with two 20mm Ho-5 cannon. The new fuselage was 20cm longer, and had a detachable rear section, with a fixed tail wheel replacing the earlier retractable version. The wings were stronger, allowing pylons to be added outside the undercarriage. These allowed the aircraft to carry either drop tanks or two 550lb bombs. The KAIc was armed with two 12.7mm machine guns in the wings while the two cannon were placed in upper fuselage. Production of the KAIc averaged over 100 aircraft per month from November 1943, peaking at 354 aircraft in July 1944. It was produced alongside the Ki-61-Ib until August 1944, and production ended in January 1945.

Ki-61-I KAId

The Ki-61-I KAId was a specialised anti-bomber version of the KAIc, produced in small numbers late in 1944. It reversed the armament of the KAIc, with 12.7mm machine guns in the fuselage and 30mm Ho-105 cannon in the wings.

Ki-61-II

The Ki-61-II was designed around the Kawasaki Ha-140, a more powerful but less reliable development of the Ha-40. The first prototype -II was completed in August 1943, and had a modified cockpit and a larger wing. Eight prototypes of the -II were produced, but the new wing was a failure.

Ki-61-II KAI

The Ki-61-II KAI was produced in response to the failure of the -II. Takeo Doi reverted to the standard Ki-61 wing, made the fuselage 22cm longer and increased the size of the rudder. The first Ki-61-II KAI made its maiden flight in April 1944 and was a great success. It could reach 16,450ft in six minutes, had a top speed of 379mph and could operate at the 30,000ft cruising altitude of the B-29 bomber. It was ordered into production as the Army Type 3 Fighter Model 2.

Ki-61-II KAIa

The Ki-61-II KAIa was the first production version of the -II, and carried the same guns as the Ki-61-I KAIc, with two 20mm cannon in the fuselage and two 12.7mm machine guns in the wings.

Ki-61-II KAIb

The Ki-61-II KAIb was similar to the KAIa, but was armed with four 20mm cannon, two in the fuselage and two in the wings. A total of 374 airframes of the two models were completed, but only 99 of them received their Ha-140 engines. On 19 January 1945 B-29 bombers from the US 20th Air Force destroyed the Akashi engine factory, ending production of the Ha-140 and leaving 275 fuselages without engines. Kawasaki responded by installed the Mitsubishi Ha-112-II double-row air-cooled radial engine into the airframes to produce the Kawasaki Ki-100 Army Type 5 Fighter.

Ki-61-III

The Ki-61-III was a single prototype of an improved version of the aircraft with a cut-down rear fuselage and an bubble canopy designed to improve the pilot's view (the same change was made to many Allied fighters).

Stats (Ki-61-I KAIc)
Engine: Kawasaki Ha-40 V-12 piston engine
Power: 1,175hp
Crew: 1
Wing span: 39ft 4.5in
Length: 29ft 4.25in
Height: 12ft 1.75in
Empty Weight: 5,789lb
Maximum take-off Weight: 7,650lb
Max Speed: 366mph at 13,980ft
Cruising Speed:
Service Ceiling: 32,810ft
Range: 1,181 miles
Armament: two 12.7mm machine guns and two 20mm Ho-5 cannon in wings
Bomb-load: Two drop tanks or two 551lb bombs under the wings


Kawasaki Ki-61 Hien (Tony)

Authored By: Staff Writer | Last Edited: 05/19/2018 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

The Kawasaki Ki-61 Hien (meaning "Swallow" and codenamed "Tony" by the Allies) was another of the oft-forgotten yet impressive Japanese-brand fighter designs of the Second World War, joining the equally impressive Kawanishi N1K1-J Shiden - in this author's opinion. Not without its developmental problems early on, the Ki-61 nonetheless forged into a well-oiled killing machine with a potent armament, sufficient armor for pilot and fuel alike and impressive performance numbers to rival anything offered up by the Allies at the time.

The Ki-61 became a design reality by 1940 and was the brainchild of Shin Owada and Takeo Doi. Their previous design experiences saw them working under German aircraft designer Richard Vogt and the German influence in the Ki-61 could readily be seen to the aviation-educated eye. Additionally, the German mark on this series of aircraft was made ever moreso with the inclusion of a license-produced Daimler-Benz DB 601A which were being fielded under the recognizable Japanese label of Ha-40 under the Kawasaki brand. The prototype would be ready to fly by 1941 with full production beginning in 1943.

From an external design standpoint, the Ki-61 featured a sleek and slender fuselage design. The engine was placed well ahead of the cockpit, with the latter being situated in the center-forward position of the upper fuselage. The wings were of a monoplane low-mounted type with rounded edges, as were the horizontal and vertical tail surfaces adorning the empennage. Power was derived form a single Kawasaki V-12 piston engine, offering up performance statistics including a 367 miles per hour top speed, a 16,404 foot ceiling limit and an equally impressive 1,118 mile operational range. To the trained observer, the Ki-61 definitely shared some similarities to other nation aircraft designs, almost always compared favorably as a meshing of the German Messerschmitt Bf 109 and the American North American P-51 Mustang. The nose design could easily be associated with either design, as can the placement of the cockpit, smallish tail section and the under-fuselage scoop.

The Ki-61 proved a worthwhile platform in service through to the end of the war. The system was actually one of the few Japanese aircraft to be able to engage the Boeing B-29 Superfortress at its normal operating altitude and was capable of handling it with some power thanks to the Hien's powerful 4 x 20mm cannon array. Joining the ranks of capable fighters in World War 2, the Kawasaki Ki-61 Hien certainly is a worthy mention in any discussion - at the very least earning the title of one of the better Japanese-branded fighters of the conflict. Some 3,000 Hiens in various forms were produced.


Kawasaki Ki-61 Hien / TONY

Sometimes described as a cross between a Messerschmitt Bf 109 and a North American P-51 Mustang, the Kawasaki Ki-61 certainly had the distinctive nose shape associated with an inverted V-12 inline engine, the Kawasaki Ha-40 being in effect a Daimler- Benz DB 601A built under licence. The Ki-61's designers, Takeo Doi and Shin Owada, had moreover worked under the German Richard Vogt, In December 1940 they were instructed to go ahead with the Ki-61, and one year later the prototype was flown. The first production Ki-61-I fighters were deployed operationally in April 1943 when the 68th and 78th Sentais arrived in New Guinea. Named Hien (swallow) in service (and codenamed 'Tony' by the Allies), the new aircraft proved popular with its pilots, being unusually well-armed and armoured, and the type was at least a match for opposing American fighters. Its armament (of four 12.7-mm machine-guns) proved inadequate to knock down enemy bombers, however, and the Ki- 61-I KAIc was introduced with a pair of 20-mm cannon in the nose, these being replaced in a small number of Ki-61- I KAId fighters by two 30-mm cannon. The Ki-61- I and Ki-61-I KAI remained in production until 1945, but in 1944 they were joined in service by the Ki- 61-II with more powerful Kawasaki Ha- 140 engine (producing 1119-kW) with a top speed of 610km/h this would have been an excellent fighter but for constant engine problems yet when fully serviceable the Ki-61-II was one of the few Japanese fighters fully able to combat the Boeing B-29 at its normal operating altitude, particularly when armed with four 20-mm cannon. Excluding prototypes and development aircraft, production totalled 1,380 Ki-61-Is, 1,274 Ki- 61-I KAIs and 374 Ki-61-Ils.

Some say Ichikawa had his Ki 61-I'd Kai with the 30mm Ho-155-I cannons in the cowl with successintercepting B-29s. If true, the only problem would be the 58 r /m or so rate of fire each. The already slow rate of fire at 120 r /m would be cut by over half to synchronize through the prop. But at least it would be accurate vs the wing mounted 30s that damaged the spar with it's recoil. Putting the 20mm Ho-5s in the wings instead works fine and is very fast firing at 850 r /m each. But still better would be putting only one 30mm cannon in the hub fire half the weight of 2 and still the rate of fire of 2. This cuts out the weight of the interrupt or gear too.
Lighter on it's feet but with the same punch, his Hien would've been a better dogfight as well as B-29 slayer.
Then there is the fast and light 30mm Ho-155-II in 1944.
It did 600 r /m! The perfect motor-cannon for the 1944 Ki 61-II.

I like the fact that the Japanese at least had the potential to overcome the main faults of the Ki 61-I.

The 20mm Mausers cannons could've been in the cowl or wing-roots at 630 r /m RoF. Their drawback was only an OK 800-850m firing-range. The Mineshell was their plus, in addition to the synchronized RoF advantage vs Browning-based Japanese cowl guns and cannons.
Japanese copies could keep Japanese fighters in good supply beyond the imported batch.
The 30mm Ho-155 could've been in the hub with good 900m range vs the faster 30mm MK 108 cannon.
This suite of 3 cannons would leave the wings unweighted for agility but still great firepower.

The speed /climb penalty could be more than offset with triple ventral rocket boosters like the Judy D4Y4 used!

The wingloading penalty could be addressed with the automatic combat flaps used on the N1K1 for a 30% tighter turn radius!

Then, the unreliable engine could've been beefed up. If chromium was not available, why not add more supports with slider-bearings so the drive shaft wouldn't fail around 200 hours run time, for example. etc?

The Ki 61-II could entertain the bigger DB 603 or Jumo 213 based engine and the long-range 37mm Ho-204 hub-cannon or fast 30mm Ho-155-II with the Mauser-based 20mm cannons.
Of course the bubble canopy for this new Tony would've been sweet.

The Hydraulics and electronics would've needed to be addressed too, perhaps by crossing over from IJA to IJN suppliers if necessary.

The Ta 152H was received by sub in Japan. The Ki 61-II Tony could've been effectively the equivalent, potentially.

The 20mm Mauser wing cannons hurt the turn radius but putting the Ho-5 cannons in the cowl tightened the radius again. Electric gun fuses were prone to blow at inopportune times.
Against the USN F6F the Tony pilots adopted hit-and-run tactics with relative effectiveness.

Against B-29s, the Tony would be stripped of armor and perhaps all but one cannon for better altitude.

The Tony was prone to stall on take-off, landing, and pullout. The Ki 61-II prototype still had a very weak crankshaft and an unreliable engine. The revised airframe was weak and the new wing was rejected.
The Ki 61-II had frequent failures of main bearings and superchargers, oil and coolant systems. But when working right, it held it's own if well piloted.

Fighter Gun kg Wt R /S GP kg /s M /V m Range GP /Gun Wt
_________________________________________________________
Ki 61-Ib Kai 130 39 471 3.228 775 /727 900 /850 3.6
Ki 61-Ic Kai 120 43 285 2.324 775 /820 900 2.4
Ki 61-IIa 120 43 261 2.324 775 /703 900 /600 2.2
Ki 61-IIbKai 148 41 437 4.040 703 600 3

These are my estimates. Take with a grain of salt.
These don't include Tony fighters without 20mm cannons.
The Ki 61-Ia and -Ib with only 7.7mm and 12.7mm MGs aren't in this comparison.

As a B-29 interceptor, the 20mm cannon was key in the Tony. The first is with the Mauser MG 151 /20 next version has the cowl Ho-5 twins then the same but after the Ho-5 was degraded finally the Ho-5 quartet.

If you wonder about the discrepancy between the WoF and the GP of the Maser version, the potent HE /M shell is included in the ammo belt in my opinion.
But remember, these were in limited supply and may have been gone by the time the B-29s arrived.

These Tonys did not utilize hub-cannons like their German brother, the Bf 109 Gustav with mostly 30mm cannons in the hub. These were the very short range 30mm MK 108 cannon. The IJA had a better one, the 30mm Ho-155 cannon. This was called for when Ki 61s were intercepting B-29s, which the Gustav never had to face.
No other Japanese fighter could have a motor-cannon, only the inline engine Tony (and fighter version of the inline D4Y2-S Judy perhaps). It would be curious to know how such a Ki 61 would've done in WW2.
The Ki 61-Id had this 30mm cannon, but only in the wings. Thus accuracy was non-existant and the wingspar cracked from the recoil, so these were sidelined at training bases. Putting it in the spinner would've avoided these drawbacks. Thousands of Tonys were available to be converted to dragon slayers. They would only need 2 Ho-5 cannons to compliment it. 118-124kg for gun weight. The Ho-155-II was only 44kg and about as fast as the MK 108!
Both versions of the Ho-155 had more than twice the firing range at 900m vs 365-400m! And the MK 108 was also more prone to jam!!

I like the idea of a motor-cannon in the Ki 61.
The 30mm Ho-155 cannon outperforms the MK108 in the nose of 17,000 Bf 109 Gustavs in the Luftwaffe.
The Ha-40 and 140 should accommodate it since the DB 601 is the parent engine. (It is interesting that the RLM considered the DB 605 a sick engine) Anyway, the Gustav made heavy use of motor-cannons.
Does anyone know why the Tony didn't use it?

1. The Italian versions of the DB 601 and 605 should've been built in Japan instead of the Japanese versions which proved so much more unreliable.

2. The Ki 61 was lacking the advantage of a motor-cannon. Why? The Bf 109 and Fiat G.55 had motor-cannons with basically the same inline engine. Perhaps over 80,000 fighters of WW2 utilized this advantage. But not Japan!
P-39s, P-63s, MiGs, LaGGs, Yaks, Reggianes, Fiats, Bf 109s, Fw 190Ds, and Ta 152s had hub-guns and cannons firing through the spinner.
The best 20mm, 30mm, and 37mm cannons of late-WW2 were arguably Japanese. Perfect as world-class motor-cannons. The 400 r /m 37mm Ho-204 was the fastest 37mm and out-ranged the defensive fire of US bombers.
The 30mm Ho-155-II was lightest at 44kg and fast at 600 r /m and had good range. Everyone knows about the fastest 20mm cannon of the war, the 850 r /m Ho-5. The IJN had good ones too.

These 2 changes could've made the Tony so much better.
Of course this is the advantage of hindsight.
As it was, the biggest production version of the Ki 61s only had 4x12.7mm HMGs, and all versions were unreliably powered! It's no wonder the Tony had the worst loss ratio vs the USN (28 /1) of all Japanese fighters in the last year of WW2!
On the other hand it was a good B-29 interceptor.

About 30 Ki 61-IIKai were produced with 4x20mm cannon. The remaining 69 had HMGs in the wings as well as the 2x20mm nose-cannon the wings. Another 25 were preproduction.

The 30mm wing-cannon in some Ki 61-Is had no accuracy besides warping the wing and cracking the spar. So they were sidelined.
In my opinion, a dorsal mounting of the 30mm on an angle ala Zero night fighter would have worked.

Ki 61s were successful at ramming B-29s due to their strong build vs all other Japanese fighters. Pilots would many times survive and ram again.
On one raid, over 900 interceptors rose to combat the B-29 force.

Kawasaki biuld quality was superior to Nakajima. Maybe the best in Japan. Of course I'm not talking about the engine, hydrolics, or electrical. Just everything else. Stronger and protected.

That brings us to 6 /1944 and the Ki 61-II in response to the bitter complaints of mechanical nightmares near and far. The cockpit was roomier. All the better to quickly bailout when ramming B-29s and do it again on the next raid.
26were built. Then came 69 of the Ki 61-IIa from 8 /1944, followed by 30 of the 4x20mm Ki 61-IIb starting from 9 /1944. Reason for the slow production? The new high altitude Ha-140 engine production.

You guessed it, the engines were more unreliable than before. Another big problem now was frequent electrical system breakdowns.

The weight was increasing and since the new wing was rejected, the old wing bore the burden. 1929 lb increase from the tight-turning Ki 61-Ia to the heavily armored 4 cannon Ki 61-IIbKai. that's about a ton!
Still it could climb to 5Km /6min.30sec. and top speed was 373 mph unboosted. The main 2 cannon Ki 61-IIa did better at 379 mph and 6 min. 5 sec /5Km climb.

The comparison test of the captured Ki 61-Ib by the Navy vs late and post-war navy fighters is misleading in my opinion.
The -Ib of 1942-3 is hardly a contemporary of the 1944-46 USN fighters even if it was in good repair and it wasn't. I can see why it was captured.

Anyway, a properly working Ki 61-Ib had a top speed of 368 mph at 5km altitude which it could reach in 5 min 31 sec. Few US fighters could climb better in 1943. Normal loaded weight was 6900 lbs. 4x12.7mm Ho-103 HMGs.

Then in August came the Mauser armed Ki 61-IbKai. It was slowed to 360 mph. But those cannon were good.

Hydrolics was one of the biggest problems for the Ki 61-I.
The prop, guns, flaps, undercarriage, all involved.

Then in January 1944 the Ki 61-Ic weighs in, at 7650 lbs normal load. Climb to 5Km /7 min! But it had the cowl mounted 20mm Ho-5s.
Probably heavy enough to dive with a P-40.

Don't forget, the early Ki 61-Ia at 6504 lbs could out-dive a P-39 and turn almost as well as an Oscar from 8 /1942. Of course it only had double the guns (2x7.7mm & 2x12.7mm) of the typical Ki 43.

The 30mm armed Tony was the Ki 61-Id Kai. They were unsatisfactory and few were made. So these were largely relegated to training duty.

The early Italian MC.205 and Re.2005 overheated in sustained climb but the G.55 was no problem. I don't know if they fixed the others.
The faster, more agile Re.2005 dove at 609 mph but rudder balance was easily abused causing flutter and fuselage deformity.
An example of the Re.2005 was bought by the Germans who installed a boosted domestic DB 605 and VDM prop of the Bf 109 attaining speeds of 437-447 mph! So it was a world-beater but iffy.

I wonder how the Ki 61-II would have done with that version of the DB 605 and prop instead of the weak, lightened, unreliable Kawasaki version?
It could probably compare favorably or beat the 417 mph (boosted) G.55 but with much better max range.
I'd add a hub-cannon to the Ki 61 like the 30mm Ho-155 with 900m range to best the MK 108 of the Bf 109 low velocity 30mm (even in a trade-off with the cowl Ho-5s). Swap the Ho-155 for the reliable German DB 605 in exchange.
Worthy of tackling B-29s, this could have been the best DB 605 powered fighter. If wing loading is too high given the failure of the new lareg Kawasaki wing, copy the wing of the Re.2005 or G.55 and hold off on adding the tail ballast and drop tanks to save weight.

The Allies were fortune things didn't go this way.

I often wondered why the Japanese had so many of their Broning derived guns installed in the cowl when synchronising reduced the RoF so much more than others (like the MG 151 /20 cannon).

The Tony imported Mausers for wing mounting but when the nose was lenthened to replace the Ho-103 with cannons in the cow, The up-sized the Browning 0.50 Cal to 20mm for the H0-5. Why not a Mauser derivative? The synchronised HMG and cannon designs on most Japanese fighters were Browning-based, cutting RoF in half. Note this post on synchronised Brownings:

"A practical example of the effect of synchronisation is graphically provided by comparative tests held by the USN in 1926 /7 of the .30" M1921 and .50" M1921, both on a test stand and in synchronised mountings. These also shed some light on the differences between claimed and actual rates of fire, and between different installations of the same gun. The .30" had a claimed RoF of 1,200 rpm, but proved capable of between 800 and 900 rpm on the test stand. When synchronised, the RoF went down to an average of 730 rpm (a fall of about 15%), with a range of between 667 and 818 rpm for different installations and propeller speeds. The .50" had a claimed RoF of 600 rpm, and did rather well to achieve between 500 and 700 rpm, depending on the recoil buffer adjustment (although a contemporary British report put this at 400-650 rpm, the difference possibly caused by belt drag when installed), but this fell to an average of 438 rpm when synchronised, varying between 383 and 487 rpm. As the synchronised guns were adjusted for maximum RoF, this represented a reduction of around 37%. There is no inherent reason why a larger calibre weapon would suffer a bigger reduction in RoF, so the synchronisation conditions must have been better suited to the .30" gun's natural RoF."

The Mauser was synchronised with much success by the Luftwaffe electrically for a 10% reduction in RoF!

The Type 3 and Ho-103 HMGs as well as the Ho-5 cannon all got 400 or so RoF synchronised. All Browning style designs.

Imagine the Tony with 4 Mausers!
One reason the synchronised LMG persisted in Japanese fighters so long was their rapid RoF since they were not Browning-based.

Unfortunately with episodes like the one where 2 /3 of the Tonys transfering from one base to another were lost in flight, pilots were wishing they had their Oscars back.
With Ki 61 losses like that due to engine trouble, you don't need enemies.
Tropical climates didn't help either. They should have been kept in temperate climates close to maintenance depots. At least until they could get reliable engines ala Ki 100 but in 1943 at the latest. It's not like they had to wait for the inline engine factory to be bombed to have the Ki 100 engine. It existed mid-war.

Failing that, put the reliable Tojo on fast track production to take up the slack, at least in the tropics.

The odd tail was the P-40K. But the Gypsy Rose Lee was the P-40L stripper with various degrees of undress, reducing guns, armor, and fuel loads for performance and handling. 720 built. Still the Ki 61-I was much lighter without sacrificing firepower, range, and armor. At least the Ki 61-II weighed more perhaps but it had much greater firepower than the Gypsy's 2 MGs!

Biair,
Are you speaking of the P-40 version with the odd tail?
That's the only plane I know of by that name if I'm not mistaken.

What was the KI-61 that flew into Yontan and was captured and painted USMC colors? I know they had to get the smallest pilot to fly to Kadena. Yjen USAF took it over. My question is He flew in from Korea or at least he had Koren currency on him. Who was the Pilot? Where is that plane, I dont think it went to scap like the others. and it had blue german swatski maker mark inside the fuselage,(metal imported I guessing for the manufacture of this one aircraft.

I have to vote for Miss. Gypsy Rose Lee

The DB605 engine was not without troubles even in Germany early on. They beefed up certain parts etc. and were able to use boost thereafter. The Fiat version powering the Italian series 5 fighters, was likewise corected later (1944). Unfortunately the Kawasaki version of the engine never got rid of its problems in the Ki 61-II 'Tony'. (check out my Fiat post recently).
Perhaps the Japanese tendency to make a lighter version of the DB601 from the begining in the Ki 61-I fighter (instead of beefing it up) had something to do with this all along.

Aaron
I think it's an overstatement to say that "the majority of B-29s lost to Japanese fighters were shot down by the Ki.61-II". Very few model IIs went into combat units, probably just 55 and 56 sentais plus a few at the Air Evaluation Unit at Tachikawa (Koku-Shinsa Bu). The famous B-29 intercepition unit, the 244 Sentai, were equipped with model Is of various marks which were later replaced by Ki100s instead of Ki61 IIs.

The tactic was to have a "Shinten Seiku Unit" (Sky-Quake Air Superiority Unit) whose aircraft were stripped of armament and armour and ramming the B-29s to break up formation. The sturdy Hiens were suited for such tactic, as several Hien Shinten Seiku Tai pilots such as Matsumi Nakano, Masao Itagaki, and Teruhiko Kobayashi survived the crash to fight again. In fact Nakano and Itagaki rammed other B-29s late and survived again. However, such feats are not recorded in other units using Ki44 or Ki45 planes, the pilots disintegrating with their planes on impact.


Kawasaki Ki-61 Hien (Swallow) 'Tony' - History

The Kawasaki Ki-61 was the only fighter with a liquid-cooled engine that the Japanese Army Air Force put into the field during World War II. It was this that made the Ki-61 Hien ("Swallow") so unlike the other Japanese planes that the Allies initially thought that it was German or Italian-made. While the engine was a license-built version of a German Daimler Benz engine, the rest of the aircraft was an all-Japanese design. The Ki-61, known as "Tony" in the Allied code, proved to be a match for Allied fighters, due chiefly to its particularly heavy armament, good protective armor, and high speed in dives. The Ki-61 was one of the few interceptors that could reach the same altitude as the the American B-29 Superfortresses. Because it was so successful a total of 3078 aircraft were built between August 1942 and August 1945. However, problems with production and with its engine kept it from being even more widely used during the war. The plane's engine problems included being difficult to tune and being subject to constant breakdowns. A solution to the engine problem was to substitute a more reliable radial engine for the liquid-cooled one. This caused a slight redesign of the fuselage, with the resulting aircraft type being designated the Ki-100, which turned out to be an even more outstanding fighter.

Kawasaki Ki.61-Ib


Additional information on this aircraft can be found at Wikipedia HERE .

For several very nice scale color drawings of this aircraft, see here (15 versions available on left).

Additional color schemes for this aircraft can be found here.

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Ki-61 “Tony”, Japanese Fighter


The Ki-61 Hien (Swallow) was fast and maneuverable, and it was the first Japanese Army aircraft equipped with self-sealing fuel tanks and armor. It also had a good dive rate, which made it an unpleasant surprise to Allied pilots in New Guinea who were accustomed to shaking Japanese fighters off their tails with a steep turning dive. It would have been a good aircraft in which to practice hit-and-run tactics against the Allies, but the Japanese seem never to have made the jump in tactics. As it was, "Tony" was the only Japanese fighter in service during the mid-war years that was a decent match for the second-generation Allied fighters.

"Tony" was about the only fighter with a liquid-cooled engine that the Japanese Army produced, and it was often mistaken for a German or Italian fighter by Allied airmen. Indeed, the Allied code name "Tony" was selected on the belief that the aircraft had Italian origins. In fact, the Ha-40 engine used by the aircraft was essentially the German DB-601A built under license. Many of the early production aircraft also used a German electrically-fired 20mm cannon, but ammunition was limited and the German gun was replaced with the Japanese Ho-5.

The Japanese had acquired manufacturing rights to the DB-601A in April 1940 and manufacture of the Japanese version began in July 1941. A specification for aircraft built around the new engine had already been issued, in February 1940, when Kawasaki was instructed to develop both light and heavy fighter designs. The light fighter was given priority after December 1940, and the design team, led by Doi Takeo and Owada Shin, completed a prototype a year later. Preparations had already begun by then for quantity production, which commenced in August 1942.

The operational history of the "Tony" illustrates the weaknesses of the Japanese aircraft industry and of Japanese logistics. The aircraft was difficult to produce, averaging just 50 planes a month in the crucial mid-1943 time period. Many of these failed inspection and had to be returned to the factory for repair. Those already deployed to the Southwest Pacific and needing an engine change had to go clear back to Clark Field.

The Ki-61-II was designed specifically for improved high-altitude performance, but the Ha-140 engine had serious teething problems and only 99 production aircraft were completed. The destruction of the Akashi engine works by a B-29 Superfortress raid on 19 January 1945 left 275 Ki-61-II airframes without engines. These aircraft were modified to use the Ha-112 engine and became the prototypes and first production run of the Ki-100.


The Kawasaki Ki-61 Hien ("Tony") & Ki-100

* The Kawasaki Ki-61 Hien ("Swallow") fighter represented a major departure for Japanese aircraft design in World War II. While other Japanese fighters were designed with air-cooled radials and were optimized for maneuverability, the Ki-61 used a liquid-cooled in-line engine and was designed for speed and power.

In fact, the Ki-61 was so different from other Japanese fighters that when the type was first encountered in combat over New Guinea in June 1943, the Allies thought it wasn't a Japanese design at all. At first they believed it was a copy of the German Messerschmitt Me-109, then suspected it was a copy of the Italian Macchi C.202 Foglore or similar Italian fighter. For this reason they gave it the code-name "Antonio", or "Tony", though by the summer of 1943 the Allies had realized the Ki-61 was in fact a Japanese design.

The Hien proved initially successful in combat against American fighters. As the war in the Pacific ground on, however, the Ki-61 found itself increasingly outclassed, but it soldiered on until the end of hostilities. This document describes the history of the Ki-61 and its radial-engine derivative, the Ki-100.

* The confusion of the Ki-61 with German and Italian fighters had some basis in the aircraft's origins. Between 1923 and 1933, Kawasaki Aircraft Engineering Company's head designer was a German named Dr. Richard Vogt, who returned to Germany in 1933 to take a similar position at the firm of Blohm und Voss during the war. Not surprisingly, Kawasaki continued to be strongly influenced by Dr. Vogt's beliefs after he left, particularly a faith in the usefulness of liquid-cooled inline engines. This made Kawasaki something of a heretic among Japanese aircraft manufacturers, who preferred air-cooled radials.

In March 1938, Kawasaki signed an agreement with Daimler-Benz of Germany for manufacturing rights to the liquid-cooled inline engines then under development by the German firm. In April 1940, a Kawasaki engineering team visited Daimler-Benz in Stuttgart to obtain plans and samples of the DB-601A engine, then being used in the Me-109.

The Kawasaki engine team managed to increase the take-off power of their version of the engine to 875 kW (1,175 HP) and reduce its weight slightly. The engine was put into production in November 1941. It was designated the "Ha-40", or "Army Type 2", though it would be later redesignated the "Ha-60" in a combined Army/Navy nomenclature.

In the meantime, certain officers at the Air Headquarters of the Imperial Japanese Army were very interested in the new fighters powered by liquid-cooled being developed in Britain, the USA, the USSR, Germany, and France. The Japanese Army also had unpleasant experiences in air combat against the Soviet Polikarpov I-16 fighter during the beating the Imperial Army took in their Manchurian border clash with the USSR in the summer of 1939. This experience suggested the the single-minded focus on agility above all that characterized Japanese fighter design doctrine might need to yield to a focus on speed and improved armor protection and firepower.

* In February 1940, the Army initiated work with Kawasaki on two single-seat fighters based on the DB-601 derivative engine: a heavy interceptor, designated the "Ki-60", and a general-purpose fighter, designated the "Ki-61". Kawasaki decided to build the Ki-60 first, and the design team, under Kawasaki chief designer Takeo Doi and his deputy Shin Owada, constructed three prototypes of the interceptor in 1941.

The Ha-40 engine was not available at that time, so the three aircraft were powered by sample DB-601A engines obtained from Germany. The Ki-60 was a low-wing monoplane, with plenty of power and heavy armament by Japanese standards. The first and second prototypes had two 12.7 millimeter (0.50 caliber) Ho-103 machine guns mounted on the nose in front of the pilot and two 20 millimeter Mauser MG-151 cannons, one mounted in each wing, for a total of four guns. The third prototype had four 12.7 millimeter guns. Flight tests began in March 1941 and showed that the Ki-60 was too unmaneuverable and didn't meet its speed and climb requirements. Various tweaks to improve the aircraft failed, and so the Ki-60 was abandoned.

* The experience was valuable, however. Design work on the Ki-61, whose development had been proceeding in parallel with the Ki-60 since December 1940, incorporated new features derived from the lessons learned by the Ki-60 program:

The first prototype was rolled out in early December 1941, and its performance proved excellent. Eleven more prototypes were delivered to the Army, which performed intensive trials with them. The Ki-61 was pitted against other Japanese fighters, as well as against the Messerschmitt Bf-109E-3, of which two had been bought by the Army from the Germans, and the Curtiss P-40E, several of which had been captured during the seizure of the Dutch East Indies.

While the test pilots were a little skeptical of the new aircraft at first, pilots with combat experience appreciated the Ki-61's self-sealing fuel tanks, heavier armor and armament, and fast diving speed. The air combat tests showed the Ki-61 to be faster than all its adversaries in the tests, and easily out-maneuvered all of them except the Japanese Nakajima Ki-43 ("Oscar").

The 13th Ki-61, a production prototype, was delivered in August 1942. The Army gave the green light for production, and the fighter began to roll off the assembly line, with 34 delivered by the end of 1942. The type was formally known as the "Army Type 3 Fighter Model 1 Hien", or "Ki-61-I".

The production machines differed from the prototypes only in tweaky details. Initial production consisted of two variants: the "Ki-61-Ia", with two 12.7 millimeter guns in the nose and a 7.7 millimeter gun in each wings for a total of four guns and the "Ki-61-Ib", with 12.7 millimeter guns in both fuselage and wings. These aircraft could be fitted with two 200 liter (53 US gallon) drop tanks.

* The Hien entered combat in the spring of 1943 in the New Guinea war zone, covering 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. 5th Air Force Commander General George Kenney 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 demonstrated only a few teething problems in field use, such as a tendency towards engine overheating during ground running under tropical conditions. However, despite the heavier armament, it still didn't have the punch to easily knock rugged and well-armed Allied bombers out of the sky.

The Kawasaki designers had forseen this problem. The Japanese Ho-5 20 millimeter cannon wasn't available at the time, but the Japanese obtained 800 Mauser MG-151/20 20 millimeter cannon from Germany in August 1943, and modified 388 Ki-61-I airframes on the production line to carry the German weapons in place of the two 12.7 millimeter wing guns. The cannon had to be mounted on their sides to fit into a wing, with an underwing blister for the breech, and some reinforcements were added to the wing to absorb the increased recoil.

* Once the Ho-5 cannon became available, Kawasaki designers then reversed the arrangement of the guns, putting the 20 millimeter cannon in the nose and the 12.7 millimeter guns in the wings. While they were making these modifications, they also made a few changes to streamline manufacturing and simplify field maintenance.

This new variant was designated the "Ki-61-I KAIc" (where "KAI" was for "kaizo", or "modified") was 19 centimeters (7.5 inches) longer than its predecessors, with a detachable rear section, a fixed tailwheel instead of the retractable tailwheel previously used, stronger wings, and stores pylons outboard of the main landing gear, allowing it to carry two 250 kilogram (550 pound) bombs. The Ki-61-I KAIc went into production in January 1944 and ultimately replaced production of all earlier models in August 1944. A few "Ki-61-I KAId" bomber interceptors were also built in late 1944. These aircraft featured two 12.7 millimeter guns in the fuselage and a 30 millimeter Ho-105 cannon in each wing.

Total production of all subvariants of the Ki-61-I was 2,654, with the Ki-61-I KAIc accounting for over half that number.

* Even before the Hien saw combat, the Army had been pressing Kawasaki for an improved version of the same aircraft. To this end, Kawasaki engineers focused on an improved version of the Ha-40 engine known as the "Ha-140", which was expected to have a take-off power of 1,120 kW (1,500 HP).

The first prototype of the new variant, the "Ki-61-II", flew in August 1943. Ten more prototypes were ordered. They featured a wing with 10% more area, and an improved canopy to provide better rear visibility, but the Ha-140 development program ran into troubles, and only eight of the prototypes received engines. Even then, they suffered from engine troubles, structural failures due to weaknesses in the new wing, and handling problems.

In an attempt to fix the problems, after delivery of the eighth Ki-61-II prototype, the ninth prototype was extensively modified during manufacture. The extended wing was replaced with the original Hien wing, the fuselage was lengthened, and the rudder area increased. The result was the "Ki-61-II KAI", with initial flight of the prototype in April 1944. It was followed by 30 more prototypes. As long as the temperamental Ha-140 engine worked properly, the Ki-61-II KAI proved to be a promising interceptor, with a fast climb rate and good high-altitude flight characteristics.

Despite the problems with the engine, the military situation was increasingly desperate, and so the Ki-61-II KAI was put into production anyway in September 1944. Two versions were produced, one designated "Ki-61-II KAIa", with 12.7 millimeter guns in the wings and 20 millimeter cannon in the nose, and the other designated "Ki-61-II KAIb", with four 20 millimeter cannon.

374 Ki-61-II KAI airframes were built and 99 of them fitted with engines. Then, on 19 January 1945, US Army Air Force B-29 Superfortresses turned the plant at Akashi that was building the Ha-140 engine into cinders and rubble. That abruptly ended concerns over the reliability of the Ha-140 engine, but left 275 airframes sitting around without powerplants.

* However, in November 1944 concerns over the availability (or lack thereof) of the Ha-140 engine had led the Munitions Ministry to request that Kawasaki redesign the Ki-61-II KAI to use an available engine. Company engineers performed a lightning design effort to mate the fighter to the 1,120 kW (1,500 HP) Mitsubishi Ha-112-II 14-cylinder double-row air-cooled radial engine. The engineers inspected the radial engine installation of a sample Focke-Wulf FW-190 fighter obtained from Germany and, in an example of interservice cooperation that was far more the exception than the rule between the Imperial Japanese Army and Navy, took advantage of Navy efforts to use the Ha-112-II.

The first prototype conversion of three took to the air on 1 February 1945. Sometimes improvisations work poorly, sometimes they work surprisingly well, and the new variant demonstrated excellent performance. The rest of the engineless Ki-61-II KAI airframes were then converted to the new fighter type, which was designated the "Ki-100-Ia". They retained the armament of the Ki-61-II KAIb, consisting of 12.7 millimeter guns in the wings and 20 millimeter guns in the fuselage.

Performance was roughly the same but engine reliability was vastly improved. The Ki-100 was in fact an excellent fighter, a nasty customer for Allied aircraft to deal with while being surprisingly comfortable and easy to fly, an important consideration when experienced Japanese pilots were in increasingly short supply.

A batch of 118 new-production Ki-100s were then built, incorporating an all-round vision canopy, tested on a modified Ki-61-II KAI, and given the designation "Ki-100-Ib".

Work was then done to add a turbosupercharger and water-methanol engine boost to the Ki-100 to provide improved high-altitude performance. The first prototype of this variant, designated the "Ki-100-II", flew in May 1945, with two more prototypes completed before Japan's surrender ended plans for production. * As Allied forces pushed in the bounds of Japan's overextended ocean empire, the Hien fought in the South Pacific, in the Philippines, on Okinawa, and finally in defense of the Japanese home islands themselves. Some Hien units also served on in China and on Formosa.

The home defense units operating on Japan used a mixed bag of Ki-61 variants, essentially anything they could get their hands on. The most famous of these units was the 244th Sentai (Fighter Group) under Japanese ace Major Tembico Kobayashi. Major Kobayashi encouraged his men to perform frontal attacks on B-29s and press their assaults to close range, even ramming if that was what was needed. Major Kobayashi set an example by fighting with almost suicidal determination.

By this time, the Hien was outclassed by American Mustangs and other late-model US fighters. In fact, when attacking B-29s Hiens often had to be protected by Ki-100s. Operations dwindled as planes and pilots continued to fall in combat and fuel and spare parts dried up. By the end, the home defense units were no longer capable of posing a real threat to the Americans.

Of the 3,159 Hiens built, not many survived the war. Several were evaluated by the Americans and one was presented back to Japan by the US Air Force later. This was the only surviving Hien as of the mid-1960s. American aircraft restorer Kermit Weeks has a Ki-61 airframe in slow process of restoration.

* The Ki-61 wasn't the only fighter design to be powered by the Ha-40 engine. Kawasaki also experimented with an unusual twin-engine design conceived by Takeo Doi in 1939 and approved for prototype development in October 1940 as the Kawasaki "Ki-64".

The Ki-64 actually had both engines in a line, straddling the cockpit and driving a single contra-rotating prop system with twin three-bladed props. The combined engine was known as the "Ha-201", and generated 1,755 kW (2,350 HP) take-off power. It featured an unusual steam cooling system with radiators in the wing and flap surfaces. The front engine used the right wing for cooling, while the rear engine used the left wing. The Ki-64 had a vague configurational resemblance to the Hien, though it was larger. One prototype was finished in December 1943, but the rear engine caught fire on the fifth test flight. The aircraft made an emergency landing and survived. However, it was never repaired and the project was abandoned in the middle of 1944.

* I seem to be strongly inclined in my writing to describe aircraft I made models of when I was a kid. This is something of an attempt at vindication, I think, because I was such an inept modelmaker. However, I do recall that I did a fair-to-middling job on my 1/72 scale Ki-61, and it still sticks in my mind, though the sleek "sky shark" look of the Hien helped make it memorable as well.

One of the puzzles in writing about Japanese aircraft is trying to figure out whether to use the Japanese name ("Hien") or the Allied codename ("Tony") in the text. Obviously one of the reasons for giving codenames was to give Allied forces a more easily recognized "handle" for the aircraft than the Japanese designation, if the Allies even knew what the Japanese designation was when a new aircraft appeared.

Using the Allied codename might be a bit more convenient, but somehow giving an aircraft a name assigned by an enemy seems disrespectful. The Hien is the hero of its own story and even if it was used against my own countrymen, it deserves to be respected on its own terms.


Kawasaki Ki-61 Hien (Swallow) 'Tony' - History

Kawasaki Ki-61 Hien' Tony'

In 1937 Kawasaki purchased a licence to build the German DB.601 engine - the resulting revised and lightened Japanese engine emerged in 1940 as the Ha-40.

Around this engine Kawasaki planned the Ki-60 fighter, and a lighter aircraft designated the Ki-6 Hien ('Flying Swallow'). The latter was completed in December 1941, and flew well, reaching a speed of 368 mph. During the first half of 1942 the prototype was extensively tested, performing very well against a captured P-40E Warhawk and a German Messerschmidt Bf-109E sent to Japan by submarine.

The submarine also brought 800 Mauser MG151 cannon, which were fitted to the early Ki-61s despite the unreliable supply of electrically-fired ammunition for this weapon.

The Gifu plant delivered 2,654 (or, according to one source, 2,750) of the Ki-61-1 and -1a versions - the latter being redesigned for easier servicing and increased manouevrability. They went into action around New Guinea in April 1943 and were given the reporting-name 'Tony' by the Allies. They were the only Japanese fighters with a liquid-cooled engine.

In 1944 the Ki-61-II was being built, but was only trickling off the production lines, and was suffering from the unreliability of its engine. Moreover the engine was not being produced in sufficient numbers. The initial version of the -II had a larger wing and a new canopy, but it was soon replaced by the -IIa with the older and proven wing. Only 374 of all variants of the -II were built.

In early 1945 one of 275 engineless airframes was fitted with the Ha-112 radial engine. Although a sudden lash-up conversion this produced a staggeringly fine fighter, by far the best ever produced in Japan. This aircraft, designated the Ki-100, was put into production with desperate haste. One of the first Ki-100 units destroyed 14 F6F Hellcats over Okinawa in their first major encounter - without loss to themselves. The easily-flown and serviced Ki-100 fought supremely well against Allied fighters and B-29 bombers to the very end of hostilities in the Pacific.
Data

Origin:
Kawasaki Kokuki Kogyo

Type:
Single-seat fighter

Span: 39' 5" (12 metres ) Length: (Ki-61-1) 29' 4" (8.94 metres ) (Ki-61-II) 30' 1" (9.16 metres )

Engines:
(K-61-I) One 1,175 hp Kawasaki Ha-40 inverted-vee 12- cylinder ( liquid-cooled)
(Ki-61-II) One 1,450 hp Kawasaki Ha-140 inverted-vee 12-cylinder (liquid-cooled)

Armament
(Ki-61-Ia) 2 x 20mm MG151/20 in wings, 2 x 12.7 mm mchine guns above engines
(Ki-61-Id) As with K-61-Ia but with 30mm cannon in wings
(Ki-61-II) Four x 20 mm Ho-5 cannon in wings

Performance:
Maximum speed (Ki-61-I) 348 mph (560 km/hour) (Ki-61-II) 379 mph (610 km/hour)
Initial climb (All Ki-61 versions) 2,200 feet (675 metres) per minute
Service ceiling (Ki-61-I) 32,800 feet (10,000 metres) (Ki-61-II) 36,100 feet (11,000 metres)

History:
First flight (Ki-60) March 1941 (Ki-61) December 1941 (Ki-61-II) August 1943
Service delivery (Ki-61-I) August 1941


Kawasaki Ki-61 Hien (Swallow) 'Tony' - History

Industry/ Capability:
One of Japan's first aircraft companies. It developed numerous successful aircraft for the Imperial Japanese Army.

Head Office:
Minato, Tokyo, Japan Chūō-ku, Kobe, Japan

Noteworthy:
Ki-32 Army Type 98
Ki-45 Army Type 2
Ki-48 Army Type 99
Ki-61 Army Type 3
Ki-100 Army Type 5
Ki-102 Army Type 4 .
* partial list

One of the first Ki-100 units destroyed 14 F6F Hellcats over Okinawa in their first major encounter - without loss to themselves.

From 1923-1933 Kawasaki hired the noted German Aerospace engineer and designer, Dr. Richard Vogt, to assist with design work and to train Japanese engineers.

A clean, streamlined fast and maneuverable aircraft the Ki-61 was the only liquid-cooled fighter to enter service with the. continues below

The Hien entered combat in the spring of 1943 in the New Guinea war zone, covering 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. 5th Air Force Commander General George Kenney found his P-40 Warhawks completely outclassed, and begged for more P-38 Lightnings to counter the threat of the new enemy fighter.

The Kawasaki Ki-61 Hien ("Swallow") fighter represented a major departure for Japanese aircraft design in World War II. While other Japanese fighters were designed with air-cooled radials and were optimized for maneuverability, the Ki-61 used a liquid-cooled in-line engine and was designed for speed and power. In fact, the Ki-61 was so different from other Japanese fighters that when the type was first encountered in combat over New Guinea in June 1943, the Allies thought it wasn't a Japanese design at all. At first they believed it was a copy of the German Messerschmitt Me-109, then suspected it was a copy of the Italian Macchi C.202 Foglore or similar Italian fighter. For this reason they gave it the code-name "Antonio", or "Tony", though by the summer of 1943 the Allies were convinced the Ki-61 was in fact a Japanese design.


Kawasaki Ki-61 Hien (Swallow) 'Tony' - History

Kawasaki Ki-61 Tony - Hien - Swallow

29 mei 2014 dari website http://www.largescaleplanes.com/articles/article.php?aid=1862 d itemukan kit bikinan Brad Gaff dengan sedikit ceritanya dan lukisan Om Ian Wongkar

There were many Japanese aircraft left in Indonesia at the end of the war and as many as possible were quickly snapped up by Indonesian forces, who managed to gather a surprising amount of serviceable equipment. In early 1946, Dutch intelligence reported 14 Ki-61s were operational with a further 4 unserviceable aircraft, but it is thought that 6 aircraft were acquired with only 1 serviceable. The Dutch called the Ki 61 'Mustang Jepang' Japanese Mustang. They would have been a formidable opponent for a Dutch Kittyhawk, less so for the Mustangs. Aside from a period water colour painting upon which my model is based, this is all the information known of these aircraft.

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Beberapa pabrikan mokit diantaranya Hasegawa membuat model kit 1/72 khusus dengan livery AURI


The Kawasaki Ki-61 Hien ("Tony") & Ki-100

* The Kawasaki Ki-61 Hien ("Swallow") fighter represented a major departure for Japanese aircraft design in World War II. While other Japanese fighters were designed with air-cooled radials and were optimized for maneuverability, the Ki-61 used a liquid-cooled in-line engine and was designed for speed and power.

In fact, the Ki-61 was so different from other Japanese fighters that when the type was first encountered in combat over New Guinea in June 1943, the Allies thought it wasn't a Japanese design at all. At first they believed it was a copy of the German Messerschmitt Me-109, then suspected it was a copy of the Italian Macchi C.202 Foglore or similar Italian fighter. For this reason they gave it the code-name "Antonio", or "Tony", though by the summer of 1943 the Allies had realized the Ki-61 was in fact a Japanese design.

The Hien proved initially successful in combat against American fighters. As the war in the Pacific ground on, however, the Ki-61 found itself increasingly outclassed, but it soldiered on until the end of hostilities. This document describes the history of the Ki-61 and its radial-engine derivative, the Ki-100.

* The confusion of the Ki-61 with German and Italian fighters had some basis in the aircraft's origins. Between 1923 and 1933, Kawasaki Aircraft Engineering Company's head designer was a German named Dr. Richard Vogt, who returned to Germany in 1933 to take a similar position at the firm of Blohm und Voss during the war. Not surprisingly, Kawasaki continued to be strongly influenced by Dr. Vogt's beliefs after he left, particularly a faith in the usefulness of liquid-cooled inline engines. This made Kawasaki something of a heretic among Japanese aircraft manufacturers, who preferred air-cooled radials.

In March 1938, Kawasaki signed an agreement with Daimler-Benz of Germany for manufacturing rights to the liquid-cooled inline engines then under development by the German firm. In April 1940, a Kawasaki engineering team visited Daimler-Benz in Stuttgart to obtain plans and samples of the DB-601A engine, then being used in the Me-109.

The Kawasaki engine team managed to increase the take-off power of their version of the engine to 875 kW (1,175 HP) and reduce its weight slightly. The engine was put into production in November 1941. It was designated the "Ha-40", or "Army Type 2", though it would be later redesignated the "Ha-60" in a combined Army/Navy nomenclature.

In the meantime, certain officers at the Air Headquarters of the Imperial Japanese Army were very interested in the new fighters powered by liquid-cooled being developed in Britain, the USA, the USSR, Germany, and France. The Japanese Army also had unpleasant experiences in air combat against the Soviet Polikarpov I-16 fighter during the beating the Imperial Army took in their Manchurian border clash with the USSR in the summer of 1939. This experience suggested the the single-minded focus on agility above all that characterized Japanese fighter design doctrine might need to yield to a focus on speed and improved armor protection and firepower.

* In February 1940, the Army initiated work with Kawasaki on two single-seat fighters based on the DB-601 derivative engine: a heavy interceptor, designated the "Ki-60", and a general-purpose fighter, designated the "Ki-61". Kawasaki decided to build the Ki-60 first, and the design team, under Kawasaki chief designer Takeo Doi and his deputy Shin Owada, constructed three prototypes of the interceptor in 1941.

The Ha-40 engine was not available at that time, so the three aircraft were powered by sample DB-601A engines obtained from Germany. The Ki-60 was a low-wing monoplane, with plenty of power and heavy armament by Japanese standards. The first and second prototypes had two 12.7 millimeter (0.50 caliber) Ho-103 machine guns mounted on the nose in front of the pilot and two 20 millimeter Mauser MG-151 cannons, one mounted in each wing, for a total of four guns. The third prototype had four 12.7 millimeter guns. Flight tests began in March 1941 and showed that the Ki-60 was too unmaneuverable and didn't meet its speed and climb requirements. Various tweaks to improve the aircraft failed, and so the Ki-60 was abandoned.

* The experience was valuable, however. Design work on the Ki-61, whose development had been proceeding in parallel with the Ki-60 since December 1940, incorporated new features derived from the lessons learned by the Ki-60 program:

The first prototype was rolled out in early December 1941, and its performance proved excellent. Eleven more prototypes were delivered to the Army, which performed intensive trials with them. The Ki-61 was pitted against other Japanese fighters, as well as against the Messerschmitt Bf-109E-3, of which two had been bought by the Army from the Germans, and the Curtiss P-40E, several of which had been captured during the seizure of the Dutch East Indies.

While the test pilots were a little skeptical of the new aircraft at first, pilots with combat experience appreciated the Ki-61's self-sealing fuel tanks, heavier armor and armament, and fast diving speed. The air combat tests showed the Ki-61 to be faster than all its adversaries in the tests, and easily out-maneuvered all of them except the Japanese Nakajima Ki-43 ("Oscar").

The 13th Ki-61, a production prototype, was delivered in August 1942. The Army gave the green light for production, and the fighter began to roll off the assembly line, with 34 delivered by the end of 1942. The type was formally known as the "Army Type 3 Fighter Model 1 Hien", or "Ki-61-I".

The production machines differed from the prototypes only in tweaky details. Initial production consisted of two variants: the "Ki-61-Ia", with two 12.7 millimeter guns in the nose and a 7.7 millimeter gun in each wings for a total of four guns and the "Ki-61-Ib", with 12.7 millimeter guns in both fuselage and wings. These aircraft could be fitted with two 200 liter (53 US gallon) drop tanks.

* The Hien entered combat in the spring of 1943 in the New Guinea war zone, covering 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. 5th Air Force Commander General George Kenney 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 demonstrated only a few teething problems in field use, such as a tendency towards engine overheating during ground running under tropical conditions. However, despite the heavier armament, it still didn't have the punch to easily knock rugged and well-armed Allied bombers out of the sky.

The Kawasaki designers had forseen this problem. The Japanese Ho-5 20 millimeter cannon wasn't available at the time, but the Japanese obtained 800 Mauser MG-151/20 20 millimeter cannon from Germany in August 1943, and modified 388 Ki-61-I airframes on the production line to carry the German weapons in place of the two 12.7 millimeter wing guns. The cannon had to be mounted on their sides to fit into a wing, with an underwing blister for the breech, and some reinforcements were added to the wing to absorb the increased recoil.

* Once the Ho-5 cannon became available, Kawasaki designers then reversed the arrangement of the guns, putting the 20 millimeter cannon in the nose and the 12.7 millimeter guns in the wings. While they were making these modifications, they also made a few changes to streamline manufacturing and simplify field maintenance.

This new variant was designated the "Ki-61-I KAIc" (where "KAI" was for "kaizo", or "modified") was 19 centimeters (7.5 inches) longer than its predecessors, with a detachable rear section, a fixed tailwheel instead of the retractable tailwheel previously used, stronger wings, and stores pylons outboard of the main landing gear, allowing it to carry two 250 kilogram (550 pound) bombs. The Ki-61-I KAIc went into production in January 1944 and ultimately replaced production of all earlier models in August 1944. A few "Ki-61-I KAId" bomber interceptors were also built in late 1944. These aircraft featured two 12.7 millimeter guns in the fuselage and a 30 millimeter Ho-105 cannon in each wing.

Total production of all subvariants of the Ki-61-I was 2,654, with the Ki-61-I KAIc accounting for over half that number.

* Even before the Hien saw combat, the Army had been pressing Kawasaki for an improved version of the same aircraft. To this end, Kawasaki engineers focused on an improved version of the Ha-40 engine known as the "Ha-140", which was expected to have a take-off power of 1,120 kW (1,500 HP).

The first prototype of the new variant, the "Ki-61-II", flew in August 1943. Ten more prototypes were ordered. They featured a wing with 10% more area, and an improved canopy to provide better rear visibility, but the Ha-140 development program ran into troubles, and only eight of the prototypes received engines. Even then, they suffered from engine troubles, structural failures due to weaknesses in the new wing, and handling problems.

In an attempt to fix the problems, after delivery of the eighth Ki-61-II prototype, the ninth prototype was extensively modified during manufacture. The extended wing was replaced with the original Hien wing, the fuselage was lengthened, and the rudder area increased. The result was the "Ki-61-II KAI", with initial flight of the prototype in April 1944. It was followed by 30 more prototypes. As long as the temperamental Ha-140 engine worked properly, the Ki-61-II KAI proved to be a promising interceptor, with a fast climb rate and good high-altitude flight characteristics.

Despite the problems with the engine, the military situation was increasingly desperate, and so the Ki-61-II KAI was put into production anyway in September 1944. Two versions were produced, one designated "Ki-61-II KAIa", with 12.7 millimeter guns in the wings and 20 millimeter cannon in the nose, and the other designated "Ki-61-II KAIb", with four 20 millimeter cannon.

374 Ki-61-II KAI airframes were built and 99 of them fitted with engines. Then, on 19 January 1945, US Army Air Force B-29 Superfortresses turned the plant at Akashi that was building the Ha-140 engine into cinders and rubble. That abruptly ended concerns over the reliability of the Ha-140 engine, but left 275 airframes sitting around without powerplants.

* However, in November 1944 concerns over the availability (or lack thereof) of the Ha-140 engine had led the Munitions Ministry to request that Kawasaki redesign the Ki-61-II KAI to use an available engine. Company engineers performed a lightning design effort to mate the fighter to the 1,120 kW (1,500 HP) Mitsubishi Ha-112-II 14-cylinder double-row air-cooled radial engine. The engineers inspected the radial engine installation of a sample Focke-Wulf FW-190 fighter obtained from Germany and, in an example of interservice cooperation that was far more the exception than the rule between the Imperial Japanese Army and Navy, took advantage of Navy efforts to use the Ha-112-II.

The first prototype conversion of three took to the air on 1 February 1945. Sometimes improvisations work poorly, sometimes they work surprisingly well, and the new variant demonstrated excellent performance. The rest of the engineless Ki-61-II KAI airframes were then converted to the new fighter type, which was designated the "Ki-100-Ia". They retained the armament of the Ki-61-II KAIb, consisting of 12.7 millimeter guns in the wings and 20 millimeter guns in the fuselage.

Performance was roughly the same but engine reliability was vastly improved. The Ki-100 was in fact an excellent fighter, a nasty customer for Allied aircraft to deal with while being surprisingly comfortable and easy to fly, an important consideration when experienced Japanese pilots were in increasingly short supply.

A batch of 118 new-production Ki-100s were then built, incorporating an all-round vision canopy, tested on a modified Ki-61-II KAI, and given the designation "Ki-100-Ib".

Work was then done to add a turbosupercharger and water-methanol engine boost to the Ki-100 to provide improved high-altitude performance. The first prototype of this variant, designated the "Ki-100-II", flew in May 1945, with two more prototypes completed before Japan's surrender ended plans for production. * As Allied forces pushed in the bounds of Japan's overextended ocean empire, the Hien fought in the South Pacific, in the Philippines, on Okinawa, and finally in defense of the Japanese home islands themselves. Some Hien units also served on in China and on Formosa.

The home defense units operating on Japan used a mixed bag of Ki-61 variants, essentially anything they could get their hands on. The most famous of these units was the 244th Sentai (Fighter Group) under Japanese ace Major Tembico Kobayashi. Major Kobayashi encouraged his men to perform frontal attacks on B-29s and press their assaults to close range, even ramming if that was what was needed. Major Kobayashi set an example by fighting with almost suicidal determination.

By this time, the Hien was outclassed by American Mustangs and other late-model US fighters. In fact, when attacking B-29s Hiens often had to be protected by Ki-100s. Operations dwindled as planes and pilots continued to fall in combat and fuel and spare parts dried up. By the end, the home defense units were no longer capable of posing a real threat to the Americans.

Of the 3,159 Hiens built, not many survived the war. Several were evaluated by the Americans and one was presented back to Japan by the US Air Force later. This was the only surviving Hien as of the mid-1960s. American aircraft restorer Kermit Weeks has a Ki-61 airframe in slow process of restoration.

* The Ki-61 wasn't the only fighter design to be powered by the Ha-40 engine. Kawasaki also experimented with an unusual twin-engine design conceived by Takeo Doi in 1939 and approved for prototype development in October 1940 as the Kawasaki "Ki-64".

The Ki-64 actually had both engines in a line, straddling the cockpit and driving a single contra-rotating prop system with twin three-bladed props. The combined engine was known as the "Ha-201", and generated 1,755 kW (2,350 HP) take-off power. It featured an unusual steam cooling system with radiators in the wing and flap surfaces. The front engine used the right wing for cooling, while the rear engine used the left wing. The Ki-64 had a vague configurational resemblance to the Hien, though it was larger. One prototype was finished in December 1943, but the rear engine caught fire on the fifth test flight. The aircraft made an emergency landing and survived. However, it was never repaired and the project was abandoned in the middle of 1944.

* I seem to be strongly inclined in my writing to describe aircraft I made models of when I was a kid. This is something of an attempt at vindication, I think, because I was such an inept modelmaker. However, I do recall that I did a fair-to-middling job on my 1/72 scale Ki-61, and it still sticks in my mind, though the sleek "sky shark" look of the Hien helped make it memorable as well.

One of the puzzles in writing about Japanese aircraft is trying to figure out whether to use the Japanese name ("Hien") or the Allied codename ("Tony") in the text. Obviously one of the reasons for giving codenames was to give Allied forces a more easily recognized "handle" for the aircraft than the Japanese designation, if the Allies even knew what the Japanese designation was when a new aircraft appeared.

Using the Allied codename might be a bit more convenient, but somehow giving an aircraft a name assigned by an enemy seems disrespectful. The Hien is the hero of its own story and even if it was used against my own countrymen, it deserves to be respected on its own terms.


Watch the video: Kawasaki Ki-61 Hien Tony (June 2022).


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