Kawasaki Ki-61 Hien/Tony

The design of Ki-61 Hien was very different from the usual Japanese aircrafts made in the World War 2. Most of the other Japanese fighters were designed with air-cooled radials which were intended to provide ease of maneuverability. But the Ki-61 using a liquid-cooled engine was primarily designed for speed and power. In fact, the Ki-61 looked so different from other Japanese fighters that when it was first appeared in combat over New Guinea (June 1943), the Allies almost concluded that it couldn’t be a Japanese design at all. Initially it appeared as a copy of the German Messerschmitt Me-109. Later it was confused with Italian Macchi C.202 Foglore. Because of this it was code named “Tony” derived from Italian name “Antonio” while the Japanese word “Hien” means shallow.

Kawasaki Ki-61 Hien/Tony

By 1940, Shin Owada and Takeo Doi had designed Ki-61 under the recognizable Japanese label of the Kawasaki brand. The prototype was completed in 1941 while full production finally began 1943.

The Ki-61 had a pretty sleek and slender fuselage design. The engine was located in front of the cockpit. The wings were of a monoplane low-mounted type with rounded edges. The horizontal and vertical tail surfaces of the empennage were made in a similar way. A single Kawasaki V-12 piston engine offered impressive 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.

The Hien entered the WW2 scene in 1943 in the New Guinea war zone, covering New Guinea, the Admiralty Islands, New Britain, and New Ireland. It seriously 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.


Crew: 1
Length: 29.33ft (8.94m)
Width: 39.37ft (12.00m)
Wingspan: 12.00 m (39 ft 4 in)
Wing area: 20.00 m² (215.28 ft²)
Height: 12.14ft (3.70m)
Max Speed: 367mph (590kmh; 319kts)
Empty weight: 2,630 kg (5,800 lb)
Loaded weight: 3,470 kg (7,650 lb)
Maximum speed: 580 km/h (360 mph) at 5,000 m (16,405 ft)
Max Range: 1,118miles (1,800km)
Power/mass: 0.25 kW/kg (0.15 hp/lb)
Rate-of-Climb: 2,343ft/min (714m/min)
Ceiling: 32,808ft (10,000m; 6.2miles)
Empty Weight: 5,798lbs (2,630kg)
MTOW: 7,650lbs (3,470kg)
Engine(s): 1 x Kawasaki Ha-40 V-12 piston engine generation 1,180hp
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
Share the KnowledgeShare on FacebookTweet about this on TwitterShare on LinkedInPin on Pinterest

One thought on “Kawasaki Ki-61 Hien/Tony

  1. ron

    The Ki 61 had a DB 601 derived Ha-40 engine but no hub-cannon, what gives?
    Late in the war, the 37mm Ho-204 cannon was long range enough at 1100+m, to fire at B-29s without risking return fire. The Dinah and the Randy twin engine fighters mounted this cannon.
    The Ki 61-II should have put this cannon in the spinner. This would make it likewise as potent!

    It would be like a Yak-9T with altitude performance and range, plus a pair of 20mm Ho-5 wing-cannons.
    The Ho-5 was very similar to the Russian 20mm ShVAK cannon. Both were fast (800-850 r/m) but light per hit. Better for dogfighting than stopping bombers. That is what the 37mm cannon does so well.

    Ho-204 RoF was 400 r/m; Range 1100m – Japan
    Ho-203 RoF was 120 r/m; Range 900m – Japan
    NS-37 RoF was 250 r/m; Range 1200m – USSR
    Colt M4 RoF was 140 r/m; Range 460m – USA
    Colt M10 RoF was 165 r/m; Range 460m – USA
    BK3,7 RoF was 160 r/m; Range 500m – Luftwaffe

    The Ki 61 with this 37mm cannon would have really left a mark on history. Both could fire with impunity but no 37mm was as fast as the Japanese Ho-204!

    The main problem for the Ki 61 was the unreliable engine. The Ki 61-II should have simply done like the Italians and produced their Tifone version of the DB 605. They used slider bearings. Ball bearings were a problem for Kawasaki. This would’ve helped make the Ki 61 reliable. The hydraulic and electrical systems needed attention too. But the Ki 61 was not alone on that.
    With a reliable DB 605 style engine, the Ki 61 would have the best high altitude performance of the Japanese fighters.

    The sole factory for the engine was bombed which ended the Ki 61. This was easy to anticipate and avoid. At least one engine factory should have been underground. The Ha-140 was good riddance, but a more reliable version of the DB 605 AS would be worthy to mass produce with top priority.
    Only an inline powered Ki 61 could mount the Ho-204 as a motor cannon ala Yak-9T.

    The Ki 61-II and the 37mm Ho-204 both were available in 1944 and they should’ve met.


Leave a Reply

Your email address will not be published. Required fields are marked *