Nakajima Ki-44

Purpose: Interceptor fighter with high speed and climb rate to assist in the defense of the Japanese mainland.

Original Specifications:

1. Climb to 13,125 ft in less than 5 minutes
2. Reach a speed of 373 mph at that altitude
3. Armament of two 7.7 mm and two 12.7 mm machin guns

Revisions & Types: - Major Revisions

Ki-44 - Prototype (SN 4401-4403)

Ki-44-I(a) Army Type 2 Single-seat Fighter

• Rigidity of the engine mounting was increased
• Shape and frontal area of the supercharger's intake revised
• Cowl Flaps modified
• Firewall installation modified to improve the engine cooling and dispensed with the five cooling vents mounted on both sides of the forward fuselage behind the cowling gills
• Two section canopy with the front section being fixed and the rear section sliding

• Radio antenna mast mounted on the forward starboard fuselage side
• Redesigned rudder
• Two drop tanks
• Two - 7.7 mm Type 89 machine-guns, one - 12.7 mm Type 1 (Ho-103) machine-gun in each wing outboard of the main undercarriage well
• Telesopic gunsight protruded through the windscreen

Ki-44-Ib

• Armament increased to four 12.7 mm Type 1 (Ho-103) machine-guns.
• Oil cooler was removed from inside the cowling and placed under the cowl gills

Ki-44-Ic

• Lower hinged portions of the mainwheel fairings from the legs to teh fuselage

Ki-44-IIa

• Nakajima Ha-109 Army Type 2 radial engine Rated at 1,450hp

Ki-44-IIb

• Armament changed to two synchronized 7.7mm Type 89 machine-guns and two wing-mounted 12.7 mm Type 1 (ho-103) machine guns.
• This airframe and armament was identical to the Ki-44-Ic

Ki-44-IIc

• Armament changed to four 20 mm Ho-3 cannons
• Some armed with two 12.7 mm Type 1 (Ho-103) and two wing-mounted 40 mm Ho-301 cannons
• A small number of IIcs were fitted with a pair of 37mm Ho-203 cannons

Ki-44-IIIa

• Nakajima Ha-145, 2,000 hp, eighteen-cylinder air-cooled radial featuring thrust augmentation exhaust stacks
• Wing area increased to 204.5 square feet
• Tail surfaces enlarged
• Four 20mm Ho-5 cannon

Ki-44-IIIb

• Two 20 mm Ho-5 cannons and two 37 mm Ho-203 cannon

Additional Ki-44 Notes from Peter Starkings

Dave - I am preparing an article (for Jottings) on the Ki-44 and have taken a peek at your website info. on it. I entirely agree with much of it, but (as is usual with most Japanese aircraft!) there are a few anomalies, conflicts and additional points as follows:

Ki-44-I: I see you have followed the a/b/c variant identification given in some English publications such as by Francillon. Japanese publications (FAOW and Maru Mechanic) do not use these for the -I and Aircam/Schiffer suggest that the various modifications to the -I took place progressively thru the short production run. Retro-fitting some of these modifications would seem to make it all the more difficult and confusing to relate them to a clearly defined variant anyway!

For example:

• Your -1b: I cannot find photo evidence that any -I had the under cowling oil cooler (see -IIa below). One -1 aircraft was fitted with a modified Ha.41 Pe Shi engine and two bladed contra-prop and which did have a small oil cooler under the cowling. Also, whilst a few late production -Is were apparently fitted with 4X12.7mm guns, (12.7mm F guns had slightly larger gas ports than 7.7mm) it is a big step to tie this in with the alleged under cowling oil cooler as variant -Ib, particularly in view of:
• Your -Ic: The lower hinged u/c covers were moved to the inner end of the u/c wells during the production run and before the so called -1b mods. In any event, I think it hardly likely that such a minor mod. would warrant the cidentification.
• Here are some more -1 items for you to ponder over:- The butterfly combat flaps were added to the 12th a/c assembled onwards.
• Some late production a/c had a small fuel cooler under the fuselage,roughly in line with the aerial mast.
• A/c used for pilot training had the wing guns removed and the muzzleports skinned over. (NB.This also applied to some -IIswhen used for pilot training.)
• Some a/c had a half pear shaped spent cartridge collector under the wing guns.
• Now on to the -IIs:-
• Your -IIa: Notwithstanding that a few late production -Is were fitted with 4X12.7mm guns, Japanese sources state that the standard-II Ko (a) a/c armament was 2X7.7mm (F) + 2X12.7mm (W). The first few -IIa still retained the annular oil cooler, but this was soon replaced with the under cowling scoop, thus spoiling the clean lower fuselage line.
• Your -IIb: Now we have a problem because Japanese sources state that the-IIOtsu (b) was fitted with 2x12.7mm guns (F) and 2x40mm cannon (W) to tackle the B-29s.In fact, this variant was not a success because the added weight of the 40mm cannon reduced the a/c performance (making it difficult to catch up with the B-29s), their rate of fire was too slow and the range too short. Some reports suggest that 37mm H cannons were tried instead, but I can find no photo evidence to support this and, in any event, that particular weapon would appear to be too big physically to fit in the Ki-44 wing. In order to restore performance the 40mm cannon were removed, but that lead to lack of fire power and then to:
• Your -IIc: Another problem because Japanese sources state that the -IIHei (c) was fitted with 4X12.7mm guns! I can find no photo evidence that the -IIc was ever fitted with 4X20mm cannon, but see -IIIa following. Before moving onto that, I would note that the IIc incorporated a reflector sight instead of the telescopic one, although the former were retro-fitted to -IIa and -b variants. Some late production -IIc a/c were fitted with thrust augmentation exhaust stacks. All -II aircraft could be fitted with underwing bomb racks outboard of the u/c, a short type for 30kg and a longer type for 60/100kg bombs. Even so, it is difficult to find photos of a bomb laden a/c!
• Your -IIIa and b: I agree about the -IIIa but am doubtful about the -IIIb and 37mm cannon for the same reason as already stated above. This is academic anyhow as none of either was built!! One thing which might have caused confusion over the -IIko/otsu/hei and -IIa/b/c armament differences arises with the protruding W gun/cannonbarrels. Some a/c had their 12.7mm W gun muzzles covered with a phallic shaped removeable cover looking more like a possible 20mm cannon. Then again, the 40mm cannon muzzles had a cover in two parts. With the only the wing end part fitted the muzzle still protruded, looking vaguely like a possible 37mm cannon. With the outer end part fitted as well the muzzle was flush with it, giving quite a different look to the whole thing.
• Now a word about the Hasegawa 1/48 kits which you identify as Ki-44 Otsu. In fact, I have:
• #JT122 - Ki-44-I
• #JT37 - Ki-44-IIKo Kit states 2X7.7mm F + 2X12.7mm W
• #JT117 - Ki-44-IIOtsu do 2X12.7mm F + 2X40mm W
• #JT36 - Ki-44-IIHei do 4X12.7mm
• I think your JT134 is a re-issue with different markings, but I don't know whether it is Ko, Otsu or Hei.

Units that flew the Ki-44

9th, 22nd, 29th, 47th, 70th, 856th, 87th and 246th Sentais

47th Dokuritsu Dai Shijugo Chutai

Akeno and Hitachi Army Fighter Training Schools

Production

(Drawing by Jim Perry)

Last Revision 11/28/99