Diffrences between the Ki-61-I-Otsu and the Ki-61-I-Hei ?

[Broadside]

So the obvious differences between the Ki-61-I-Otsu and the Ki-61-I-Hei is the wing armament. What I want to know is there any other diffrences between the 2. I heard the Hei had more armor, but didn't have any luck find sources on that.
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Other changes included were "powered by 1 × Kawasaki Ha-40 radial, rated at 1,180 hp (880 kW), a lengthened fuselage with a detacheable tail, and strengthened wings with 2 hardpoints rated at 551 lb (250 kg). Other details are: ;ength of 29 ft 4 inch (8,94 m), empty weight of 5,798 lb (2.630 kg), normal take-off weight of 7,650 lb (3.470 kg), max level speed of 360 mph (590 km/h) at 13,980 ft (4.260 m), max range of 1,119 miles (1.800 km), Climb to 16,405 ft (5.000 m) in 7 min 0 sec, and a service ceiling of 32,810 ft (10.000 m)" - SourceWW2 Warbirds: the Kawasaki Ki-61 Hien Allied codename 'Tony' - Frans Bonné Not sure how reliable that source is.
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Thank you for your help,
Broadside

 

[Denniss]

Wikipedia is actually a better source than the other site, especially with a book reference. Otsu and Hei were the same aircraft just that Hei had german MG 151/20 wing guns instead of 12.7mm guns in the Otsu.
https://en.wikipedia.org/wiki/Kawasaki_Ki-61#Variants

 

[tomo pauk]

Kawasaki Ha-40 was not a radial engine, but an V-12. Copy of the German DB-601Aa.
The offspring, the Ki-100, received the radial engine.

 

[muscogeemike]

Broadside, are you sure about the Ha-40 radial engine? I thought the Ki-61 used liquid cooled engines, until they became the Ki-100.

 

[Broadside]

Welp I guess that source is thrown completely out of the water I know the Ki-61 has a inverted inline engine. I just copy and pasted what was on the website. I found something else 78th Sentai Forum ? View topic - Errors w/the Ki-61-I in the IL2-1946 Simulation Its so hard to find information on Japanese planes most of the time people just put information down and don't even link their sources its getting really annoying. :/

Edit: Would anyone know of any good online references for Japanese planes?

 

[tomo pauk]

Good start might be the wwiiaircraftperformance.com.

 

[Vincenzo]

Here J-aircraft.com Main Page

 

[Broadside]

Good start might be the wwiiaircraftperformance.com.

I have been there already unfortunately it doesn't give me in in depth technical data on the Ki-61 besides performance characteristics.

Here J-aircraft.com Main Page

I will be sure to check that out thank you.

 

[Denniss]

Kawasaki Ha-40 was not a radial engine, but an V-12. Copy of the German DB-601Aa.

Not a copy, license-built. Later they pushed the design to new limits with increasing rpm to 2800 to achieve 1400-1500PS. It may be possible they converted them to pressurized water cooling or they simply got drawings from the 601E engine and adopted this.

 

[GregP]

Hi Vincenzo,

Thanks for the link. Might you also have a good link for Italian aircraft? I have some data, but want more ...

 

[Hiromachi]

I see some confusion here, what is listed in first post as Hei is actually Tei. It is known misconception made by western authors, including well known Mr. Francilion with his "Japanese Aircraft of the Pacific War".

Basically Ko, Otsu and Hei were not different except of :
- armament change - Otsu had 4 x 12.7 mm Ho-103 machine cannons, Hei had two 12.7 mm Ho-103 machine cannons in nose and two Mauser MG 151/20 in wings.
- fuel - Otsu appeared in three sub-variants, first models had 750 l of fuel on board, middle ones had less due to removal of rear fuselage fuel tank and late model had even less fuel, due to reduction of capacity of wing fuel tanks because of introduction of thicker rubber layers.
- armor and fuel protection - late Otsu and Hei received mentioned fuel protection, or rather increase of it. There was also introduced 8 mm armored plate protecting radiator.

Overall Hei was not only better protected than early Ki-61 Otsu but also had stronger armament and was lighter - the 3130 kgs of weight listed for Otsu dropped due to reduction of fuel up to 500 liters. It is generally presumed that Hei would have a weight of ... 2980 kg ? Maybe saying less than 3000 kg would be enough.
The disadvantage was reduction of range ... but in late 1943 it didn't really matter.


To end, what you listed feats perfectly Tei. Which indeed was heavier and largely modified. But it has not much to do with Hei in case of your question.
I hope I cleared the situation

 

[cherry blossom]

I see some confusion here, what is listed in first post as Hei is actually Tei....
...

Help! I am confused. I thought that the tei was the long nosed variant with the Ho-5 20 mm cannon.

Added as edit: After looking, I now understand that the wing was also changed, adding the hard points, at the same time as the nose was lengthened to fit the Ho-5 cannons.

 

[Broadside]

-snip-

Would you know of any good reference books on the Ki-61? I found a few, but most of them just give a little history and some stats here or there, but nothing in depth.

 

[Broadside]

I found one hell of a reference book. "Encyclopedia of Japanese Aircraft 1900-1945" now if only I had $280 and could read Japanese. :/