Mitsubishi Ki-21-IIb Sally/Gwen

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Mitsubishi Ki-21-IIb (九七式重爆撃機 キ21-II乙)
Mitsubishi Ki-21-IIb is the last modification of the Ki-21 aircraft. The aircraft in this version was produced from 1942 to 1944, during which 688 aircraft were built.
History
In 1940, the Ki-21-IIa was introduced into service, which installed Mitsubishi Ha-101 engines with 1,500 hp instead of Nakajima Ha 5 KAI engines with 940 hp. In this version, the armament was not changed, which was the same as that of the Ki-21-Ic (hei), which resulted in the defense capabilities being the same or even worse than before. In 1940, the armament of the Ki-21-IIa was no longer sufficient, so the search for a solution to this problem slowly began. When the war between the USA and Japan broke out in December 1941, the defensive armament of the Ki-21-IIa immediately became insufficient, which resulted in the acceleration of work on improving this aircraft. Work on the prototype probably began in mid-1941, and the prototype was ready in the same year. At the end of 1941, the aircraft passed army tests and was adopted as the Ki-21-IIb. The changes introduced to this aircraft consisted in strengthening the defense capabilities (more on this later). Serial production began in 1942 and ended in September 1944. Unfortunately, this modification did not help the Ki-21 to remain an obsolete aircraft, it was quickly outclassed by modern American aircraft. These planes were quickly withdrawn from line units and by 1945 only a handful of planes remained that acted as bombers, the rest were converted into transport planes.

Photos of the Ki-21-IIb

Ki-21-IIb Art

Construction description
Modifications compared to the Ki-21-ic (hei):

1. Replacing the “greenhouse” with a 12.7 caliber Ho-103 machine gun turret
2. installed Mitsubishi Ha-101 engines with 1,500 hp instead of Nakajima Ha 5 KAI engines with 940 hp
3. The fuel tanks were covered with 16mm layers of rubber, which was to seal them in case of a hit.
4. The pilot’s seat, the co-pilot and the gunner operating the Ho-103 rifle were armored with 16 mm armor.
5. In the windshield and the Ho-103 rifle shooter’s glass, 70 mm thick bulletproof glass is mounted.
6. A nitrogen-based fire extinguishing system has been installed in the fuel tanks.

Technical sketches

Comparison with the ki-21-Ia

General characteristics

• Crew: 7
• Length: 16 m (52 ft 6 in)
• Wingspan: 22.5 m (73 ft 10 in)
• Height: 4.85 m (15 ft 11 in)
• Wing area: 69.9 m2 (752 sq ft)
• Empty weight: 6,070 kg (13,382 lb)
• Gross weight: 10,600 kg (23,369 lb)
• Powerplant: 2 × Mitsubishi Ha101 14-cylinder air-cooled radial piston engine, 1,100 kW (1,500 hp) each
• Propellers: 3-bladed variable-pitch propellers

Performance

• Maximum speed: 485 km/h (301 mph, 262 kn)
• Cruise speed: 380 km/h (240 mph, 210 kn)
• Range: 2,700 km (1,700 mi, 1,500 nmi)
• Service ceiling: 10,000 m (33,000 ft)
• Time to altitude: 6,000 m (20,000 ft) in 13 minutes 13 seconds

Armament

1. Guns:

• 4 x 7.7 mm Te 4 Rotary Machine Gun (Front 1, Rear Rear Lower 1, Rear Left 1, Rear Right 1)
• 1 x Remote-controlled Type 89 7.7 mm machine gun (tail)
• Cockpit side: 1 x 7.7 mm Te-1 or Te-4 on both sides (Field Modification)
• 1 × 12.7 mm Ho-103 machine gun (back up)

Rifle firing range

2. Bombs:

• 750-1,000 kg of bombs

Armour

• 16mm thick armor plates behind the pilots’ seats, the top gunner and in front of the pilots

Special thanks

• @yo_sat

Summary
The Mitsubishi Ki-21-IIb would be a very interesting aircraft for Japan in War Thunder. It would be a very nice low-rank bomber that would be able to cope with some of the weaker fighters. Although its load is small (only 1000kg), it complements it with maneuverability and speed. I encourage you to discuss in the comments and to share your own knowledge on this topic.
Finally, I apologize for the linguistic and logical errors because unfortunately English is not my main language and I had to use google translator.

Internet sources

九七式重爆撃機 - Wikipedia
Mitsubishi Ki-21 - Wikipedia
Mitsubishi Ki-21-IIb / キ21-II乙 九七式重型爆击机 : Mitsubishi (armedconflicts.com)
Mitsubishi Ki-21 (warintheskies.org)
Imperial Japanese Aviation Resource Center - A Warbirds Resource Group Site
Mitsubishi Ki-21 - bomber (aviastar.org)
Mitsubishi Ki-21 (Sally) Twin-Engine Medium Bomber Aircraft (militaryfactory.com)
Уголок неба ¦ Mitsubishi Ki-21 (airwar.ru)
Mitsubishi Ki.21 («Sally»/«Gwene») (narod.ru)
Mitsubishi Ki-21-IIb/ late ( Type 97 Heavy Bomber Model 2 Otsu late productions) - Japan - War Thunder - Official Forum

Book sources

• Japanese Aircraft of Wolrld War II : 1937-1945 ,Thomas Newdick, Edition 2 2017, page 15-16
• (Maru Mechanic 00) Ki-21 Army Type 97 Heavy Bomber | PDF (scribd.com)
• 世界の傑作機 No.153 陸軍九七式重爆撃機
  Amazon.co.jp: 世界の傑作機No.153 陸軍九七式重爆撃機 (世界の傑作機 NO. 153) : Japanese Books
• Manual on Japanese aircraft, TAIC No. 1, July 1945.* Report No. 9-a(43), USSBS Index Section 6. Frame Number 119-122.
  国立国会図書館デジタルコレクション (ndl.go.jp)

[PercussionCap]

+1, japanese bomber line could use one more.

[SinisterIsRandom]

I’d recommend using DEEPL it isn’t perfect but it’s far more accurate.

[yo_sat]

The Ki-21 has an excellent carrying capacity for 50 kg bombs, with a capacity of 20. This is the most of any Japanese bomber.
Especially in SB from BR3.7 to 4.7, it is the only land-based bomber that can destroy two small bases in one sortie.
However, it clearly lacks defensive firepower and speed to be used in that BR.
Please implement Ki-21-IIb.

[SinisterIsRandom]

You don’t need speed considering how well it turns. Since most Under estimate it.

[yo_sat]

We apologize. I did not understand the truth of your statement. Perhaps the translation is not working.
As for the “Since most Under estimate it” part, are you referring to “those who fly low”? Do you mean “those who use low-ranking aircraft?” It would be helpful to know.

[SinisterIsRandom]

When you become experienced, you can turn and shoot. The Aircraft turns incredibly well. Which many pilots underestimate since they expect it to be slow and sluggish.
Use DEEPL for a more accurate translation.

[yo_sat]

I see! I see what you mean.
The Japanese translation of “turn” didn’t work on either google or DeepL. In Japanese, it seems to have multiple meanings.

Indeed, Ki-21-Ia in WT can turn very lightly. It is hard to believe that it is a bomber. But that being said, I think the Ki-21-IIb should have the speed to match. The Ki-21-IIb should have the same speed as the Ki-21-IIb, because its turning performance will be reduced due to the enhanced defensive firepower and bulletproofing, and to compensate for this, and above all, the faster speed will simply allow it to reach the bombing target more quickly. I mainly play Air SB, so I can contribute more to the team if I can destroy small bases in a time efficient manner.

Again, translated by DeepL. I hope it is translated correctly.

Translated with DeepL.com (free version)

[SinisterIsRandom]

More armaments would make a craft heavier. Just not by much. I do agree it should be faster than the Ki-21 Ia. However this is Gaijin. Difficult to expect that. Anyway, you have a nice day/night :D 0/ (Waving)

[yo_sat]

I found a video showing Ki-21-IIb and will share the URL.
First, this one shows Ki-21 after 4:17.

日本ニュース 第１８７号｜戦争｜NHKアーカイブス

Second, here is the Ki-21 after 6:57.

日本ニュース 第１８９号｜戦争｜NHKアーカイブス

In both videos, you can clearly see the shape of the upper gun turret and the position of the right side gun turret.

[MifuneToshiro]

Honestly, this is my favorite version of the Sally. Please make this a reality.

[SinisterIsRandom]

Cool :D

[yo_sat]

The notable feature of this aircraft is the Ho-103 gun turret, but the shape of the left and right lateral gun turrets also differs significantly from that of the Ki-21-I hei in the game.
I will post a reference drawing of the primary source here.

This is the gun turret on the right side.

And this is the gun turret on the left.

The URL of the primary source will also be posted.
(Note that this is the manual for Ki-21-IIa (ko), not Ki-21-IIb (otsu))
https://dl.ndl.go.jp/pid/8815752

[yo_sat]

I found a document that shows the internal structure of the upper gun turret and I will share it with you.
It was probably taken from a gun turret part of an aircraft captured by the U.S. military (because it makes dimensional sense, assuming that the scale on the lower right is in inches).

source:
日本陸軍航空武器 機関銃・機関砲の発達と変遷, 光人社NF文庫, 2021年1月24日発行, ISBN978-4-7698-3197-6

P.S.
I share this with you because the material I have on hand shows the number of bullets for the Ho-103.

It appears to be equipped with 600 rounds.

source
「日本陸軍機キ番号カタログ」, 文林堂, 1997-2-1

[yo_sat]

Page 68 of the Ki-21-II manual lists the firing range for each gun turret.

Based on the above, we have plotted the angle of fire for each gun turret.

Since the upper gun turret has a different shape for ko and otsu, the values in the manual are not applicable. I think it is appropriate to apply the values from the U.S. military survey data.

For your information, the number of 7.7mm rounds is as follows.
(from the IJA manual)
Front: 476 rounds
Rear bottom: 544 rounds
Side: 816 total (408 rounds each)
Tail: 500 rounds

[PlayedStatue626-live]

+1 to make up for the lack of domestic jets, Japan should get as many domestic prop planes as possible