Tuesday, March 3, 2015

G7M1 Taizan

Facing enemy fighters and a barrage of anti-aircraft artillery fire, the crew of this G7M1 Taizan bomber nevertheless continues their torpedo run against a US carrier. A failed successor to the famous G4M “Betty”, it never made it beyond the mock-up stage. created by RonnieOlsthoorn


The G7M shown is Takahashi's version. The Japanese were investigating turboprops but the G7M as envisioned by Takahashi did not use them.

The G7M as designed by Kiro Honjo. There was a version designed first, however, by Kijiro Takahashi which was quite different from what Honjo came up with (which, basically, was a derivative of the G4M which he also worked on). Takahashi's design used two 24-cylinder, H-engines and had a nose not unlike the Heinkel He 177 (among other similar features) and used a tricycle landing gear system. The design was doomed when the needed machinery to produce the H-engines could not be imported. With Takahashi's project shelved, Honjo took over but, ultimately, even the G7M (and its competitor, the Kawanishi K-100) was canceled in favor of four-engined bomber designs.

As a note, the G7M was intended as a long range, strategic bomber, not a medium bomber like the G4M (despite its great range). In the end, the constant revisions to the G7M resulted in a design little better than the G4M which helped speed its demise.

Takahashi's design, with a lighter payload, was expected to meet the 4,598 mile range dictated by the 16-shi specification. The Dornier Do 17 couldn't even touch this kind of range. For reference, from Tokyo, Japan to Los Angeles, California is 5,478 miles.

With Takahashi's version of the G7M doomed, Honjo's version, while also estimated to be able to attain the 16-shi range, was wishful thinking. No doubt the Kaigun Koku Hombu realized to attain such a range would have resulted in a relatively worthless bomb load.

The G7M was a strategic bomber, not a heavy bomber. By strategic, we are talking about a plane capable of a very large operational radius.

Honjo's original concept for the G7M had four engines but just the mere suggestion of using four engines saw Honjo's idea squashed by the Kaigun Koku Hombu before it ever got anywhere. This is when Takahashi stepped up with his two engine design. It wasn't until the failure of the G7M1 (Honjo's two-engine design) and the K-100 to meet the 16-shi and 17-shi specifications respectively did the Kaigun Koku Hombu become more receptive to four engine bombers. Of course, by then, it was too little, too late.

Mitsubishi G7M1 "Taizan" Ground Bomber
(Type16 Experimental Ground Bomber "Taizan")
Length: 20.00m
Wing Span: 25.00m
All-Up Weight: 16,000Kg
Engine: Mitsubishi Ha42 Model 31 (2,400hp) X 4
Max Speed: 556Km/h
Range: 2,780Km
Crew: 5
Armament: 20mm Machine Gun X 2, 13mm Machine Gun X 6
Bomb: 800Kg X 1 or 500Kg X 2 or 250Kg X 6 or Torpedo X 1

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