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20 November 2008
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Hello folks im looking for the Kawanishi K-100 bomber, it was an competitor to the projected G7M
Im looking for drawnings or artist inpressions of this aircraft
cheers T-50
Another site, http://www.ww2aircraft.net/forum/aviation/4-engine-japanese-heavy-bomber-4388.html, described the K-100 as:

"Another contender for a high-speed long-range bomber that was fulfilled by the G8M1 “Rita” was a Kawanishi proposal- the K-100 (Type17). This thing was small like the Mitsubishi Type 17 with a crew of four in a short 50-foot fuselage. Four Nakajima Mamoru-Kai 18-cylinder radials each with 2,300 HP mounted on the 75-foot wings. Weighing just 30,000 lbs. loaded this thing could scream with a 376 MPH top speed and cruised at 230 MPH for 3,450 miles range. A ceiling of 30,732 feet was projected. Armament was just three 20 mm cannon a 1,760-lb. torpedo or bob of the same weight."

I doubt the validity of this given the same poster said the G7M1 was a four-engine design. The K-100 was a twin-engine bomber as it was the competitor of the G7M and was canned later so it couldn't have been a competing design against the G8M.
Hi Kawanishi K100.
K100 did not have G number. Estimeted performance was excellent as follows. Detail design began at the day, but Mamori-kai(護-改) engine cancelled.
Span : 21.60m, Length : 15.00m, Height : 6.07m, Wing area : 64.0sqm, Aspect ratio : 7.3, Dihedral 0°(central wing)/5°(outer wing), Sweep back angle : 30°!?, Empty weight : 8,550kg, Gross weight : 13,500kg~16,000kg
Engine : Nakajima Mamori-kai aircooling 18 cylinders ×2, Take off power : 2,300hp(each), propeller : metal constant speed 4 blades, diameter : 4.50m, Fuel : 12,800L, Oil : 240L, Maximum speed : 327kt(606km/h)/7,600m, Landing speed : 78kt(145km/h), Climb to 4,000m~6′16″, Service ceiling : 11,200m, Range : 3,000nm(5,556km)/at cruising speed 200kt(370km/h), Armaments : 20mm×3, Torpedo 800kg×1, Crew : 4(inline position)
Tail turret was remote controlled?


  • The artistic impression of Kawanishi 17-shi land bomber K100[1].jpg
    The artistic impression of Kawanishi 17-shi land bomber K100[1].jpg
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blackkite, thank you for very interesting information.
But 12800l of gasoline weights about 9200 kg.
And the difference between empty mass and MTOW is only 16000 - 8850 = 7150 kg.

So I suppose that here is a mistake in the data.

From the other side in valka.cz forum there is only 2800, not 12800 l are mentioned.
It seems too small: 2800 l gasoline + 240 l oil = 2400 kg, crew and cartridges are about 600 kg, torpedo 800 kg, totally

8850 + 2400 + 600 + 800 = about 12700 kg, much less than normal take-off mass and 3,3 ton less than MTOW (16 ton).

So, please, check weights one more time, if it's possible.
Many thanks burunduk for your sharp and precious opinion. I will check K100 weight distribution. But perhaps it's hard for me. :)
Knowing the history of Mamoru engines, it's not very difficult understand why Mamoru-Kai was cancelled + disastrous situation (1944-1945)
G4M2 Betty Engine : Mitsubishi Kasei21, displacement : 42L, take off power : 1850hp, Range : 3270n.m.(6056km), Fuel : 6300L
Kawanishi K100 Engine : Nakajima Mamoru-kai, displacement : 57.7L, take off power : 2300hp, Range : 3000n.m.(5556km)
So I suppose Kawanishi K100’s fuel 6300L×3000n.m./3270n.m.×57.5L/42L = 7940L
The K-100 was definitely not the G9K. The the whole designation of the G9K is confusing as so many authors kick it around various places. What gets me is that in some sources, it puts the G9K ahead and before the G8N. The G10N designation was not used by the Japanese for the Fugaku projects and was a post-war creation based on the progression of bomber designs. Robert C. Mikesh in an article for Airpower magazine feels the Kawanishi 19-shi elliptical winged, 6-engined bomber is likely the G9K. But then he muddles it by stating the design was also called the TB which I've seen listed as distinct from the 19-shi plane in some sources. If Mikesh is right, then the G9K would have followed the G8N and keep the progression intact. Maybe Kawanishi called their design the TB internally.

airman said:
about Kawanishi 17-shi
http://forum.valka.cz/viewtopic.php/t/64996 surely was G9K1
"Kawanishi K-100
Kawanishi Kokuki K.K., founded in 1928, built its reputation on this flying boats and seaplanes. Aircraft such as the Kawanishi H6K (code-named ‘Mavis’) and the H8K (‘Emily’), the latter being considered the best flying boat of the war, were the pinnacle of Kawanishi’s work. And while the company continued to explore the boundaries of flying boat design, it dipped into the fighter realm, creating the potent and fearsome N1K-J Shiden (‘Violet Lightning’, Code-named ‘George’) from the earlier N1K Kyöfü (‘Great Wind’, code-name ‘Rex’) floatplane. But kawanishi would dip into another realm, that of bombers. Its first was the answer to a 17-shi specification for a bomber, and it was the Kawanishi K-100.

In 1941 the Kaigun Koku Hombu issued a 16-shi specification for a bomber to replace the Mitsubishi G4M (code-name ‘Betty’). There were two key components of the specification: a minimum speed of 580 km/h (361 mph) and a range of at least 7,340 km (4,598 miles). Mitsubishi was tasked with creating a bomber design to meet the 16-shi requirements and this would be the G7M Taizan (‘Great Mountain’). The initial G7M was a four-engine design by Kiro Honko, which was immediately rejected by the Kaigun Koku Hombu. The design was revised into a radical twin-engine departure from the norm by engineer Kijiro Takahashi. The powerplant was to be the Nu engine, which was a 24-cylinder, horizontal -H, liquid-cooled motor capable of 2,200hp. The design had more than a passing resemblance to the German Heinkel He 177 Greif. But Germany’s inability to export the machinery to produce the Nu engine spelled the demise of Takahashi’s G7M. Honjo took back the G7M reins and based his two-engine bomber on the G4M that he had designed back in 1937. By the time the mock-up of the G7M was completed in 1942, the projected performance was well below the 16-shi specifications. Also in that year the Kaigun koku Hombu issued a new 17-shi specification for a bomber, to which Kawanishi responded. The G7M now hat to compete with Kawanishi’s K-100. Mitsubishi was instructed to halt all further development of the G7M until such time as the K-100 could be evaluated.

Within Kawanishi, the K-100 was designated the KX-1, and, like the G7M, it was a twin-engine bomber design. But whereas the G7M was to use two Mitsubishi MK10A (Ha-42-11) 18-cylinder, air-cooled radials rated at 2,000hp each, Kawanishi elected to use the prototype Nakajima Mamoru-Kai (NK10A). This was an 18-cylinder variant of the standard 14-cylinder Mamoru engine (NK7A) and was projected to provide 2,300hp. Overall, the K-100 was smaller and lighter than the G7M but exceeded the G7M’s range projection as well as speed. In part, this came at the expense of defensive weaponry; Kawanishi planned to arm the K-100 with only three 20mm Type 99 Model 2 cannons, which was paltry compared to the G7M, which boasted six 13mm type 2 machine guns and two 20mm type 99 Model 2 cannons. The K-100 was a mid-wing design with a 0-degree dihedral on the inner wing surface and a 5-degree dihedral on the outer win portion. The overall wing aspect ratio was 7.3. The four-man crew was housed in the forward portion of the fuselage. It was proposed to make the tail turret remote-controlled so as to eliminate the need to house a gunner in the tail section. For offensive mission, a single 800kg (1,763lb) torpedo could be carried (which, incidentally, was the same war load capacity as the G7M). Fuel capacity was approximately 2,800 liters (739 gallons) with 240 liters (63 gallons) of oil. By the summer of 1943 Kawanishi had completed its initial design draft of the K-100 and presented it, along with the estimated performance measurements, to the Kaigun Koku Hombu for evaluation.

Unfortunately for Kawanishi, the Kaigun Koku Hombu felt that neither the G7M nor the K-100 would meet the 16-shi and 17-shi specifications. For the G7M, it was felt that the defensive armament was inadequately distributed, the estimated performance was little better than the G4M already in service, and that the Kaigun Koku Hombu was now looking to four-engine bombers to fulfil the specifications. For the K-100, the Kaigun Koku Hombu found that the payload capacity was not superior enough and that the decision to use only three cannons was too light a defensive weapon fit. Another problem with the K-100 was the choice of the NK10A Mamoru-Kai engine. The production Mamoru, as used in the Nakajima G5N Shinzan (‘Mountain Recess’, code-named ‘Liz’) and the Nakajima B6N Tenzan (‘Heavenly Mountain’, code-named ‘Jill’), was mechanically unreliable and rarely met its horsepower rating. The Mamoru-Kai was even more problematic and Nakajima was not able to overcome the motor’s teething difficulties. Consequently, Nakajima cancelled further work on the Mamoru-Kai. This, then left the K-100 without a powerplant, and none of the available engine types offered any edge in terms of power. The K-100 like the G7M, also fell victim to the IJA’s lack of interest in twin-engine bombers to fulfil its specification requirements. With no further interest being shown by the Kaigun Koku Hombu in the K-100, Kawanishi shelved the project.

As a side note, some sources cite that the K-100 was given the IJN designation Kawanishi G9K Gunzan (‘Mountain Group’). There is no evidence to support this, especially in light of the quick termination of the K-100 project.

Kawanishi K-100 - data
Because the K-100 was never built, these specifications are estimated
Type Bomber
Crew Four
Two Nakajima NK10A Mamoru-Kai 18-cylinder, air-cooled radial engines developing 2,300hp, each driving at 4.5m (14.7ft) diameter, four-bladed, constant-speed metal propeller.
Span 21.6m 70.8ft
Length 15m 49.2ft
Height 6.07m 19.9ft
Wing Area 64.0sq m 688.8sq ft
Wing loading 210.9kg/sq m 43.2lb/sq ft
Empty 8,550kg 18,849lb
Loaded 13,500kg 29,672lb
Maximum loaded 16,000kg 35,274lb
Maximum speed 606km/h 376mph
Cruise speed 370km/h 229mph
Landing speed 145km/h 90mph
Climb 6min 16sec to 4,000m (13,123ft)
Range 5,556km (3,452 miles)
Ceiling 11,200m (36,745ft)
Three 20mm type 99 model 2 cannons, one 800kg (1,763lb) torpedo."


  • KAWANISHI K-100.jpg
    KAWANISHI K-100.jpg
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