00:20This aircraft is regarded by many as the best flying boat of WWII, with its exceptional
00:25performance, range, heavy armament and robust construction, which was quite the opposite
00:31of other early Japanese designs.
00:34The type served all through the war and proved its worth in numerous combat missions.
00:39This was the Kawanish H-8K Flying Boat, or as the Allied Forces called it, Emily.
00:45So let's see the history of this aircraft today.
00:55These big flying boats were used by the Japanese Navy on the Pacific, and they were created
00:59after their predecessors showed the same drawbacks we can find on many early WWII Japanese designs.
01:05The weak construction, lack of armour plating and insufficient defensive armament, which
01:10were usually sacrificed for more range, speed and manoeuvrability.
01:15To understand the history of these flying boats, let's first take a look how the Kawanishi
01:19company well before WWII started to build its expertise with flying boats, and how those
01:24developments led to the H-8K design.
01:28The company built several aircraft for the military in the 1920s, and in 1929 the officials
01:34tossed them to acquire a new advanced flying boat.
01:37So a team of engineers from Kawanishi visited the Short Brothers Company in England, looking
01:42for suitable designs.
01:44After evaluating several types, it was decided to purchase the license to build a modified
01:49version of the Short Rangoon flying boat in Japan, which became the Kawanishi H-3K type, and
01:55was accepted into service in 1932.
01:59But only two years later, in 1934, the Navy already issued exclusive requirements to Kawanishi for
02:06the so-called X-9 project, a big four-engine monoplane flying boat.
02:11These new specifications were extremely ambitious for the time, asking for at least 220 km an hour
02:18cruise speed and more than 4,500 km range, with powerful armament and ability to carry torpedoes
02:24or bombs.
02:27And the resulting design was not just the biggest Japanese flying boat, but the biggest
02:31Japanese aircraft of its time, featuring the largest wingspan on seaplanes up to that
02:35date with 40 meters.
02:37But similarly to many other contemporary Japanese aircraft, the designers had to balance between
02:42the extremely ambitious requirements and the relatively underpowered engines available,
02:47so their design completely lagged armor plating and fuel tank protection.
02:51This type was accepted by the Navy in January 1938 as H-6K-1 Navy Type 97 flying boat, Model
02:5911.
03:00But when the type started flying combat missions over the Pacific, the weakness of the design
03:05quickly became obvious.
03:06Though they had excellent range, but the H-6K models were very vulnerable to enemy fire.
03:12But already back when the H-6K just entered service, the Navy already ordered Kawanishi to develop
03:18a larger, more advanced new flying boat.
03:21Through 1940 a team at Kawanishi under the lead of Shizuo Kikuhara already worked on this new design,
03:27using the experience gathered on their former flying boats.
03:30And this was the aircraft that eventually became the H-8K.
03:34If you're interested in the detailed history of the Kawanishi H-6K type as well, check out my earlier
03:40video dedicated to that type. But now back to the development of the H-8K.
03:47The specifications for the new flying boat again were very ambitious.
03:51450 km an hour maximum and 330 km an hour cruise speed,
03:57around 4000 km combat range, a maximum combat load between 2000 and 3500 kg,
04:03and a ferry range between 6500 and 7500 km.
04:11Kawanishi's new design featured a taller, bigger hull than its predecessor,
04:15and instead of a parasol wing, used a conventional high wing configuration and a single tail.
04:21The first prototype was completed in December 1940, and the test flight started in January.
04:28Right at the beginning problems were found on the aircraft.
04:30On the takeoff runs, the spray from the bow flooded the wings, inboard engines and the cockpit.
04:36It was clear the hull needed a redesign, so with the help of the Tokyo University, changes were made on
04:42the aircraft.
04:43The hull was increased in depth by 50 cm, the bottom was modified,
04:48and spray strips were installed to divert the flow.
04:52These changes improved water handling by a great margin,
04:55so soon the modified prototype was handed over to the Navy for testing.
05:00Contrary to the earlier H6K model, which carried a relatively light bomb load and defensive armament,
05:06this new design was finally not constrained by lack of power,
05:09as it used four Mitsubishi Kasei 11 engines, each of them delivering 1530 horsepower,
05:16which allowed the designers to improve on both offensive and defensive weaponry,
05:20based on the experiences gathered on earlier models.
05:24The new plane could carry 8 250 kg bombs or 2 torpedoes,
05:29and this defensive armament included 5 20 mm cannons and additional 3 7.7 mm machine guns.
05:36The fuel tanks were also armored contrary to its predecessors,
05:40and they were designed in a way that if any of them gets punctured, the fuel could be transferred to
05:45another tank.
05:46The crew protection was also improved over the H6K type, with the installation of armor plating at crucial areas.
05:54During 1941, two pre-production models joined the testing, which incorporated further improvements.
06:00On the last one, the nose was lengthened by 1.3 meters, the tailfin area increased,
06:06and it featured the new Kasei 12 engines.
06:09For added protection, now the fuel tanks were also pressurized with the exhaust gases.
06:14After completing the test flights, these models were accepted into service in February 1942,
06:20under the designation H8K1 Type 2 Flying Boat Model 11.
06:26However, the production variants armament had to be reduced.
06:29It only featured two 20 mm cannons and four machine guns,
06:33because of the weight increase after the installation of all necessary equipment.
06:38The more powerful armament returned on later variants of the aircraft,
06:41so let's now take a look at those.
06:51The initial prototype was the experimental Type 13 large flying boat, powered by the Kasei 11 engines,
06:57and it carried five 20 mm cannons and three machine guns.
07:02The H8K1 was the first production series, powered by the Mitsubishi Kasei 12 engines,
07:08but featuring reduced armament.
07:10Only 16 units were built, as its upgraded version, the H8K2 variant appeared only a few months after the
07:16Type entered service.
07:18In early 1942, the original prototype was tested with the new 1850 horsepower Kasei 22 engines.
07:26And the performance upgrade was immediately noticeable, so the new engines were incorporated into the design,
07:32and this upgraded version soon entered production.
07:36The increased power allowed the designers to improve the armor protection and increase the defensive armament,
07:42which now again included five 20 mm cannons and four additional machine guns.
07:47The fuel tanks also received the thickest protective coating on any Japanese aircraft of World War II,
07:52with approximately 40 mm of rubber sheets around them.
07:55These models were the most numerous, with 112 units built.
08:01Both the H8K1 and the H8K2 models had transport variants, the H8K1L and the H8K2L,
08:10which featured reduced armament and armor protection.
08:13The H8K1L was a single aircraft, modified from the original prototype,
08:18while from the H8K2L model 36 units were built.
08:23The more experimental versions of the type included the H8K3 variant,
08:27which was tested with retractable floats on the wings.
08:30But this variant didn't go to production, only two aircraft were modified for testing.
08:36They were later rebuilt with Kasei 25B engines, and became the H8K4 models.
08:49The H8K2 was 28.13 meters long, with a wingspan of 38 meters,
08:55making it comparable in size to the B-29 Superfortress.
08:59It had an empty weight of 18,380 kg, and a maximum takeoff weight of 32,500 kg.
09:09The plane was powered by four Mitsubishi Kasei 22 air-cooled radial engines,
09:13each of them producing 1850 hp.
09:17With these engines, despite its size, the plane could reach a top speed of 467 km an hour,
09:24and a cruise speed of 296 km an hour.
09:28It had a range of 7,150 km, and a service ceiling of 8,850 meters.
09:37The flying boat's defensive armament was impressive.
09:40It included five 20 mm cannons in the bow, tail, dorsal turret, and side blisters,
09:46plus five 7.7 mm machine guns, which could fire from hatches on the fuselage.
09:52The plane could carry either 2,000 kg of bombs, or two 800 kg torpedoes.
10:08The first combat mission of the type took place in March 1942, during Operation K,
10:13when two H8K1 models took off from the Marshall Islands, refueled from submarines,
10:18and attempted to bomb Pearl Harbor. But most of their bombs missed due to bad weather.
10:23The type soon took over the long-range maritime patrol and anti-submarine roles from its predecessor.
10:29And it was a successful aircraft in these tasks, responsible for sinking many Allied submarines.
10:35With its robust construction, and very strong defensive armament,
10:38the type proved to be a hard nut to crack for the American pilots,
10:41who had to spend a lot of ammunition to bring these planes down.
10:45In 1943, after Admiral Yamamoto's G4M bomber transport was shut down, the building of the H8K2L
10:52transport variants started, as the Japanese commanders needed more resilient planes to travel.
10:58Four of these were built as VIP transports, the remaining 32 as troop carriers.
11:04By 1944, the improved H8K3 models were tested, but they didn't enter production.
11:10As the tide of the war turned on the Pacific, the flying boats faced more and more American fighters,
11:15and despite their strong construction and heavy defensive armament, their losses mounted.
11:20By the end of the war, only four of these planes remained, from the 167 produced.
11:26Though the H8K3 was a vast improvement over earlier designs, especially in survivability and
11:31defensive armament, and it is widely regarded as the best flying boat of World War II,
11:36they couldn't really influence the outcome of the war, even though they were very successful designs.
11:44Hope you guys enjoyed this video. Please leave a like, subscribe to my channel,
11:48and in the comments let me know if there's any interesting events or vehicles you'd like to see.
